WorldWideScience

Sample records for big-bang nucleosynthesis reactions

  1. Capture reactions on C-14 in nonstandard big bang nucleosynthesis

    Science.gov (United States)

    Wiescher, Michael; Gorres, Joachim; Thielemann, Friedrich-Karl

    1990-01-01

    Nonstandard big bang nucleosynthesis leads to the production of C-14. The further reaction path depends on the depletion of C-14 by either photon, alpha, or neutron capture reactions. The nucleus C-14 is of particular importance in these scenarios because it forms a bottleneck for the production of heavier nuclei A greater than 14. The reaction rates of all three capture reactions at big bang conditions are discussed, and it is shown that the resulting reaction path, leading to the production of heavier elements, is dominated by the (p, gamma) and (n, gamma) rates, contrary to earlier suggestions.

  2. Big Bang Nucleosynthesis: 2015

    CERN Document Server

    Cyburt, Richard H; Olive, Keith A; Yeh, Tsung-Han

    2015-01-01

    Big-bang nucleosynthesis (BBN) describes the production of the lightest nuclides via a dynamic interplay among the four fundamental forces during the first seconds of cosmic time. We briefly overview the essentials of this physics, and present new calculations of light element abundances through li6 and li7, with updated nuclear reactions and uncertainties including those in the neutron lifetime. We provide fits to these results as a function of baryon density and of the number of neutrino flavors, N_nu. We review recent developments in BBN, particularly new, precision Planck cosmic microwave background (CMB) measurements that now probe the baryon density, helium content, and the effective number of degrees of freedom, n_eff. These measurements allow for a tight test of BBN and of cosmology using CMB data alone. Our likelihood analysis convolves the 2015 Planck data chains with our BBN output and observational data. Adding astronomical measurements of light elements strengthens the power of BBN. We include a ...

  3. Astrophysical S-factor for destructive reactions of lithium-7 in big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Komatsubara, Tetsuro; Kwon, YoungKwan; Moon, JunYoung; Kim, Yong-Kyun [Rare Isotope Science Project, Institute for Basic Science, Daejeon (Korea, Republic of); Moon, Chang-Bum [Hoseo University, Asan, Chungnam (Korea, Republic of); Ozawa, Akira; Sasa, Kimikazu; Onishi, Takahiro; Yuasa, Toshiaki; Okada, Shunsuke; Saito, Yuta [Division of Physics, University of Tsukuba, Tsukuba, Ibaraki (Japan); Hayakawa, Takehito; Shizuma, Toshiyuki [Japan Atomic Energy Agency, Shirakata Shirane, Tokai, Ibaraki (Japan); Kubono, Shigeru [RIKEN, Hirosawa, Wako, Saitama (Japan); Kusakabe, Motohiko [School of Liberal Arts and Science, Korea Aerospace University (Korea, Republic of); Kajino, Toshitaka [National Astronomical Observatory, Osawa, Mitaka, Tokyo (Japan)

    2014-05-02

    One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for {sup 4}He. In spite of the success, abundances of lithium isotopes are still inconsistent between observations and their calculated results, which is known as lithium abundance problem. Since the calculations were based on the experimental reaction data together with theoretical estimations, more precise experimental measurements may improve the knowledge of the Big Bang nucleosynthesis. As one of the destruction process of lithium-7, we have performed measurements for the reaction cross sections of the {sup 7}L({sup 3}He,p){sup 9}Be reaction.

  4. Big bang nucleosynthesis: Present status

    Science.gov (United States)

    Cyburt, Richard H.; Fields, Brian D.; Olive, Keith A.; Yeh, Tsung-Han

    2016-01-01

    Big bang nucleosynthesis (BBN) describes the production of the lightest nuclides via a dynamic interplay among the four fundamental forces during the first seconds of cosmic time. A brief overview of the essentials of this physics is given, and new calculations presented of light-element abundances through 6Li and 7Li, with updated nuclear reactions and uncertainties including those in the neutron lifetime. Fits are provided for these results as a function of baryon density and of the number of neutrino flavors Nν. Recent developments are reviewed in BBN, particularly new, precision Planck cosmic microwave background (CMB) measurements that now probe the baryon density, helium content, and the effective number of degrees of freedom Neff. These measurements allow for a tight test of BBN and cosmology using CMB data alone. Our likelihood analysis convolves the 2015 Planck data chains with our BBN output and observational data. Adding astronomical measurements of light elements strengthens the power of BBN. A new determination of the primordial helium abundance is included in our likelihood analysis. New D/H observations are now more precise than the corresponding theoretical predictions and are consistent with the standard model and the Planck baryon density. Moreover, D/H now provides a tight measurement of Nν when combined with the CMB baryon density and provides a 2 σ upper limit Nνpointing to new physics. This paper concludes with a look at future directions including key nuclear reactions, astronomical observations, and theoretical issues.

  5. Big-bang nucleosynthesis revisited

    Science.gov (United States)

    Olive, Keith A.; Schramm, David N.; Steigman, Gary; Walker, Terry P.

    1989-01-01

    The homogeneous big-bang nucleosynthesis yields of D, He-3, He-4, and Li-7 are computed taking into account recent measurements of the neutron mean-life as well as updates of several nuclear reaction rates which primarily affect the production of Li-7. The extraction of primordial abundances from observation and the likelihood that the primordial mass fraction of He-4, Y(sub p) is less than or equal to 0.24 are discussed. Using the primordial abundances of D + He-3 and Li-7 we limit the baryon-to-photon ratio (eta in units of 10 exp -10) 2.6 less than or equal to eta(sub 10) less than or equal to 4.3; which we use to argue that baryons contribute between 0.02 and 0.11 to the critical energy density of the universe. An upper limit to Y(sub p) of 0.24 constrains the number of light neutrinos to N(sub nu) less than or equal to 3.4, in excellent agreement with the LEP and SLC collider results. We turn this argument around to show that the collider limit of 3 neutrino species can be used to bound the primordial abundance of He-4: 0.235 less than or equal to Y(sub p) less than or equal to 0.245.

  6. Measurements Of Stellar And Big-Bang Nucleosynthesis Reactions Using Inertially-Confined Plasmas

    Science.gov (United States)

    Zylstra, Alex; Herrmann, Hans; Gatu Johnson, Maria; Kim, Yongho; Frenje, Johan; Hale, Gerry; Li, Chikang; Rubery, Mike; Paris, Mark; Bacher, Andy; Brune, Carl; Forrest, Chad; Glebov, Vladimir; Janezic, Roger; McNabb, Dennis; Nikroo, Abbas; Pino, Jesse; Sangster, Craig; Seguin, Fredrick; Sio, Hong; Stoeckl, Christian; Petrasso, Richard

    2016-09-01

    The 3He+ 3He, T+3He, and p+D reactions directly relevant to either Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using inertially-confined plasmas, created using shock-driven `exploding pusher' implosions. These plasmas better mimic astrophysical systems than cold-target accelerator experiments. A new measured S-factor for the T(3He, γ)6Li reaction rules out an anomalously-high 6Li production during the Big Bang as an explanation to the high observed values in metal poor first generation stars. Our value is also inconsistent with values used in previous BBN calculations. Proton spectra from the 3He+3He and T+3He reactions are used to constrain nuclear R-matrix modeling, and recent experiments have probed the p+D reaction for the first time in a plasma. This work was partially supported by the LDRD program at LANL, US DOE, NLUF, LLE, and GA.

  7. Big-Bang Nucleosynthesis

    CERN Document Server

    Fields, Brian D.; Sarkar, Subir

    2014-01-01

    A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, η, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of η from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range η=(5.7−6.7)×10−10 at 95% CL (corresponding to a cosmological baryon density ΩBh2=0.021−0.025). The D and He-4 abundances, when combined with the CMB determination of η, provide the bound Nν=3.28±0.28 on the effective number of neutrino species. Other constraints on new physics are discussed briefly.

  8. Neutrino oscillations and Big Bang Nucleosynthesis

    OpenAIRE

    Bell, Nicole F.

    2001-01-01

    We outline how relic neutrino asymmetries may be generated in the early universe via active-sterile neutrino oscillations. We discuss possible consequences for big bang nucleosynthesis, within the context of a particular 4-neutrino model.

  9. Neutrino energy transport in weak decoupling and big bang nucleosynthesis

    CERN Document Server

    Grohs, E; Kishimoto, C T; Paris, M W; Vlasenko, A

    2015-01-01

    We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. Such an approach allows a detailed accounting of the evolution of the $\

  10. Neutrino statistics and big bang nucleosynthesis

    CERN Document Server

    Dolgov, A D; Smirnov, A Yu

    2005-01-01

    Neutrinos may possibly violate the spin-statistics theorem, and hence obey Bose statistics or mixed statistics despite having spin half. We find the generalized equilibrium distribution function of neutrinos which depends on a single fermi-bose parameter, \\kappa, and interpolates continuously between the bosonic and fermionic distributions when \\kappa changes from -1 to +1. We consider modification of the Big Bang Nucleosynthesis (BBN) in the presence of bosonic or partly bosonic neutrinos. For pure bosonic neutrinos the abundances change (in comparison with the usual Fermi-Dirac case) by -3.2% for He4 (which is equivalent to a decrease of the effective number of neutrinos by \\Delta N_\

  11. The Big Bang Nucleosynthesis limit on $N_{\

    CERN Document Server

    Lisi, E; Villante, F L

    1999-01-01

    Recently we presented a simple method for determining the correlated uncertainties of the light element abundances expected from big bang nucleosynthesis, which avoids the need for lengthy Monte Carlo simulations. We now extend this approach to consider departures from the Standard Model, in particular to constrain any new light degrees of freedom present in the thermal plasma during nucleosynthesis. Since the observational situation regarding the inferred primordial abundances has not yet stabilized, we present illustrative bounds on the equivalent number of neutrino species N_nu for various combinations of individual abundance determinations. Our 95% C.L. bounds on N_nu range between 2 and 4, and can easily be reevaluated using the technique provided when the abundances are known more accurately.

  12. Big-Bang Nucleosynthesis verifies classical Maxwell-Boltzmann distribution

    CERN Document Server

    Hou, S Q; Parikh, A; Daid, K; Bertulani, C

    2014-01-01

    We provide the most stringent constraint to date on possible deviations from the usually-assumed Maxwell-Boltzmann (MB) velocity distribution for nuclei in the Big-Bang plasma. The impact of non-extensive Tsallis statistics on thermonuclear reaction rates involved in standard models of Big-Bang Nucleosynthesis (BBN) has been investigated. We find that the non-extensive parameter $q$ may deviate by, at most, $|\\delta q|$=6$\\times$10$^{-4}$ from unity for BBN predictions to be consistent with observed primordial abundances; $q$=1 represents the classical Boltzmann-Gibbs statistics. This constraint arises primarily from the {\\em super}sensitivity of endothermic rates on the value of $q$, which is found for the first time. As such, the implications of non-extensive statistics in other astrophysical environments should be explored. This may offer new insight into the nucleosynthesis of heavy elements.

  13. Big Bang 6Li nucleosynthesis studied deep underground (LUNA collaboration)

    Science.gov (United States)

    Trezzi, D.; Anders, M.; Aliotta, M.; Bellini, A.; Bemmerer, D.; Boeltzig, A.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Cavanna, F.; Corvisiero, P.; Costantini, H.; Davinson, T.; Depalo, R.; Elekes, Z.; Erhard, M.; Ferraro, F.; Formicola, A.; Fülop, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Junker, M.; Lemut, A.; Marta, M.; Mazzocchi, C.; Menegazzo, R.; Mossa, V.; Pantaleo, F.; Prati, P.; Rossi Alvarez, C.; Scott, D. A.; Somorjai, E.; Straniero, O.; Szücs, T.; Takacs, M.

    2017-03-01

    The correct prediction of the abundances of the light nuclides produced during the epoch of Big Bang Nucleosynthesis (BBN) is one of the main topics of modern cosmology. For many of the nuclear reactions that are relevant for this epoch, direct experimental cross section data are available, ushering the so-called "age of precision". The present work addresses an exception to this current status: the 2H(α,γ)6Li reaction that controls 6Li production in the Big Bang. Recent controversial observations of 6Li in metal-poor stars have heightened the interest in understanding primordial 6Li production. If confirmed, these observations would lead to a second cosmological lithium problem, in addition to the well-known 7Li problem. In the present work, the direct experimental cross section data on 2H(α,γ)6Li in the BBN energy range are reported. The measurement has been performed deep underground at the LUNA (Laboratory for Underground Nuclear Astrophysics) 400 kV accelerator in the Laboratori Nazionali del Gran Sasso, Italy. The cross section has been directly measured at the energies of interest for Big Bang Nucleosynthesis for the first time, at Ecm = 80, 93, 120, and 133 keV. Based on the new data, the 2H(α,γ)6Li thermonuclear reaction rate has been derived. Our rate is even lower than previously reported, thus increasing the discrepancy between predicted Big Bang 6Li abundance and the amount of primordial 6Li inferred from observations.

  14. Big Bang nucleosynthesis revisited via Trojan Horse Method measurements

    CERN Document Server

    Pizzone, R G; Bertulani, C A; Spitaleri, C; La Cognata, M; Lalmansingh, J; Lamia, L; Mukhamedzhanov, A; Tumino, A

    2014-01-01

    Nuclear reaction rates are among the most important input for understanding the primordial nucleosynthesis and therefore for a quantitative description of the early Universe. An up-to-date compilation of direct cross sections of 2H(d,p)3H, 2H(d,n)3He, 7Li(p,alpha)4He and 3He(d,p)4He reactions is given. These are among the most uncertain cross sections used and input for Big Bang nucleosynthesis calculations. Their measurements through the Trojan Horse Method (THM) are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the 2H, 3,4He and 7Li primordial abundances, which are then compared with observations.

  15. Big bang nucleosynthesis revisited via Trojan Horse method measurements

    Energy Technology Data Exchange (ETDEWEB)

    Pizzone, R. G.; Spartá, R.; Spitaleri, C.; La Cognata, M.; Tumino, A. [INFN—Laboratori Nazionali del Sud, Via Santa Sofia 62, I-95123 Catania (Italy); Bertulani, C. A.; Lalmansingh, J. [Department of Physics and Astronomy, Texas A and M University, Commerce, TX 75025 (United States); Lamia, L. [Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, Via Santa Sofia 64, I-95123 Catania (Italy); Mukhamedzhanov, A., E-mail: rgpizzone@lns.infn.it [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States)

    2014-05-10

    Nuclear reaction rates are among the most important input for understanding primordial nucleosynthesis and, therefore, for a quantitative description of the early universe. An up-to-date compilation of direct cross-sections of {sup 2}H(d, p){sup 3}H, {sup 2}H(d, n){sup 3}He, {sup 7}Li(p, α){sup 4}He, and {sup 3}He(d, p){sup 4}He reactions is given. These are among the most uncertain cross-sections used and input for big bang nucleosynthesis calculations. Their measurements through the Trojan Horse method are also reviewed and compared with direct data. The reaction rates and the corresponding recommended errors in this work were used as input for primordial nucleosynthesis calculations to evaluate their impact on the {sup 2}H, {sup 3,4}He, and {sup 7}Li primordial abundances, which are then compared with observations.

  16. Big bang photosynthesis and pregalactic nucleosynthesis of light elements

    Science.gov (United States)

    Audouze, J.; Lindley, D.; Silk, J.

    1985-01-01

    Two nonstandard scenarios for pregalactic synthesis of the light elements (H-2, He-3, He-4, and Li-7) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate He-4 (formed in the standard hot big bang) to produce H-2 and He-3. In this case, primordial nucleosynthesis no longer constrains the baryon density of the universe, or the number of neutrino species. Alternatively, one may dispense partially or completely with the hot big bang and produce the light elements by bombardment of primordial gas, provided that He-4 is synthesized by a later generation of massive stars.

  17. Dark/Visible Parallel Universes and Big Bang Nucleosynthesis

    CERN Document Server

    Bertulani, C A; Fuqua, J; Hussein, M S; Oliveira, O; de Paula, W

    2012-01-01

    We develop a model for visible matter-dark matter interaction based on the exchange of a massive gray boson called herein the Mulato. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. A close study of big bang nucleosynthesis (BBN), baryon asymmetries, cosmic microwave background (CMB) bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. Modification of the statistics underlying the kinetic energy distribution of particles during the BBN is also discussed. The changes in reaction rates during the BBN due to a departure from the Debye-Hueckel electron screening model is also investigated.

  18. Dark/visible parallel universes and Big Bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, C. A.; Frederico, T.; Fuqua, J.; Hussein, M. S.; Oliveira, O.; Paula, W. de [Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce TX 75429 (United States); Departamento de Fisica, Instituto Tecnologico de Aeronautica, DCTA 12.228-900, Sao Jose dos Campos, SP (Brazil); Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce TX 75429 (United States); Instituto de Fisica, Universidade de Sao Paulo, Caixa Postal 66318, 05314-970 Sao Paulo, SP (Brazil); Departamento de Fisica, Instituto Tecnologico de Aeronautica, DCTA 12.228-900, Sao Jose dos Campos, SP, Brazil and Departamento de Fisica, Universidade de Coimbra, 3004-516 Coimbra (Portugal); Departamento de Fisica, Instituto Tecnologico de Aeronautica, DCTA 12.228-900, Sao Jose dos Campos, SP (Brazil)

    2012-11-20

    We develop a model for visible matter-dark matter interaction based on the exchange of a massive gray boson called herein the Mulato. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. A close study of big bang nucleosynthesis (BBN), baryon asymmetries, cosmic microwave background (CMB) bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. Modification of the statistics underlying the kinetic energy distribution of particles during the BBN is also discussed. The changes in reaction rates during the BBN due to a departure from the Debye-Hueckel electron screening model is also investigated.

  19. Quark mass variation constraints from Big Bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bedaque, P; Luu, T; Platter, L

    2010-12-13

    We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.

  20. Big-Bang nucleosynthesis with updated nuclear data

    Energy Technology Data Exchange (ETDEWEB)

    Coc, Alain [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS/IN2P3, Universite Paris Sud 11, UMR 8609, Batiment 104, F-91405 Orsay Campus (France); Vangioni, Elisabeth, E-mail: Alain.Coc@csnsm.in2p3.f, E-mail: vangioni@iap.f [Institut d' Astrophysique de Paris, UMR-7095 du CNRS, Universite Pierre et Marie Curie, 98 bis bd Arago, 75014 Paris (France)

    2010-01-01

    Primordial nucleosynthesis is one of the three evidences for the Big-Bang model together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of {sup 4}He, D, {sup 3}He and {sup 7}Li deduced from observations and calculated primordial nucleosynthesis. This comparison was used to determine the baryonic density of the Universe. For this purpose, it is now superseded by the analysis of the Cosmic Microwave Background (CMB) radiation anisotropies. Big-Bang nucleosynthesis remains, nevertheless, a valuable tool to probe the physics of the early Universe. However, the yet unexplained, discrepancy between the calculated and observed lithium primordial abundances, has not been reduced, neither by recent nuclear physics experiments, nor by new observations.

  1. Astrophysical Li-7 as a product of big bang nucleosynthesis and galactic cosmic-ray spallation

    Science.gov (United States)

    Olive, Keith A.; Schramm, David N.

    1992-01-01

    The astrophysical Li-7 abundance is considered to be largely primordial, while the Be and B abundances are thought to be due to galactic cosmic ray (GCR) spallation reactions on top of a much smaller big bang component. But GCR spallation should also produce Li-7. As a consistency check on the combination of big bang nucleosynthesis and GCR spallation, the Be and B data from a sample of hot population II stars is used to subtract from the measured Li-7 abundance an estimate of the amount generated by GCR spallation for each star in the sample, and then to add to this baseline an estimate of the metallicity-dependent augmentation of Li-7 due to spallation. The singly reduced primordial Li-7 abundance is still consistent with big bang nucleosynthesis, and a single GCR spallation model can fit the Be, B, and corrected Li-7 abundances for all the stars in the sample.

  2. Particle physics catalysis of thermal big bang nucleosynthesis.

    Science.gov (United States)

    Pospelov, Maxim

    2007-06-08

    We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.

  3. Possible evidence for dark radiation from Big Bang Nucleosynthesis data

    Energy Technology Data Exchange (ETDEWEB)

    Flambaum, V.V. [New South Wales Univ., School of Physics, Sydney NSW (Australia); Argonne National Laboratory, Physics Div., Argonne, IL (United States); Shuryak, E.V. [State University of New York Stony Brook, Dept. of Physics and Astronomy, NY (United States)

    2006-06-15

    We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)

  4. Constraining axion dark matter with Big Bang Nucleosynthesis

    Directory of Open Access Journals (Sweden)

    Kfir Blum

    2014-10-01

    Full Text Available We show that Big Bang Nucleosynthesis (BBN significantly constrains axion-like dark matter. The axion acts like an oscillating QCD θ angle that redshifts in the early Universe, increasing the neutron–proton mass difference at neutron freeze-out. An axion-like particle that couples too strongly to QCD results in the underproduction of He4 during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for a time-varying neutron EDM. The QCD axion does not couple strongly enough to affect BBN.

  5. High-energy break-up of 6Li as a tool to study the Big-Bang nucleosynthesis reaction 2H(alpha,gamma)6Li

    CERN Document Server

    Hammache, F; Typel, S; Galaviz, D; Sümmerer, K; Coc, A; Uhlig, F; Attallah, F; Caamano, M; Cortina, D; Geissel, H; Hellström, M; Iwasa, N; Kiener, J; Koczon, P; Kohlmeyer, B; Mohr, P; Schwab, E; Schwarz, K; Schümann, F; Senger, P; Sorlin, O; Tatischeff, V; Thibaud, J P; Vangioni, E; Wagner, A; Walus, W

    2010-01-01

    The recently claimed observations of non-negligible amounts of 6Li in old halo stars have renewed interest in the Big-Bang Nucleosynthesis (BBN) of 6Li. One important ingredient in the predicted BBN abundance of 6Li is the low-energy 2H(alpha,gamma)6Li cross section. Up to now, the only available experimental result for this cross section showed an almost constant astrophysical S-factor below 400 keV, contrary to theoretical expectations. We report on a new measurement of the 2H(alpha,gamma)6Li reaction using the break-up of 6Li at 150 A MeV. Even though we cannot separate experimentally the Coulomb contribution from the nuclear one, we find clear evidence for Coulomb-nuclear interference by analyzing the scattering-angular distributions. This is in-line with our theoretical description which indicates a drop of the S_24-factor at low energies as predicted also by most other models. Consequently, we find even lower upper limits for the calculated primordial 6Li abundance than before.

  6. Relic neutrino asymmetries and big bang nucleosynthesis in a four neutrino model

    OpenAIRE

    Bell, N. F.; Foot, R.; Volkas, R. R.

    1998-01-01

    Oscillations between ordinary and sterile neutrinos can generate large neutrino asymmetries in the early universe. These asymmetries can significantly affect big bang nucleosynthesis (BBN) through modification of nuclear reaction rates. We study this phenomenon within a model consisting of the three ordinary neutrinos plus one sterile neutrino that can be motivated by the neutrino anomalies and the dark matter problem. We calculate how the lepton asymmetries produced evolve at temperatures wh...

  7. THE 2H(alpha, gamma6LI REACTION AT LUNA AND BIG BANG NUCLEOSYNTHETIS

    Directory of Open Access Journals (Sweden)

    Carlo Gustavino

    2013-12-01

    Full Text Available The 2H(α, γ6Li reaction is the leading process for the production of 6Li in standard Big Bang Nucleosynthesis. Recent observations of lithium abundance in metal-poor halo stars suggest that there might be a 6Li plateau, similar to the well-known Spite plateau of 7Li. This calls for a re-investigation of the standard production channel for 6Li. As the 2H(α, γ6Li cross section drops steeply at low energy, it has never before been studied directly at Big Bang energies. For the first time the reaction has been studied directly at Big Bang energies at the LUNA accelerator. The preliminary data and their implications for Big Bang nucleosynthesis and the purported 6Li problem will be shown.

  8. Big bang nucleosynthesis: The standard model and alternatives

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    Big bang nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the big bang cosmological model. This paper reviews the standard homogeneous-isotropic calculation and shows how it fits the light element abundances ranging from He-4 at 24% by mass through H-2 and He-3 at parts in 10(exp 5) down to Li-7 at parts in 10(exp 10). Furthermore, the recent large electron positron (LEP) (and the stanford linear collider (SLC)) results on the number of neutrinos are discussed as a positive laboratory test of the standard scenario. Discussion is presented on the improved observational data as well as the improved neutron lifetime data. Alternate scenarios of decaying matter or of quark-hadron induced inhomogeneities are discussed. It is shown that when these scenarios are made to fit the observed abundances accurately, the resulting conlusions on the baryonic density relative to the critical density, omega(sub b) remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that omega(sub b) approximately equals 0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming omega(sub total) = 1) and the need for dark baryonic matter, since omega(sub visible) is less than omega(sub b).

  9. Big bang nucleosynthesis and the quark-hadron transition

    Science.gov (United States)

    Kurki-Suonio, Hannu; Matzner, Richard A.; Olive, Keith A.; Schramm, David N.

    1990-01-01

    An examination and brief review is made of the effects of quark-hadron transition induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp e), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

  10. Big bang nucleosynthesis and the quark-hadron transition

    Science.gov (United States)

    Kurki-Suonio, Hannu; Matzner, Richard A.; Olive, Keith A.; Schramm, David N.

    1990-01-01

    An examination and brief review is made of the effects of quark-hadron transition induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp e), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

  11. Big Bang Nucleosynthesis: Probing the First 20 Minutes

    CERN Document Server

    Steigman, G

    2003-01-01

    Within the first 20 minutes of the evolution of the hot, dense, early Universe, astrophysically interesting abundances of deuterium, helium-3, helium-4, and lithium-7 were synthesized by the cosmic nuclear reactor. The primordial abundances of these light nuclides produced during Big Bang Nucleosynthesis (BBN) are sensitive to the universal density of baryons and to the early-Universe expansion rate which at early epochs is governed by the energy density in relativistic particles (``radiation'') such as photons and neutrinos. Some 380 kyr later, when the cosmic background radiation (CBR) radiation was freed from the embrace of the ionized plasma of protons and electrons, the spectrum of temperature fluctuations imprinted on the CBR also depended on the baryon and radiation densities. The comparison between the constraints imposed by BBN and those from the CBR reveals a remarkably consistent picture of the Universe at two widely separated epochs in its evolution. Combining these two probes leads to new and tig...

  12. Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Schelke, M. [Istituto Nazionale di Fisica Nucleare, Torino (Italy); Catena, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fornengo, N. [Torino Univ. (Italy). Dipt. di Fisica Teorica]|[Istituto Nazionale di Fisica Nucleare, Torino (Italy); Masiero, A. [Pavoa Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padova (Italy); Pietroni, M. [Istituto Nazionale di Fisica Nucleare, Padova (Italy)

    2006-06-15

    A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)

  13. Big Bang Nucleosynthesis and the Helium Isotope Ratio

    CERN Document Server

    Cooke, Ryan

    2015-01-01

    The conventional approach to search for departures from the standard model of physics during Big Bang Nucleosynthesis involves a careful, and subtle measurement of the mass fraction of baryons consisting of helium. Recent measurements of this quantity tentatively support new physics beyond the standard model but, historically, this method has suffered from hidden systematic uncertainties. In this letter, I show that a combined measurement of the primordial deuterium abundance and the primordial helium isotope ratio has the potential to provide a complementary and reliable probe of new physics beyond the standard model. Using the recent determination of the primordial deuterium abundance and assuming that the measured pre-solar 3He/4He meteoritic abundance reflects the primordial value, a bound can be placed on the effective number of neutrino species, Neff(BBN) = 3.01 (+0.95 -0.76, with 95 per cent confidence). Although this value of Neff supports the standard model, it is presently unclear if the pre-solar 3...

  14. Modified big bang nucleosynthesis with non-standard neutron sources

    CERN Document Server

    Coc, Alain; Uzan, Jean-Philippe; Vangioni, Elisabeth

    2014-01-01

    During big bang nucleosynthesis, any injection of extra neutrons around the time of the $^7$Be formation, i.e. at a temperature of order $T \\simeq 50$~keV, can reduce the predicted freeze-out amount of $^7$Be + $^7$Li that otherwise remains in sharp contradiction with the Spite plateau value inferred from the observations of Pop II stars. However, the growing confidence in the primordial D/H determinations puts a strong constraint on any such scenario. We address this issue in detail, analyzing different temporal patterns of neutron injection, such as decay, annihilation, resonant annihilation, and oscillation between mirror and standard model world neutrons. For this latter case, we derive the realistic injection pattern taking into account thermal effects (damping and refraction) in the primordial plasma. If the extra neutron supply is the sole non-standard mechanism operating during the BBN, the suppression of lithium abundance below Li/H~$\\leq 1.9 \\times 10^{-10}$ always leads to the overproduction of deu...

  15. Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Kawasaki, Masahiro [Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa 277-8582 (Japan); Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Kohri, Kazunori [Theory Center, IPNS, KEK, Tsukuba 305-0801 (Japan); Sokendai, Tsukuba 305-0801 (Japan); Moroi, Takeo [Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa 277-8583 (Japan); Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan); Takaesu, Yoshitaro, E-mail: takaesu@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, University of Tokyo, Tokyo 113-0033 (Japan)

    2015-12-17

    We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

  16. Majorana Neutrino Magnetic Moment and Neutrino Decoupling in Big Bang Nucleosynthesis

    CERN Document Server

    Vassh, N; Balantekin, A B; Fuller, G M

    2015-01-01

    We examine the physics of the early universe when neutrinos (electron neutrino, muon neutrino, tau neutrino) possess transition magnetic moments. These extra couplings beyond the usual weak interaction couplings alter the way neutrinos decouple from the plasma of electrons/positrons and photons. We calculate how transition magnetic moment couplings modify neutrino decoupling temperatures, and then use a full weak, strong, and electromagnetic reaction network to compute corresponding changes in Big Bang Nucleosynthesis abundance yields. We find that light element observational constraints and other cosmological constraints may allow probes of neutrino transition magnetic moments which are not directly available in the laboratory.

  17. Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

    Science.gov (United States)

    Kawasaki, Masahiro; Kohri, Kazunori; Moroi, Takeo; Takaesu, Yoshitaro

    2015-12-01

    We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

  18. Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation

    Directory of Open Access Journals (Sweden)

    Masahiro Kawasaki

    2015-12-01

    Full Text Available We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.

  19. Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.

    Science.gov (United States)

    Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C

    2006-12-08

    Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He.

  20. Review of Big Bang Nucleosynthesis and Primordial Abundances

    Science.gov (United States)

    Tytler, David; O'Meara, John M.; Suzuki, Nao; Lubin, Dan

    2001-03-01

    Big Bang Nucleosynthesis (BBN) is the synthesis of the light nuclei, Deuterium (D or 2H), 3He, 4He and 7Li during the first few minutes of the universe. This review concentrates on recent improvements in the measurement of the primordial (after BBN, and prior to modification) abundances of these nuclei. We mention improvement in the standard theory, and the non-standard extensions which are limited by the data. We have achieved an order of magnitude improvement in the precision of the measurement of primordial D/H, using the HIRES spectrograph on the W. M. Keck telescope to measure D in gas with very nearly primordial abundances towards quasars. From 1994 - 1996, it appeared that there could be a factor of ten range in primordial D/H, but today four examples of low D are secure. High D/H should be much easier to detect, and since there are no convincing examples, it must be extremely rare or non-existent. All data are consistent with a single low value for D/H, and the examples which are consistent with high D/H are readily interpreted as H contamination near the position of D. The new D/H measurements give the most accurate value for the baryon to photon ratio, η, and hence the cosmological baryon density. A similar density is required to explain the amount of Lyα absorption from neutral Hydrogen in the intergalactic medium (IGM) at redshift z ≃ 3, and to explain the fraction of baryons in local clusters of galaxies. The D/H measurements lead to predictions for the abundances of the other light nuclei, which generally agree with measurements. The remaining differences with some measurements can be explained by a combination of measurement and analysis errors or changes in the abundances after BBN. The measurements do not require physics beyond the standard BBN model. Instead, the agreement between the abundances is used to limit the non-standard physics. New measurements are giving improved understanding of the difficulties in estimating the abundances of all

  1. Low-lying Resonances and Relativistic Screening in Big Bang Nucleosynthesis

    CERN Document Server

    Famiano, Michael A; Kajino, Toshitaka

    2016-01-01

    We explore effects of the screening due to the relativistic electron-positron plasma and presence of resonances in the secondary reactions leading to A=7 nuclei during the Big Bang Nucleosynthesis. In particular, we investigate and examine possible low-lying resonances in the 7Be(3He, g)10C reaction and examine the resultant destruction of 7Be for various resonance locations and strengths. While a resonance in the 10C compound nucleus is thought to have negligible effects we explore the possibility of an enhancement from plasma screening that may adjust the final 7Be abundance. We find the effects of relativistic screening and possible low-lying resonances to be relatively small in the standard Early Universe models.

  2. Constraining nuclear data via cosmological observations: Neutrino energy transport and big bang nucleosynthesis

    Science.gov (United States)

    Paris, Mark; Fuller, George; Grohs, Evan; Kishimoto, Chad; Vlasenko, Alexey

    2017-09-01

    We introduce a new computational capability that moves toward a self-consistent calculation of neutrino transport and nuclear reactions for big bang nucleosynthesis (BBN). Such a self-consistent approach is needed to be able to extract detailed information about nuclear reactions and physics beyond the standard model from precision cosmological observations of primordial nuclides and the cosmic microwave background radiation. We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our approach allows the dissection of the relative contributions of each process responsible for evolving the dynamics of the early universe. Such an approach allows a detailed account of the evolution of the active neutrino energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and 'ow between the neutrino and photon/electron/positron/baryon plasma components. Our calculations reveal nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions. We discuss the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma. These e↑ects result in changes in the computed values of the BBN deuterium and helium-4 yields that are on the order of a half-percent relative to a baseline standard BBN calculation with no neutrino transport. This is an order of magnitude larger e↑ect than in previous estimates. For particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium and a 0.6% decrease in 4He over our baseline. The magnitude of these changes are on the order of uncertainties in the nuclear

  3. Big Bang Nucleosynthesis in the presence of sterile neutrinos with altered dispersion relations

    CERN Document Server

    Aeikens, Elke; Pakvasa, Sandip; Weiler, Thomas J

    2016-01-01

    Big Bang Nucleosynthesis imposes stringent bounds on light sterile neutrinos mixing with the active flavors. Here we discuss how altered dispersion relations can weaken such bounds and allow compatibility of new sterile neutrino degrees of freedom with a successful generation of the light elements in the early Universe.

  4. 178th International School of Physics "Enrico Fermi" : From the Big Bang to the Nucleosynthesis

    CERN Document Server

    Nappi, E

    2011-01-01

    Physicists have devoted much effort to reproducing the conditions of the primordial universe in laboratory conditions in their quest to work out a comprehensive theory of the appearance and evolution of nuclear matter. Whether it be trying to recreate the predicted primordial state of high-energy density matter in which quarks and gluons are effectively deconfined - the so-called Quark Gluon Plasma (QGP) - or exploring the structure and reaction properties of very unstable nuclei in experiments using radioactive beams, they have striven to understand the events which characterized the Big Bang and the various nucleosynthesis mechanisms which occur in the stars. This book contains the proceedings of the 2010 Enrico Fermi summer school held in Varenna, Italy, in July 2010, and devoted to the present understanding of the primordial universe and the origin of the elements, as achieved by studying nuclei and their constituents in extreme regimes of energy and composition. Subjects covered include: QGP formation; e...

  5. Big bang nucleosynthesis - The standard model and alternatives

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    The standard homogeneous-isotropic calculation of the big bang cosmological model is reviewed, and alternate models are discussed. The standard model is shown to agree with the light element abundances for He-4, H-2, He-3, and Li-7 that are available. Improved observational data from recent LEP collider and SLC results are discussed. The data agree with the standard model in terms of the number of neutrinos, and provide improved information regarding neutron lifetimes. Alternate models are reviewed which describe different scenarios for decaying matter or quark-hadron induced inhomogeneities. The baryonic density relative to the critical density in the alternate models is similar to that of the standard model when they are made to fit the abundances. This reinforces the conclusion that the baryonic density relative to critical density is about 0.06, and also reinforces the need for both nonbaryonic dark matter and dark baryonic matter.

  6. Constraints on unparticle long range forces from big bang nucleosynthesis bounds on the variation of the gravitational coupling

    OpenAIRE

    2009-01-01

    We use big bang nucleosynthesis bounds on the variation of the gravitational coupling to derive constraints on the strength of the deviation from the gravitational inverse-square law due to tensor and vector unparticle exchange.

  7. Constraining nuclear data via cosmological observations: Neutrino energy transport and big bang nucleosynthesis

    Directory of Open Access Journals (Sweden)

    Paris Mark

    2017-01-01

    Full Text Available We introduce a new computational capability that moves toward a self-consistent calculation of neutrino transport and nuclear reactions for big bang nucleosynthesis (BBN. Such a self-consistent approach is needed to be able to extract detailed information about nuclear reactions and physics beyond the standard model from precision cosmological observations of primordial nuclides and the cosmic microwave background radiation. We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our approach allows the dissection of the relative contributions of each process responsible for evolving the dynamics of the early universe. Such an approach allows a detailed account of the evolution of the active neutrino energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and 'ow between the neutrino and photon/electron/positron/baryon plasma components. Our calculations reveal nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions. We discuss the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma. These e↑ects result in changes in the computed values of the BBN deuterium and helium-4 yields that are on the order of a half-percent relative to a baseline standard BBN calculation with no neutrino transport. This is an order of magnitude larger e↑ect than in previous estimates. For particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium and a 0.6% decrease in 4He over our baseline. The magnitude of these changes are on the order of uncertainties

  8. The Effects of Cold Dark Matter on Big Bang Nucleosynthesis.

    Science.gov (United States)

    Parker, Ronald John David

    We show that the annihilation of cold, weakly -interacting dark matter candidates (chi) subsequent to chichi freeze -out can significantly affect the primordial abundance of light elements. The largest effects are (1) between the n/p freeze-out temperature (T ~eq 0.7 MeV) and the onset of nucleosynthesis at T ~eq 0.1 MeV, chichi annihilations increase the n/p ratio, leading to increased ^4He production; (2) following ^4He synthesis, baryonic products n,n,p of chichi annihilations dissociate some the the ^4He into D and ^3He, leading to increased D + ^3He abundances; (3) toward the end of nucleosynthesis, neutrons from chi chi annihilation lead to n + ^7 Be to p + ^7 Li, resulting in increased ^7Li + ^7Be production for low values of eta equiv n_{rm b}/n _gamma and decreased ^7 Li + ^7Be production for large eta, and (4) long after nucleosynthesis, once the universe cools below T ~eq 1 keV, the electromagnetic shower produced by electrons, positrons and photons from residual chichi annihilations cause further dissociation of ^4He, leading to increased CD + ^3He abundances. The most important result is that for Direc and Majorna neutrinos, the ^7 Li constraints on eta from SBBN are noticeably affected, with larger values of eta being favored. A summary of scattering rates for processes in the electromagnetic shower, containing corrections to numerous misprints in other sources, is presented in an Appendix. A listing of FORTRAN code used in the shower calculation is also included. Finally, the results are discussed in the light of Maharishi's Vedic Science, an ancient science which presents both knowledge and experience of the transcendental basis of life.

  9. High Energy Density Plasmas (HEDP) for studies of basic nuclear science relevant to Stellar and Big Bang Nucleosynthesis

    Science.gov (United States)

    Frenje, Johan

    2014-06-01

    Thermonuclear reaction rates and nuclear processes have been explored traditionally by means of conventional accelerator experiments, which are difficult to execute at conditions relevant to stellar nucleosynthesis. Thus, nuclear reactions at stellar energies are often studied through extrapolations from higher-energy data or in low-background underground experiments. Even when measurements are possible using accelerators at relevant energies, thermonuclear reaction rates in stars are inherently different from those in accelerator experiments. The fusing nuclei are surrounded by bound electrons in accelerator experiments, whereas electrons occupy mainly continuum states in a stellar environment. Nuclear astrophysics research will therefore benefit from an enlarged toolkit for studies of nuclear reactions. In this presentation, we report on the first use of High Energy Density Plasmas for studies of nuclear reactions relevant to basic nuclear science, stellar and Big Bang nucleosynthesis. These experiments were carried out at the OMEGA laser facility at University of Rochester and the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory, in which spherical capsules were irradiated with powerful lasers to compress and heat the fuel to high enough temperatures and densities for nuclear reactions to occur. Four experiments will be highlighted in this presentation. In the first experiment, the differential cross section for the elastic neutron-triton (n-T) scattering at 14.1 MeV was measured with significantly higher accuracy than achieved in accelerator experiments. In the second experiment, the T(t,2n)4He reaction, a mirror reaction to the 3He(3He,2p)4He reaction that plays an important role in the proton-proton chain that transforms hydrogen into ordinary 4He in stars like our Sun, was studied at energies in the range 15-40 keV. In the third experiment, the 3He+3He solar fusion reaction was studied directly, and in the fourth experiment, we

  10. Reply to 'Comment on 'Heavy element production in inhomogeneous big bang nucleosynthesis''

    CERN Document Server

    Matsuura, Shunji; Hashimoto, Masa-aki; Sato, Katsuhiko

    2007-01-01

    This is a reply report to astro-ph/0604264. We studied heavy element production in high baryon density region in early universe astro-ph/0507439. However it is claimed in astro-ph/0604264 that small scale but high baryon density region contradicts observations for the light element abundance or in order not to contradict to observations high density region must be so small that it cannot affect the present heavy element abundance. In this paper we study big bang nucleosynthesis in high baryon density region and show that in certain parameter spaces it is possible to produce enough amount of heavy element without contradiction to CMB and light element observations.

  11. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    Science.gov (United States)

    Dai, Wei-Ming; Guo, Zong-Kuan; Cai, Rong-Gen; Zhang, Yuan-Zhong

    2017-06-01

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density.

  12. Lorentz invariance violation in the neutrino sector: a joint analysis from big bang nucleosynthesis and the cosmic microwave background

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Wei-Ming; Cai, Rong-Gen [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Guo, Zong-Kuan [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Astronomy and Space Science, Beijing (China); Zhang, Yuan-Zhong [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)

    2017-06-15

    We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)

  13. Observational Constraint on Heavy Element Production in Inhomogeneous Big Bang Nucleosynthesis

    CERN Document Server

    Nakamura, Riou; Fujimoto, Shin-ichiro; Nishimura, Nobuya; Sato, Katsuhiko

    2010-01-01

    Based on a scenario of the inhomogeneous big-bang nucleosynthesis (IBBN), we investigate the detailed nucleosynthesis that includes the production of heavy elements beyond Li-7. From the observational constraints on light elements of He4 and D for the baryon-to-photon ratio given by WMAP, possible regions found on the plane of the volume fraction of the high density region against the ratio between high- and low-density regions. In these allowed regions, we have confirmed that the heavy elements beyond Fe can be produced appreciably, where p- and/or r-process elements are produced well simultaneously compared to the solar system abundances. We suggest that recent observational signals such as He4 overabundance in globular clusters and high metallicity abundances in quasars could be partly due to the results of IBBN. Possible implications are given for the formation of the first generation stars

  14. Revisiting constraints on small scale perturbations from big-bang nucleosynthesis

    Science.gov (United States)

    Inomata, Keisuke; Kawasaki, Masahiro; Tada, Yuichiro

    2016-08-01

    We revisit the constraints on the small scale density perturbations (1 04 Mpc-1≲k ≲1 05 Mpc-1 ) from the modification of the freeze-out value of the neutron-proton ratio at the big-bang nucleosynthesis era. Around the freeze-out temperature T ˜0.5 MeV , the universe can be divided into several local patches that have different temperatures since any perturbation that enters the horizon after the neutrino decoupling has not diffused yet. Taking account of this situation, we calculate the freeze-out value in detail. We find that the small scale perturbations decrease the n -p ratio in contrast to previous works. With the use of the latest observed 4He abundance, we obtain the constraint on the power spectrum of the curvature perturbations as ΔR2≲0.018 on 1 04 Mpc-1≲k ≲1 05 Mpc-1 .

  15. Constraining f( T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN

    Science.gov (United States)

    Capozziello, S.; Lambiase, G.; Saridakis, E. N.

    2017-09-01

    We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f( T) gravity. The three most studied viable f( T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f( T) models can successfully satisfy the BBN constraints.

  16. Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data

    CERN Document Server

    Flambaum, V V

    2002-01-01

    Recent data on cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of possible variation of other constants. We discuss variation of strong scale and quark masses. We derive the limits on their relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii) Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals.

  17. A revised thermonuclear rate of $^{7}$Be($n$,$\\alpha$)$^{4}$He relevant to Big-Bang nucleosynthesis

    CERN Document Server

    Hou, S Q; Kubono, S; Chen, Y S

    2015-01-01

    In the standard Big-Bang nucleosynthesis (BBN) model, the primordial $^7$Li abundance is overestimated by about a factor of 2--3 comparing to the astronomical observations, so called the pending cosmological lithium problem. The $^7$Be($n$,$\\alpha$)$^4$He reaction, which may affect the $^7$Li abundance, was regarded as the secondary important reaction in destructing the $^7$Be nucleus in BBN. However, the thermonuclear rate of $^7$Be($n$,$\\alpha$)$^4$He has not been well studied so far. This reaction rate was firstly estimated by Wagoner in 1969, which has been generally adopted in the current BBN simulations and the reaction rate library. This simple estimation involved only a direct-capture reaction mechanism, but the resonant contribution should be also considered according to the later experimental results. In this work, we have revised this rate based on the indirect cross-section data available for the $^4$He($\\alpha$,$n$)$^7$Be and $^4$He($\\alpha$,$p$)$^7$Li reactions, with the charge symmetry and deta...

  18. The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis

    Science.gov (United States)

    Grohs, E.; Fuller, George M.

    2016-10-01

    The weak interaction charged current processes (νe + n ↔ p +e-; νbare + p ↔ n +e+; n ↔ p +e- +νbare) interconvert neutrons and protons in the early universe and have significant influence on Big Bang Nucleosynthesis (BBN) light-element abundance yields, particularly that for 4He. We demonstrate that the influence of these processes is still significant even when they operate well below temperatures T ∼ 0.7 MeV usually invoked for "weak freeze-out," and in fact down nearly into the alpha-particle formation epoch (T ≈ 0.1 MeV). This physics is correctly captured in commonly used BBN codes, though this late-time, low-temperature persistent effect of the isospin-changing weak processes, and the sensitivity of the associated rates to lepton energy distribution functions and blocking factors are not widely appreciated. We quantify this late-time influence by analyzing weak interaction rate dependence on the neutron lifetime, lepton energy distribution functions, entropy, the proton-neutron mass difference, and Hubble expansion rate. The effects we point out here render BBN a keen probe of any beyond-standard-model physics that alters lepton number/energy distributions, even subtly, in epochs of the early universe all the way down to near T = 100 keV.

  19. General neutralino NLSP with gravitino dark matter vs. big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hasenkamp, Jasper

    2009-08-15

    We study the scenario of gravitino dark matter with a general neutralino being the next-to-lightest supersymmetric particle (NLSP). Therefore, we compute analytically all 2- and 3-body decays of the neutralino NLSP to determine the lifetime and the electromagnetic and hadronic branching ratio of the neutralino decaying into the gravitino and Standard Model particles. We constrain the gravitino and neutralino NLSP mass via big bang nucleosynthesis and see how those bounds are relaxed for a Higgsino or a wino NLSP in comparison to the bino neutralino case. At neutralino masses >or similar 1 TeV, a wino NLSP is favoured, since it decays rapidly via a newly found 4-vertex. The Higgsino component becomes important, when resonant annihilation via heavy Higgses can occur. We provide the full analytic results for the decay widths and the complete set of Feynman rules necessary for these computations. This thesis closes any gap in the study of gravitino dark matter scenarios with neutralino NLSP coming from approximations in the calculation of the neutralino decay rates and its hadronic branching ratio. (orig.)

  20. Implication of the proton-deuteron radiative capture for Big Bang Nucleosynthesis

    CERN Document Server

    Marcucci, L E; Kievsky, A; Viviani, M

    2015-01-01

    The astrophysical $S$-factor for the radiative capture $d(p,\\gamma)^3$He in the energy-range of interest for Big Bang Nucleosynthesis (BBN) is calculated using an {\\it ab-initio} approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions - the Argonne $v_{18}$ and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the $1/m$ leading order contribution ($m$ is the nucleon mass), also the next-to-leading order term, proportional to $1/m^3$. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the $A=3$ bound and scattering states. A particular attention is used in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical $S$-factor of the order or below $\\sim$1 %. Then, in this energy range, the $S$-factor i...

  1. Concordance of X-ray cluster data with big bang nucleosynthesis in mixed dark matter models

    Energy Technology Data Exchange (ETDEWEB)

    Strickland, R.W. [University of Chicago, Chicago, Illinois 60637 (United States); Schramm, D.N. [University of Chicago, Chicago, Illinois 60637 (United States)]|[NASA/Fermilab Theoretical Astrophysics Group, Fermilab, Batavia, Illinois 60510 (United States)

    1997-06-01

    If the hot, X-ray-emitting gas in rich clusters forms a fair sample of the universe as in cold dark matter (CDM) models and the universe is at the critical density {Omega}{sub T}=1, then the data appear to imply a baryon fraction {Omega}{sub b,X} ({Omega}{sub b,X}{equivalent_to}{Omega}{sub b} derived from X-ray cluster data), larger than that predicted by big bang nucleosynthesis (BBN). While other systematic effects such as clumping can lower {Omega}{sub b,X}, in this paper we use an elementary analysis to show that a simple admixture of hot dark matter (HDM; low-mass neutrinos) with CDM to yield mixed dark matter shifts {Omega}{sub b,X} down so that significant overlap with {Omega}{sub b} from BBN can occur for H{sub 0}{approx_lt}73kms{sup {minus}1}Mpc{sup {minus}1}, even without invoking the possible aforementioned effects. The overlap interval is slightly larger for lower mass neutrinos since fewer of them cluster on the scale of the hot X-ray gas. We illustrate this result quantitatively in terms of a simple isothermal model. More realistic velocity dispersion profiles, with less centrally peaked density profiles, imply that fewer neutrinos are trapped and thus further increase the interval of overlap. {copyright} {ital 1997} {ital The American Astronomical Society}

  2. Implication of the Proton-Deuteron Radiative Capture for Big Bang Nucleosynthesis.

    Science.gov (United States)

    Marcucci, L E; Mangano, G; Kievsky, A; Viviani, M

    2016-03-11

    The astrophysical S factor for the radiative capture d(p,γ)^{3}He in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions-the Argonne v_{18} and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m^{3}. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below ∼1%. Then, in this energy range, the S factor is found to be ∼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m^{3} one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)^{3}He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for ^{2}H/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom N_{eff}=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.

  3. Ultra-cold weakly interacting massive particles: relics of non-standard pre-big-bang-nucleosynthesis cosmologies

    Energy Technology Data Exchange (ETDEWEB)

    Gelmini, Graciela B [Department of Physics and Astronomy, UCLA, 475 Portola Plaza, Los Angeles, CA 90095 (United States); Gondolo, Paolo, E-mail: gelmini@physics.ucla.edu, E-mail: paolo@physics.utah.edu [Department of Physics, University of Utah, 115 S 1400 E 201, Salt Lake City, UT 84112 (United States)

    2008-10-15

    Weakly interacting massive particles (WIMPs) constitute one of very few probes of cosmology before big bang nucleosynthesis (BBN). We point out that in scenarios in which the Universe evolves in a non-standard manner during and after WIMP kinetic decoupling, the horizon mass scale at decoupling can be smaller and the dark matter WIMPs can be colder than in standard cosmology. This would lead to much smaller first objects in hierarchical structure formation. In low reheating temperature scenarios the effect may be large enough to noticeably enhance indirect detection signals in GLAST and other detectors, by up to two orders of magnitude.

  4. Constraint on Heavy Element Production in Inhomogeneous Big-Bang Nucleosynthesis from The Light-Element Observations

    CERN Document Server

    Nakamura, Riou; Fujimoto, Shin-ichiro; Sato, Katsuhiko

    2013-01-01

    We investigate the observational constraints on the inhomogeneous big-bang nucleosynthesis that Matsuura et al. suggested the possibility of the heavy element production beyond ${}^7$Li in the early universe. From the observational constraints on light elements of ${}^4$He and D, possible regions are found on the plane of the volume fraction of the high density region against the ratio between high-and low-density regions. In these allowed regions, we have confirmed that the heavy elements beyond Ni can be produced appreciably, where $p$- and/or $r$-process elements are produced well simultaneously.

  5. Big-Bang Nucleosynthesis in comparison with observed helium and deuterium abundances - possibility of a non-standard model

    CERN Document Server

    Ichimasa, R; Hashimoto, M; Arai, K

    2014-01-01

    Comparing the latest observed abundances of 4He and D, we make a ?2 analysis to see whether it is possible to reconcile primordial nucleosynthesis using up-to-date nuclear data of NACRE II and the mean-life of neutrons. If we adopt the observational data of ${}^4_{}$He by Izotov et al., we find that it is impossible to get reasonable concordance against the standard Big-Bang nucleosynthesis. However, including degenerate neutrinos, we have succeeded in obtaining consistent constraints between the neutrino degeneracy and the baryon-to-photon ratio from detailed comparison of calculated abundances with the observational data of ${}^4_{}$He and D: the baryon-to-photon ratio in units of $10^{-10}$ is found to be in the range 6.02 < $\\eta^{}_{10}$ < 6:54 for the specified parameters of neutrino degeneracy.

  6. From First Stars to the Spite Plateau: a Possible Reconciliation of Halo Stars Observations with Predictions from Big Bang Nucleosynthesis

    CERN Document Server

    Piau, L; Beers, T C; Ferguson, J W; Sivarani, T; Truran, J W

    2006-01-01

    Since the pioneering observations of Spite & Spite in 1982, the constant lithium abundance of metal-poor ([Fe/H]<-1.3) halo stars near the turnoff has been attributed a cosmological origin. Closer analysis revealed that the observed abundance lies at $\\Delta$ Li~0.4 dex below the predictions of Big Bang Nucleosynthesis. The measurements of deuterium abundances on the lines of sight toward quasars and the recent data from the Wilkinson Microwave Anisotropy Probe independently confirmed this gap. We suggest here that part of the discrepancy is explained by the first generation of stars that efficiently depleted lithium. Assuming that the models for lithium evolution in the halo turnoff stars and $\\Delta$ Li estimates are correct, we infer that between 1/3 and 1/2 of the baryonic matter of the early halo (~10^9 Mo) was processed through Population III stars. This new paradigm proposes a very economical solution to the lingering difficulty of understanding the properties of the Spite Plateau and its lack o...

  7. Fixing the Big Bang Theory's Lithium Problem

    Science.gov (United States)

    Kohler, Susanna

    2017-02-01

    How did our universe come into being? The Big Bang theory is a widely accepted and highly successful cosmological model of the universe, but it does introduce one puzzle: the cosmological lithium problem. Have scientists now found a solution?Too Much LithiumIn the Big Bang theory, the universe expanded rapidly from a very high-density and high-temperature state dominated by radiation. This theory has been validated again and again: the discovery of the cosmic microwave background radiation and observations of the large-scale structure of the universe both beautifully support the Big Bang theory, for instance. But one pesky trouble-spot remains: the abundance of lithium.The arrows show the primary reactions involved in Big Bang nucleosynthesis, and their flux ratios, as predicted by the authors model, are given on the right. Synthesizing primordial elements is complicated! [Hou et al. 2017]According to Big Bang nucleosynthesis theory, primordial nucleosynthesis ran wild during the first half hour of the universes existence. This produced most of the universes helium and small amounts of other light nuclides, including deuterium and lithium.But while predictions match the observed primordial deuterium and helium abundances, Big Bang nucleosynthesis theory overpredicts the abundance of primordial lithium by about a factor of three. This inconsistency is known as the cosmological lithium problem and attempts to resolve it using conventional astrophysics and nuclear physics over the past few decades have not been successful.In a recent publicationled by Suqing Hou (Institute of Modern Physics, Chinese Academy of Sciences) and advisorJianjun He (Institute of Modern Physics National Astronomical Observatories, Chinese Academy of Sciences), however, a team of scientists has proposed an elegant solution to this problem.Time and temperature evolution of the abundances of primordial light elements during the beginning of the universe. The authors model (dotted lines

  8. Big bang nucleosynthesis and the cosmic neutrino background%大爆炸核合成与宇宙背景中微子

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    We present a brief overview of the neutrino decoupling and big bang nucleosynthe-sis in the early universe. The big bang relic neutrinos formed one of the backgrounds of the universe.A few possible ways to directly detect the cosmic neutrino background are briefly introduced, and partic-ular attention is paid to the relic neutrino capture on b-decaying nuclei.%  文章基于大爆炸宇宙学描述了发生于宇宙早期的中微子退耦与轻核素合成事件。退耦后的中微子形成宇宙的背景之一。文章介绍了几种探测宇宙背景中微子的方法,侧重于利用b衰变核俘获超低动能的中微子。

  9. Effect of exotic long-lived sub-strongly interacting massive particles in big bang nucleosynthesis and a new solution to the Li problem

    Directory of Open Access Journals (Sweden)

    Kawasaki Masahiro

    2012-02-01

    Full Text Available The plateau of 7Li abundance as a function of the iron abundance by spectroscopic observations of metal-poor halo stars (MPHSs indicates its primordial origin. The observed abundance levels are about a factor of three smaller than the primordial 7Li abundance predicted in the standard Big Bang Nucleosynthesis (BBN model. This discrepancy might originate from exotic particle and nuclear processes operating in BBN epoch. Some particle models include heavy (m >> 1 GeV long-lived colored particles which would be confined inside exotic heavy hadrons, i.e., strongly interacting massive particles (SIMPs. We have found reactions which destroy 7Be and 7Li during BBN in the scenario of BBN catalyzed by a long-lived sub-strongly interacting massive particle (sub-SIMP, X. The reactions are non radiative X captures of 7 Be and 7Li which can be operative if the X particle interacts with nuclei strongly enough to drive 7 Be destruction but not strongly enough to form a bound state with 4 He of relative angular momentum L = 1. We suggest that 7Li problem can be solved as a result of a new process beyond the standard model through which the observable signature was left on the primordial Li abundance.

  10. Gravitino, dark matter candidate and implications for big bang nucleosynthesis; Le gravitino, candidat a la matiere noire et les implications en nucleosynthese primordiale

    Energy Technology Data Exchange (ETDEWEB)

    Bailly, S

    2008-11-15

    The Standard Model of particle physics was developed in the seventies. Despite many experimental successes, it presents many problems that can only be solved with models beyond the Standard Model. Supersymmetry is an interesting candidate, postulating a new symmetry between fermions and bosons. This model can also have interesting applications in cosmology. It offers potentially good candidates for dark matter, what represents 25% of the energy density of the Universe, and its nature is unknown. Another cosmological problem is the lithium problems in Big Bang Nucleosynthesis describing the production of light elements in the first seconds of the Universe. The lithium abundance predicted by the theory is inconsistent with observations. I study a scenario in which a supersymmetric particle, the gravitino, is the candidate for dark matter and the production of this particle through the decay of other supersymmetric particles may solve the lithium problems. (author)

  11. Big bang darkleosynthesis

    Directory of Open Access Journals (Sweden)

    Gordan Krnjaic

    2015-12-01

    Full Text Available In a popular class of models, dark matter comprises an asymmetric population of composite particles with short range interactions arising from a confined nonabelian gauge group. We show that coupling this sector to a well-motivated light mediator particle yields efficient darkleosynthesis, a dark-sector version of big-bang nucleosynthesis (BBN, in generic regions of parameter space. Dark matter self-interaction bounds typically require the confinement scale to be above ΛQCD, which generically yields large (≫MeV/dark-nucleon binding energies. These bounds further suggest the mediator is relatively weakly coupled, so repulsive forces between dark-sector nuclei are much weaker than Coulomb repulsion between standard-model nuclei, which results in an exponential barrier-tunneling enhancement over standard BBN. Thus, darklei are easier to make and harder to break than visible species with comparable mass numbers. This process can efficiently yield a dominant population of states with masses significantly greater than the confinement scale and, in contrast to dark matter that is a fundamental particle, may allow the dominant form of dark matter to have high spin (S≫3/2, whose discovery would be smoking gun evidence for dark nuclei.

  12. Inhomogeneous Big Bang Cosmology

    CERN Document Server

    Wagh, S M

    2002-01-01

    In this letter, we outline an inhomogeneous model of the Big Bang cosmology. For the inhomogeneous spacetime used here, the universe originates in the infinite past as the one dominated by vacuum energy and ends in the infinite future as the one consisting of "hot and relativistic" matter. The spatial distribution of matter in the considered inhomogeneous spacetime is {\\em arbitrary}. Hence, observed structures can arise in this cosmology from suitable "initial" density contrast. Different problems of the standard model of Big Bang cosmology are also resolved in the present inhomogeneous model. This inhomogeneous model of the Big Bang Cosmology predicts "hot death" for the universe.

  13. The Big Bang Singularity

    Science.gov (United States)

    Ling, Eric

    The big bang theory is a model of the universe which makes the striking prediction that the universe began a finite amount of time in the past at the so called "Big Bang singularity." We explore the physical and mathematical justification of this surprising result. After laying down the framework of the universe as a spacetime manifold, we combine physical observations with global symmetrical assumptions to deduce the FRW cosmological models which predict a big bang singularity. Next we prove a couple theorems due to Stephen Hawking which show that the big bang singularity exists even if one removes the global symmetrical assumptions. Lastly, we investigate the conditions one needs to impose on a spacetime if one wishes to avoid a singularity. The ideas and concepts used here to study spacetimes are similar to those used to study Riemannian manifolds, therefore we compare and contrast the two geometries throughout.

  14. Constraining Big Bang lithium production with recent solar neutrino data

    CERN Document Server

    Takács, Marcell P; Szücs, Tamás; Zuber, Kai

    2015-01-01

    The 3He({\\alpha},{\\gamma})7Be reaction affects not only the production of 7Li in Big Bang nucleosynthesis, but also the fluxes of 7Be and 8B neutrinos from the Sun. This double role is exploited here to constrain the former by the latter. A number of recent experiments on 3He({\\alpha},{\\gamma})7Be provide precise cross section data at E = 0.5-1.0 MeV center-of-mass energy. However, there is a scarcity of precise data at Big Bang energies, 0.1-0.5 MeV, and below. This problem can be alleviated, based on precisely calibrated 7Be and 8B neutrino fluxes from the Sun that are now available, assuming the neutrino flavour oscillation framework to be correct. These fluxes and the standard solar model are used here to determine the 3He(alpha,gamma)7Be astrophysical S-factor at the solar Gamow peak, S(23+6-5 keV) = 0.548+/-0.054 keVb. This new data point is then included in a re-evaluation of the 3He({\\alpha},{\\gamma})7Be S-factor at Big Bang energies, following an approach recently developed for this reaction in the c...

  15. Constraining big bang lithium production with recent solar neutrino data

    Science.gov (United States)

    Takács, Marcell P.; Bemmerer, Daniel; Szücs, Tamás; Zuber, Kai

    2015-06-01

    The 3He (α ,γ )7Be reaction affects not only the production of 7Li in big bang nucleosynthesis, but also the fluxes of 7Be and 8B neutrinos from the Sun. This double role is exploited here to constrain the former by the latter. A number of recent experiments on 3He α ,γ )7Be provide precise cross section data at E =0.5 - 1.0 MeV center-of-mass energies. However, there is a scarcity of precise data at big bang energies, 0.1-0.5 MeV, and below. This problem can be alleviated, based on precisely calibrated 7Be and 8B neutrino fluxes from the Sun that are now available, assuming the neutrino flavor oscillation framework to be correct. These fluxes and the standard solar model are used here to determine the 3He α ,γ )7Be astrophysical S -factor at the solar Gamow peak, S34ν(2 3-5+6 keV ) =0.548 ±0.054 keV b . This new data point is then included in a reevaluation of the 3He α ,γ )7Be S -factor at big bang energies, following an approach recently developed for this reaction in the context of solar fusion studies. The reevaluated S -factor curve is then used to redetermine the 3He α ,γ )7Be thermonuclear reaction rate at big bang energies. The predicted primordial lithium abundance is 7Li H =5.0 ×10-10 , far higher than the Spite plateau.

  16. The big bang

    Science.gov (United States)

    Silk, Joseph

    Our universe was born billions of years ago in a hot, violent explosion of elementary particles and radiation - the big bang. What do we know about this ultimate moment of creation, and how do we know it? Drawing upon the latest theories and technology, this new edition of The big bang, is a sweeping, lucid account of the event that set the universe in motion. Joseph Silk begins his story with the first microseconds of the big bang, on through the evolution of stars, galaxies, clusters of galaxies, quasars, and into the distant future of our universe. He also explores the fascinating evidence for the big bang model and recounts the history of cosmological speculation. Revised and updated, this new edition features all the most recent astronomical advances, including: Photos and measurements from the Hubble Space Telescope, Cosmic Background Explorer Satellite (COBE), and Infrared Space Observatory; the latest estimates of the age of the universe; new ideas in string and superstring theory; recent experiments on neutrino detection; new theories about the presence of dark matter in galaxies; new developments in the theory of the formation and evolution of galaxies; the latest ideas about black holes, worm holes, quantum foam, and multiple universes.

  17. The Big Bang

    CERN Multimedia

    Moods, Patrick

    2006-01-01

    How did the Universe begin? The favoured theory is that everything - space, time, matter - came into existence at the same moment, around 13.7 thousand million years ago. This event was scornfully referred to as the "Big Bang" by Sir Fred Hoyle, who did not believe in it and maintained that the Universe had always existed.

  18. Finding the big bang

    CERN Document Server

    Page, Lyman A; Partridge, R Bruce

    2009-01-01

    Cosmology, the study of the universe as a whole, has become a precise physical science, the foundation of which is our understanding of the cosmic microwave background radiation (CMBR) left from the big bang. The story of the discovery and exploration of the CMBR in the 1960s is recalled for the first time in this collection of 44 essays by eminent scientists who pioneered the work. Two introductory chapters put the essays in context, explaining the general ideas behind the expanding universe and fossil remnants from the early stages of the expanding universe. The last chapter describes how the confusion of ideas and measurements in the 1960s grew into the present tight network of tests that demonstrate the accuracy of the big bang theory. This book is valuable to anyone interested in how science is done, and what it has taught us about the large-scale nature of the physical universe.

  19. Big Bang 8

    CERN Document Server

    Apolin, Martin

    2008-01-01

    Physik soll verständlich sein und Spaß machen! Deshalb beginnt jedes Kapitel in Big Bang mit einem motivierenden Überblick und Fragestellungen und geht dann von den Grundlagen zu den Anwendungen, vom Einfachen zum Komplizierten. Dabei bleibt die Sprache einfach, alltagsorientiert und belletristisch. Band 8 vermittelt auf verständliche Weise Relativitätstheorie, Kern- und Teilchenphysik (und deren Anwendungen in der Kosmologie und Astrophysik), Nanotechnologie sowie Bionik.

  20. Big Bang 6

    CERN Document Server

    Apolin, Martin

    2008-01-01

    Physik soll verständlich sein und Spaß machen! Deshalb beginnt jedes Kapitel in Big Bang mit einem motivierenden Überblick und Fragestellungen und geht dann von den Grundlagen zu den Anwendungen, vom Einfachen zum Komplizierten. Dabei bleibt die Sprache einfach, alltagsorientiert und belletristisch. Der Band 6 RG behandelt die Gravitation, Schwingungen und Wellen, Thermodynamik und eine Einführung in die Elektrizität anhand von Alltagsbeispielen und Querverbindungen zu anderen Disziplinen.

  1. Big Bang 5

    CERN Document Server

    Apolin, Martin

    2007-01-01

    Physik soll verständlich sein und Spaß machen! Deshalb beginnt jedes Kapitel in Big Bang mit einem motivierenden Überblick und Fragestellungen und geht dann von den Grundlagen zu den Anwendungen, vom Einfachen zum Komplizierten. Dabei bleibt die Sprache einfach, alltagsorientiert und belletristisch. Der Band 5 RG behandelt die Grundlagen (Maßsystem, Größenordnungen) und die Mechanik (Translation, Rotation, Kraft, Erhaltungssätze).

  2. Big Bang 7

    CERN Document Server

    Apolin, Martin

    2008-01-01

    Physik soll verständlich sein und Spaß machen! Deshalb beginnt jedes Kapitel in Big Bang mit einem motivierenden Überblick und Fragestellungen und geht dann von den Grundlagen zu den Anwendungen, vom Einfachen zum Komplizierten. Dabei bleibt die Sprache einfach, alltagsorientiert und belletristisch. In Band 7 werden neben einer Einführung auch viele aktuelle Aspekte von Quantenmechanik (z. Beamen) und Elektrodynamik (zB Elektrosmog), sowie die Klimaproblematik und die Chaostheorie behandelt.

  3. Big Bang Circus

    Science.gov (United States)

    Ambrosini, C.

    2011-06-01

    Big Bang Circus is an opera I composed in 2001 and which was premiered at the Venice Biennale Contemporary Music Festival in 2002. A chamber group, four singers and a ringmaster stage the story of the Universe confronting and interweaving two threads: how early man imagined it and how scientists described it. Surprisingly enough fancy, myths and scientific explanations often end up using the same images, metaphors and sometimes even words: a strong tension, a drumskin starting to vibrate, a shout…

  4. Passport to the Big Bang

    CERN Multimedia

    De Melis, Cinzia

    2013-01-01

    Le 2 juin 2013, le CERN inaugure le projet Passeport Big Bang lors d'un grand événement public. Affiche et programme. On 2 June 2013 CERN launches a scientific tourist trail through the Pays de Gex and the Canton of Geneva known as the Passport to the Big Bang. Poster and Programme.

  5. The Last Big Bang

    Energy Technology Data Exchange (ETDEWEB)

    McGuire, Austin D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meade, Roger Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-13

    As one of the very few people in the world to give the “go/no go” decision to detonate a nuclear device, Austin “Mac” McGuire holds a very special place in the history of both the Los Alamos National Laboratory and the world. As Commander of Joint Task Force Unit 8.1.1, on Christmas Island in the spring and summer of 1962, Mac directed the Los Alamos data collection efforts for twelve of the last atmospheric nuclear detonations conducted by the United States. Since data collection was at the heart of nuclear weapon testing, it fell to Mac to make the ultimate decision to detonate each test device. He calls his experience THE LAST BIG BANG, since these tests, part of Operation Dominic, were characterized by the dramatic displays of the heat, light, and sounds unique to atmospheric nuclear detonations – never, perhaps, to be witnessed again.

  6. Probing the Big Bang with LEP

    Science.gov (United States)

    Schramm, David N.

    1990-01-01

    It is shown that LEP probes the Big Bang in two significant ways: (1) nucleosynthesis, and (2) dark matter constraints. In the first case, LEP verifies the cosmological standard model prediction on the number of neutrino types, thus strengthening the conclusion that the cosmological baryon density is approximately 6 percent of the critical value. In the second case, LEP shows that the remaining non-baryonic cosmological matter must be somewhat more massive and/or more weakly interacting than the favorite non-baryonic dark matter candidates of a few years ago.

  7. Probing the Big Bang with LEP

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Chicago Univ., IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))

    1990-06-01

    It is shown that LEP probes the Big Bang in two significant ways: (1) nucleosynthesis and (2) dark matter constraints. In the first case, LEP verifies the cosmological standard model prediction on the number of neutrino types, thus strengthening the conclusion that the cosmological baryon density is {approximately}6% of the critical value. In the second case, LEP shows that the remaining non-baryonic cosmological matter must be somewhat more massive and/or more weakly interacting that the favorite non-baryonic dark matter candidates of a few years ago. 59 refs., 4 figs., 2 tabs.

  8. Big Bang of Massenergy and Negative Big Bang of Spacetime

    Science.gov (United States)

    Cao, Dayong

    2017-01-01

    There is a balance between Big Bang of Massenergy and Negative Big Bang of Spacetime in the universe. Also some scientists considered there is an anti-Big Bang who could produce the antimatter. And the paper supposes there is a structure balance between Einstein field equation and negative Einstein field equation, a balance between massenergy structure and spacetime structure, a balance between an energy of nucleus of the stellar matter and a dark energy of nucleus of the dark matter-dark energy, and a balance between the particle and the wave-a balance system between massenergy (particle) and spacetime (wave). It should explain of the problems of the Big Bang. http://meetings.aps.org/Meeting/APR16/Session/M13.8

  9. Was There A Big Bang?

    CERN Document Server

    Soberman, Robert K

    2008-01-01

    The big bang hypothesis is widely accepted despite numerous physics conflicts. It rests upon two experimental supports, galactic red shift and the cosmic microwave background. Both are produced by dark matter, shown here to be hydrogen dominated aggregates with a few percent of helium nodules. Scattering from these non-radiating intergalactic masses produce a red shift that normally correlates with distance. Warmed by our galaxy to an Eigenvalue of 2.735 K, drawn near the Earth, these bodies, kept cold by ablation, resonance radiate the Planckian microwave signal. Several tests are proposed that will distinguish between this model and the big bang.

  10. 淀粉Big Bang!

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Big Bang,也叫"大爆炸",指的是宇宙诞生时期从密度极大且温度极高的太初状态开始发生不断膨胀的过程。换句话说,从Big Bang开始,我们现在的宇宙慢慢形成了。0K,从本期开始,"少电"将在微博引发Big Bang!——淀粉大爆炸!具体怎么爆呢?我想,看到本页版式的你已经明白了七八分了吧?

  11. Big Bang nucleosynthesis with a stiff fluid

    CERN Document Server

    Dutta, Sourish

    2010-01-01

    Models that lead to a cosmological stiff fluid component, with a density $\\rho_S$ that scales as $a^{-6}$, where $a$ is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking $\\rho_{S10}$ and $\\rho_{R10}$ to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at $T = 10$ MeV, we find that the change in the primordial helium abundance is well-fit by $\\Delta Y_p = 0.00024(\\rho_{S10}/\\rho_{R10})$. The changes in the helium-4 abundance produced by ad...

  12. An embedding for the big bang

    Science.gov (United States)

    Wesson, Paul S.

    1994-01-01

    A cosmological model is given that has good physical properties for the early and late universe but is a hypersurface in a flat five-dimensional manifold. The big bang can therefore be regarded as an effect of a choice of coordinates in a truncated higher-dimensional geometry. Thus the big bang is in some sense a geometrical illusion.

  13. Baryon symmetric big bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1978-01-01

    Both the quantum theory and Einsteins theory of special relativity lead to the supposition that matter and antimatter were produced in equal quantities during the big bang. It is noted that local matter/antimatter asymmetries may be reconciled with universal symmetry by assuming (1) a slight imbalance of matter over antimatter in the early universe, annihilation, and a subsequent remainder of matter; (2) localized regions of excess for one or the other type of matter as an initial condition; and (3) an extremely dense, high temperature state with zero net baryon number; i.e., matter/antimatter symmetry. Attention is given to the third assumption, which is the simplest and the most in keeping with current knowledge of the cosmos, especially as pertains the universality of 3 K background radiation. Mechanisms of galaxy formation are discussed, whereby matter and antimatter might have collided and annihilated each other, or have coexisted (and continue to coexist) at vast distances. It is pointed out that baryon symmetric big bang cosmology could probably be proved if an antinucleus could be detected in cosmic radiation.

  14. Georges et le big bang

    CERN Document Server

    Hawking, Lucy; Parsons, Gary

    2011-01-01

    Georges et Annie, sa meilleure amie, sont sur le point d'assister à l'une des plus importantes expériences scientifiques de tous les temps : explorer les premiers instants de l'Univers, le Big Bang ! Grâce à Cosmos, leur super ordinateur, et au Grand Collisionneur de hadrons créé par Éric, le père d'Annie, ils vont enfin pouvoir répondre à cette question essentielle : pourquoi existons nous ? Mais Georges et Annie découvrent qu'un complot diabolique se trame. Pire, c'est toute la recherche scientifique qui est en péril ! Entraîné dans d'incroyables aventures, Georges ira jusqu'aux confins de la galaxie pour sauver ses amis...Une plongée passionnante au coeur du Big Bang. Les toutes dernières théories de Stephen Hawking et des plus grands scientifiques actuels.

  15. Primordial Nucleosynthesis

    CERN Document Server

    Coc, Alain

    2016-01-01

    Primordial or big bang nucleosynthesis (BBN) is now a parameter free theory whose predictions are in good overall agreement with observations. However, the 7Li calculated abundance is significantly higher than the one deduced from spectroscopic observations. Most solutions to this lithium problem involve a source of extra neutrons that inevitably leads to an increase of the deuterium abundance. This seems now to be excluded by recent deuterium observations that have drastically reduced the uncertainty on D/H and also calls for improved precision on thermonuclear reaction rates.

  16. Was the Big Bang hot?

    Science.gov (United States)

    Wright, E. L.

    1983-01-01

    Techniques for verifying the spectrum defined by Woody and Richards (WR, 1981), which serves as a base for dust-distorted models of the 3 K background, are discussed. WR detected a sharp deviation from the Planck curve in the 3 K background. The absolute intensity of the background may be determined by the frequency dependence of the dipole anisotropy of the background or the frequency dependence effect in galactic clusters. Both methods involve the Doppler shift; analytical formulae are defined for characterization of the dipole anisotropy. The measurement of the 30-300 GHz spectra of cold galactic dust may reveal the presence of significant amounts of needle-shaped grains, which would in turn support a theory of a cold Big Bang.

  17. George and the big bang

    CERN Document Server

    Hawking, Lucy; Parsons, Gary

    2012-01-01

    George has problems. He has twin baby sisters at home who demand his parents’ attention. His beloved pig Freddy has been exiled to a farm, where he’s miserable. And worst of all, his best friend, Annie, has made a new friend whom she seems to like more than George. So George jumps at the chance to help Eric with his plans to run a big experiment in Switzerland that seeks to explore the earliest moment of the universe. But there is a conspiracy afoot, and a group of evildoers is planning to sabotage the experiment. Can George repair his friendship with Annie and piece together the clues before Eric’s experiment is destroyed forever? This engaging adventure features essays by Professor Stephen Hawking and other eminent physicists about the origins of the universe and ends with a twenty-page graphic novel that explains how the Big Bang happened—in reverse!

  18. Cosmic relics from the big bang

    Energy Technology Data Exchange (ETDEWEB)

    Hall, L.J.

    1988-12-01

    A brief introduction to the big bang picture of the early universe is given. Dark matter is discussed; particularly its implications for elementary particle physics. A classification scheme for dark matter relics is given. 21 refs., 11 figs., 1 tab.

  19. Primordial nucleosynthesis

    Science.gov (United States)

    Gustavino, C.; Anders, M.; Bemmerer, D.; Elekes, Z.; Trezzi, D.

    2016-04-01

    Big Bang nucleosynthesis (BBN) describes the production of light nuclei in the early phases of the Universe. For this, precise knowledge of the cosmological parameters, such as the baryon density, as well as the cross section of the fusion reactions involved are needed. In general, the energies of interest for BBN are so low ( E Big Bang nucleosynthesis using protons, 3He and alpha particles as projectiles. The main reaction studied in the past at LUNA is the 2H(4He, γ)6Li . Its cross section was measured directly, for the first time, in the BBN energy range. Other processes like 2H(p, γ)3He , 3He(2H, p)4He and 3He(4He, γ)7Be were also studied at LUNA, thus enabling to reduce the uncertainty on the overall reaction rate and consequently on the determination of primordial abundances. The improvements on BBN due to the LUNA experimental data will be discussed and a perspective of future measurements will be outlined.

  20. COBE looks back to the Big Bang

    Science.gov (United States)

    Mather, John C.

    1993-01-01

    An overview is presented of NASA-Goddard's Cosmic Background Explorer (COBE), the first NASA satellite designed to observe the primeval explosion of the universe. The spacecraft carries three extremely sensitive IR and microwave instruments designed to measure the faint residual radiation from the Big Bang and to search for the formation of the first galaxies. COBE's far IR absolute spectrophotometer has shown that the Big Bang radiation has a blackbody spectrum, proving that there was no large energy release after the explosion.

  1. Trojan Horse Method for neutrons-induced reaction studies

    Science.gov (United States)

    Gulino, M.; Asfin Collaboration

    2017-09-01

    Neutron-induced reactions play an important role in nuclear astrophysics in several scenario, such as primordial Big Bang Nucleosynthesis, Inhomogeneous Big Bang Nucleosynthesis, heavy-element production during the weak component of the s-process, explosive stellar nucleosynthesis. To overcome the experimental problems arising from the production of a neutron beam, the possibility to use the Trojan Horse Method to study neutron-induced reactions has been investigated. The application is of particular interest for reactions involving radioactive nuclei having short lifetime.

  2. Quantum nature of the big bang.

    Science.gov (United States)

    Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet

    2006-04-14

    Some long-standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big-bang singularity in loop quantum cosmology are significantly extended as follows: (i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the "emergent time" idea; (ii) the physical Hilbert space, Dirac observables, and semiclassical states are constructed rigorously; (iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the nonperturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime.

  3. One Second After the Big Bang

    CERN Document Server

    CERN. Geneva

    2014-01-01

    A new experiment called PTOLEMY (Princeton Tritium Observatory for Light, Early-Universe, Massive-Neutrino Yield) is under development at the Princeton Plasma Physics Laboratory with the goal of challenging one of the most fundamental predictions of the Big Bang – the present-day existence of relic neutrinos produced less than one second after the Big Bang. Using a gigantic graphene surface to hold 100 grams of a single-atomic layer of tritium, low noise antennas that sense the radio waves of individual electrons undergoing cyclotron motion, and a massive array of cryogenic sensors that sit at the transition between normal and superconducting states, the PTOLEMY project has the potential to challenge one of the most fundamental predictions of the Big Bang, to potentially uncover new interactions and properties of the neutrinos, and to search for the existence of a species of light dark matter known as sterile neutrinos.

  4. Big Bang riddles and their revelations

    CERN Document Server

    Magueijo, J; Magueijo, Joao; Baskerville, Kim

    1999-01-01

    We describe how cosmology has converged towards a beautiful model of the Universe: the Big Bang Universe. We praise this model, but show there is a dark side to it. This dark side is usually called ``the cosmological problems'': a set of coincidences and fine tuning features required for the Big Bang Universe to be possible. After reviewing these ``riddles'' we show how they have acted as windows into the very early Universe, revealing new physics and new cosmology just as the Universe came into being. We describe inflation, pre Big Bang, and varying speed of light theories. At the end of the millennium, these proposals are seen respectively as a paradigm, a tentative idea, and outright speculation.

  5. The 7Be(d,p)2alpha cross section at Big Bang energies and the primordial 7Li abundance

    CERN Document Server

    Angulo, C; Couder, M; Demaret, P; Leleux, P; Vanderbist, F; Coc, A; Kiener, J; Tatischeff, V; Davinson, T; Murphy, A S; Achouri, N L; Orr, N A; Cortina-Gil, D; Figuera, P; Fulton, B R; Mukha, I; Vangioni, E

    2005-01-01

    The WMAP satellite, devoted to the observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, has recently provided a determination of the baryonic density of the Universe with unprecedented precision. Using this, Big Bang Nucleosynthesis (BBN) calculations predict a primordial 7Li abundance which is a factor 2-3 higher than that observed in galactic halo dwarf stars. It has been argued that this discrepancy could be resolved if the 7Be(d,p)2alpha reaction rate is around a factor of 100 larger than has previously been considered. We have now studied this reaction, for the first time at energies appropriate to the Big Bang environment, at the CYCLONE radioactive beam facility at Louvain-la-Neuve. The cross section was found to be a factor of 10 smaller than derived from earlier measurements. It is concluded therefore that nuclear uncertainties cannot explain the discrepancy between observed and predicted primordial 7Li abundances, and an alternative astrophysical solution must be inve...

  6. How quantum is the big bang?

    Science.gov (United States)

    Bojowald, Martin

    2008-06-06

    When quantum gravity is used to discuss the big bang singularity, the most important, though rarely addressed, question is what role genuine quantum degrees of freedom play. Here, complete effective equations are derived for isotropic models with an interacting scalar to all orders in the expansions involved. The resulting coupling terms show that quantum fluctuations do not affect the bounce much. Quantum correlations, however, do have an important role and could even eliminate the bounce. How quantum gravity regularizes the big bang depends crucially on properties of the quantum state.

  7. "Big Bang" project put off to 2008

    CERN Multimedia

    Evans, Robert

    2007-01-01

    "First tests in a scientific project aimed at solving myteries of the universe and the "Big Bang" that created it have been put off from November to late April or early May next year, an official said on Wednesday" (1/2 page)

  8. Lifting gear crucial in Big Bang experiment

    CERN Multimedia

    2007-01-01

    "On November 26 2007, the most complex scientific instrument ever built will be turned on in an attempt to rerun the Big Bang - but i would never have got off the ground - litteraly - without the hundreds of hoists and cranes on site." (1/2 page)

  9. The Big Bang (one more time)

    CERN Multimedia

    Spotts, P

    2002-01-01

    For 20 years, Paul Steinhardt has played a key role in helping to write and refine the inflationary "big bang" origin of the universe. But over the past few years, he decided to see if he could come up with a plausible alternative to the prevailing notion (1 page).

  10. Teoria del Big Bang e buchi neri

    CERN Document Server

    Wald, Robert M

    1980-01-01

    Un giovane fisico americano delinea con chiarezza in questo volume le attuali concezioni dello spazio, del tempo e della gravitazione, cosi come si sono andate delineando dopo e innovazioni teoriche aperte da Einstein. Esse investono problemi affascinanti, come la teoria del big bang, da cui avrebbe avuto origine l'universo, e l'enigma dei buchi neri.

  11. Gamma-rays and the case for baryon symmetric big-bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1977-01-01

    The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1-200 MeV range, and a mechanism for galaxy formation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.

  12. Science Big Bang comes to the Alps

    CERN Multimedia

    2008-01-01

    The most extensive and expensive scientific instrument in history is due to start working this summer at Cern, the European particle physics laboratory near Geneva. Two beams of protons will accelerate in opposite directions around a 27km tunnel under the Alpine foothills until they are travelling almost at the speed of light - and then smash together, reproducing on a tiny scale the intense energy of the new-born universe after the inaugural Big Bang 15bn years ago.

  13. Science: Big Bang comes to the Alps

    CERN Multimedia

    Cookson, Clive

    2008-01-01

    "The most extensive and expensive scientific instrument in history is due to start working this summer at CERN, the European particle physics laboratory near Geneva. Two beams of protons will accelerate in opposite directions around a 27 km tunnel under the alpine foothills until they are travelling almost at the speed of light - and then smash together, reproducing on a tiny scale the intense energy of the new-born universe after the inaugural Big Bang 15bn years ago. (1 page)

  14. Singularities in big-bang cosmology

    Science.gov (United States)

    Penrose, R.

    1988-03-01

    A review of the history of the development of the big bang theory is presented, including the nature of singularities in black holes and their contribution to the study of the origin of the universe. Various models of the origin of the universe, the question of cosmic censorship, and the possible effects of gravitational collapse are examined. The relationship between considerations of quantum gravity and the structure of quantum theory is discussed.

  15. Rotational inhomogeneities from pre-big bang?

    CERN Document Server

    Giovannini, Massimo

    2005-01-01

    The evolution of the rotational inhomogeneities is investigated in the specific framework of four-dimensional pre-big bang models. While minimal (dilaton-driven) scenarios do not lead to rotational fluctuations, in the case of non-minimal (string-driven) models, fluid sources are present in the pre-big bang phase. The rotational modes of the geometry, coupled to the divergenceless part of the velocity field, can then be amplified depending upon the value of the barotropic index of the perfect fluids. In the light of a possible production of rotational inhomogeneities, solutions describing the coupled evolution of the dilaton field and of the fluid sources are scrutinized in both the string and Einstein frames. In semi-realistic scenarios, where the curvature divergences are regularized by means of a non-local dilaton potential, the rotational inhomogeneities are amplified during the pre-big bang phase but they decay later on. Similar analyses can also be performed when a contraction occurs directly in the str...

  16. Primordial nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Gustavino, C. [INFN, Sezione di Roma La Sapienza, Roma (Italy); Anders, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Bemmerer, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Elekes, Z. [Institute for Nuclear Research of the Hungarian Academy of Sciences (MTA Atomki), Debrecen (Hungary); Trezzi, D. [Universita degli Studi di Milano (Italy); INFN, Milano (Italy)

    2016-04-15

    Big Bang nucleosynthesis (BBN) describes the production of light nuclei in the early phases of the Universe. For this, precise knowledge of the cosmological parameters, such as the baryon density, as well as the cross section of the fusion reactions involved are needed. In general, the energies of interest for BBN are so low (E < 1 MeV) that nuclear cross section measurements are practically unfeasible at the Earth's surface. As of today, LUNA (Laboratory for Underground Nuclear Astrophysics) has been the only facility in the world available to perform direct measurements of small cross section in a very low background radiation. Owing to the background suppression provided by about 1400 meters of rock at the Laboratori Nazionali del Gran Sasso (LNGS), Italy, and to the high current offered by the LUNA accelerator, it has been possible to investigate cross sections at energies of interest for Big Bang nucleosynthesis using protons, {sup 3}He and alpha particles as projectiles. The main reaction studied in the past at LUNA is the {sup 2}H({sup 4}He, γ){sup 6}Li. Its cross section was measured directly, for the first time, in the BBN energy range. Other processes like {sup 2}H(p, γ){sup 3}He, {sup 3}He({sup 2}H, p){sup 4}He and {sup 3}He({sup 4}He, γ){sup 7}Be were also studied at LUNA, thus enabling to reduce the uncertainty on the overall reaction rate and consequently on the determination of primordial abundances. The improvements on BBN due to the LUNA experimental data will be discussed and a perspective of future measurements will be outlined. (orig.)

  17. Effects of variation of fundamental constants from Big Bang to atomic clocks

    Science.gov (United States)

    Flambaum, Victor

    2004-05-01

    Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental "constants" in expanding Universe. I discuss effects of variation of the fine structure constant, strong interaction, quark mass and gravitational constant. The measurements of these variations cover the lifespan of the Universe from few minutes after Big Bang to the present time and give controversial results. There are some hints for the variations in Big Bang nucleosynthesis, quasar absorption spectra and Oklo natural nuclear reactor data. A very promising method to search for the variation of the fundamental constants consists in comparison of different atomic clocks. A billion times enhancement of the variation effects happens in transitions between accidentally degenerate atomic energy levels.

  18. Nuclear Receptors, RXR, and the Big Bang.

    Science.gov (United States)

    Evans, Ronald M; Mangelsdorf, David J

    2014-03-27

    Isolation of genes encoding the receptors for steroids, retinoids, vitamin D, and thyroid hormone and their structural and functional analysis revealed an evolutionarily conserved template for nuclear hormone receptors. This discovery sparked identification of numerous genes encoding related proteins, termed orphan receptors. Characterization of these orphan receptors and, in particular, of the retinoid X receptor (RXR) positioned nuclear receptors at the epicenter of the "Big Bang" of molecular endocrinology. This Review provides a personal perspective on nuclear receptors and explores their integrated and coordinated signaling networks that are essential for multicellular life, highlighting the RXR heterodimer and its associated ligands and transcriptional mechanism.

  19. Echoes of Big Bang Found in Galaxies

    Institute of Scientific and Technical Information of China (English)

    Mark; Peplow; 吴铭

    2005-01-01

    想了解宇宙的奥秘吗?英澳等国的天文学家近日共同破解了宇宙大爆炸(BigBang)后物质如何分布的秘密,声称物质非平均分布的原因在于宇宙波纹和重力的共同作用,并对早期雾状宇宙的混沌状态如何发展到如今的状况做出了解释。

  20. Pre - big bang inflation requires fine tuning

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Michael S. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Weinberg, Erick J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    1997-10-01

    The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.

  1. Nucleosynthesis by photon-induced reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mohr, P. E-mail: mohr@ikpAu-darmstadt.de; Babilon, M.; Galaviz, D.; Sonnabend, K.; Vogt, K.; Zilges, A

    2003-05-19

    Similar to the well-known Gamow window for charged particle induced reactions, there exists an effective energy window for photon-induced reactions. Properties of this window are discussed in detail for ({gamma}, n) and ({gamma}, {alpha}) reactions. These reactions are important for the nucleosynthesis of rare neutron-deficient p nuclei.

  2. First direct measurement of the 2H(α,γ)6Li cross section at big bang energies and the primordial lithium problem.

    Science.gov (United States)

    Anders, M; Trezzi, D; Menegazzo, R; Aliotta, M; Bellini, A; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Prati, P; Rossi Alvarez, C; Scott, D A; Somorjai, E; Straniero, O; Szücs, T

    2014-07-25

    Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature.

  3. The Whole Shebang: How Science Produced the Big Bang Model.

    Science.gov (United States)

    Ferris, Timothy

    2002-01-01

    Offers an account of the accumulation of evidence that has led scientists to have confidence in the big bang theory of the creation of the universe. Discusses the early work of Ptolemy, Copernicus, Kepler, Galileo, and Newton, noting the rise of astrophysics, and highlighting the birth of the big bang model (the cosmic microwave background theory…

  4. Quarks, leptons and the big bang

    CERN Document Server

    Allday, Jonathan

    2016-01-01

    Quarks, Leptons and The Big Bang, Third Edition, is a clear, readable and self-contained introduction to particle physics and related areas of cosmology. It bridges the gap between non-technical popular accounts and textbooks for advanced students. The book concentrates on presenting the subject from the modern perspective of quarks, leptons and the forces between them. This book will be of interest to students, teachers and general science readers interested in fundamental ideas of modern physics. This edition brings the book completely up to date by including advances in particle physics and cosmology, such as the discovery of the Higgs boson, the LIGO gravitational wave discovery and the WMAP and PLANCK results.

  5. L'Univers avant le Big Bang

    CERN Multimedia

    Rouat, Sylvie

    2003-01-01

    "Tout n'a pas commencé par une explosion. L'historie du cosmos avait débuté biena vant le Big Bang, si l'on suit la théorie défendue par les partisans d'une nouvelle cosmologie issue de la mystérieuse théorie des cordes. A l'heure où vacillent les scénarios classiques du XXe siècle, se prépare un grand chamboulement de nos idées sur la naissance de l'Univers et son devenir, sur l'existence possible d'univers parallèles. Des théories séduisantes qui seront mises à l'épreuve au cours de la prochaine décennie" (11 pages)

  6. Gamma rays and the case for baryon symmetric big-bang cosmology

    Science.gov (United States)

    Stecker, F. W.

    1977-01-01

    The baryon symmetric big-bang cosmologies offer an explanation of the present photon-baryon ratio in the universe, the best present explanation of the diffuse gamma-ray background spectrum in the 1 to 200 MeV range, and a mechanism for galaxy formation. In the context of an open universe model, the value of omega which best fits the present gamma-ray data is omega equals approx. 0.1 which does not conflict with upper limits on Comptonization distortion of the 3K background radiation. In regard to He production, evidence is discussed that nucleosynthesis of He may have taken place after the galaxies were formed.

  7. Estudiarán el Big Bang por Internet

    CERN Multimedia

    2007-01-01

    The most powerful Internet, star of the present, goes for another challenge that mixes past and future: to join the scientific world community to clarify the orígines of the universe, the Big Bang. (1/2 page)

  8. L'antimatière questionne toujours le Big Bang

    CERN Multimedia

    Daninos, Franck

    2005-01-01

    A few moments after the Big Bang, matter and antimatter were created in the same quantities. But, the actual Universe is made only from matter. Will the problem of disappearance of the antimatter be solved? (4 pages)

  9. Big Bang test delayed at CERN's LHC until 2008

    CERN Multimedia

    Atkins, William

    2007-01-01

    "Scientists at the proton-proton Large Hadron Collider (LHC) particle accelerator and collider will postpone a test that could help solve the mystery of what happened a few nanoseconds after the Big Bang." (1 page)

  10. Scientists seek to explain how Big Bang let us live

    CERN Multimedia

    Hawke, N

    2000-01-01

    Scientists at CERN have opened an antimatter factory, the Antiproton Decelerator. They hope to discover why, in the Big Bang, the amount of matter and antimatter produced was not equal, so allowing the universe to exist at all (1 page).

  11. Indian microchip for Big Bang research in Geneva

    CERN Multimedia

    Bhabani, Soudhriti

    2007-01-01

    "A premier nuclear physics institute here has come up with India's first indigenously designed microchip that will facilitate research on the Big Bang theory in Geneva's CERN, the world's largest particle physics laboratory." (1 page)

  12. Big Bang Nucleosynthesis in Visible and Hidden-Mirror Sectors

    Directory of Open Access Journals (Sweden)

    Paolo Ciarcelluti

    2014-01-01

    dark matter. The production of ordinary nuclides shows differences from the standard model for a ratio of the temperatures between mirror and ordinary sectors x=T′/T≳0.3, and they present an interesting decrease of the abundance of Li7. For the mirror nuclides, instead, one observes an enhanced production of He4, which becomes the dominant element for x≲0.5, and much larger abundances of heavier elements.

  13. Big-bang nucleosynthesis with high-energy photon injection

    Energy Technology Data Exchange (ETDEWEB)

    Holtmann, Erich N. [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    The author discusses the photodissociation of light elements due to the radiative decay of a massive particle, and he has shown how to constrain the model parameters from the observed light-element abundances. He adopted two quasar absorption system (QAS) D/H values, as well as solar system data for D/H and 3He/H. For each of these, he used two 4He values. He presents his results in terms of the confidence level at which each theoretical parameter set (i.e., the set of properties of a radiatively decaying particle) is excluded by the observed abundances. His algorithm for computing the confidence level is consistent and general enough to apply not only to the scenarios investigated in this work, but also to many other non-standard theories of BBN.

  14. Passport to the Big Bang moves across the road

    CERN Multimedia

    Corinne Pralavorio

    2015-01-01

    The ATLAS platform of the Passport to the Big Bang circuit has been relocated in front of the CERN Reception.   The ATLAS platform of the Passport to the Big Bang, outside the CERN Reception building. The Passport to the Big Bang platform of the ATLAS Experiment has been moved in front of the CERN Reception to make it more visible and accessible. It had to be dismantled and moved from its previous location in the garden of the Globe of Science and Innovation due to the major refurbishment work in progress on the Globe, and is now fully operational in its new location on the other side of the road, in the Main Reception car-park. The Passport to the Big Bang circuit, inaugurated in 2013, comprises ten platforms installed in front of ten CERN sites and aims to help local residents and visitors to the region understand CERN's research. Dedicated Passport to the Big Bang flyers, containing all necessary information and riddles for you to solve, are available at the CERN Rec...

  15. Generating Ekpyrotic Curvature Perturbations Before the Big Bang

    CERN Document Server

    Lehners, J L; Steinhardt, P J; Turok, N G; Fadden, Paul Mc; Lehners, Jean-Luc; Steinhardt, Paul J.; Turok, Neil

    2007-01-01

    We analyze a general mechanism for producing a nearly scale-invariant spectrum of cosmological curvature perturbations during a contracting phase preceding a big bang, that can be entirely described using 4d effective field theory. The mechanism, based on first producing entropic perturbations and then converting them to curvature perturbations, can be naturally incorporated in cyclic and ekpyrotic models in which the big bang is modelled as a brane collision, as well as other types of cosmological models with a pre-big bang phase. We show that the correct perturbation amplitude can be obtained and that the scalar spectral tilt n tends to range from slightly blue to red, with 0.97 < n < 1.02 for the simplest models, a range compatible with current observations but shifted by a few per cent towards the blue compared to the prediction of the simplest, large-field inflationary models.

  16. "Beyond the Big Bang: a new view of cosmology"

    CERN Document Server

    CERN. Geneva

    2012-01-01

    and parameters? Can one conceive of a completion of the scenario which resolves the big bang singularity and explains the dark energy now coming to dominate? Are we forced to resort to anthropic explanations? In this talk, I will develop an alternate picture, in which the big bang singularity is resolved and in which the value of the dark energy might be fixed by physical processes. The key is a resolution of the singularity. Using a combination of arguments,involving M theory and holography as well as analytic continuation in time within the low energy effective theory, I argue that there is a unique way to match cosmic evolution across the big bang singularity. The latter is no longer the beginning of time but is instead the gateway to an eternal, cyclical universe. If time permits, I shall describe new work c...

  17. Reaction Sensitivity of r-Process Nucleosynthesis

    CERN Document Server

    Sasaqui, T; Mathews, G J; Otsuki, K; Nakamura, K; Sasaqui, Taka.

    2005-01-01

    We study the efficiency and sensitivity of r-process nucleosynthesis to a number of light nuclear reaction rates. We adopt empirical power-law relations to parameterize the reaction sensitivities. We utilize two different hydrodynamic models for the neutrino-driven winds in order to study the dependence of our result on supernova wind models. We also utilize an exponential model to approximate a wide variety of other plausible conditions for the r-process. We identify several specific nuclear reactions among light neutron-rich nuclei that play a critical role in determining the final r-process nucleosynthesis yields. As an illustration, we examine ``semi-waing'' points among the carbon isotopes. We show that not only neutron capture and $\\beta$-decay, but also $(\\alpha, \\mathrm{n})$ reactions are important in determining waiting points along the r-process path. Our numerical results from this sensitivity analysis serve foremost to clarify which light nuclear reactions are most influential in determining the f...

  18. The Standard Model Higgs as the origin of the hot Big Bang

    CERN Document Server

    Figueroa, Daniel G.

    2017-04-10

    If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation -- via non-perturbative effects -- into an out-of-equilibrium distribution of SM species, which thermalize soon afterwards. If the post-inflationary equation of state of the universe is stiff, $w \\simeq +1$, the SM species eventually dominate the total energy budget. This provides a natural origin for the relativistic thermal plasma of SM species, required for the onset the `hot Big Bang' era. The viability of this scenario requires the inflationary Hubble scale $H_*$ to be lower than the instability scale for Higgs vacuum decay, the Higgs not to generate too large curvature perturbations at cosmological scales, and the SM dominance to occur before Big Bang Nucleosynthesis. We show that successful reheating into the SM can only be obtained in the presence of a non-minimal coupling to gravity $\\x...

  19. The Standard Model Higgs as the origin of the hot Big Bang

    Science.gov (United States)

    Figueroa, Daniel G.; Byrnes, Christian T.

    2017-04-01

    If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation - via non-perturbative effects - into an out-of-equilibrium distribution of SM species, which thermalize soon afterwards. If the post-inflationary equation of state of the universe is stiff, w ≃ + 1, the SM species eventually dominate the total energy budget. This provides a natural origin for the relativistic thermal plasma of SM species, required for the onset of the 'hot Big Bang' era. The viability of this scenario requires the inflationary Hubble scale H* to be lower than the instability scale for Higgs vacuum decay, the Higgs not to generate too large curvature perturbations at cosmological scales, and the SM dominance to occur before Big Bang Nucleosynthesis. We show that successful reheating into the SM can only be obtained in the presence of a non-minimal coupling to gravity ξ ≳ 1, with a reheating temperature of TRH ≳ O (1010)ξ 3 / 2(H* /1014 GeV) 2 GeV.

  20. Beyond the Friedmann-Lemaatre-Robertson-Walker Big Bang Singularity

    Institute of Scientific and Technical Information of China (English)

    Cristi Stoica

    2012-01-01

    Einstein's equation,in its standard form,breaks down at the Big Bang singularity.A new version,equivalent to Einstein's whenever the latter is defined,but applicable in wider situations,is proposed.The new equation remains smooth at the Big Bang singularity of the Friedmann-Lemaatre-Robertson-Walker model.It is a tensor equation defined in terms of the Ricci part of the Riemann curvature.It is obtained by taking the Kulkarni-Nomizu product between Einstein's equation and the metric tensor.

  1. Baryon symmetric big-bang cosmology. [matter-antimatter symmetry

    Science.gov (United States)

    Stecker, F. W.

    1978-01-01

    The framework of baryon-symmetric big-bang cosmology offers the greatest potential for deducing the evolution of the universe as a consequence of physical laws and processes with the minimum number of arbitrary assumptions as to initial conditions in the big-bang. In addition, it offers the possibility of explaining the photon-baryon ratio in the universe and how galaxies and galaxy clusters are formed, and also provides the only acceptable explanation at present for the origin of the cosmic gamma ray background radiation.

  2. Film Presentation: The Big Bang Machine by BBC (2008)

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Professor Brian Cox visits Geneva to take a look around CERN's Large Hadron Collider before the vast, 27km long machine is sealed off and a simulation experiment begins to try to create the conditions that existed a billionth of a second after the Big Bang. Cox is joined by fellow scientists, including CERN theorist John Ellis and Nobel Laureate Leon Lederman from Fermilab, who hope that the LHC will change our understanding of the early Universe and solve some of its mysteries. The Big Bang Machine will be presented on Friday, 15 October from 13:00 to 14:00 in the Council Chamber, Bldg.503 Language: English

  3. On The Big Bang Singularity in $k=0$ FLRW Cosmologies

    CERN Document Server

    Kohli, Ikjyot Singh

    2016-01-01

    In this brief paper, we consider the dynamics of a spatially flat FLRW spacetime with a positive cosmological constant and matter obeying a barotropic equation of state. By performing a change of variables on the Raychaudhuri equation, we are able to compactify the big bang singularity to a finite point. We then use Chetaev's instability theorem to prove that such a model is always past asymptotic to a big bang singularity assuming only the weak energy condition, which is more general than the strong energy condition used in the classical singularity theorems of cosmology.

  4. Pre-big bang cosmology end of a myth?

    CERN Document Server

    Veneziano, Gabriele

    1999-01-01

    The myth according to which the Universe-and time itself-started with /near a big bang singularity is questioned. Superstring theory, through its duality symmetries, favours a pre- (rather than a post-) big bang solution to standard cosmology's puzzles. Sufficiently homogeneous, flat, and hot baby universes naturally spring out of asymptotically trivial (but otherwise generic) initial conditions, after a long period of dilaton-driven inflation. Several characteristic observable consequences should soon provide stringent tests of this new cosmological scenario. (30 refs).

  5. The Big Bang: UK Young Scientists' and Engineers' Fair 2010

    Science.gov (United States)

    Allison, Simon

    2010-01-01

    The Big Bang: UK Young Scientists' and Engineers' Fair is an annual three-day event designed to promote science, technology, engineering and maths (STEM) careers to young people aged 7-19 through experiential learning. It is supported by stakeholders from business and industry, government and the community, and brings together people from various…

  6. EMR implementation: big bang or a phased approach?

    Science.gov (United States)

    Owens, Kathleen

    2008-01-01

    There are two major strategies to implementing an EMR: the big-bang approach and the phased, or incremental, approach. Each strategy has pros and cons that must be considered. This article discusses these approaches and the risks and benefits of each as well as some training strategies that can be used with either approach.

  7. A Guided Inquiry on Hubble Plots and the Big Bang

    Science.gov (United States)

    Forringer, Ted

    2014-01-01

    In our science for non-science majors course "21st Century Physics," we investigate modern "Hubble plots" (plots of velocity versus distance for deep space objects) in order to discuss the Big Bang, dark matter, and dark energy. There are two potential challenges that our students face when encountering these topics for the…

  8. Recrean el Big Bang a nivel microscópico

    CERN Multimedia

    2007-01-01

    Although the scientists assure that the Universe was created from great explosion or Big Bang, that gave origin to the matter which we know today - including the alive beings - What happened after this strong snap is still a mystery regarding the formation of the cosmos. (1 page)

  9. HydraPower out to make a big bang

    CERN Multimedia

    Revill, John

    2006-01-01

    "An engineering company has provided equipment for a £1.3 billion international project to recreate the conditions of the 'Big Bang". Garry Williams, technical director of hydraPower dynamics, has been asked to return to Switzerland by CERN."

  10. Film Presentation: Big Bang, mes ancêtres et moi

    CERN Multimedia

    2010-01-01

    Big Bang, mes ancêtres et moi, by Franco-German TV producer ARTE (2009)   What do we know about the origins of the world today? This documentary presents a voyage into the mystery of these origins, accompanied by passionate scientists such as paleoanthropologist Pascal Picq, astrophysicist Hubert Reeves, physicist Etienne Klein and quantum gravity theorist Abhay Ashtekar. Organized around three key moments – the birth of the Universe, the appearance of life and the origins of mankind – this investigation takes us to various research areas around the world, including the large underground particle accelerator at CERN. The German version of this film, Big Bang im Labor, will be presented on 1st October. Big Bang, mes ancêtres et moi will be shown on Friday, 24 September from 13:00 to 14:00 in room 222-R-001 Language: French Big Bang im Labor will be shown on Friday, 1 October from 13:00 to 14:00 in the Main Auditorium Language : German   &nbs...

  11. A Guided Inquiry on Hubble Plots and the Big Bang

    Science.gov (United States)

    Forringer, Ted

    2014-01-01

    In our science for non-science majors course "21st Century Physics," we investigate modern "Hubble plots" (plots of velocity versus distance for deep space objects) in order to discuss the Big Bang, dark matter, and dark energy. There are two potential challenges that our students face when encountering these topics for the…

  12. Big Bang, Blowup, and Modular Curves: Algebraic Geometry in Cosmology

    Science.gov (United States)

    Manin, Yuri I.; Marcolli, Matilde

    2014-07-01

    We introduce some algebraic geometric models in cosmology related to the ''boundaries'' of space-time: Big Bang, Mixmaster Universe, Penrose's crossovers between aeons. We suggest to model the kinematics of Big Bang using the algebraic geometric (or analytic) blow up of a point x. This creates a boundary which consists of the projective space of tangent directions to x and possibly of the light cone of x. We argue that time on the boundary undergoes the Wick rotation and becomes purely imaginary. The Mixmaster (Bianchi IX) model of the early history of the universe is neatly explained in this picture by postulating that the reverse Wick rotation follows a hyperbolic geodesic connecting imaginary time axis to the real one. Penrose's idea to see the Big Bang as a sign of crossover from ''the end of previous aeon'' of the expanding and cooling Universe to the ''beginning of the next aeon'' is interpreted as an identification of a natural boundary of Minkowski space at infinity with the Big Bang boundary.

  13. Small wormholes change our picture of the big bang

    CERN Multimedia

    1990-01-01

    Matt Visser has studied tiny wormholes, which may be produced on a subatomic scale by quantum fluctuations in the energy of the vacuum. He believes these quantum wormholes could change our picture of the origin of the Universe in the big bang (1/2 p)

  14. Constructing "Nerdiness": Characterisation in "The Big Bang Theory"

    Science.gov (United States)

    Bednarek, Monika

    2012-01-01

    This paper analyses the linguistic construction of the televisual character Sheldon--the "main nerd" in the sitcom "The Big Bang Theory" (CBS, 2007-), approaching this construction of character through both computerised and "manual" linguistic analysis. More specifically, a computer analysis of dialogue (using concordances and keyword analysis) in…

  15. Cosmologie L'Univers avant le Big Bang

    CERN Multimedia

    Rouat, Sylvie

    2003-01-01

    Tout n'a pas commencé par une explosion. L'histoire du cosmos avait débuté bien avant le Big Bang, si l'on suit la théorie défendue par les partisans d'une nouvelle cosmologie issue de la mystérieuse théorie des cordes

  16. Adiabatic CMB perturbations in pre-big bang string cosmology

    DEFF Research Database (Denmark)

    Enqvist, Kari; Sloth, Martin Snoager

    2001-01-01

    We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations...

  17. Detection of pristine gas two billion years after the Big Bang.

    Science.gov (United States)

    Fumagalli, Michele; O'Meara, John M; Prochaska, J Xavier

    2011-12-02

    In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the lowest heavy-element abundance in the early universe, and thus are potential fuel for the most metal-poor halo stars. The detection of deuterium in one system at the level predicted by primordial nucleosynthesis provides a direct confirmation of the standard cosmological model. The composition of these clouds further implies that the transport of heavy elements from galaxies to their surroundings is highly inhomogeneous.

  18. Detection of Pristine Gas Two Billion Years after the Big Bang

    CERN Document Server

    Fumagalli, Michele; Prochaska, J Xavier

    2011-01-01

    In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the lowest heavy-element abundance in the early universe and thus are potential fuel for the most metal poor halo stars. The detection of deuterium in one system at the level predicted by primordial nucleosynthesis provides a direct confirmation of the standard cosmological model. The composition of these clouds further implies that the transport of heavy elements from galaxies to their surroundings is highly inhomogeneous.

  19. Quantifying uncertainties in primordial nucleosynthesis without Monte Carlo simulations

    CERN Document Server

    Fiorentini, G; Sarkar, S; Villante, F L

    1998-01-01

    We present a simple method for determining the (correlated) uncertainties of the light element abundances expected from big bang nucleosynthesis, which avoids the need for lengthy Monte Carlo simulations. Our approach helps to clarify the role of the different nuclear reactions contributing to a particular elemental abundance and makes it easy to implement energy-independent changes in the measured reaction rates. As an application, we demonstrate how this method simplifies the statistical estimation of the nucleon-to-photon ratio through comparison of the standard BBN predictions with the observationally inferred abundances.

  20. Determination of the Astrophysical S(E) Factors or Rates for Radiative Capture Reaction with One Nucleon Transfer Reaction%Determination of the Astrophysical S(E) Factors or Rates for Radiative Capture Reaction with One Nucleon Transfer Reaction

    Institute of Scientific and Technical Information of China (English)

    李志宏; 郭冰; 李云居; 苏俊; 李二涛; 白希祥; 王友宝; 曾晟; 王宝祥; 颜胜权; 李志常; 刘建成; 连钢; 金孙均; 刘鑫; 柳卫平

    2012-01-01

    The radiative capture reaction plays an important role in nuclear astrophysics. We have indirectly measured the astrophysical S(E) factors for some proton capture reactions and reaction rates for several neutron capture reactions with one nucleon transfer reactions at HI-13 tandem accelerator in recent years. Some of them are compiled into IAEA EXFOR database and JINA REACLIB project, and used in the network calculations of Big Bang nucleosynthesis and type-I X-ray bursts.

  1. Primordial beryllium as a big bang calorimeter.

    Science.gov (United States)

    Pospelov, Maxim; Pradler, Josef

    2011-03-25

    Many models of new physics including variants of supersymmetry predict metastable long-lived particles that can decay during or after primordial nucleosynthesis, releasing significant amounts of nonthermal energy. The hadronic energy injection in these decays leads to the formation of ⁹Be via the chain of nonequilibrium transformations: Energy(h)→T, ³He→⁶He, ⁶Li→⁹Be. We calculate the efficiency of this transformation and show that if the injection happens at cosmic times of a few hours the release of O(10 MeV) per baryon can be sufficient for obtaining a sizable ⁹Be abundance. The absence of a plateau structure in the ⁹Be/H abundance down to a O(10⁻¹⁴) level allows one to use beryllium as a robust constraint on new physics models with decaying or annihilating particles.

  2. Primordial Nucleosynthesis

    CERN Document Server

    Coc, Alain

    2012-01-01

    Primordial nucleosynthesis, or Big-Bang Nucleosynthesis (BBN), is one of the three evidences for the Big-Bang model, together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of 4He, D, 3He and 7Li deduced from observations, and calculated in primordial nucleosynthesis. This comparison was used to determine the baryonic density of the Universe. For this purpose, it is now superseded by the analysis of the Cosmic Microwave Background (CMB) radiation anisotropies. However, there remain, a yet unexplained, discrepancy of a factor 3-5, between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations. We review here the nuclear physics aspects of BBN for the production of 4He, D, 3He and 7Li, but also 6Li, 9Be, 11B and up to CNO isotopes. These are, for instance, important for the initial composition o...

  3. Quantization of Big Bang in crypto-Hermitian Heisenberg picture

    CERN Document Server

    Znojil, Miloslav

    2015-01-01

    A background-independent quantization of the Universe near its Big Bang singularity is considered using a drastically simplified toy model. Several conceptual issues are addressed. (1) The observable spatial-geometry characteristics of our empty-space expanding Universe is sampled by the time-dependent operator $Q=Q(t)$ of the distance between two space-attached observers (``Alice and Bob''). (2) For any pre-selected guess of the simple, non-covariant time-dependent observable $Q(t)$ one of the Kato's exceptional points (viz., $t=\\tau_{(EP)}$) is postulated {\\em real-valued}. This enables us to treat it as the time of Big Bang. (3) During our ``Eon'' (i.e., at all $t>\\tau_{(EP)}$) the observability status of operator $Q(t)$ is mathematically guaranteed by its self-adjoint nature with respect to an {\\em ad hoc} Hilbert-space metric $\\Theta(t) \

  4. Big Bang Day : The Great Big Particle Adventure - 3. Origins

    CERN Multimedia

    2008-01-01

    In this series, comedian and physicist Ben Miller asks the CERN scientists what they hope to find. If the LHC is successful, it will explain the nature of the Universe around us in terms of a few simple ingredients and a few simple rules. But the Universe now was forged in a Big Bang where conditions were very different, and the rules were very different, and those early moments were crucial to determining how things turned out later. At the LHC they can recreate conditions as they were billionths of a second after the Big Bang, before atoms and nuclei existed. They can find out why matter and antimatter didn't mutually annihilate each other to leave behind a Universe of pure, brilliant light. And they can look into the very structure of space and time - the fabric of the Universe

  5. Big Bang Day: 5 Particles - 3. The Anti-particle

    CERN Document Server

    Franck Close

    2008-01-01

    Simon Singh looks at the stories behind the discovery of 5 of the universe's most significant subatomic particles: the Electron, the Quark, the Anti-particle, the Neutrino and the "next particle". 3. The Anti-particle. It appears to be the stuff of science fiction. Associated with every elementary particle is an antiparticle which has the same mass and opposite charge. Should the two meet and combine, the result is annihilation - and a flash of light. Thanks to mysterious processes that occurred after the Big Bang there are a vastly greater number of particles than anti-particles. So how could their elusive existence be proved? At CERN particle physicists are crashing together subatomic particles at incredibly high speeds to create antimatter, which they hope will finally reveal what happened at the precise moment of the Big Bang to create the repertoire of elementary particles and antiparticles in existence today.

  6. The Shallow Waters of the Big-Bang

    CERN Document Server

    Laguna, P

    2006-01-01

    Loop quantum cosmology homogeneous models with a massless scalar field show that the big-bang singularity can be replaced by a big quantum bounce. To gain further insight on the nature of this bounce, we study the semi-discrete loop quantum gravity Hamiltonian constraint equation from the point of view of numerical analysis. We show that the bounce is closely related to the method for the temporal update of the system and demonstrate that, in particular, explicit time-updates in general yield bounces. These bounces can be understood as spurious reflections in finite difference discretizations of wave equations in nonuniform grids or, equivalently, as spurious reflections found when solving wave equations with varying coefficients, such as the shallow water equations. We present an implicit time-update devoid of bounces and show back-in-time, deterministic evolutions that reach and partially jump over the big-bang singularity.

  7. Expansion of the Universe - Standard Big Bang Model

    CERN Document Server

    Roos, Matts

    2008-01-01

    After a brief introduction to the sixteenth and seventeenth century views of the Universe and the nineteenth century paradox of Olbers, we start the history of the cosmic expansion with Hubble's epochal discovery of the recession velocities of spiral galaxies. By then Einstein's theories of relativity were well known, but no suitable metric was known. Prior to introducing General Relativity we embark on a non-chronological derivation of the Robertson-Walker metric directly from Special Relativity and the Minkowski metric endowed with a Gaussian curvature. This permits the definition of all relativistic distance measures needed in observational astronomy. Only thereafter do we come to General Relativity, and describe some of its consequences: gravitational lensing, black holes, various tests, and the cornerstone of the standard Big Bang model, the Friedmann-Lemaitre equations. Going backwards in time towards Big Bang we first have to trace the thermal history, and then understand the needs for a cosmic inflati...

  8. American Humor reflected in English Film The Big Bang Theory

    Institute of Scientific and Technical Information of China (English)

    刘珍

    2016-01-01

    With the accelerated process of globalization, we are able to access to the wide variety of cultural forms from all over the world conveniently. The United States, a typical country of immigrants, enjoys the world's first place of ethnic cultural melt-ing. In this paper, the writer takes popular sitcom, The Big Bang Theory, for example to explore the humorous culture of the United States as well as its sources and characteristics from the perspective of subtitle translation.

  9. Adiabatic CMB perturbations in pre-big bang string cosmology

    CERN Document Server

    Enqvist, Kari; Enqvist, Kari; Sloth, Martin S.

    2002-01-01

    We consider the pre-big bang scenario with a massive axion field which starts to dominate energy density when oscillating in an instanton-induced potential and subsequently reheats the universe as it decays into photons, thus creating adiabatic CMB perturbations. We find that the fluctuations in the axion field can give rise to a nearly flat spectrum of adiabatic perturbations with a spectral tilt $\\Delta n$ in the range $-0.1 \\lesssim \\Delta n \\lesssim 0.3$.

  10. Physicists create a "perfect" way to study the Big Bang

    CERN Multimedia

    2005-01-01

    Physicists have created the state of matter thought to have filled the Universe just a few microseconds after the big bang and found it to be different from what they were expecting: instead of a gas, it is more like a liquid. Understanding why it is a liquid that should take physicists a step closer to explaining the earliest moments of our Universe (1 ½ page)

  11. No ``explosion'' in Big Bang cosmology: teaching kids the truth of what cosmologists really know

    Science.gov (United States)

    Gangui, Alejandro

    2011-06-01

    Common wisdom says that cosmologists are smart: they have developed a theory that can explain the ``origin of the universe''. Every time an astro-related, heavily funded ``big-science'' project comes to the media, naturally the question arises: will science -through this or that experiment- explain the origin of the cosmos? Can this be done with the LHC, for example? Will this dream machine create other universes? Of course, the very words we employ in cosmology reinforce this misconception: so Big Bang must be associated with an ``explosion'', even if a ``peculiar'' one, as it took place nowhere (there was presumably no space before the beginning) and happened virtually in no time (supposedly, space-time was created on this peculiar -singular- event). Right, the issue sounds confusing. Let us imagine what kids may get out of all this. We have recently presented a series of brief astronomy and cosmology books aimed at helping both kids and their teachers in these and other arcane subjects, all introduced with carefully chosen words and images that young children can understand. In particular, Volume Four deals with the Big Bang and emphasizes the notion of ``evolution'' as opposed to the -wrong- notion of ``origin'' behind the scientific model. We then explain some of the pillars of Big Bang cosmology: the expansion of space that drags away distant galaxies, as seen in the redshift of their emitted light; the build-up of light elements in a cooling bath of radiation, as explained by primordial nucleosynthesis; and the existence and main features of the ubiquitous cosmic microwave background radiation, where theory and observations agree to a highly satisfactory degree. Of course, one cannot attempt to answer the ``origins'' question when it is well known that all theories so far break down close to this origin (if there was actually an origin). It is through observations, analyses, lively discussions and recognition of the basic limitations of current theories and

  12. Evidence for Evolution as Support for Big Bang

    Science.gov (United States)

    Gopal-Krishna

    1997-12-01

    With the exception of ZERO, the concept of BIG BANG is by far the most bizarre creation of the human mind. Three classical pillars of the Big Bang model of the origin of the universe are generally thought to be: (i) The abundances of the light elements; (ii) the microwave back-ground radiation; and (iii) the change with cosmic epoch in the average properties of galaxies (both active and non-active types). Evidence is also mounting for redshift dependence of the intergalactic medium, as discussed elsewhere in this volume in detail. In this contribution, I endeavour to highlight a selection of recent advances pertaining to the third category. The widely different levels of confidence in the claimed observational constraints in the field of cosmology can be guaged from the following excerpts from two leading astrophysicists: "I would bet odds of 10 to 1 on the validity of the general 'hot Big Bang' concept as a description of how our universe has evolved since it was around 1 sec. old" -M. Rees (1995), in 'Perspectives in Astrophysical Cosmology' CUP. "With the much more sensitive observations available today, no astrophysical property shows evidence of evolution, such as was claimed in the 1950s to disprove the Steady State theory" -F. Hoyle (1987), in 'Fifty years in cosmology', B. M. Birla Memorial Lecture, Hyderabad, India. The burgeoning multi-wavelength culture in astronomy has provided a tremendous boost to observational cosmology in recent years. We now proceed to illustrate this with a sequence of examples which reinforce the picture of an evolving universe. Also provided are some relevant details of the data used in these studies so that their scope can be independently judged by the readers.

  13. The case for the relativistic hot big bang cosmology

    Science.gov (United States)

    Peebles, P. J. E.; Schramm, D. N.; Kron, R. G.; Turner, E. L.

    1991-01-01

    What has become the standard model in cosmology is described, and some highlights are presented of the now substantial range of evidence that most cosmologists believe convincingly establishes this model, the relativistic hot big bang cosmology. It is shown that this model has yielded a set of interpretations and successful predictions that substantially outnumber the elements used in devising the theory, with no well-established empirical contradictions. Brief speculations are made on how the open puzzles and work in progress might affect future developments in this field.

  14. Making a Big Bang on the small screen

    Science.gov (United States)

    Thomas, Nick

    2010-01-01

    While the quality of some TV sitcoms can leave viewers feeling cheated out of 30 minutes of their lives, audiences and critics are raving about the science-themed US comedy The Big Bang Theory. First shown on the CBS network in 2007, the series focuses on two brilliant postdoc physicists, Leonard and Sheldon, who are totally absorbed by science. Adhering to the stereotype, they also share a fanatical interest in science fiction, video-gaming and comic books, but unfortunately lack the social skills required to connect with their 20-something nonacademic contemporaries.

  15. State of the Universe. If Not with a Big Bang, Then What?

    Science.gov (United States)

    Peterson, Ivars

    1991-01-01

    The Big Bang Theory and alternatives to the Big Bang Theory as an explanation for the origin of the universe are discussed. The importance of the discovery of redshift, the percentage of hydrogen found in old stars, and the existence of a uniform sea of radiation are explained. (KR)

  16. Light-like Big Bang singularities in string and matrix theories

    CERN Document Server

    Craps, Ben

    2011-01-01

    Important open questions in cosmology require a better understanding of the Big Bang singularity. In string and matrix theories, light-like analogues of cosmological singularities (singular plane wave backgrounds) turn out to be particularly tractable. We give a status report on the current understanding of such light-like Big Bang models, presenting both solved and open problems.

  17. Relationalism Evolves the Universe Through the Big Bang

    CERN Document Server

    Koslowski, Tim A; Sloan, David

    2016-01-01

    We investigate the singularities of homogeneous cosmologies from the point of view of relational (and physically relevant) degrees of freedom of the gravitational field. These do not depend on absolute units of length and duration - thus they do not include the volume and extrinsic curvature. We find that the fully relational dynamical system remains well posed for all physical times, even at the point that would be described as the big bang when evolving present day data backwards in time.This result is achieved in two steps: (1) for solutions which are gravity-dominated near the singularity, we show that any extended physical clock (whose readings only depend on the relational degrees of freedom) will undergo an infinite number of ticks before reaching the big bang. The singularity is therefore pushed into the infinite physical past of any physical clock. (2) for solutions where a stiff matter component (e.g. a massless scalar field) dominates at the singularity, we show that the relational degrees of freed...

  18. Re-evaluation of the immunological Big Bang.

    Science.gov (United States)

    Flajnik, Martin F

    2014-11-03

    Classically the immunological 'Big Bang' of adaptive immunity was believed to have resulted from the insertion of a transposon into an immunoglobulin superfamily gene member, initiating antigen receptor gene rearrangement via the RAG recombinase in an ancestor of jawed vertebrates. However, the discovery of a second, convergent adaptive immune system in jawless fish, focused on the so-called variable lymphocyte receptors (VLRs), was arguably the most exciting finding of the past decade in immunology and has drastically changed the view of immune origins. The recent report of a new lymphocyte lineage in lampreys, defined by the antigen receptor VLRC, suggests that there were three lymphocyte lineages in the common ancestor of jawless and jawed vertebrates that co-opted different antigen receptor supertypes. The transcriptional control of these lineages during development is predicted to be remarkably similar in both the jawless (agnathan) and jawed (gnathostome) vertebrates, suggesting that an early 'division of labor' among lymphocytes was a driving force in the emergence of adaptive immunity. The recent cartilaginous fish genome project suggests that most effector cytokines and chemokines were also present in these fish, and further studies of the lamprey and hagfish genomes will determine just how explosive the Big Bang actually was.

  19. Pre-Big Bang, fundamental Physics and noncyclic cosmologies

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres L.

    2014-04-01

    Full Text Available Detailed analyses of WMAP and Planck data can have significant implications for noncyclic pre-Big Bang approaches incorporating a new fundamental scale beyond the Planck scale and, potentially, new ultimate constituents of matter with unconventional basic properties as compared to standard particles. Cosmic-ray experiments at the highest energies can also yield relevant information. Hopefully, future studies will be able to deal with alternatives: i to standard physics for the structure of the physical vacuum, the nature of space-time, the validity of quantum field theory and conventional symmetries, the interpretation of string-like theories...; ii to standard cosmology concerning the origin and evolution of our Universe, unconventional solutions to the cosmological constant problem, the validity of inflationary scenarios, the need for dark matter and dark energy... Lorentz-like symmetries for the properties of matter can then be naturally stable space-time configurations resulting from more general primordial scenarios that incorporate physics beyond the Planck scale and describe the formation and evolution of the physical vacuum. A possible answer to the question of the origin of half-integer spins can be provided by a primordial spinorial space-time with two complex coordinates instead of the conventional four real ones, leading to a really new cosmology. We discuss basic questions and phenomenological topics concerning noncyclic pre-Big Bang cosmologies and potentially related physics.

  20. Big Bang pour le grand public - French version only

    CERN Multimedia

    2004-01-01

    Pour commémorer les 50 ans du CERN et l'année de la physique en 2005, la section de physique de l'Université de Genève ouvre une fois de plus ses portes aux non initiés et organise une série de conférences de vulgarisation scientifique. La première conférence, le 7 décembre prochain aura pour thème le Big-Bang et les observations qui corroborent cette théorie. Le Professeur Georges Meylan, Directeur du Laboratoire d'Astrophysique de l'EPFL, donnera cette conférence destinée à tous les publics. Chacune des conférences débutera par une démonstration de détection de rayons cosmiques dans l'auditoire et l'utilisation de ces signaux venus du fond de l'univers pour créer une ?musique cosmique', en collaboration avec le Professeur Ellberger et Nikolai Mihailov du conservatoire de musique de Genève. Ces processus cosmiques étant aléatoires, chacun de ces concerts sera unique. Les preuves observationnelles du Big Bang par le Professeur Georges Meylan Directeur du Laboratoire d'Astrophysique ...

  1. The big-bang theory: construction, evolution and status

    CERN Document Server

    Uzan, Jean-Philippe

    2016-01-01

    Over the past century, rooted in the theory of general relativity, cosmology has developed a very successful physical model of the universe: the {\\em big-bang model}. Its construction followed different stages to incorporate nuclear processes, the understanding of the matter present in the universe, a description of the early universe and of the large scale structure. This model has been confronted to a variety of observations that allow one to reconstruct its expansion history, its thermal history and the structuration of matter. Hence, what we refer to as the big-bang model today is radically different from what one may have had in mind a century ago. This construction changed our vision of the universe, both on observable scales and for the universe as a whole. It offers in particular physical models for the origins of the atomic nuclei, of matter and of the large scale structure. This text summarizes the main steps of the construction of the model, linking its main predictions to the observations that bac...

  2. From the Big Bang to the Nobel Prize

    Science.gov (United States)

    Mather, John

    2007-04-01

    The Cosmic Background Explorer (COBE) satellite, proposed in 1974 and launched by NASA in 1989, measured the cosmic microwave and infrared background radiation from the Big Bang and everything that happened later. The COBE team made three key measurements: the spectrum of the cosmic microwave background radiation (CMBR) matches a blackbody within 50 ppm (rms), the CMBR is anisotropic, with 10 ppm variations on a 7^o angular scale, and the cosmic infrared background from previously unknown objects is as bright as all the known classes of galaxies. The first measurement confirmed the Hot Big Bang theory with unprecedented accuracy, the second is interpreted as representing quantum mechanical fluctuations in the primordial soup and the seeds of cosmic structure and the basis for the existence of galaxies, and the third is still not fully understood. I will describe the project history, the team members, the hardware and data processing, the major results, and their implications for science, and end with the outlook for future progress with new background measurements and large telescopes.

  3. Cosmic inflation and big bang interpreted as explosions

    CERN Document Server

    Rebhan, Eckhard

    2012-01-01

    It has become common understanding that the recession of galaxies and the corresponding redshift of light received from them can only be explained by an expansion of the space between them and us. In this paper, for the presently favored case of a universe without spatial curvature, it is shown that this interpretation is restricted to comoving coordinates. It is proven by construction that within the framework of general relativity other coordinates exist in relation to which these phenomena can be explained by a motion of the cosmic substrate across space, caused by an explosion like big bang or by inflation preceding an almost big bang. At the place of an observer, this motion occurs without any spatial expansion. It is shown that in these "explosion coordinates" the usual redshift comes about by a Doppler shift and a subsequent gravitational shift. Making use of this interpretation, it can easily be understood why in comoving coordinates light rays of short spatial extensions expand and thus constitute an...

  4. The biological big bang: the first oceans of primordial planets at 2-8 million years explain Hoyle/Wickramasinghe cometary panspermia

    Science.gov (United States)

    Gibson, Carl H.

    2011-10-01

    Hydrogravitional-dynamics (HGD) cosmology of Gibson/Schild 1996 predicts that the primordial H-He4 gas of big bang nucleosynthesis became proto-globular-star-cluster clumps of Earth-mass planets at 300 Kyr. The first stars formed from mergers of these 3000 K gas planets. Chemicals C, N, O, Fe etc. created by stars and supernovae then seeded many of the reducing hydrogen gas planets with oxides to give them hot water oceans with metallic iron-nickel cores. Water oceans at critical temperature 647 K then hosted the first organic chemistry and the first life, distributed to the 1080 planets of the cosmological big bang by comets produced by the new (HGD) planet-merger star formation mechanism. The biological big bang scenario occurs between 2 Myr when liquid oceans condensed and 8 Myr when they froze. HGD cosmology explains, very naturally, the Hoyle/Wickramasinghe concept of cometary panspermia by giving a vast, hot, nourishing, cosmological primordial soup for abiogenesis, and the means for transmitting the resulting life forms and their evolving chemical mechanisms widely throughout the universe. A primordial astrophysical basis is provided for astrobiology by HGD cosmology. Concordance ΛCDMHC cosmology is rendered obsolete by the observation of complex life on Earth.

  5. The Biological Big Bang: The First Oceans of Primordial Planets at 2-8 Million Years Explain Hoyle/Wickramasinghe Cometary Panspermia

    CERN Document Server

    Gibson, Carl H

    2011-01-01

    Hydrogravitional-dynamics (HGD) cosmology of Gibson/Schild 1996 predicts that the primordial H-He^4 gas of big bang nucleosynthesis became proto-globular-star-cluster clumps of Earth-mass planets at 300 Kyr. The first stars formed from mergers of these 3000 K gas planets. Chemicals C, N, O, Fe etc. created by stars and supernovae then seeded many of the reducing hydrogen gas planets with oxides to give them hot water oceans with metallic iron-nickel cores. Water oceans at critical temperature 647 K then hosted the first organic chemistry and the first life, distributed to the 10^80 planets of the cosmological big bang by comets produced by the new (HGD) planet-merger star formation mechanism. The biological big bang scenario occurs between 2 Myr when liquid oceans condensed and 8 Myr when they froze. HGD cosmology explains, very naturally, the Hoyle/Wickramasinghe concept of cometary panspermia by giving a vast, hot, nourishing, cosmological primordial soup for abiogenesis, and the means for transmitting the ...

  6. The Biological Big Bang: The First Oceans of Primordial Planets at 2-8 Myr Explains Hoyle-Wickramasinghe Cometary Panspermia and a Primordial LUCA

    Science.gov (United States)

    Gibson, Carl H.; Wickramasinghe, N. C.; Schild, R. E.

    2011-10-01

    Hydrogravitional-dynamics (HGD) cosmology of Gibson/Schild 1996 predicts that the primordial H-He4 gas of big bang nucleosynthesis became proto-globular-star-cluster clumps of Earth-mass planets at 300 Kyr. The first stars formed from mergers of these 3000 K gas planets. Chemicals C, N, O, Fe etc. created by stars and supernovae then seeded many of the reducing hydrogen gas planets with oxides to give them hot water oceans with metallic iron-nickel cores. Water oceans at critical temperature 647 K then hosted the first organic chemistry and the first life, distributed to the 1080 planets of the cosmological big bang by comets produced by the new (HGD) planet-merger star formation mechanism. The biological big bang scenario occurs between 2 Myr when liquid oceans condensed and 8 Myr when they froze. HGD cosmology explains, very naturally, the Hoyle/Wickramasinghe concept of cometary panspermia by giving a vast, hot, nourishing, cosmological primordial soup for abiogenesis, and the means for transmitting the resulting life forms and their evolving chemical mechanisms widely throughout the universe from the resulting RNA last-universal-common-ancestor LUCA. A primordial astrophysical basis is provided for astrobiology by HGD cosmology. Concordance ΛCDMHC cosmology is rendered obsolete by the observation of complex life on Earth.

  7. Neutron-induced background by an alpha-beam incident on a deuterium gas target and its implications for the study of the 2H(alpha,gamma)6Li reaction at LUNA

    CERN Document Server

    Anders, M; Bellini, A; Aliotta, M; Bemmerer, D; Broggini, C; Caciolli, A; Costantini, H; Corvisiero, P; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Menegazzo, R; Prati, P; Alvarez, C Rossi; Scott, D; Somorjai, E; Straniero, O; Szücs, T

    2013-01-01

    The production of the stable isotope Li-6 in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological Li-6 plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of Li-7 abundances and would point to a predominantly primordial origin of Li-6, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang Li-6 production must be revisited. The main production channel for Li-6 in the Big Bang is the 2H(alpha,gamma)6Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an {\\alpha}-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2H(d,n)3He reaction....

  8. Geneva Festival, 2004: Opened with the Big Bang, closed with Creation

    CERN Multimedia

    2004-01-01

    In its 50th Anniversary year, CERN had the honour of opening and closing this year's Geneva Festival. The Geneva Festival traditionally opens with a bang, but this year's was the biggest yet. On 30 July, on a warm summer's evening by Lake Geneva, several tons of fireworks replayed the early history of the Universe. Starting with the Big Bang, the display had acts representing inflation, the breaking of symmetries, the clash of antimatter and matter, hadrons and nucleosynthesis, the first atoms and the Universe becoming transparent, and the formation of stars and planets. It was a challenge to translate these very abstract ideas into more than a thousand kilograms of TNT of different colour. But, set to the music of The Matrix, Alan Parsons, and Jurassic Park, one of the most spectacular physics presentations ever staged dazzled the audience of two hundred thousand spectators. CERN physicist Rolf Landua, who scripted the narrative and worked with the pyrotechnicians on the realization, said: "From the many e...

  9. COBE's search for structure in the Big Bang

    Science.gov (United States)

    Soffen, Gerald (Editor); Guerny, Gene (Editor); Keating, Thomas (Editor); Moe, Karen (Editor); Sullivan, Walter (Editor); Truszkowski, Walt (Editor)

    1989-01-01

    The launch of Cosmic Background Explorer (COBE) and the definition of Earth Observing System (EOS) are two of the major events at NASA-Goddard. The three experiments contained in COBE (Differential Microwave Radiometer (DMR), Far Infrared Absolute Spectrophotometer (FIRAS), and Diffuse Infrared Background Experiment (DIRBE)) are very important in measuring the big bang. DMR measures the isotropy of the cosmic background (direction of the radiation). FIRAS looks at the spectrum over the whole sky, searching for deviations, and DIRBE operates in the infrared part of the spectrum gathering evidence of the earliest galaxy formation. By special techniques, the radiation coming from the solar system will be distinguished from that of extragalactic origin. Unique graphics will be used to represent the temperature of the emitting material. A cosmic event will be modeled of such importance that it will affect cosmological theory for generations to come. EOS will monitor changes in the Earth's geophysics during a whole solar color cycle.

  10. Antigravity and the big crunch/big bang transition

    CERN Document Server

    Bars, Itzhak; Steinhardt, Paul J; Turok, Neil

    2011-01-01

    We point out a new phenomenon which seems to be generic in 4d effective theories of scalar fields coupled to Einstein gravity, when applied to cosmology. A lift of such theories to a Weyl-invariant extension allows one to define classical evolution through cosmological singularities unambiguously, and hence construct geodesically complete background spacetimes. An attractor mechanism ensures that, at the level of the effective theory, generic solutions undergo a big crunch/big bang transition by contracting to zero size, passing through a brief antigravity phase, shrinking to zero size again, and re-emerging into an expanding normal gravity phase. The result may be useful for the construction of complete bouncing cosmologies like the cyclic model.

  11. Solution of a Braneworld Big Crunch/Big Bang Cosmology

    CERN Document Server

    McFadden, P; Turok, N G; Fadden, Paul Mc; Steinhardt, Paul J.; Turok, Neil

    2005-01-01

    We solve for the cosmological perturbations in a five-dimensional background consisting of two separating or colliding boundary branes, as an expansion in the collision speed V divided by the speed of light c. Our solution permits a detailed check of the validity of four-dimensional effective theory in the vicinity of the event corresponding to the big crunch/big bang singularity. We show that the four-dimensional description fails at the first nontrivial order in (V/c)^2. At this order, there is nontrivial mixing of the two relevant four-dimensional perturbation modes (the growing and decaying modes) as the boundary branes move from the narrowly-separated limit described by Kaluza-Klein theory to the well-separated limit where gravity is confined to the positive-tension brane. We comment on the cosmological significance of the result and compute other quantities of interest in five-dimensional cosmological scenarios.

  12. The Big Bang as the Ultimate Traffic Jam

    CERN Document Server

    Jejjala, Vishnu; Minic, Djordje; Tze, Chia-Hsiung

    2009-01-01

    We present a novel solution to the nature and formation of the initial state of the Universe. It derives from the physics of a generally covariant extension of Matrix theory. We focus on the dynamical state space of this background independent quantum theory of gravity and matter, an infinite dimensional, complex non-linear Grassmannian. When this space is endowed with a Fubini--Study-like metric, the associated geodesic distance between any two of its points is zero. This striking mathematical result translates into a physical description of a hot, zero entropy Big Bang. The latter is then seen as a far from equilibrium, large fluctuation driven, metastable ordered transition, a ``freezing by heating'' jamming transition. Moreover, the subsequent unjamming transition could provide a mechanism for inflation while rejamming may model a Big Crunch, the final state of gravitational collapse.

  13. Antigravity and the big crunch/big bang transition

    Science.gov (United States)

    Bars, Itzhak; Chen, Shih-Hung; Steinhardt, Paul J.; Turok, Neil

    2012-08-01

    We point out a new phenomenon which seems to be generic in 4d effective theories of scalar fields coupled to Einstein gravity, when applied to cosmology. A lift of such theories to a Weyl-invariant extension allows one to define classical evolution through cosmological singularities unambiguously, and hence construct geodesically complete background spacetimes. An attractor mechanism ensures that, at the level of the effective theory, generic solutions undergo a big crunch/big bang transition by contracting to zero size, passing through a brief antigravity phase, shrinking to zero size again, and re-emerging into an expanding normal gravity phase. The result may be useful for the construction of complete bouncing cosmologies like the cyclic model.

  14. A Big Bang model of human colorectal tumor growth.

    Science.gov (United States)

    Sottoriva, Andrea; Kang, Haeyoun; Ma, Zhicheng; Graham, Trevor A; Salomon, Matthew P; Zhao, Junsong; Marjoram, Paul; Siegmund, Kimberly; Press, Michael F; Shibata, Darryl; Curtis, Christina

    2015-03-01

    What happens in early, still undetectable human malignancies is unknown because direct observations are impractical. Here we present and validate a 'Big Bang' model, whereby tumors grow predominantly as a single expansion producing numerous intermixed subclones that are not subject to stringent selection and where both public (clonal) and most detectable private (subclonal) alterations arise early during growth. Genomic profiling of 349 individual glands from 15 colorectal tumors showed an absence of selective sweeps, uniformly high intratumoral heterogeneity (ITH) and subclone mixing in distant regions, as postulated by our model. We also verified the prediction that most detectable ITH originates from early private alterations and not from later clonal expansions, thus exposing the profile of the primordial tumor. Moreover, some tumors appear 'born to be bad', with subclone mixing indicative of early malignant potential. This new model provides a quantitative framework to interpret tumor growth dynamics and the origins of ITH, with important clinical implications.

  15. Antigravity and the big crunch/big bang transition

    Energy Technology Data Exchange (ETDEWEB)

    Bars, Itzhak [Department of Physics and Astronomy, University of Southern California, Los Angeles, CA 90089-2535 (United States); Chen, Shih-Hung [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada); Department of Physics and School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404 (United States); Steinhardt, Paul J., E-mail: steinh@princeton.edu [Department of Physics and Princeton Center for Theoretical Physics, Princeton University, Princeton, NJ 08544 (United States); Turok, Neil [Perimeter Institute for Theoretical Physics, Waterloo, ON N2L 2Y5 (Canada)

    2012-08-29

    We point out a new phenomenon which seems to be generic in 4d effective theories of scalar fields coupled to Einstein gravity, when applied to cosmology. A lift of such theories to a Weyl-invariant extension allows one to define classical evolution through cosmological singularities unambiguously, and hence construct geodesically complete background spacetimes. An attractor mechanism ensures that, at the level of the effective theory, generic solutions undergo a big crunch/big bang transition by contracting to zero size, passing through a brief antigravity phase, shrinking to zero size again, and re-emerging into an expanding normal gravity phase. The result may be useful for the construction of complete bouncing cosmologies like the cyclic model.

  16. Cosmologie l'univers avant le Big Bang

    CERN Multimedia

    Larousserie, David

    2003-01-01

    Tout n'a pas commencé par une explosion. L'histoire du cosmos avait débuté bien avant le Big Bang, si l'on suit la théorie défendue par les partisans d'une nouvelle cosmologie issue de la mystérieuse théorie des cords. A l'heure où vacillent les scénarios classiques du XXe siècle, se prépare un grand chamboulement de nos idées sur la naissance de l'Univers et son devenir, sur l'existence possible d'univers parallèles.

  17. Response of VIRGO detectors to pre-big-bang gravitons

    CERN Document Server

    Babusci, D; Babusci, Danilo; Giovannini, Massimo

    2001-01-01

    The sensitivity achievable by a pair of VIRGO detectors to stochastic and isotropic gravitational wave backgrounds produced in pre-big-bang models is discussed in view of the development of a second VIRGO interferometer. We describe a semi-analytical technique allowing to compute the signal-to-noise ratio for (monotonic or non-monotonic) logarithmic energy spectra of relic gravitons of arbitrary slope. We apply our results to the case of two correlated and coaligned VIRGO detectors and we compute their achievable sensitivities. We perform our calculations both for the usual case of minimal string cosmological scenario and in the case of a non-minimal scenario where a long dilaton dominated phase is present prior to the onset of the ordinary radiation dominated phase. In this framework, we investigate possible improvements of the achievable sensitivities by selective reduction of the thermal contributions (pendulum and pendulum's internal modes) to the noise power spectra of the detectors. Since a reduction of...

  18. The Biological Big Bang: The First Oceans of Primordial Planets at 2-8 Million Years Explain Hoyle/Wickramasinghe Cometary Panspermia

    OpenAIRE

    Carl H. Gibson

    2011-01-01

    Hydrogravitional-dynamics (HGD) cosmology of Gibson/Schild 1996 predicts that the primordial H-He^4 gas of big bang nucleosynthesis became proto-globular-star-cluster clumps of Earth-mass planets at 300 Kyr. The first stars formed from mergers of these 3000 K gas planets. Chemicals C, N, O, Fe etc. created by stars and supernovae then seeded many of the reducing hydrogen gas planets with oxides to give them hot water oceans with metallic iron-nickel cores. Water oceans at critical temperature...

  19. Statistical Methods for Thermonuclear Reaction Rates and Nucleosynthesis Simulations

    CERN Document Server

    Iliadis, Christian; Coc, Alain; Timmes, F X; Champagne, Art E

    2014-01-01

    Rigorous statistical methods for estimating thermonuclear reaction rates and nucleosynthesis are becoming increasingly established in nuclear astrophysics. The main challenge being faced is that experimental reaction rates are highly complex quantities derived from a multitude of different measured nuclear parameters (e.g., astrophysical S-factors, resonance energies and strengths, particle and gamma-ray partial widths). We discuss the application of the Monte Carlo method to two distinct, but related, questions. First, given a set of measured nuclear parameters, how can one best estimate the resulting thermonuclear reaction rates and associated uncertainties? Second, given a set of appropriate reaction rates, how can one best estimate the abundances from nucleosynthesis (i.e., reaction network) calculations? The techniques described here provide probability density functions that can be used to derive statistically meaningful reaction rates and final abundances for any desired coverage probability. Examples ...

  20. Using Inertial Fusion Implosions to Measure the T + 3He Fusion Cross Section at Nucleosynthesis-Relevant Energies

    Science.gov (United States)

    Zylstra, A. B.; Herrmann, H. W.; Johnson, M. Gatu; Kim, Y. H.; Frenje, J. A.; Hale, G.; Li, C. K.; Rubery, M.; Paris, M.; Bacher, A.; Brune, C. R.; Forrest, C.; Glebov, V. Yu.; Janezic, R.; McNabb, D.; Nikroo, A.; Pino, J.; Sangster, T. C.; Séguin, F. H.; Seka, W.; Sio, H.; Stoeckl, C.; Petrasso, R. D.

    2016-07-01

    Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6Li in in low-metallicity stars. Using high-energy-density plasmas we measure the T (3He, ,γ )6Li reaction rate, a candidate for anomalously high 6Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

  1. Using Inertial Fusion Implosions to Measure the T+^{3}He Fusion Cross Section at Nucleosynthesis-Relevant Energies.

    Science.gov (United States)

    Zylstra, A B; Herrmann, H W; Johnson, M Gatu; Kim, Y H; Frenje, J A; Hale, G; Li, C K; Rubery, M; Paris, M; Bacher, A; Brune, C R; Forrest, C; Glebov, V Yu; Janezic, R; McNabb, D; Nikroo, A; Pino, J; Sangster, T C; Séguin, F H; Seka, W; Sio, H; Stoeckl, C; Petrasso, R D

    2016-07-15

    Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of ^{6}Li in low-metallicity stars. Using high-energy-density plasmas we measure the T(^{3}He,γ)^{6}Li reaction rate, a candidate for anomalously high ^{6}Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

  2. What's in a Name: History and Meanings of the Term "Big Bang"

    CERN Document Server

    Kragh, Helge

    2013-01-01

    The name "big bang" introduced by Fred Hoyle in 1949 is one of the most successful scientific neologisms ever. How did the name originate and how was it received by physicists and astronomers in the period leading up to the hot big bang consensus model in the late 1960s? How did it reflect the meanings of the big bang, a concept that predates the name by nearly two decades? The paper gives a detailed account of names and concepts associated with finite-age cosmological models from the 1920s to the 1970s. It turns out that Hoyle's celebrated name has a richer and more surprising history than commonly assumed and also that the literature on modern cosmology and its history includes many common mistakes and errors. By following the story of "big bang" a new dimension is added to the historical understanding of the emergence of modern cosmology.

  3. Beyond Einstein: From the Big Bang to Black Holes

    Science.gov (United States)

    2005-01-01

    How did the Universe begin? Does time have a beginning and an end? Does space have edges? The questions are clear and simple. They are as old as human curiosity. But the answers have always seemed beyond the reach of science. Until now. In their attempts to understand how space, time, and matter are connected, Einstein and his successors made three predictions. First, space is expanding from a Big Bang; second, space and time can tie themselves into contorted knots called black holes where time actually comes to a halt; third, space itself contains some kind of energy that is pull- ing the Universe apart. Each of these three predictions seemed so fantastic when it was made that everyone, including Einstein himself, regarded them as unlikely. Incredibly, all three have turned out to be true. Yet Einstein's legacy is one of deep mystery, because his theories are silent on three questions raised by his fantastic predictions: (1) What powered the Big Bang? (2) What happens to space, time, and matter at the edge of a black hole? (3) What is the mysterious dark energy pulling the Universe apart? The answers to these questions-which lie at the crux of where our current theories fail us-will lead to a profound, new understanding of the nature of time and space. To find answers, however, we must venture beyond Einstein. The answers require new theories, such as the inflationary Universe and new insights in high-energy particle theory. Like Einstein s theories, these make fantastic predictions that seem hard to believe: unseen dimensions and entire universes beyond our own. We must find facts to confront and guide these new theories. Powerful new technologies now make this possible. And NASA and its partners are developing an armada of space-based observatories to chart the path to discovery. Here is where the Beyond Einstein story begins. By exploring the three questions that are Einstein s legacy, we begin the next revolution in understanding our Universe. We plot our way

  4. A method for investigation of the D(4He, γ)6Li reaction in the Ultralow energy region under a high background

    Science.gov (United States)

    Bystritsky, V. M.; Dudkin, G. N.; Krylov, A. R.; Gazi, S.; Huran, J.; Nechaev, B. A.; Padalko, V. N.; Sadovsky, A. B.; Tuleushev, Yu. Zh.; Filipowicz, M.; Philippov, A. V.

    2016-07-01

    The cosmological lithium problem, that is, a noticeable discrepancy between the predicted and observed abundances of lithium, is in conflict with the Standard Big Bang Nucleosynthesis model. For example, the abundance of 7Li is 2-4 times smaller than predicted by the Standard Big Bang Nucleosynthesis. As to the abundance of 6Li, recent more accurate optical investigations have yielded only the upper limit on the 6Li/7Li ratio, which makes the problem of 6Li abundance and accordingly of disagreement with the Standard Big Bang Nucleosynthesis predictions less acute. However, experimental study of the D(4He, γ)6Li reaction cross section is still of current importance because there is a theoretical approach predicting its anomalously large value in the region of energies below the Standard Big Bang Nucleosynthesis energy. The work is dedicated to the measurement of the cross section for the D(4He, γ)6Li reaction proceeding in zirconium deuteride at the incident 4He+ion energy of 36 keV. The experiment is performed at a pulsed Hall plasma accelerator with an energy spread of 20% FWHM. A method for direct measurement of the background from the reaction chain D(4He, 4He)D→D(D, n)3He→(n, γ) and/or (n, n‧γ) ending with activation of the surrounding material by neutrons is proposed and implemented in the work. An upper limit on the D(4He, γ)6Li reaction cross section σ≤7·10-36 cm2 at the 90% confidence level is obtained.

  5. A method for investigation of the D({sup 4}He, γ){sup 6}Li reaction in the Ultralow energy region under a high background

    Energy Technology Data Exchange (ETDEWEB)

    Bystritsky, V.M. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Dudkin, G.N. [National Research Tomsk Polytechnic University, Tomsk (Russian Federation); Krylov, A.R. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Gazi, S.; Huran, J. [Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava (Slovakia); Nechaev, B.A.; Padalko, V.N. [National Research Tomsk Polytechnic University, Tomsk (Russian Federation); Sadovsky, A.B. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Tuleushev, Yu.Zh. [Institute of Nuclear Physics, Ministry of Power Engineering, Almaty (Kazakhstan); Filipowicz, M. [Faculty of Energy and Fuels, University of Science and Technologies, Krakow (Poland); Philippov, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2016-07-21

    The cosmological lithium problem, that is, a noticeable discrepancy between the predicted and observed abundances of lithium, is in conflict with the Standard Big Bang Nucleosynthesis model. For example, the abundance of {sup 7}Li is 2–4 times smaller than predicted by the Standard Big Bang Nucleosynthesis. As to the abundance of {sup 6}Li, recent more accurate optical investigations have yielded only the upper limit on the {sup 6}Li/{sup 7}Li ratio, which makes the problem of {sup 6}Li abundance and accordingly of disagreement with the Standard Big Bang Nucleosynthesis predictions less acute. However, experimental study of the D({sup 4}He, γ){sup 6}Li reaction cross section is still of current importance because there is a theoretical approach predicting its anomalously large value in the region of energies below the Standard Big Bang Nucleosynthesis energy. The work is dedicated to the measurement of the cross section for the D({sup 4}He, γ){sup 6}Li reaction proceeding in zirconium deuteride at the incident {sup 4}He{sup +}ion energy of 36 keV. The experiment is performed at a pulsed Hall plasma accelerator with an energy spread of 20% FWHM. A method for direct measurement of the background from the reaction chain D({sup 4}He, {sup 4}He)D→D(D, n){sup 3}He→(n, γ) and/or (n, n′γ) ending with activation of the surrounding material by neutrons is proposed and implemented in the work. An upper limit on the D({sup 4}He, γ){sup 6}Li reaction cross section σ≤7·10{sup −36} cm{sup 2} at the 90% confidence level is obtained.

  6. Massive Star Evolution Nucleosynthesis and Nuclear Reaction Rate Uncertainties

    CERN Document Server

    Heger, A; Rauscher, T; Hoffman, R D; Boyes, M M

    2002-01-01

    We present a nucleosynthesis calculation of a 25 solar mass star of solar composition that includes all relevant isotopes up to polonium. In particular, all stable isotopes and necessary nuclear reaction rates are covered. We follow the stellar evolution from hydrogen burning till iron core collapse and simulate the explosion using a ``piston'' approach. We discuss the influence of two key nuclear reaction rates, C12(a,g) and Ne22(a,n), on stellar evolution and nucleosynthesis. The former significantly influences the resulting core sizes (iron, silicon, oxygen) and the overall presupernova structure of the star. It thus has significant consequences for the supernova explosion itself and the compact remnant formed. The later rate considerably affects the s-process in massive stars and we demonstrate the changes that different currently suggested values for this rate cause.

  7. String theory and pre-big bang cosmology

    Science.gov (United States)

    Gasperini, M.; Veneziano, G.

    2016-09-01

    In string theory, the traditional picture of a Universe that emerges from the inflation of a very small and highly curved space-time patch is a possibility, not a necessity: quite different initial conditions are possible, and not necessarily unlikely. In particular, the duality symmetries of string theory suggest scenarios in which the Universe starts inflating from an initial state characterized by very small curvature and interactions. Such a state, being gravitationally unstable, will evolve towards higher curvature and coupling, until string-size effects and loop corrections make the Universe "bounce" into a standard, decreasing-curvature regime. In such a context, the hot big bang of conventional cosmology is replaced by a "hot big bounce" in which the bouncing and heating mechanisms originate from the quantum production of particles in the high-curvature, large-coupling pre-bounce phase. Here we briefly summarize the main features of this inflationary scenario, proposed a quarter century ago. In its simplest version (where it represents an alternative and not a complement to standard slow-roll inflation) it can produce a viable spectrum of density perturbations, together with a tensor component characterized by a "blue" spectral index with a peak in the GHz frequency range. That means, phenomenologically, a very small contribution to a primordial B-mode in the CMB polarization, and the possibility of a large enough stochastic background of gravitational waves to be measurable by present or future gravitational wave detectors.

  8. The big bang? An eventful year in workers' compensation.

    Science.gov (United States)

    Guidotti, Tee L

    2006-01-01

    Workers' compensation in the past two years has been dominated by events in California, which have been so fundamental as to merit the term big bang. Passage of Senate Bill 899 has led to a comprehensive program of reform in access to medical care, access to rehabilitation services, temporary and permanent disability, evidence-based management, dispute resolution, and system innovation. Two noteworthy developments thus arose: a new requirement for apportionment by cause in causation analysis, and the adoption of evidence-based criteria for impairment assessment, treatment guidelines, and, soon, utilization review. Elsewhere in the United States, changes were modest, but extensive legislative activity in Texas suggests that Texas will be next to make major changes. In Canada, the Workers' Compensation Board of British Columbia has adopted an ambitious strategic initiative, and there is a Canadawide movement to establish presumption for certain diseases in firefighters. Suggestions for future directions include an increased emphasis on prevention, integration of programs, worker participation, enhancing the expertise of health care professionals, evidence-based management, process evaluation, and opportunities for innovation.

  9. big bang gene modulates gut immune tolerance in Drosophila.

    Science.gov (United States)

    Bonnay, François; Cohen-Berros, Eva; Hoffmann, Martine; Kim, Sabrina Y; Boulianne, Gabrielle L; Hoffmann, Jules A; Matt, Nicolas; Reichhart, Jean-Marc

    2013-02-19

    Chronic inflammation of the intestine is detrimental to mammals. Similarly, constant activation of the immune response in the gut by the endogenous flora is suspected to be harmful to Drosophila. Therefore, the innate immune response in the gut of Drosophila melanogaster is tightly balanced to simultaneously prevent infections by pathogenic microorganisms and tolerate the endogenous flora. Here we describe the role of the big bang (bbg) gene, encoding multiple membrane-associated PDZ (PSD-95, Discs-large, ZO-1) domain-containing protein isoforms, in the modulation of the gut immune response. We show that in the adult Drosophila midgut, BBG is present at the level of the septate junctions, on the apical side of the enterocytes. In the absence of BBG, these junctions become loose, enabling the intestinal flora to trigger a constitutive activation of the anterior midgut immune response. This chronic epithelial inflammation leads to a reduced lifespan of bbg mutant flies. Clearing the commensal flora by antibiotics prevents the abnormal activation of the gut immune response and restores a normal lifespan. We now provide genetic evidence that Drosophila septate junctions are part of the gut immune barrier, a function that is evolutionarily conserved in mammals. Collectively, our data suggest that septate junctions are required to maintain the subtle balance between immune tolerance and immune response in the Drosophila gut, which represents a powerful model to study inflammatory bowel diseases.

  10. Stilometrie en karakterisering in The Big Bang Theory

    Directory of Open Access Journals (Sweden)

    Maryka van Zyl

    2016-09-01

    Full Text Available Dialoog is ’n belangrike aspek van televisuele karakterkonstruering. Skrywers maak talige keuses namens die karakters en hierdie keuses kan daartoe aanleiding gee dat kykers ’n karakter met ’n spesifieke stereotipe subkultuur of sosiale groep vereenselwig. Hierdie studie ondersoek die talige konstruering van die karakter Sheldon Cooper in die CBS-sitkom The Big Bang Theory. ’n Trosanaliseboom van die spraak van elk van die vyf hoofkarakters in die eerste sewe seisoene (gegenereer deur die R-skrip Stylo 0.6.0 dui daarop dat die karakter Sheldon Cooper van die ander hoofkarakters (Leonard, Penny, Howard en Rajesh verskil ten opsigte van taalstyl. Hierdie verskille word verder ondersoek deur gebruik te maak van die korpusanalise program (WordSmith 6.0. om sleutelwoorde en leksikale bondels te identifiseer en om die gebruik van aktiewe en passiewe werkwoordkonstruksies te vergelyk. Sheldon se keuse van wetenskaplike of meer formele woorde en sy relatiewe voorkeur vir die passiefkonstruksie tipeer sy taalstyl as verduidelikend eerder as tipies van omgangstaal.

  11. Big Bang Day : Afternoon Play - Torchwood: Lost Souls

    CERN Multimedia

    2008-01-01

    Martha Jones, ex-time traveller and now working as a doctor for a UN task force, has been called to CERN where they're about to activate the Large Hadron Collider. Once activated, the Collider will fire beams of protons together recreating conditions a billionth of a second after the Big Bang - and potentially allowing the human race a greater insight into what the Universe is made of. But so much could go wrong - it could open a gateway to a parallel dimension, or create a black hole - and now voices from the past are calling out to people and scientists have started to disappear... Where have the missing scientists gone? What is the secret of the glowing man? What is lurking in the underground tunnel? And do the dead ever really stay dead? Lost Souls is a spin-off from the award-winning BBC Wales TV production Torchwood. It stars John Barrowman, Freema Agyeman, Eve Myles, Gareth David-Lloyd, Lucy Montgomery (of Titty Bang Bang) and Stephen Critchlow.

  12. big bang gene modulates gut immune tolerance in Drosophila

    Science.gov (United States)

    Bonnay, François; Cohen-Berros, Eva; Hoffmann, Martine; Kim, Sabrina Y.; Boulianne, Gabrielle L.; Hoffmann, Jules A.; Matt, Nicolas; Reichhart, Jean-Marc

    2013-01-01

    Chronic inflammation of the intestine is detrimental to mammals. Similarly, constant activation of the immune response in the gut by the endogenous flora is suspected to be harmful to Drosophila. Therefore, the innate immune response in the gut of Drosophila melanogaster is tightly balanced to simultaneously prevent infections by pathogenic microorganisms and tolerate the endogenous flora. Here we describe the role of the big bang (bbg) gene, encoding multiple membrane-associated PDZ (PSD-95, Discs-large, ZO-1) domain-containing protein isoforms, in the modulation of the gut immune response. We show that in the adult Drosophila midgut, BBG is present at the level of the septate junctions, on the apical side of the enterocytes. In the absence of BBG, these junctions become loose, enabling the intestinal flora to trigger a constitutive activation of the anterior midgut immune response. This chronic epithelial inflammation leads to a reduced lifespan of bbg mutant flies. Clearing the commensal flora by antibiotics prevents the abnormal activation of the gut immune response and restores a normal lifespan. We now provide genetic evidence that Drosophila septate junctions are part of the gut immune barrier, a function that is evolutionarily conserved in mammals. Collectively, our data suggest that septate junctions are required to maintain the subtle balance between immune tolerance and immune response in the Drosophila gut, which represents a powerful model to study inflammatory bowel diseases. PMID:23378635

  13. Cosmic Heritage Evolution from the Big Bang to Conscious Life

    CERN Document Server

    Shaver, Peter

    2011-01-01

    This book follows the evolutionary trail all the way from the Big Bang 13.7 billion years ago to conscious life today. It is an accessible introductory book written for the interested layperson – anyone interested in the ‘big picture’ coming from modern science. It covers a wide range of topics including the origin and evolution of our universe, the nature and origin of life, the evolution of life including questions of birth and death, the evolution of cognition, the nature of consciousness, the possibility of extraterrestrial life and the future of the universe. The book is written in a narrative style, as these topics are all parts of a single story. It concludes with a discussion on the nature and future of science.  “Peter Shaver has written engagingly for anyone curious about the world we inhabit.  If you'd like to know how the Universe began, where the chemical elements originated, how life may have started on Earth, how man, ants and bacteria are related to each other, or why we humans think...

  14. Direct nuclear reaction experiments for stellar nucleosynthesis

    Science.gov (United States)

    Cherubini, S.

    2017-09-01

    During the last two decades indirect methods where proposed and used in many experiments in order to measure nuclear cross sections between charged particles at stellar energies. These are among the lowest to be measured in nuclear physics. One of these methods, the Trojan Horse method, is based on the Quasi-Free reaction mechanism and has proved to be particularly flexible and reliable. It allowed for the measurement of the cross sections of various reactions of astrophysical interest using stable beams. The use and reliability of indirect methods become even more important when reactions induced by Radioactive Ion Beams are considered, given the much lower intensity generally available for these beams. The first Trojan Horse measurement of a process involving the use of a Radioactive Ion Beam dealt with the ^{18} F(p, α ^{15} O process in Nova conditions. To obtain pieces of information on this process, in particular about its cross section at Nova energies, the Trojan Horse method was applied to the ^{18} F(d, α ^{15} O)n three body reaction. In order to establish the reliability of the Trojan Horse method approach, the Treiman-Yang criterion is an important test and it will be addressed briefly in this paper.

  15. Primordial nucleosynthesis revisited via Trojan Horse Results

    Directory of Open Access Journals (Sweden)

    Pizzone R.G.

    2016-01-01

    Full Text Available Big Bang Nucleosynthesis (BBN requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,pt, d(d,n3He and 3He(d,p4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM to study reactions of relevance for the BBN and measure their astrophysical S(E-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These were compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

  16. Primordial nucleosynthesis revisited via Trojan Horse Results

    Science.gov (United States)

    Pizzone, R. G.; Spartá, R.; Bertulani, C.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Tumino, A.

    2016-05-01

    Big Bang Nucleosynthesis (BBN) requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,p)t, d(d,n)3He and 3He(d,p)4He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S(E)-factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN (0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, 3,4He and 7Li. These were compared with the observational primordial abundance estimates in different astrophysical sites. A comparison was also performed with calculations using other reaction rates compilations available in literature.

  17. THM and primordial nucleosynthesis: Results and perspectives

    Science.gov (United States)

    Pizzone, R. G.; Spartá, R.; Bertulani, C.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Tumino, A.

    2017-09-01

    Big Bang Nucleosynthesis (BBN) requires several nuclear physics inputs and nuclear reaction rates. An up-to-date compilation of direct cross sections of d(d,p)t, d(d,n) 3 He and 3 He(d,p) 4 He reactions is given, being these ones among the most uncertain bare-nucleus cross sections. An intense experimental effort has been carried on in the last decade to apply the Trojan Horse Method (THM) to study reactions of relevance for the BBN and measure their astrophysical S( E) -factor. The reaction rates and the relative error for the four reactions of interest are then numerically calculated in the temperature ranges of relevance for BBN ( 0.01nucleosynthesis calculations in order to evaluate their impact on the calculated primordial abundances of D, ^{3,4} He and ^7 Li. These were compared with the observational primordial abundance estimates in different astrophysical sites. Reactions to be studied in perspective will also be discussed.

  18. L'universo prima del Big Bang cosmologia e teoria delle stringhe

    CERN Document Server

    Gasperini, Maurizio

    2002-01-01

    Termini come "universo in espansione", "big bang", "singolarità iniziale" sono ormai entrati a far parte del linguaggio comune. L'idea che l'universo che oggi osserviamo abbia avuto origine da una grossa esplosione (big bang) è ormai ampiamente diffusa e accettata nella moderna cultura popolare, a tutti i libelli. Ma cosa c'era prima del big bang? E ha senso porsi questo interrogativo in un contesto scientifico? I recenti progressi della fisica teoria, e in particolare della cosiddetta teoria delle stringhe, suggeriscono una risposta a questa domanda, fornendo degli strumenti matematici capaci, in linea di principio, di ricostruire la storia dell'universo spingendosi anche oltre l'istante del big bang. Ne emerge un possibile scenario cosmologico nel quale l'universo, anzichè essere "appena nato" al momento del big bang, era piuttosto nel punto di mezzo della sua evoluzione, di durata probabilmente infinita. In questo libro si cerca di illustrare tale scenario usando un linguaggio non troppo tecnico, rivolt...

  19. M Theory Model of a Big Crunch/Big Bang Transition

    CERN Document Server

    Turok, N G; Steinhardt, P J; Turok, Neil; Perry, Malcolm; Steinhardt, Paul J.

    2004-01-01

    We consider a picture in which the transition from a big crunch to a big bang corresponds to the collision of two empty orbifold planes approaching each other at a constant non-relativistic speed in a locally flat background space-time, a situation relevant to recently proposed cosmological models. We show that $p$-brane states which wind around the extra dimension propagate smoothly and unambiguously across the orbifold plane collision. In particular we calculate the quantum mechanical production of winding M2-branes extending from one orbifold to the other. We find that the resulting density is finite and that the resulting gravitational back-reaction is small. These winding states, which include the string theory graviton, can be propagated smoothly across the transition using a perturbative expansion in the membrane tension, an expansion which from the point of view of string theory is an expansion in {\\it inverse} powers of $\\alpha'$. We argue that interactions should be well-behaved because the string c...

  20. HD 140283: A STAR IN THE SOLAR NEIGHBORHOOD THAT FORMED SHORTLY AFTER THE BIG BANG

    Energy Technology Data Exchange (ETDEWEB)

    Bond, Howard E.; Nelan, Edmund P. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); VandenBerg, Don A. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada); Schaefer, Gail H. [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Harmer, Dianne, E-mail: bond@stsci.edu, E-mail: nelan@stsci.edu, E-mail: vandenbe@uvic.ca, E-mail: schaefer@chara-array.org, E-mail: diharmer@noao.edu [National Optical Astronomy Observatories, 950 North Cherry Avenue, Tucson, AZ 85726 (United States)

    2013-03-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the Hertzsprung-Russell diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 {+-} 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 {+-} 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especially the oxygen content, now contribute more to the error budget for the age of HD 140283 than does its distance, increasing the total uncertainty to about {+-}0.8 Gyr. Within the errors, the age of HD 140283 does not conflict with the age of the Universe, 13.77 {+-} 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang.

  1. The Big Bang and the Search for a Theory of Everything

    Science.gov (United States)

    Kogut, Alan

    2010-01-01

    How did the universe begin? Is the gravitational physics that governs the shape and evolution of the cosmos connected in a fundamental way to the sub-atomic physics of particle colliders? Light from the Big Bang still permeates the universe and carries within it faint clues to the physics at the start of space and time. I will describe how current and planned measurements of the cosmic microwave background will observe the Big Bang to provide new insight into a "Theory of Everything" uniting the physics of the very large with the physics of the very small.

  2. El concepto de big bang como inicio del proceso creativo del dibujo

    OpenAIRE

    2015-01-01

    Este artículo establece un paralelismo entre la teoría del big bang y el comienzo de elaboración de un dibujo. Pretende sintetizar una serie de planteamientos de artistas, teóricos del arte y los experimentados a través del dibujo gracias a una propuesta artística personal. Unos trabajos, expuestos como un ejemplo de proceso creativo basado en el big bang, que muestran cómo los nuevos parámetros del dibujo contemporáneo ofrecen al artista numerosas posibilidades para enfocar la investigación ...

  3. On Subtitle Translation of Sitcoms-A Case Study of The Big Bang Theory

    Institute of Scientific and Technical Information of China (English)

    杨雯婷

    2013-01-01

    As we all know that exquisite subtitle translation of foreign film and television series is the fatal elements for them to spread among Chinese audiences. This article is based on Eugene·Nida’s“the Functional Equivalence”principle with three char⁃acteristics of sitcoms’subtitle to study the type, form and features of the Big Bang Theory, which lead to the conclusion of sitcom subtitle’s characteristics. It helps us to analyze its subtitle from six aspects. As the result, the author of the paper makes the conclu⁃sion of translation tactic about Big Bang Theory, which could help the subtitle translation of similar sitcoms.

  4. An Analysis of Verbal Humor in American Sitcom The Big Bang Theory

    Institute of Scientific and Technical Information of China (English)

    吴珍; 芮艳芳

    2015-01-01

    Humor plays an indispensable part in human communication. This thesis is a tentative analysis of verbal humor under-standing within the framework of Relevance Theory. This paper, using The Big Bang Theory as a corpus, analyzes the humor gener-ated in the cognitive process of searching for relevance. According to the Relevance Theory, the understanding of humor is a pro-cess in which the hearer finds"relevance"in what seems"irrelevant". The author hopes that this analysis can help more people un-derstand and appreciate the humor in The Big Bang Theory. And meanwhile their personal sense of humor can also be improved.

  5. Time, space, stars and man the story of the Big Bang

    CERN Document Server

    Woolfson, Michael M

    2009-01-01

    Most well-read, but non-scientific, people will have heard of the term "Big Bang" as a description of the origin of the Universe. They will recognize that DNA identifies individuals and will know that the origin of life is one of the great unsolved scientific mysteries. This book brings together all of that material. Starting with the creation of space and time - known as the Big Bang - the book traces causally related steps through the formation of matter, of stars and planets, the Earth itself, the evolution of the Earth's surface and atmosphere, and then through to the beginnings of life an

  6. El concepto de big bang como inicio del proceso creativo del dibujo

    Directory of Open Access Journals (Sweden)

    Manuel Bru Serrano

    2015-01-01

    Full Text Available Este artículo establece un paralelismo entre la teoría del big bang y el comienzo de elaboración de un dibujo. Pretende sintetizar una serie de planteamientos de artistas, teóricos del arte y los experimentados a través del dibujo gracias a una propuesta artística personal. Unos trabajos, expuestos como un ejemplo de proceso creativo basado en el big bang, que muestran cómo los nuevos parámetros del dibujo contemporáneo ofrecen al artista numerosas posibilidades para enfocar la investigación artística.

  7. Pre-Big Bang, space-time structure, asymptotic Universe

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres Luis

    2014-04-01

    Full Text Available Planck and other recent data in Cosmology and Particle Physics can open the way to controversial analyses concerning the early Universe and its possible ultimate origin. Alternatives to standard cosmology include pre-Big Bang approaches, new space-time geometries and new ultimate constituents of matter. Basic issues related to a possible new cosmology along these lines clearly deserve further exploration. The Planck collaboration reports an age of the Universe t close to 13.8 Gyr and a present ratio H between relative speeds and distances at cosmic scale around 67.3 km/s/Mpc. The product of these two measured quantities is then slightly below 1 (about 0.95, while it can be exactly 1 in the absence of matter and cosmological constant in patterns based on the spinorial space-time we have considered in previous papers. In this description of space-time we first suggested in 1996-97, the cosmic time t is given by the modulus of a SU(2 spinor and the Lundmark-Lemaître-Hubble (LLH expansion law turns out to be of purely geometric origin previous to any introduction of standard matter and relativity. Such a fundamental geometry, inspired by the role of half-integer spin in Particle Physics, may reflect an equilibrium between the dynamics of the ultimate constituents of matter and the deep structure of space and time. Taking into account the observed cosmic acceleration, the present situation suggests that the value of 1 can be a natural asymptotic limit for the product H t in the long-term evolution of our Universe up to possible small corrections. In the presence of a spinorial space-time geometry, no ad hoc combination of dark matter and dark energy would in any case be needed to get an acceptable value of H and an evolution of the Universe compatible with observation. The use of a spinorial space-time naturally leads to unconventional properties for the space curvature term in Friedmann-like equations. It therefore suggests a major modification of

  8. Global Fluctuation Spectra in Big Crunch/Big Bang String Vacua

    CERN Document Server

    Craps, B; Craps, Ben; Ovrut, Burt A.

    2004-01-01

    We study Big Crunch/Big Bang cosmologies that correspond to exact world-sheet superconformal field theories of type II strings. The string theory spacetime contains a Big Crunch and a Big Bang cosmology, as well as additional ``whisker'' asymptotic and intermediate regions. Within the context of free string theory, we compute, unambiguously, the scalar fluctuation spectrum in all regions of spacetime. Generically, the Big Crunch fluctuation spectrum is altered while passing through the bounce singularity. The change in the spectrum is characterized by a function $\\Delta$, which is momentum and time-dependent. We compute $\\Delta$ explicitly and demonstrate that it arises from the whisker regions. The whiskers are also shown to lead to ``entanglement'' entropy in the Big Bang region. Finally, in the Milne orbifold limit of our superconformal vacua, we show that $\\Delta\\to 1$ and, hence, the fluctuation spectrum is unaltered by the Big Crunch/Big Bang singularity. We comment on, but do not attempt to resolve, su...

  9. Limits to the primordial helium abundance in the baryon-inhomogeneous big bang

    Science.gov (United States)

    Mathews, G. J.; Schramm, D. N.; Meyer, B. S.

    1993-01-01

    The parameter space for baryon inhomogeneous big bang models is explored with the goal of determining the minimum helium abundance obtainable in such models while still satisfying the other light-element constraints. We find that the constraint of (D + He-3)/H less than 10 exp -4 restricts the primordial helium mass fraction from baryon-inhomogeneous big bang models to be greater than 0.231 even for a scenario which optimizes the effects of the inhomogeneities and destroys the excess lithium production. Thus, this modification to the standard big bang as well as the standard homogeneous big bang model itself would be falsifiable by observation if the primordial He-4 abundance were observed to be less than 0.231. Furthermore, a present upper limit to the observed helium mass fraction of Y(obs)(p) less than 0.24 implies that the maximum baryon-to-photon ratio allowable in the inhomogeneous models corresponds to eta less than 2.3 x 10 exp -9 (omega(b) h-squared less than 0.088) even if all conditions are optimized.

  10. From the Big Bang to the Nobel Prize and on to the James Webb Space Telescope

    Science.gov (United States)

    Mather, John C.

    2008-01-01

    The history of the universe in a nutshell, from the Big Bang to now. and on to the future - John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history. Mather was Project Scientist for NASA's Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion. He will explain Einstein's biggest mistake, show how Edwin Hubble discovered the expansion of the univerre, how the COBE mission was built, and how the COBE data support the Big Bang theory. He will also show NASA's plans for the next great telescope in space, the Jarnes Webb Space Telescope. It will look even farther back in time than the Hubble Space Telescope, and will look inside the dusty cocoons where rtars and planets are being born today. Planned for launch in 2013, it may lead to another Nobel Prize for some lucky observer.

  11. From the Big Bang to the Nobel Prize and on to James Webb Space Telescope

    Science.gov (United States)

    Mather, John C.

    2009-01-01

    The history of the universe in a nutshell, from the Big Bang to now, and on to the future - John Mather will tell the story of how we got here, how the Universe began with a Big Bang, how it could have produced an Earth where sentient beings can live, and how those beings are discovering their history. Mather was Project Scientist for NASA s Cosmic Background Explorer (COBE) satellite, which measured the spectrum (the color) of the heat radiation from the Big Bang, discovered hot and cold spots in that radiation, and hunted for the first objects that formed after the great explosion. He will explain Einstein s biggest mistake, show how Edwin Hubble discovered the expansion of the universe, how the COBE mission was built, and how the COBE data support the Big Bang theory. He will also show NASA s plans for the next great telescope in space, the James Webb Space Telescope. It will look even farther back in time than the Hubble Space Telescope, and will look inside the dusty cocoons where stars and planets are being born today. Planned for launch in 2013, it may lead to another Nobel Prize for some lucky observer.

  12. Superhorizon curvaton amplitude in inflation and pre-big bang cosmology

    DEFF Research Database (Denmark)

    Sloth, Martin Snoager

    2002-01-01

    the same way. We also discuss the amplitude of the density perturbations, which leads to some interesting constrains on the pre-big bang scenario. It is shown that within a SL(3,R) non-linear sigma model one of the three axions has the right coupling to the dilaton and moduli to yield a flat spectrum...

  13. Entropy generation and inflation in collision induced pre-big-bang cosmology

    NARCIS (Netherlands)

    Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.

    2000-01-01

    We study inflation and entropy generation in a recently proposed pre-big-bang model universe produced in a collision of gravitational and dilaton waves. It is shown that enough inflation occurs provided the incoming waves are sufficiently weak. We also find that entropy in this model is dynamically

  14. Initial conditions and the structure of the singularity in pre-big-bang cosmology

    NARCIS (Netherlands)

    Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.

    2000-01-01

    We propose a picture, within the pre-big-bang approach, in which the universe emerges from a bath of plane gravitational and dilatonic waves. The waves interact gravitationally breaking the exact plane symmetry and lead generically to gravitational collapse resulting in a singularity with the Kasner

  15. Challenges in Cosmology from the Big Bang to Dark Energy, Dark Matter and Galaxy Formation

    CERN Document Server

    Silk, Joseph

    2016-01-01

    I review the current status of Big Bang Cosmology, with emphasis on current issues in dark matter, dark energy, and galaxy formation. These topics motivate many of the current goals of experimental cosmology which range from targeting the nature of dark energy and dark matter to probing the epoch of the first stars and galaxies.

  16. In search of the big bang the life and the death of the universe

    CERN Document Server

    Gribbin, John

    1998-01-01

    Where do we come from? How did the universe of stars, planets and people come into existence? Now revised and expanded, this second edition takes into account developments in cosmology and quantum physics since its first publication in 1986, and traces the historical path which has led physicists to an understanding of the big bang, the fireball in which our universe was born.

  17. Initial conditions and the structure of the singularity in pre-big-bang cosmology

    NARCIS (Netherlands)

    Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.

    2000-01-01

    We propose a picture, within the pre-big-bang approach, in which the universe emerges from a bath of plane gravitational and dilatonic waves. The waves interact gravitationally breaking the exact plane symmetry and lead generically to gravitational collapse resulting in a singularity with the Kasner

  18. Before the Big Bang? A Novel Resolution of a Profound Cosmological Puzzle

    Energy Technology Data Exchange (ETDEWEB)

    Penrose, Roger

    2007-02-06

    The second law of thermodynamics says, in effect, that things get more random as time progresses. Thus, we can deduce that the beginning of the universe - the Big Bang - must have been an extraordinarily precisely organized state. What was the nature of this state? How can such a special state have come about? In Penrose's talk, a novel explanation is suggested.

  19. Initial conditions and the structure of the singularity in pre-big-bang cosmology

    NARCIS (Netherlands)

    Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.

    2000-01-01

    We propose a picture, within the pre-big-bang approach, in which the universe emerges from a bath of plane gravitational and dilatonic waves. The waves interact gravitationally breaking the exact plane symmetry and lead generically to gravitational collapse resulting in a singularity with the

  20. Entropy generation and inflation in collision induced pre-big-bang cosmology

    NARCIS (Netherlands)

    Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.

    2000-01-01

    We study inflation and entropy generation in a recently proposed pre-big-bang model universe produced in a collision of gravitational and dilaton waves. It is shown that enough inflation occurs provided the incoming waves are sufficiently weak. We also find that entropy in this model is dynamically

  1. After the Big Bang: What's Next in Design Education? Time to Relax?

    Science.gov (United States)

    Fleischmann, Katja

    2015-01-01

    The article "Big Bang technology: What's next in design education, radical innovation or incremental change?" (Fleischmann, 2013) appeared in the "Journal of Learning Design" Volume 6, Issue 3 in 2013. Two years on, Associate Professor Fleischmann reflects upon her original article within this article. Although it has only been…

  2. Nucleosynthesis and the variation of fundamental couplings

    OpenAIRE

    2004-01-01

    We determine the influence of a variation of the fundamental ``constants'' on the predicted helium abundance in Big Bang Nucleosynthesis. The analytic estimate is performed in two parts: the first step determines the dependence of the helium abundance on the nuclear physics parameters, while the second step relates those parameters to the fundamental couplings of particle physics. This procedure can incorporate in a flexible way the time variation of several couplings within a grand unified t...

  3. From the big bang to the eureka moment

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, Peter

    2002-02-01

    A Brief History of Time made Stephen Hawking famous, but he was already a world leader in cosmology. Peter Rodgers reports from the celebrations to mark Hawking's 60th birthday. Masters of the universe Stephen Hawking is the most famous physicist in the world. Indeed, the sales of Hawking's books and his appearances on The Simpsons and Star Trek have tended to overshadow his scientific achievements. But that was not the case in Cambridge last month when Hawking's contributions to physics and cosmology were celebrated at a week-long conference to mark his 60th birthday. 'We organized the meeting to look back on the immense contribution that Stephen has made to many areas of gravitational physics and cosmology,' said Gary Gibbons, one of Hawking's colleagues at Cambridge. 'We also wanted to look forward to what the future might hold for theoretical physics and cosmology, with special reference to the areas that Stephen has been most interested and most active in.' Hawking made his name with a series of papers in the 1960s on singularities in cosmology. Building on work by Roger Penrose, he showed that Einstein's general theory of relativity implied that space and time would have a beginning in the big bang and would end in a singularity. 'How unlike particle physics, where people were falling over themselves to latch onto the latest idea. They still are.' Hawking then switched his attention to black holes - regions of space where gravity is so strong that nothing can escape. He was also one of the first physicists to make progress in combining general relativity - the classical theory of gravity - and quantum mechanics. First he showed that when two black holes collide and merge, the area of the 'event horizon' around the resulting black hole is greater than the sum of the two original areas. This led Hawking and co-workers to link the area of the event horizon, A, with the entropy of a black hole, S

  4. Comment on "Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis".

    Science.gov (United States)

    Balser, Dana S; Rood, Robert T; Bania, T M

    2007-08-31

    Eggleton et al. (Reports, 8 December 2006, p. 1580) reported on a deep-mixing mechanism in low-mass stars caused by a Rayleigh-Taylor instability that destroys all of the helium isotope 3He produced during the star's lifetime. Observations of 3He in planetary nebulae, however, indicate that some stars produce prodigious amounts of 3He. This is inconsistent with the claim that all low-mass stars should destroy 3He.

  5. Engine of life and big bang of evolution: a personal perspective.

    Science.gov (United States)

    Barber, James

    2004-01-01

    Photosystem II (PS II) is the engine for essentially all life on our planet and its beginning 2.5 billion years ago was the 'big bang of evolution.' It produces reducing equivalents for making organic compounds on an enormous scale and at the same time provides us with an oxygenic atmosphere and protection against UV radiation (in the form of the ozone layer). In 1967, when I began my career in photosynthesis research, little was known about PS II. The Z-scheme had been formulated [Hill and Bendall (1960) Nature 186: 136-137] and Boardman and Anderson [(1964) Nature 203: 166-167] had isolated PS II as a discrete biochemical entity. PS II was known not only to be the source of oxygen but of variable chlorophyll fluorescence [Duysens and Sweers (1963) In: Studies on Microalgae and Photosynthetic Bacteria, pp. 353-372. University of Tokyo Press, Tokyo] and delayed chlorophyll fluorescence [Arnold and Davidson (1954) J Gen Physiol 37: 677-684]. P680 had just been discovered [Döring et al. (1967) Z Naturforsch 22b: 639-644]. No wonder the 'black box of PS II' was described at that time by Bessel Kok and George Cheniae [Current Topics in Bioenergetics 1: 1-47 (1966)] as the 'inner sanctum of photosynthesis.' What a change in our level of understanding of PS II since then! The contributions of many talented scientists have unraveled the mechanisms and structural basis of PS II function and we are now very close to revealing the molecular details of the remarkable and thermodynamically demanding reaction which it catalyzes, namely the splitting of water into its elemental constituents. It has been a privilege to be involved in this journey.

  6. Interview de l'astrophysicien Trinh Xuan Thuan: du Big Bang à la naissance de la vie

    CERN Multimedia

    Lorens, Sachat

    2006-01-01

    Born in Hanoi, the astrophysicist is Professor of astronomy at Virginia University, and wrote many books of scientific popularization. His last book "Origines" makes the family treee of the world, from the Big Bang to the birth of alive beings

  7. Using Inertial Fusion Implosions to Measure the T+He3 Fusion Cross Section at Nucleosynthesis-Relevant Energies

    Energy Technology Data Exchange (ETDEWEB)

    Zylstra, A. B.; Herrmann, H. W.; Johnson, M. Gatu; Kim, Y. H.; Frenje, J. A.; Hale, G.; Li, C. K.; Rubery, M.; Paris, M.; Bacher, A.; Brune, C. R.; Forrest, C.; Glebov, V. Yu.; Janezic, R.; McNabb, D.; Nikroo, A.; Pino, J.; Sangster, T. C.; Séguin, F. H.; Seka, W.; Sio, H.; Stoeckl, C.; Petrasso, R. D.

    2016-07-01

    Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6 Li in low-metallicity stars. Using high-energy-density plasmas we measure the T ( 3 He , γ ) 6 Li reaction rate, a candidate for anomalously high 6 Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics.

  8. The Effects of Thermonuclear Reaction Rate Variations on Nova Nucleosynthesis A Sensitivity Study

    CERN Document Server

    Iliadis, C; José, J; Starrfield, S; Tupper, P; Iliadis, Christian; Champagne, Art; Jose, Jordi; Starrfield, Sumner; Tupper, Paul

    2002-01-01

    We investigate the effects of thermonuclear reaction rate uncertainties on nova nucleosynthesis. One-zone nucleosynthesis calculations have been performed by adopting temperature-density-time profiles of the hottest hydrogen-burning zone (i.e., the region in which most of the nucleosynthesis takes place). We obtain our profiles from 7 different, recently published, hydrodynamic nova simulations covering peak temperatures in the range from Tpeak=0.145-0.418 GK. For each of these profiles, we individually varied the rates of 175 reactions within their associated errors and analyzed the resulting abundance changes of 142 isotopes in the mass range below A=40. In total, we performed 7350 nuclear reaction network calculations. We use the most recent thermonuclear reaction rate evaluations for the mass ranges A=1-20 and A=20-40. For the theoretical astrophysicist, our results indicate the extent to which nova nucleosynthesis calculations depend on presently uncertain nuclear physics input, while for the experimenta...

  9. Particle Creation in Pre-Big-Bang Cosmology theory and observational consequences

    CERN Document Server

    Durrer, R; Sakellariadou, M

    2000-01-01

    We present some phenomenological aspects of the pre-big-bang cosmological model inspired by the duality properties of string theory. In particular, assuming the spatial sections of the homogeneous background geometry to be isotropic, we discuss the quantum production of perturbations of the background fields (gravitons, dilatons, moduli fields), as well as the production of particles which do not contribute to the background, which we call ``seeds''. As such we consider the cases of electromagnetic and axionic seeds. We also discuss their possible observational consequences, for example, we study whether they can provide the origin of primordial galactic magnetic fields, and whether they can generate the initial fluctuations leading to the formation of large-scale structure and the measured cosmic microwave background anisotropies. We finally analyze axion and photon production in four dimensional anisotropic pre-big-bang cosmological models.

  10. Observable gravitational waves in pre-big bang cosmology: an update

    CERN Document Server

    Gasperini, M

    2016-01-01

    In the light of the recent results concerning CMB observations and GW detection we address the question of whether it is possible, in a self-consistent inflationary framework, to simultaneously generate a spectrum of scalar metric perturbations in agreement with Planck data and a stochastic background of primordial gravitational radiation compatible with the design sensitivity of aLIGO/Virgo and/or eLISA. We show that this is possible in a string cosmology context, for a wide region of the parameter space of the so-called pre-big bang models. We also discuss the associated values of the tensor-to-scalar ratio relevant to the CMB polarization experiments. We conclude that future, cross-correlated results from CMB observations and GW detectors will be able to confirm or disprove pre-big bang models and -- in any case -- will impose new significant constraints on the basic string theory/cosmology parameters.

  11. Time, space, stars and man the story of the Big Bang

    CERN Document Server

    Woolfson, Michael M

    2013-01-01

    The three greatest scientific mysteries, which remain poorly understood, are the origin of the universe, the origin of life and the development of consciousness. This book describes the processes preceding the Big Bang, the creation of matter, the concentration of that matter into stars and planets, the development of simple life forms and the theory of evolution that has given higher life forms, including mankind. Readership: Members of the general public who have an interest in popular science. There are many popular and excellent science books that present various aspects of science. However, this book follows a narrow scientific pathway from the Big Bang to mankind, and depicts the causal relationship between each step and the next. The science covered will be enough to satisfy most readers. Many important areas of science are dealt with, and these include cosmology, particle physics, atomic physics, galaxy and star formation, planet formation and aspects of evolution. The necessary science is described i...

  12. Effects of anisotropy and spatial curvature on the pre-big-bang scenario

    Science.gov (United States)

    Clancy, Dominic; Lidsey, James E.; Tavakol, Reza

    1998-08-01

    A class of exact, anisotropic cosmological solutions to the vacuum Brans-Dicke theory of gravity is considered within the context of the pre-big-bang scenario. Included in this class are the Bianchi type III, V and VIh models and the spatially isotropic, negatively curved Friedmann-Robertson-Walker universe. The effects of large anisotropy and spatial curvature are determined. In contrast with a negatively curved Friedmann-Robertson-Walker model, there exist regions of the parameter space in which the combined effects of curvature and anisotropy prevent the occurrence of inflation. When inflation is possible, the necessary and sufficient conditions for successful pre-big-bang inflation are more stringent than in the isotropic models. The initial state for these models is established and corresponds in general to a gravitational plane wave.

  13. Superhorizon curvaton amplitude in inflation and pre-big bang cosmology

    CERN Document Server

    Sloth, M S

    2003-01-01

    We follow the evolution of the curvaton on superhorizon scales and check that the spectral tilt of the curvaton perturbations is unchanged as the curvaton becomes non-relativistic. Both inflation and pre-big bang cosmology can be treated since the curvaton mechanism within the two scenarios works the same way. We also discuss the amplitude of the density perturbations, which leads to some interesting constrains on the pre-big bang scenario. It is shown that within a SL(3,R) non-linear sigma model one of the three axions has the right coupling to the dilaton and moduli to yield a flat spectrum with a high string scale, if a quadratic non-perturbative potential is generated and an intermediate string phase lasts long enough.

  14. Observable gravitational waves in pre-big bang cosmology: an update

    Science.gov (United States)

    Gasperini, M.

    2016-12-01

    In the light of the recent results concerning CMB observations and GW detection we address the question of whether it is possible, in a self-consistent inflationary framework, to simultaneously generate a spectrum of scalar metric perturbations in agreement with Planck data and a stochastic background of primordial gravitational radiation compatible with the design sensitivity of aLIGO/Virgo and/or eLISA. We suggest that this is possible in a string cosmology context, for a wide region of the parameter space of the so-called pre-big bang models. We also discuss the associated values of the tensor-to-scalar ratio relevant to the CMB polarization experiments. We conclude that future, cross-correlated results from CMB observations and GW detectors will be able to confirm or disprove pre-big bang models and—in any case—will impose new significant constraints on the basic string theory/cosmology parameters.

  15. The music of the Big Bang the cosmic microwave background and the new cosmology

    CERN Document Server

    Balbi, Amedeo

    2008-01-01

    The cosmic microwave background radiation is the afterglow of the big bang: a tenuous signal, more than 13 billion years old, which carries the answers to many of the questions about the nature of our Universe. It was serendipitously discovered in 1964, and thoroughly investigated in the last four decades by a large number of experiments. Two Nobel Prizes in Physics have already been awarded for research on the cosmic background radiation: one in 1978 to Arno Penzias and Robert Wilson, who first discovered it, the other in 2006, to George Smoot and John Mather, for the results of the COBE satellite. Most cosmological information is encoded in the cosmic background radiation by acoustic oscillations in the dense plasma that filled the primordial Universe: a "music" of the big bang, which cosmologists have long been trying to reconstruct and analyze, in order to distinguish different cosmological models, much like one can distinguish different musical instruments by their timbre and overtones. Only lately, this...

  16. Calixarenes and cations: a time-lapse photography of the big-bang.

    Science.gov (United States)

    Casnati, Alessandro

    2013-08-07

    The outstanding cation complexation properties emerging from the pioneering studies on calixarene ligands during a five-year period in the early 1980s triggered a big-bang burst of publications on such macrocycles that is still lasting at a distance of more than 30 years. A time-lapse photography of this timeframe is proposed which allows the readers to pinpoint the contributions of the different research groups.

  17. Analysis of Humor in The Big Bang Theory Based on the Conversational Relevance

    Institute of Scientific and Technical Information of China (English)

    XU Yang

    2014-01-01

    Humor is the life buoy in waves of life. Pragmatics and humor are closely linked. Relevance is one of the important topics of Pragmatics. This paper takes the lines from The Big Bang Theory as a case study and analyzes the humorous effect from the perspective of Principle of Relevance and Conversational Relevance, hoping to help people deepen the appreciation and un⁃derstanding of humor.

  18. Le big bang n'est pas une théorie comme les autres

    CERN Document Server

    Bonnet-Bidaud, Jean-Marc; Leglu, Dominique; Reinisch, Gilbert

    2009-01-01

    Le big bang n'est pas une théorie comme les autres. Ce n'est d'ailleurs pas une théorie physique au sens propre du terme, mais un scénario cosmologique issu des équations de la relativité générale. Il est le modèle qui s'ajuste le mieux aux observations actuelles, mais à quel prix ? Il nous livre un Univers composé à 96 % de matière et d'énergie noires inconnues. C'est donc un euphémisme que de dire que le big bang semble poser autant - sinon plus - de questions qu'il n'en résout. En ce sens, le big bang apparaît davantage comme une paramétrisation de notre ignorance plutôt que comme une modélisation d'un phénomène. Pourtant, le succès du big bang et l'adhésion qu'il suscite, tant dans la sphère scientifique que dans la sphère médiatique, ne se démentent pas. Surmédiatisé, son statut dépasse celui de modèle théorique, et la simple évocation de son nom suffit pour justifier des opérations de marketing scientifique ou rejeter des cosmologies alternatives. Pour éclaircir les pr...

  19. Gravitationally induced adiabatic particle productions: From Big Bang to de Sitter

    CERN Document Server

    de Haro, Jaume

    2015-01-01

    In the background of a flat homogeneous and isotropic space-time, we consider a scenario of the universe driven by the gravitationally induced constant `adiabatic' particle productions. We have shown that this universe attains a big bang singularity in the past and at late-time, it asymptotically becomes de Sitter. To clarify this model universe, we perform a dynamical analysis. Further, we discussed the possible effects of this particle creations in the context of loop quantum cosmology.

  20. The moment of creation big bang physics from before the first millisecond to the present universe

    CERN Document Server

    Trefil, James S

    2004-01-01

    ""Trefil surpasses almost all other scientists writing about science"" "- The New York Times""Fascinating reading. A mind-stretching book."" - John Barkham ReviewsCompelling and lucid, this reader-friendly narrative travels billions of years back in time to depict the events that culminated in the Big Bang: the colossal explosion that initiated the existence of the universe. James Trefil is one of the founders of modern quark theory, and he specializes in explaining complex scientific matters to nonspecialists.

  1. Economic consequences of German reunification : 12 months after the big bang

    OpenAIRE

    Pohl, Gerhard

    1991-01-01

    The author discusses how East Germany is faring 12 months after the big bang unification with West Germany. The experience with the German unification to date raises the question whether there would have been alternative and better courses of action. Such options can be considered in three broad areas: (a) the initial conversion rate and, closely connected, wage policies; (b) the wisdom of transferring the economic and legal system of the Federal Republic of Germany in its entirety; and (c) t...

  2. Big Bang Bifurcation Analysis and Allee Effect in Generic Growth Functions

    Science.gov (United States)

    Leonel Rocha, J.; Taha, Abdel-Kaddous; Fournier-Prunaret, D.

    2016-06-01

    The main purpose of this work is to study the dynamics and bifurcation properties of generic growth functions, which are defined by the population size functions of the generic growth equation. This family of unimodal maps naturally incorporates a principal focus of ecological and biological research: the Allee effect. The analysis of this kind of extinction phenomenon allows to identify a class of Allee’s functions and characterize the corresponding Allee’s effect region and Allee’s bifurcation curve. The bifurcation analysis is founded on the performance of fold and flip bifurcations. The dynamical behavior is rich with abundant complex bifurcation structures, the big bang bifurcations of the so-called “box-within-a-box” fractal type being the most outstanding. Moreover, these bifurcation cascades converge to different big bang bifurcation curves with distinct kinds of boxes, where for the corresponding parameter values several attractors are associated. To the best of our knowledge, these results represent an original contribution to clarify the big bang bifurcation analysis of continuous 1D maps.

  3. Out of the white hole: a holographic origin for the Big Bang

    Energy Technology Data Exchange (ETDEWEB)

    Pourhasan, Razieh; Afshordi, Niayesh; Mann, Robert B., E-mail: rpourhasan@perimeterinstitute.ca, E-mail: nafshordi@pitp.ca, E-mail: rbmann@uwaterloo.ca [Department of Physics and Astronomy, University of Waterloo, 200 University Ave. W., Waterloo, Ontario, N2L 3G1 Canada (Canada)

    2014-04-01

    While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical Big Bang singularity, whose resolution constitutes the active field of early universe cosmology. Could the Big Bang be also hidden behind a causal horizon, making us immune to the decadent impacts of a naked singularity? We describe a braneworld description of cosmology with both 4d induced and 5D bulk gravity (otherwise known as Dvali-Gabadadze-Porati, or DGP model), which exhibits this feature: the universe emerges as a spherical 3-brane out of the formation of a 5D Schwarzschild black hole. In particular, we show that a pressure singularity of the holographic fluid, discovered earlier, happens inside the white hole horizon, and thus need not be real or imply any pathology. Furthermore, we outline a novel mechanism through which any thermal atmosphere for the brane, with comoving temperature of ∼20% of the 5D Planck mass can induce scale-invariant primordial curvature perturbations on the brane, circumventing the need for a separate process (such as cosmic inflation) to explain current cosmological observations. Finally, we note that 5D space-time is asymptotically flat, and thus potentially allows an S-matrix or (after minor modifications) an AdS/CFT description of the cosmological Big Bang.

  4. The Passport to the Big Bang: a trail of discovery of CERN and its sites

    CERN Document Server

    CERN Bulletin

    2013-01-01

    Sunday 2 June 2013 will see the launch of CERN’s Passport to the Big Bang, a scientific tourist trail linking ten of the Laboratory’s sites in the Pays de Gex and the Canton of Geneva. CERN is organising a public event to celebrate the launch and needs lots of volunteers – you could be one of them!   The exhibition platform in Sergy, in front of the ALICE experiment. Does your grocer insist that the Pays de Gex is going to be swallowed up by a black hole made by the LHC? Do your neighbours ask you questions about the CERN site visible from your houses, leaving you stumped when you don’t have the answers?  Well then, take them on an accelerator tour – but above ground and with no need for access cards! How? By taking advantage of the Passport to the Big Bang, a cross-border scientific tourist trail that will be inaugurated on 2 June. The goal of the Passport to the Big Bang is provide the local population wi...

  5. Von Bertalanffy's dynamics under a polynomial correction: Allee effect and big bang bifurcation

    Science.gov (United States)

    Leonel Rocha, J.; Taha, A. K.; Fournier-Prunaret, D.

    2016-02-01

    In this work we consider new one-dimensional populational discrete dynamical systems in which the growth of the population is described by a family of von Bertalanffy's functions, as a dynamical approach to von Bertalanffy's growth equation. The purpose of introducing Allee effect in those models is satisfied under a correction factor of polynomial type. We study classes of von Bertalanffy's functions with different types of Allee effect: strong and weak Allee's functions. Dependent on the variation of four parameters, von Bertalanffy's functions also includes another class of important functions: functions with no Allee effect. The complex bifurcation structures of these von Bertalanffy's functions is investigated in detail. We verified that this family of functions has particular bifurcation structures: the big bang bifurcation of the so-called “box-within-a-box” type. The big bang bifurcation is associated to the asymptotic weight or carrying capacity. This work is a contribution to the study of the big bang bifurcation analysis for continuous maps and their relationship with explosion birth and extinction phenomena.

  6. Big Bang, Blow Up, and Modular Curves: Algebraic Geometry in Cosmology

    CERN Document Server

    Manin, Yuri I

    2014-01-01

    We introduce some algebraic geometric models in cosmology related to the "boundaries" of space--time: Big Bang, Mixmaster Universe, Penrose's crossovers between aeons. We suggest to model the kinematics of Big Bang using the algebraic geometric (or analytic) blow up of a point $x$. This creates a boundary which consists of the projective space of tangent directions to $x$ and possibly of the light cone of $x$. We argue that time on the boundary undergoes the Wick rotation and becomes purely imaginary. The Mixmaster (Bianchi IX) model of the early history of the universe is neatly explained in this picture by postulating that the reverse Wick rotation follows a hyperbolic geodesic connecting imaginary time axis to the real one. Penrose's idea to see the Big Bang as a sign of crossover from "the end of previous aeon" of the expanding and cooling Universe to the "beginning of the next aeon" is interpreted as an identification of a natural boundary of Minkowski space at infinity with the Bing Bang boundary.

  7. Nucleosynthesis Predictions and High-Precision Deuterium Measurements

    Directory of Open Access Journals (Sweden)

    Signe Riemer-Sørensen

    2017-05-01

    Full Text Available Two new high-precision measurements of the deuterium abundance from absorbers along the line of sight to the quasar PKS1937–1009 were presented. The absorbers have lower neutral hydrogen column densities (N(HI ≈ 18 cm − 2 than for previous high-precision measurements, boding well for further extensions of the sample due to the plenitude of low column density absorbers. The total high-precision sample now consists of 12 measurements with a weighted average deuterium abundance of D/H = 2 . 55 ± 0 . 02 × 10 − 5 . The sample does not favour a dipole similar to the one detected for the fine structure constant. The increased precision also calls for improved nucleosynthesis predictions. For that purpose we have updated the public AlterBBN code including new reactions, updated nuclear reaction rates, and the possibility of adding new physics such as dark matter. The standard Big Bang Nucleosynthesis prediction of D/H = 2 . 456 ± 0 . 057 × 10 − 5 is consistent with the observed value within 1.7 standard deviations.

  8. Big-Bang-Gate Cosmic Titanic: Why Aren't Physics Journal's Editors Bringing It To The Center of Scientific Attention

    Science.gov (United States)

    Gentry, Robert

    2010-02-01

    Until now science's greatest debacle occurred when Copernicus exposed Ptolemaic cosmologists' 1300 hundred year-long fraud that it must be true because observations fit theory so well, while they ignored the untested state of its central assumption of Earth centered planetary motion. With much hubris modern physicists are confident this could never happen again, that the integrity of physics journals editors suffices to guarantee that a challenge to the reigning cosmological theory -- big bang cosmology -- would immediately be brought to the center of scientific attention for analysis and discussion. In fact a decade ago it was reported [MPLA 2619 (1997); arXiv:gr-gc/9806061] that, like Ptolemaic cosmology before it, big bang's central assumption that GR expansion effects cause in-flight expansion had never been tested and, further, that experimental testing of it using GR operation of the GPS showed it to be false. This result proves it is impossible for the 2.73 K CBR to be fireball relic radiation. These results were expanded in CERN reports EXT-2003-021;022, but have been uniformly rejected by physics journals, one of which accepted a paper similar to CERN EXT-2003-022, only to reject it a few days later with the admission not to publish it because of fearing reaction of the worldwide physics community. For update on my PRL submission see http://www.alphacosmos.net. )

  9. Was the Universe actually radiation dominated prior to nucleosynthesis?

    Science.gov (United States)

    Giblin, John T.; Kane, Gordon; Nesbit, Eva; Watson, Scott; Zhao, Yue

    2017-08-01

    Maybe not. String theory approaches to both beyond the Standard Model and inflationary model building generically predict the existence of scalars (moduli) that are light compared to the scale of quantum gravity. These moduli become displaced from their low energy minima in the early Universe and lead to a prolonged matter-dominated epoch prior to big bang nucleosynthesis (BBN). In this paper, we examine whether nonperturbative effects such as parametric resonance or tachyonic instabilities can shorten, or even eliminate, the moduli condensate and matter-dominated epoch. Such effects depend crucially on the strength of the couplings, and we find that unless the moduli become strongly coupled, the matter-dominated epoch is unavoidable. In particular, we find that in string and M-theory compactifications where the lightest moduli are near the TeV scale, a matter-dominated epoch will persist until the time of big bang nucleosynthesis.

  10. Where Are the Logical Errors in the Theory of Big Bang?

    Science.gov (United States)

    Kalanov, Temur Z.

    2015-04-01

    The critical analysis of the foundations of the theory of Big Bang is proposed. The unity of formal logic and of rational dialectics is methodological basis of the analysis. It is argued that the starting point of the theory of Big Bang contains three fundamental logical errors. The first error is the assumption that a macroscopic object (having qualitative determinacy) can have an arbitrarily small size and can be in the singular state (i.e., in the state that has no qualitative determinacy). This assumption implies that the transition, (macroscopic object having the qualitative determinacy) --> (singular state of matter that has no qualitative determinacy), leads to loss of information contained in the macroscopic object. The second error is the assumption that there are the void and the boundary between matter and void. But if such boundary existed, then it would mean that the void has dimensions and can be measured. The third error is the assumption that the singular state of matter can make a transition into the normal state without the existence of the program of qualitative and quantitative development of the matter, without controlling influence of other (independent) object. However, these assumptions conflict with the practice and, consequently, formal logic, rational dialectics, and cybernetics. Indeed, from the point of view of cybernetics, the transition, (singular state of the Universe) -->(normal state of the Universe),would be possible only in the case if there was the Managed Object that is outside the Universe and have full, complete, and detailed information about the Universe. Thus, the theory of Big Bang is a scientific fiction.

  11. An origin of the universe: a model alternative to Big Bang

    OpenAIRE

    Mercik, Andrzej; Mercik, Szymon

    2006-01-01

    We propose a new approach to the model of an origin of the universe built by Oscar Klein and Hannes Alfv\\'{e}n. Some modifications of assumptions underlying the model result in a possible scenario of the universe creation consistent with observations. We explain the large scale structre of the universe and we estimate the Hubble constant value as well as the number of galaxies in the universe. The model does not require many assumptions made in the model based on the Big Bang idea.

  12. Waarop is sy voetstukke ingesink? - 'n Besinning oor die skepping en die big bang

    Directory of Open Access Journals (Sweden)

    L.C. Bezuidenhout

    1998-08-01

    Full Text Available Through the ages the debate between theology and the natural sciencesconcerning the origin of the universe was turbulent. Today the big bangtheory is almost generally accepted in scientific circles. In this article thedebate between theology and science is evaluated critically. The theologicalimplications of the big bang theory is discussed and the relevance of thecosmogony in Genesis 1 for a modem society is evaluated. Biblical modelsand scientific models of the birth of the cosmos do not have to be in conflictwith each other.

  13. The Theological Basis of Big Bang Cosmology and the Failure of General Relativity

    Science.gov (United States)

    Crothers, Stephen J.

    2013-09-01

    It is shown in this paper that the Big Bang Cosmology has its basis in theology, not in science, that it pertains to a Universe entirely filled by a single spherically symmetric continuous indivisible homogeneous body and therefore models nothing, that it violates the physical principles of General Relativity, that it violates the conservation of energy, and that General Relativity itself violates the usual conservation of energy and momentum and is therefore in conflict with experiment on a deep level, rendering Einstein's conception of the physical Universe and the gravitational field invalid.

  14. Gravitationally induced adiabatic particle production: from big bang to de Sitter

    Science.gov (United States)

    de Haro, Jaume; Pan, Supriya

    2016-08-01

    In the background of a flat homogeneous and isotropic space-time, we consider a scenario of the Universe driven by the gravitationally induced ‘adiabatic’ particle production with constant creation rate. We have shown that this Universe attains a big bang singularity in the past and at late-time it asymptotically becomes de Sitter. To clarify this model Universe, we performed a dynamical analysis and found that the Universe attains a thermodynamic equilibrium in this late de Sitter phase. Finally, for the first time, we have discussed the possible effects of ‘adiabatic’ particle creations in the context of loop quantum cosmology.

  15. A fairytale creation or the beginning of everything: Students’ pre-instructional conceptions about the Big Bang theory

    Directory of Open Access Journals (Sweden)

    Sarah Aretz

    2016-12-01

    However, it is not yet clear in science education if students’ conceptions about the Big Bang vary by nationality, and therefore, if it is possible to apply the same teaching modules to students from different countries, who may have diverse social and cultural backgrounds and different curricula. These conceptions with which students enter the classroom were investigated in our study. We implemented an open-ended questionnaire survey in Germany, with questions based on recent U.S. studies. The results clearly showed, with high interrater reliabilities, widespread misconceptions like the Big Bang being an explosion of preexisting matter into empty space or the universe having a centre. Furthermore, a comparison of results from researchers in the USA, Sweden and Germany allowed us to identify differences in students’ conceptions between the countries. Our findings appear to indicate that German students have slightly better pre-instructional conceptions about the Big Bang theory.

  16. Measurement of the reaction 2H(e,e') at 180 degrees close to the deuteron breakup threshold.

    Science.gov (United States)

    Ryezayeva, N; Arenhövel, H; Burda, O; Byelikov, A; Chernykh, M; Enders, J; Griesshammer, H W; Kalmykov, Y; von Neumann-Cosel, P; Ozel, B; Poltoratska, I; Pysmenetska, I; Rangacharyulu, C; Rathi, S; Richter, A; Schrieder, G; Shevchenko, A; Yevetska, O

    2008-05-01

    Inclusive inelastic electron scattering off the deuteron under 180 degrees has been studied at the S-DALINAC close to the breakup threshold at momentum transfers q=0.27 fm;{-1} and 0.74 fm;{-1} with good energy resolution sufficient to map in detail the spin flip M1 response, which governs the starting reaction pn-->dgamma of big-bang nucleosynthesis over most of the relevant temperature region. Results from potential model calculations and (for q=0.27 fm;{-1}) from pionless nuclear effective field theory are in excellent agreement with the data.

  17. Classical propagation of strings across a big crunch/big bang singularity

    Science.gov (United States)

    Niz, Gustavo; Turok, Neil

    2007-01-01

    One of the simplest time-dependent solutions of M theory consists of nine-dimensional Euclidean space times 1+1-dimensional compactified Milne space-time. With a further modding out by Z2, the space-time represents two orbifold planes which collide and re-emerge, a process proposed as an explanation of the hot big bang [J. Khoury, B. A. Ovrut, P. J. Steinhardt, and N. Turok, Phys. Rev. D 64, 123522 (2001).PRVDAQ0556-282110.1103/PhysRevD.64.123522][P. J. Steinhardt and N. Turok, Science 296, 1436 (2002).SCIEAS0036-807510.1126/science.1070462][N. Turok, M. Perry, and P. J. Steinhardt, Phys. Rev. D 70, 106004 (2004).PRVDAQ0556-282110.1103/PhysRevD.70.106004]. When the two planes are near, the light states of the theory consist of winding M2-branes, describing fundamental strings in a particular ten-dimensional background. They suffer no blue-shift as the M theory dimension collapses, and their equations of motion are regular across the transition from big crunch to big bang. In this paper, we study the classical evolution of fundamental strings across the singularity in some detail. We also develop a simple semiclassical approximation to the quantum evolution which allows one to compute the quantum production of excitations on the string and implement it in a simplified example.

  18. Big Bang et au-delà les nouveaux horizons de l'Univers

    CERN Document Server

    Barrau, Aurélien

    2015-01-01

    Notre Univers a-t-il un début ? Est-il unique ? La science moderne a révolutionné notre compréhension de l’Univers. Bien que l’étude du cosmos soit sans doute aussi ancienne que la pensée, notre image du réel est en ce moment même en train de se redessiner. Il est maintenant possible de connaître certains aspects des processus qui eurent lieu moins d’un milliardième de milliardième de milliardième de seconde après le Big Bang. À la lumière des dernières découvertes du satellite Planck, Aurélien Barrau décrit en termes simples le cosmos qui se dessine sous nos yeux. Trous noirs, modèle standard de la physique des particules, gravité… les piliers et les énigmes du Big Bang sont abordés les uns après les autres, à la manière d’une balade aux origines de l’Univers. « Parce que la science est avant tout une aventure humaine, j’ai esquissé, ici et là, en contrepoint des explications physiques fournies dans la langue la plus simple et la plus accessible possible, mon expér...

  19. A large neutral fraction of cosmic hydrogen a billion years after the Big Bang.

    Science.gov (United States)

    Wyithe, J Stuart B; Loeb, Abraham

    2004-02-26

    The fraction of ionized hydrogen left over from the Big Bang provides evidence for the time of formation of the first stars and quasar black holes in the early Universe; such objects provide the high-energy photons necessary to ionize hydrogen. Spectra of the two most distant known quasars show nearly complete absorption of photons with wavelengths shorter than the Lyman alpha transition of neutral hydrogen, indicating that hydrogen in the intergalactic medium (IGM) had not been completely ionized at a redshift of z approximately 6.3, about one billion years after the Big Bang. Here we show that the IGM surrounding these quasars had a neutral hydrogen fraction of tens of per cent before the quasar activity started, much higher than the previous lower limits of approximately 0.1 per cent. Our results, when combined with the recent inference of a large cumulative optical depth to electron scattering after cosmological recombination therefore suggest the presence of a second peak in the mean ionization history of the Universe.

  20. Molecular evolution of colorectal cancer: from multistep carcinogenesis to the big bang.

    Science.gov (United States)

    Amaro, Adriana; Chiara, Silvana; Pfeffer, Ulrich

    2016-03-01

    Colorectal cancer is characterized by exquisite genomic instability either in the form of microsatellite instability or chromosomal instability. Microsatellite instability is the result of mutation of mismatch repair genes or their silencing through promoter methylation as a consequence of the CpG island methylator phenotype. The molecular causes of chromosomal instability are less well characterized. Genomic instability and field cancerization lead to a high degree of intratumoral heterogeneity and determine the formation of cancer stem cells and epithelial-mesenchymal transition mediated by the TGF-β and APC pathways. Recent analyses using integrated genomics reveal different phases of colorectal cancer evolution. An initial phase of genomic instability that yields many clones with different mutations (big bang) is followed by an important, previously not detected phase of cancer evolution that consists in the stabilization of several clones and a relatively flat outgrowth. The big bang model can best explain the coexistence of several stable clones and is compatible with the fact that the analysis of the bulk of the primary tumor yields prognostic information.

  1. A big bang in a little room the quest to create new universes

    CERN Document Server

    Merali, Zeeya

    2017-01-01

    What if you could become God, with the ability to build a whole new universe? As startling as it sounds, modern physics suggests that within the next two decades, scientists may be able to perform this seemingly divine feat-to concoct an entirely new baby universe, complete with its own physical laws, star systems, galaxies, and even intelligent life. A Big Bang in a Little Room takes the reader on a journey through the history of cosmology and unravels-particle by particle, theory by theory, and experiment by experiment-the ideas behind this provocative claim made by some of the most respected physicists alive today. Beyond simply explaining the science, A Big Bang in a Little Room also tells the story of the people who have been laboring for more than thirty years to make this seemingly impossible dream a reality. What has driven them to continue on what would seem, at first glance, to be a quixotic quest? This mind-boggling book reveals that we can nurse other worlds in the tiny confines of a lab, raising...

  2. Don’t miss the Passport to the Big Bang event this Sunday!

    CERN Multimedia

    CERN Bulletin

    2013-01-01

    Word has been going around for weeks now about the inauguration of the Passport to the Big Bang on Sunday 2 June. Ideal for a family day out or a day with friends, this is a CERN event not to be missed!   The Passport to the Big Bang is a 54-km scientific tourist trail comprising ten exhibition platforms in front of ten CERN sites in the Pays de Gex and the Canton of Geneva. Linked by cycle routes, these ten platforms will mark the same number of stages in the rally for competitive cyclists and the bicycle tour for families taking place this Sunday from 9 a.m. to 12 p.m. But that’s not all: from 2 p.m., you will also have the chance to take part in a huge range of activities provided by clubs and associations from CERN and the local region. Watch an oriental dance show, have a go at building detectors out of Kapla blocks and Lego, meet different reptile species, learn about wind instruments, try your hand at Nordic walking or Zumba fitness, get a better understanding of road safety...

  3. The amazing unity of the Universe and its origin in the Big Bang

    CERN Document Server

    van den Heuvel, Edward

    2016-01-01

    In the first chapters the author describes how our knowledge of the position of Earth in space and time has developed, thanks to the work of many generations of astronomers and physicists. He discusses how our position in the Galaxy was discovered, and how in 1929, Hubble uncovered the fact that the Universe is expanding, leading to the picture of the Big Bang. He then explains how astronomers have found that the laws of physics that were discovered here on Earth and in the Solar System (the laws of mechanics, gravity, atomic physics, electromagnetism, etc.) are valid throughout the Universe. This is illustrated by the fact that all matter in the Universe consists of atoms of the same chemical elements that we know on Earth. This unity is all the more surprising when one realizes that in the original Big Bang theory, different parts of the Universe could never have communicated with each other. It then is a mystery how they could have shared the same physical laws. This problem was solved by the introduction ...

  4. Pre-big bang bubbles from the gravitational instability of generic string vacua

    CERN Document Server

    Buonanno, A; Veneziano, Gabriele

    1999-01-01

    We formulate the basic postulate of pre-big bang cosmology as one of ``asymptotic past triviality'', by which we mean that the initial state is a generic perturbative solution of the tree-level low-energy effective action. Such a past-trivial ``string vacuum'' is made of an arbitrary ensemble of incoming gravitational and dilatonic waves, and is generically prone to gravitational instability, leading to the possible formation of many black holes hiding singular space-like hypersurfaces. Each such singular space-like hypersurface of gravitational collapse becomes, in the string-frame metric, the usual big-bang t=0 hypersurface, i.e. the place of birth of a baby Friedmann universe after a period of dilaton-driven inflation. Specializing to the spherically-symmetric case, we review and reinterpret previous work on the subject, and propose a simple, scale-invariant criterion for collapse/inflation in terms of asymptotic data at past null infinity. Those data should determine whether, when, and where collapse/infl...

  5. Out of the White Hole: A Holographic Origin for the Big Bang

    CERN Document Server

    Pourhasan, Razieh; Mann, Robert B

    2013-01-01

    While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology. Could the big bang be also hidden behind a causal horizon, making us immune to the decadent impacts of a naked singularity? We describe a braneworld description of cosmology with both 4d induced and 5d bulk gravity (otherwise known as Dvali-Gabadadze-Porati, or DGP model), which exhibits this feature: The universe emerges as a spherical 3-brane out of the formation of a 5d Schwarzschild black hole. In particular, we show that a pressure singularity of the holographic fluid, discovered earlier, happens inside the white hole horizon, and thus need not be real or imply any pathology. Furthermore, we outline a novel mechanism through which any thermal atmosphere for the brane, with comoving temperature of 20% of the 5D ...

  6. Sneutrino condensate as a candidate for the hot big bang cosmology

    CERN Document Server

    Mazumdar, A; Mazumdar, Anupam

    2004-01-01

    If inflationary paradigm is correct, then it must create conditions for the hot big bang model with all observed matter, baryons and seed perturbations for the structure formation. In this paper we propose a scenario where the inflaton energy density is dumped into the bulk in a brane world setup, and all the required physical conditions are created by the right handed neutrino sector within supersymmetry. The scalar component of the right handed Majorana neutrino is responsible for generating the scale invariant fluctuations in the cosmic microwave background radiation, reheating the Universe at a temperature $T_{rh}\\leq 10^{9}$ GeV, and finally generating the lepton asymmetry, $n_{B}/s\\sim 10^{-10}$.

  7. From the Big Bang to the Nobel Prize and the JWST

    Science.gov (United States)

    Mather, John C.

    2007-01-01

    I will describe the history of the universe, from the Big Bang to 2013, when the JWST is to be launched to look back towards our beginnings. I will discuss how the COBE results led to the Nobel Prize, how the COBE results have been confirmed and extended, and their implications for future observations. The James Webb Space Telescope will be used to examine every part of our history from the first stars and galaxies to the formation of individual stars and planets and the delivery of life-supporting materials to the Earth. I will describe the plans for the JWST and how observers may use it. With luck, the JWST may produce a Nobel Prize for some discovery we can only guess today.

  8. 宇舶表 Big Bang In Red-2010年绚丽登场

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    2010年情人节来临之际,瑞士著名手表品牌Hublot宇舶表特别推出Big Bang In Red腕表。表款整体选用红色这一诠释浪漫经典爱情的永厘颜色,尽在绚丽、妩媚优雅。镶钻深红色表盘、白色陶瓷表壳与天然橡胶内衬的鳄鱼真皮腕带完美结合,尽显宇舶表“融合之艺术”的设计理念。

  9. Quantum mechanics before the big bang in heterotic-M-theory

    CERN Document Server

    Zanzi, Andrea

    2016-01-01

    In this letter we investigate the role played by quantum mechanics before the big-bang in heterotic-M-theory assuming an orbifold compactification of time. As we will see particles are localized around a black hole but only in regions where a constructive quantum interference takes place. We infer that the creation of this interference pattern is interesting for many reasons: (A) it is a mechanism to localize particles on $S^4$ branes; (B) the Casimir potential for the dilaton can be interpreted as a gravitational effective potential for a two-body problem; (C) the quantum interference is a new way to define the branes in heterotic-M-theory. Remarkably, a modified Schroedinger equation is obtained. The stabilization of the branes' position is related to the absence of a cosmological singularity.

  10. The Big Bang of picorna-like virus evolution antedates the radiation of eukaryotic supergroups.

    Science.gov (United States)

    Koonin, Eugene V; Wolf, Yuri I; Nagasaki, Keizo; Dolja, Valerian V

    2008-12-01

    The recent discovery of RNA viruses in diverse unicellular eukaryotes and developments in evolutionary genomics have provided the means for addressing the origin of eukaryotic RNA viruses. The phylogenetic analyses of RNA polymerases and helicases presented in this Analysis article reveal close evolutionary relationships between RNA viruses infecting hosts from the Chromalveolate and Excavate supergroups and distinct families of picorna-like viruses of plants and animals. Thus, diversification of picorna-like viruses probably occurred in a 'Big Bang' concomitant with key events of eukaryogenesis. The origins of the conserved genes of picorna-like viruses are traced to likely ancestors including bacterial group II retroelements, the family of HtrA proteases and DNA bacteriophages.

  11. The Biological Big Bang model for the major transitions in evolution

    Directory of Open Access Journals (Sweden)

    Koonin Eugene V

    2007-08-01

    of evolution incorporates the previously developed concepts of the emergence of protein folds by recombination of small structural units and origin of viruses and cells from a pre-cellular compartmentalized pool of recombining genetic elements. The model is extended to encompass other major transitions. It is proposed that bacterial and archaeal phyla emerged independently from two distinct populations of primordial cells that, originally, possessed leaky membranes, which made the cells prone to rampant gene exchange; and that the eukaryotic supergroups emerged through distinct, secondary endosymbiotic events (as opposed to the primary, mitochondrial endosymbiosis. This biphasic model of evolution is substantially analogous to the scenario of the origin of universes in the eternal inflation version of modern cosmology. Under this model, universes like ours emerge in the infinite multiverse when the eternal process of exponential expansion, known as inflation, ceases in a particular region as a result of false vacuum decay, a first order phase transition process. The result is the nucleation of a new universe, which is traditionally denoted Big Bang, although this scenario is radically different from the Big Bang of the traditional model of an expanding universe. Hence I denote the phase transitions at the end of each inflationary epoch in the history of life Biological Big Bangs (BBB. Conclusion A Biological Big Bang (BBB model is proposed for the major transitions in life's evolution. According to this model, each transition is a BBB such that new classes of biological entities emerge at the end of a rapid phase of evolution (inflation that is characterized by extensive exchange of genetic information which takes distinct forms for different BBBs. The major types of new forms emerge independently, via a sampling process, from the pool of recombining entities of the preceding generation. This process is envisaged as being qualitatively different from tree

  12. Quantum Oscillations Can Prevent the Big Bang Singularity in an Einstein-Dirac Cosmology

    Science.gov (United States)

    Finster, Felix; Hainzl, Christian

    2010-01-01

    We consider a spatially homogeneous and isotropic system of Dirac particles coupled to classical gravity. The dust and radiation dominated closed Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find a mechanism where quantum oscillations of the Dirac wave functions can prevent the formation of the big bang or big crunch singularity. Thus before the big crunch, the collapse of the universe is stopped by quantum effects and reversed to an expansion, so that the universe opens up entering a new era of classical behavior. Numerical examples of such space-times are given, and the dependence on various parameters is discussed. Generically, one has a collapse after a finite number of cycles. By fine-tuning the parameters we construct an example of a space-time which satisfies the dominant energy condition and is time-periodic, thus running through an infinite number of contraction and expansion cycles.

  13. Discrete gravity and the universe from big crunch to big bang

    CERN Document Server

    Ling, Y

    2003-01-01

    In this paper we present a discretized description of the universe from big crunch to big bang. In this context we find the cosmological singularity can be avoided in a general fashion. However, whether the continuum limit of such discretized theories exists is model dependent. In the case of massless scalar field coupled to gravity with $\\Lambda=0$, the continuum limit can only be achieved by fine tuning the recurrence constant. We regard this failure as the implication that cosmological constant should vary with time. For this reason we replace the massless scalar field by Chaplygin gas which may contribute an effective cosmological constant term with the evolution of the universe. It turns out that the continuum limit can be reached in this case indeed.

  14. Quantum Oscillations Prevent the Big Bang Singularity in an Einstein-Dirac Cosmology

    CERN Document Server

    Finster, Felix

    2008-01-01

    We consider a spatially homogeneous and isotropic system of Dirac particles coupled to classical gravity. The dust and radiation dominated closed Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find a mechanism where quantum oscillations of the Dirac wave functions prevent the formation of the big bang or big crunch singularity. Thus before the big crunch, the collapse of the universe is stopped by quantum effects and reversed to an expansion, so that the universe opens up entering a new era of classical behavior. Numerical examples of such space-times are given, and the dependence on various parameters is discussed. We finally give an example of a space-time which satisfies the dominant energy condition and is time-periodic, thus running through an infinite number of contraction and expansion cycles.

  15. “I am a rogue night elf”: Avatars, gaming and The Big Bang Theory

    Directory of Open Access Journals (Sweden)

    Theo Plothe

    2014-03-01

    Full Text Available CBS’s The Big Bang Theory (TBBT frequently exhibits elements of video games and gaming culture. The author uses subculture theory to consider the representation of video games, gamers, and their avatars within popular culture. This paper investigates the representation of avatars within the characterization of gaming subculture on the TBBT. The author performed a content analysis of the program’s six seasons, examining the relationship between the show’s video game playing characters and their avatars. This investigation found that almost half of the scenes that contained video gaming activities contained some aspect of avatars. TBBT reifies gaming as a subculture through the relationship between the characters and their avatars. Examining the representation of these relationships is essential to understanding the representation of the gaming subculture in the mass media and within culture at large.

  16. The Biological Big Bang model for the major transitions in evolution

    Science.gov (United States)

    Koonin, Eugene V

    2007-01-01

    previously developed concepts of the emergence of protein folds by recombination of small structural units and origin of viruses and cells from a pre-cellular compartmentalized pool of recombining genetic elements. The model is extended to encompass other major transitions. It is proposed that bacterial and archaeal phyla emerged independently from two distinct populations of primordial cells that, originally, possessed leaky membranes, which made the cells prone to rampant gene exchange; and that the eukaryotic supergroups emerged through distinct, secondary endosymbiotic events (as opposed to the primary, mitochondrial endosymbiosis). This biphasic model of evolution is substantially analogous to the scenario of the origin of universes in the eternal inflation version of modern cosmology. Under this model, universes like ours emerge in the infinite multiverse when the eternal process of exponential expansion, known as inflation, ceases in a particular region as a result of false vacuum decay, a first order phase transition process. The result is the nucleation of a new universe, which is traditionally denoted Big Bang, although this scenario is radically different from the Big Bang of the traditional model of an expanding universe. Hence I denote the phase transitions at the end of each inflationary epoch in the history of life Biological Big Bangs (BBB). Conclusion A Biological Big Bang (BBB) model is proposed for the major transitions in life's evolution. According to this model, each transition is a BBB such that new classes of biological entities emerge at the end of a rapid phase of evolution (inflation) that is characterized by extensive exchange of genetic information which takes distinct forms for different BBBs. The major types of new forms emerge independently, via a sampling process, from the pool of recombining entities of the preceding generation. This process is envisaged as being qualitatively different from tree-pattern cladogenesis. Reviewers This article

  17. On Big Bang Relics, the Neutrino Mass and the Spectrum of Cosmic Rays

    CERN Document Server

    Wigmans, R

    2000-01-01

    It is shown that high-energy features of the cosmic ray spectrum, in particular the kink around 4 PeV and the corresponding change in spectral index, may be explained from interactions between highly energetic cosmic protons and relic Big Bang antineutrinos, if the latter have a rest mass of about 0.4 eV/$c^2$. This explanation is supported by experimental data from extensive air-shower experiments, and in particular by the observation (Fly's Eye) of a second kink around 300 PeV, and by the abrupt change in the chemical composition of the cosmic ray spectrum that occurs at that energy. Both facts follow naturally from our theory, which predicts additional verifiable features of the cosmic ray spectrum in the few-PeV region, e.g. an abrupt decrease in the $p/\\alpha$ ratio.

  18. Dust production 0.7-1.5 billion years after the Big Bang

    CERN Document Server

    Michałowski, Michał J

    2015-01-01

    Cosmic dust is an important component of the Universe, and its origin, especially at high redshifts, is still unknown. I present a simple but powerful method of assessing whether dust observed in a given galaxy could in principle have been formed by asymptotic giant branch (AGB) stars or supernovae (SNe). Using this method I show that for most of the galaxies with detected dust emission between z=4 and z=7.5 (1.5-0.7 billion years after the Big Bang) AGB stars are not numerous and efficient enough to be responsible for the measured dust masses. Supernovae could account for most of the dust, but only if all of them had efficiencies close to the maximal theoretically allowed value. This suggests that a different mechanism is responsible for dust production at high redshifts, and the most likely possibility is the grain growth in the interstellar medium.

  19. Relic High Frequency Gravitational waves from the Big Bang, and How to Detect Them

    CERN Document Server

    Beckwith, A W

    2008-01-01

    We show generic conditions for HFGW detection, employing a novel entropy concept written up by Jack Ng, and Steinhard's proceedure for reconstructing tensorial representations for relic HFGW from the onset of the big bang. The issue of the reality of gravitons as a measurable physical object so eloquently raised by Rothman in 2006 is indirectly answered via a proceedure obtained from Weinberg's 1972 book on gravitation, and all the methodologies so obtained are referenced with respect to the engineering specifications of the Li-Baker HFGW detector. In addition, the document also refers to entanglement entropy, and its possible aid in refining measurement predictions by the Li-Baker HFGW detector, using Dr. Yeo's 2006 EPL paper

  20. THE WORDPLAY OF ‘THE BIG BANG THEORY’ MOVIE SUBTITLE

    Directory of Open Access Journals (Sweden)

    Sang Ayu Isnu Maharani

    2016-05-01

    Full Text Available This study aims to describe the type of wordplay in the subtitle of the movie entitled ‘The Big Bang Theory’ and also to describe the technique applied in translating the wordplay. This study is a descriptive qualitative and library study. The data was collected through observation and note taking techniques. The framework of this study is Delabatista (1993 concerning with types of wordplay translation and Humanika (2012 about the techniques to translate the wordplay. This study found that there are three types of wordplay; they are the phonological structure (homonymy and homophony, the lexical development (idiom and the syntactic structure. The techniques of translating wordplay found consist of literal translation, loan translation, situational translation and no translation.

  1. Nobel Lecture: From the Big Bang to the Nobel Prize and beyond

    Science.gov (United States)

    Mather, John C.

    NASA’s Cosmic Background Explorer satellite mission, the COBE, laid the foundations for modern cosmology by measuring the spectrum and anisotropy of the cosmic microwave background radiation and discovering the cosmic infrared background radiation. I describe the history of the COBE project, its scientific context, the people who built it, and the scientific results. The COBE observed the universe on the largest scales possible by mapping the cosmic microwave and infrared background radiation fields and determining their spectra. It produced conclusive evidence that the hot Big Bang theory of the early universe is correct, showed that the early universe was very uniform but not perfectly so, and that the total luminosity of post Big Bang objects is twice as great as previously believed. The COBE concept was developed by a Mission Definition Study Team appointed by NASA in 1976, based on three competing proposals submitted in 1974. The COBE was built in-house by Goddard Space Flight Center, with a helium cryostat provided by Ball Aerospace, and was launched on a Delta rocket built by McDonnell Douglas. It is in a circular orbit 900km above the Earth, in a plane inclined 99° to the equator and roughly perpendicular to the line to the Sun. It carried three instruments, a far infrared absolute spectrophotometer (FIRAS), a differential microwave radiometer with three channels (DMR), and a diffuse infrared background experiment (DIRBE). The helium cryostat cooled the FIRAS and DIRBE for 10months until the helium was exhausted, but operations continued for a total of 4years . Subsequent observations have confirmed the COBE results and led to measurements of the main cosmological parameters with a precision of a few percent.

  2. New reaction rates for improved primordial D /H calculation and the cosmic evolution of deuterium

    Science.gov (United States)

    Coc, Alain; Petitjean, Patrick; Uzan, Jean-Philippe; Vangioni, Elisabeth; Descouvemont, Pierre; Iliadis, Christian; Longland, Richard

    2015-12-01

    Primordial or big bang nucleosynthesis (BBN) is one of the three historically strong evidences for the big bang model. Standard BBN is now a parameter-free theory, since the baryonic density of the Universe has been deduced with an unprecedented precision from observations of the anisotropies of the cosmic microwave background radiation. There is a good agreement between the primordial abundances of 4He, D, 3He, and 7Li deduced from observations and from primordial nucleosynthesis calculations. However, the 7Li calculated abundance is significantly higher than the one deduced from spectroscopic observations and remains an open problem. In addition, recent deuterium observations have drastically reduced the uncertainty on D /H , to reach a value of 1.6%. It needs to be matched by BBN predictions whose precision is now limited by thermonuclear reaction rate uncertainties. This is especially important as many attempts to reconcile Li observations with models lead to an increased D prediction. Here, we reevaluate the d (p ,γ )3He, d (d ,n ) 3H3, and d (d ,p ) 3H reaction rates that govern deuterium destruction, incorporating new experimental data and carefully accounting for systematic uncertainties. Contrary to previous evaluations, we use theoretical ab initio models for the energy dependence of the S factors. As a result, these rates increase at BBN temperatures, leading to a reduced value of D /H =(2.45 ±0.10 )×10-5 (2 σ ), in agreement with observations.

  3. Primordial nucleosynthesis and the abundances of beryllium and boron

    Science.gov (United States)

    Thomas, David; Schramm, David N.; Olive, Keith A.; Fields, Brian D.

    1993-01-01

    The recently attained ability to make measurements of Be and B as well as to put constraints on Li-6 abundances in metal-poor stars has led to a detailed reexamination of big bang nucleosynthesis in the A is greater than about 6 regime. The nuclear reaction network has been significantly expanded, with many new rates added. It is demonstrated that although a number of A is greater than 7 reaction rates are poorly determined, even with extreme values chosen, the standard homogeneous model is unable to produce significant yields above A = 7, and the (Li-7)/(Li-6) ratio always exceeds 500. We also preliminarily explore inhomogeneous models, such as those inspired by a first-order quark-hadron phase transition, where regions with high neutron/proton ratios can allow some leakage up to A is greater than 7. However, models that fit the A is not greater than 7 abundances still seem to have difficulty in obtaining significant A is greater than 7 yields.

  4. Nuclear Reactions from Lattice QCD

    CERN Document Server

    Briceño, Raúl A; Luu, Thomas C

    2014-01-01

    One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low- energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path ...

  5. New measurement of the 8Li(α ,n )11B reaction in a lower-energy region below the Coulomb barrier

    Science.gov (United States)

    Das, S. K.; Fukuda, T.; Mizoi, Y.; Ishiyama, H.; Miyatake, H.; Watanabe, Y. X.; Hirayama, Y.; Jeong, S. C.; Ikezoe, H.; Matsuda, M.; Nishio, K.; Hashimoto, T.

    2017-05-01

    The 8Li(α ,n )11B reaction is regarded as the key reaction in the inhomogeneous big bang and in type-II supernova nucleosynthesis. Recently, the importance of this reaction to solving the 7Li problem, i.e., the inconsistency between the predicted and the observed primordial 7Li abundances, has also been noted. The most recent cross-section data published by our collaboration group in 2006 [H. Ishiyama et al., Phys. Lett. B 640, 82 (2006), 10.1016/j.physletb.2006.07.036] cover the 0.7- to 2.6-MeV energy region in the center-of-mass system. Here, we present additional data spanning the 0.45- to 1.8-MeV energy region. Thus, the predominant energy region for the big bang nucleosynthesis, corresponding to T9=1 (where T9 is a temperature unit equivalent to 109 K), is almost completely spanned by the previous [H. Ishiyama et al., Phys. Lett. B 640, 82 (2006), 10.1016/j.physletb.2006.07.036] and present results together.

  6. New reaction rates for improved primordial D/H calculation and the cosmic evolution of deuterium

    CERN Document Server

    Coc, Alain; Uzan, Jean-Philippe; Vangioni, Elisabeth; Descouvemont, Pierre; Illiadis, Christian; Longland, Richard

    2015-01-01

    Primordial or big bang nucleosynthesis (BBN) is one of the three historical strong evidences for the big bang model. Standard BBN is now a parameter free theory, since the baryonic density of the Universe has been deduced with an unprecedented precision from observations of the anisotropies of the cosmic microwave background (CMB) radiation. There is a good agreement between the primordial abundances of 4He, D, 3He and 7Li deduced from observations and from primordial nucleosynthesis calculations. However, the 7Li calculated abundance is significantly higher than the one deduced from spectroscopic observations and remains an open problem. In addition, recent deuterium observations have drastically reduced the uncertainty on D/H, to reach a value of 1.6%. It needs to be matched by BBN predictions whose precision is now limited by thermonuclear reaction rate uncertainties. This is especially important as many attempts to reconcile Li observations with models lead to an increased D prediction. Here, we re-evalua...

  7. BICEP2, Planck, spinorial space-time, pre-Big Bang.

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres Luis

    2015-01-01

    Full Text Available The field of Cosmology is currently undergoing a positive and constructive crisis. Controversies concerning inflation are not really new. But after the 2013-2014 Planck and BICEP2 announcements, and the more recent joint analysis by Planck, BICEP2 and the Keck Array (PBKA, the basic issues can involve more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental results. Open questions and new ideas on the foundations of Cosmology can emerge, while future experimental and observational programs look very promising. The BICEP2 result reporting an excess of B-mode polarization signal of the cosmic microwave background (CMB radiation was initially presented as a signature of primordial gravitational waves from cosmic inflation. But polarized dust emission can be at the origin of such a signal, and the evidence claimed by BICEP2 is no longer secure after the PBKA analysis. Furthermore, even assuming that significant CMB B-mode polarization has indeed been generated by the early Universe, its theoretical and cosmological interpretation would be far from obvious. Inflationary gravitational waves are not the only possible source of primordial CMB B-modes. Alternative cosmologies such as pre-Big Bang patterns and the spinorial space-time (SST we introduced in 1996-97 can naturally produce this polarization. Furthermore, the SST automatically generates for each comoving observer a local privileged space direction (PSD whose existence may have been confirmed by Planck data. If such a PSD exists, vector perturbations have most likely been strong in the early Universe and may have produced CMB B-modes. Pre-Big Bang cosmologies can also generate gravitational waves in the early Universe without inflation. After briefly describing detectors devoted to the study of the CMB polarization, we discuss the situation emerging from BICEP2 results, Planck results and the PBKA analysis. In particular, we

  8. 字幕翻译中幽默元素的翻译--以The Big Bang Theory为例

    Institute of Scientific and Technical Information of China (English)

    乐迁

    2016-01-01

    幽默可分为三类:语言幽默、文化幽默和普义幽默。每类幽默的特点决定了翻译时译员要采取不同的策略。本文通过对翻译The Big Bang Theory中幽默的讨论,探索各类幽默可行的翻译方法。

  9. A study on the Translation of Cultural Elements in TV Subtitles-A Case Study of The Big Bang Theory

    Institute of Scientific and Technical Information of China (English)

    胡亚庆

    2014-01-01

    With the growing popularity of one country’s TV series in foreign countries, subtitle translation has attracted consider-able attention in recent years. The Big Bang Theory (TBBT) is a widespread American TV series whose subtitles have been trans-lated into many foreign languages, and it also boasts its richness in cultural elements, the most typical ones including science ele-ments and religious cultural elements.

  10. {sup 8}Li + p reaction and the primordial nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Mendes Junior, D.R.; Lepine-Szily, A.; Lichtenthaeler, Rubens; Guimaraes, Valdir; Faria, P.N. de; Barioni, Adriana; Camargo Junior, Orli; Pires, K.C.C.; Morcelle, Viviane; Morais, Maria Carmen; Candori, R. Pampa; Scarduelli, Valdir; Leistenschneider, Erick [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Dept. de Fisica Nuclear; Assuncao, Marlete [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Descouvemont, P. [Universite Libre de Bruxelles, Brussels (Belgium). Physique Theorique et Mathematique

    2011-07-01

    Full text: We present a direct measurement of the {sup 8}Li(p,{alpha}){sup 5}He cross section, using a radioactive {sup 8}Li beam impinging on target of CH{sub 2}. This target has a thickness of 6.8 mg/cm{sup 2}, that is thick enough to stop the {sup 8}Li beam in it. The {sup 8}Li beam was produced at the primary target by the reaction {sup 9}Be({sup 7}Li,{sup 8}Li){sup 8}Be and was focalized by the first superconductor solenoid of RIBRAS on a secondary CH{sub 2} target. The reaction products were measured with four silicon barrier detectors, mounted as {Delta}E-E telescopes, where the {Delta}E detectors were 20{mu}m thick and the E detectors were 1000 {mu}m thick. The measurements were performed between Ecm=0.2 and 2.5 MeV at several laboratory angles. They show a broad peak around 1.7 MeV where the cross-section is almost isotropic. At low energies the data show a clear evidence for an increase of the S-factor. This suggests the importance of subthreshold states in {sup 9}Be. An R-matrix analysis of the experimental data has been performed in order to derive spectroscopic information (such as energies, neutron and alpha widths) of some resonances and to extrapolate the data down to zero energy. This R-matrix fit is then used to determine the {sup 8}Li(p,{alpha}){sup 5}He reaction rate, which is compared to the {sup 8}Li({alpha},n){sup 11}B reaction rate. (author)

  11. PArthENoPE: Public Algorithm Evaluating the Nucleosynthesis of Primordial Elements

    Energy Technology Data Exchange (ETDEWEB)

    Pisanti, O.; Cirillo, A.; Esposito, S.; Iocco, F.; Mangano, G.; Miele, G.; Serpico, P.D.

    2007-05-04

    We describe a program for computing the abundances of light elements produced during Big Bang Nucleosynthesis which is publicly available at http://parthenope.na.infn.it/. Starting from nuclear statistical equilibrium conditions the program solves the set of coupled ordinary differential equations, follows the departure from chemical equilibrium of nuclear species, and determines their asymptotic abundances as function of several input cosmological parameters as the baryon density, the number of effective neutrino, the value of cosmological constant and the neutrino chemical potential.

  12. Change of government: one more big bang health care reform in England's National Health Service.

    Science.gov (United States)

    Hunter, David J

    2011-01-01

    Once again the National Health Service (NHS) in England is undergoing major reform, following the election of a new coalition government keen to reduce the role of the state and cut back on big government. The NHS has been undergoing continuous reform since the 1980s. Yet, despite the significant transaction costs incurred, there is no evidence that the claimed benefits have been achieved. Many of the same problems endure. The reforms follow the direction of change laid down by the last Conservative government in the early 1990s, which the recent Labour government did not overturn despite a commitment to do so. Indeed, under Labour, the NHS was subjected to further market-style changes that have paved the way for the latest round of reform. The article considers the appeal of big bang reform, questions its purpose and value, and critically appraises the nature and extent of the proposed changes in this latest round of reform. It warns that the NHS in its current form may not survive the changes, as they open the way to privatization and a weakening of its public service ethos.

  13. A high abundance of massive galaxies 3-6 billion years after the Big Bang.

    Science.gov (United States)

    Glazebrook, Karl; Abraham, Roberto G; McCarthy, Patrick J; Savaglio, Sandra; Chen, Hsiao-Wen; Crampton, David; Murowinski, Rick; Jørgensen, Inger; Roth, Kathy; Hook, Isobel; Marzke, Ronald O; Carlberg, R G

    2004-07-08

    Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units. The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies, but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4-7), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.

  14. The Interstellar Medium In Galaxies Seen A Billion Years After The Big Bang

    CERN Document Server

    Capak, P L; Jones, G; Casey, C M; Riechers, D; Sheth, K; Carollo, C M; Ilbert, O; Karim, A; LeFevre, O; Lilly, S; Scoville, N; Smolcic, V; Yan, L

    2015-01-01

    Evolution in the measured rest frame ultraviolet spectral slope and ultraviolet to optical flux ratios indicate a rapid evolution in the dust obscuration of galaxies during the first 3 billion years of cosmic time (z>4). This evolution implies a change in the average interstellar medium properties, but the measurements are systematically uncertain due to untested assumptions, and the inability to measure heavily obscured regions of the galaxies. Previous attempts to directly measure the interstellar medium in normal galaxies at these redshifts have failed for a number of reasons with one notable exception. Here we report measurements of the [CII] gas and dust emission in 9 typical (~1-4L*) star-forming galaxies ~1 billon years after the big bang (z~5-6). We find these galaxies have >12x less thermal emission compared with similar systems ~2 billion years later, and enhanced [CII] emission relative to the far-infrared continuum, confirming a strong evolution in the interstellar medium properties in the early u...

  15. Conference | The Big Bang and the interfaces of knowledge: towards a common understanding? | 11 November

    CERN Multimedia

    2015-01-01

    The third in a series of conferences organised by CERN and Wilton Park, this event will once again bring together scientists, theologians and philosophers to discuss the themes of the nature and understanding of a common language, truth and logic.   Wednesday, 11 November at 4 p.m. in the Main Auditorium For more information and to register, click here. In 2012, CERN and Wilton Park hosted the pioneering international conference “The Big Bang and the interfaces of knowledge: towards a common language?”. The event was very successful and a follow-up conference was organised in June 2014 with the purpose of widening the spectrum of scientists, theologians and philosophers involved, continuing the dialogue on one of the key themes that emerged during the first meeting: the nature and the understanding of “truth”. A key theme emerging from the 2014 event was the nature and understanding of logic, and this third meeting will focu...

  16. A Note on the Quantization Mechanism within the Cold Big Bang Cosmology

    Directory of Open Access Journals (Sweden)

    Assis A. V. D. B.

    2011-10-01

    Full Text Available In my paper [3], I obtain a Cold Big Bang Cosmology, fitting the cosmological data, with an absolute zero primordial temperature, a natural cutoff for the cosmological data to a vanishingly small entropy at a singular microstate of a comoving domain of the cos- mological fluid. This solution resides on a negative pressure solution from the general relativity field equation and on a postulate regarding a Heisenberg indeterminacy mech- anism related to the energy fluctuation obtained from the solution of the field equations under the Robertson-Walker comoving elementar line element context in virtue of the adoption of the Cosmological Principle. In this paper, we see the, positive, differential energy fluctuation, purely obtained from the general relativity cosmological solution in [3], leads to the quantum mechanical argument of the postulate in [3], provided this energy fluctuation is quantized, strongly supporting the postulate in [3]. I discuss the postulate in [3], showing the result for the energy fluctuation follows from a discreteness hypothesis.

  17. Relative Energy Associated with a White Hole Model of the Big Bang

    CERN Document Server

    Binbay, F; Salti, M; Acikgoz, Irfan; Binbay, Figen; Salti, Mustafa

    2006-01-01

    A specific Lemaitre-Tolman model of a spherically symmetric non-rotating white hole model with a few adjustable parameters is investigated to calculate the momentum four-vector distribution (due to matter plus fields including gravity) in the teleparallel gravity. The energy-momentum distributions (due to matter and fields including gravity) of a model are found to be zero. The result that the total energy and momentum components of a white hole model of the big bang are zero supports the viewpoints of Albrow and Tryon. It is also independent of the teleparallel dimensionless coupling constant, which means that it is valid in any teleparallel model. The results we obtained support the viewpoint of Lessner that the Moller energy-momentum formulation is a powerful concept to calculate energy and momentum distributions associated with the universe, and sustains the importance of the energy-momentum definitions in the evaluation of the energy-momentum distribution of a given space-time. Furthermore, the results o...

  18. Comparison of Plasma-Redshift Cosmology and Big-Bang Cosmology

    Science.gov (United States)

    Brynjolfsson, Ari

    2009-05-01

    Plasma redshift is derived theoretically from conventional axioms of physics by using more accurate methods than those conventionally used. The main difference is the proper inclusion of the dielectric constant. The force acting on the electron is proportional to E=D/ɛ and not D as is conventionally surmised. This correction is not important in ordinary laboratory plasmas; but in the hot sparse plasmas of the intergalactic space, it explains the gradual energy loss (the cosmological redshift) of photons. This energy loss of photons is transferred to the plasma and makes it very hot. The plasma redshift explains long range of phenomena, including the intrinsic redshift of Sun, stars, galaxies and quasars, and the cosmological redshift. It explains also the beautiful black body spectrum of the CMB, and it predicts the observed XRB, and much more. There is no need for Big Bang, Inflation, Dark Energy, Dark Matter, Black Holes and much more. The universe is quasi-static and can renew itself forever. There is no cosmic time dilation. In intergalactic space the average temperature is 2.7.10^6 K, and the average electron density (Ne)avg= 2 .10-4 cm-3.

  19. CMB B-modes, spinorial space-time and Pre-Big Bang (II)

    CERN Document Server

    Gonzalez-Mestres, Luis

    2014-01-01

    The BICEP2 collaboration reported recently a B-mode polarization of the cosmic microwave background (CMB) radiation inconsistent with the null hypothesis at a significance of > 5 {\\sigma}. This result has been often interpreted as a signature of primordial gravitational waves from cosmic inflation, even if actually polarized dust emission may be at the origin of such a signal. Even assuming that part of this CMB B-mode polarization really corresponds to the early Universe dynamics, its interpretation in terms of inflation and primordial gravitational waves is not the only possible one. Alternative cosmologies such as pre-Big Bang patterns and the spinorial space-time (SST) we introduced in 1996-97 can naturally account for such CMB B-modes. In particular, the SST automatically generates a privileged space direction (PSD) whose existence may have been confirmed by Planck data. If such a PSD exists, it seems normal to infer that vector perturbations have been present in the early Universe leading to CMB B-modes...

  20. From the big bang to cleaner teeth - doppler shift - a practical engineering tool

    Energy Technology Data Exchange (ETDEWEB)

    Traynor, R [Vibrometry and Velocimetry Product Specialist, Lambda Photometrics Ltd, UK Division of Polytec GmbH, Lambda House, Batford Mill, Harpenden, Hertfordshire, AL5 5BZ (United Kingdom)], E-mail: roger@lambdaphoto.co.uk

    2008-03-01

    Many basic engineering techniques rely on fundamental science that is so well embedded and accepted, that it becomes effectively 'invisible' to the average user. Doppler Shift is one such physical phenomenon that is widely used throughout science and engineering, but often without being noticed. Probably the most familiar scientific application of Doppler is the measurement of the speed of stars, to identify the expansion of the Universe since the 'Big Bang'. But in engineering and R and D, it can and is being used as a powerful vibration measurement tool. Using laser-based interferometric techniques, with Doppler Frequency Shifting in one path of the interferometer, velocities and displacements as subtle as those of the hearing mechanisms of flies and as fierce as the motion of Formula 1 engines valves can be measured This paper describes the basics of Doppler Shift and its use within Laser Doppler Vibration and Velocity measurement instruments. It will cover the extremely wide performance capabilities of the technique and the practical advantages of such instruments, with some practical examples of how and where they are currently being used. Of these examples, many are unique and would not be practical or even feasible without the availability of such tools.

  1. From Big Crunch to Big Bang with AdS/CFT

    CERN Document Server

    Turok, Neil; Hertog, Thomas

    2007-01-01

    The AdS/CFT correspondence is used to describe a five-dimensional cosmology with a big crunch singularity in terms of a super-Yang-Mills theory on $\\Rbar\\times S^3$ deformed by a potential which is unbounded below. Classically, a Higgs field in the dual theory rolls to infinity in finite time. But since the $S^3$ is finite, the unstable mode spreads quantum mechanically and the singularity is resolved when self-adjoint boundary conditions are imposed at infinity. Asymptotic freedom of the coupling governing the instability gives us computational control and the quantum spreading provides a UV cutoff on particle creation. The bulk translation of our result is a quantum transition from a big crunch to a big bang. An intriguing consequence of the near scale-invariance of the dual theory is that a nearly scale-invariant spectrum of stress-energy perturbations is automatically generated in the boundary theory. We comment on implications for more realistic cosmologies.

  2. Product Placement em Seriados de Televisão: Um estudo sobre The Big Bang Theory

    Directory of Open Access Journals (Sweden)

    Rafael Jose Bona

    2013-05-01

    Full Text Available Este estudo teve como objetivo analisar a imagem da Apple por meio das personagens do seriado estadunidense The Big Bang Theory. Para isso, foram analisadas as ações de merchandising (Product Placement presentes na narrativa de toda a 4a temporada (24 episódios que foi exibida entre setembro de 2010 e maio de 2011, nos Estados Unidos. Para atingir os objetivos da pesquisa foram utilizados Trindade (2007 e Russel e Belch (2007 que tratam sobre ações de merchandising em narrativas audiovisuais. Também são utilizados outros autores para fundamentar o trabalho e dar tratamento aos da pesquisa. Os resultados alcançados apontam que as ações de merchandising da Apple na temporada analisada estão relacionadas aos estilos de vida das personagens do seriado e, em sua maioria, em cenas de lazer e nos conflitos básicos da narrativa.

  3. A New Damage Detection Method: Big Bang-Big Crunch (BB-BC Algorithm

    Directory of Open Access Journals (Sweden)

    Zahra Tabrizian

    2013-01-01

    Full Text Available The present paper aims to explore damage assessment methodology based on the changes in dynamic parameters properties of vibration of a structural system. The finite-element model is used to apply at an element level. Reduction of the element stiffness is considered for structural damage. A procedure for locating and quantifying damaged areas of the structure based on the innovative Big Bang-Big Crunch (BB-BC optimization method is developed for continuous variable optimization. For verifying the method a number of damage scenarios for simulated structures have been considered. For the purpose of damage location and severity assessment the approach is applied in three examples by using complete and incomplete modal data. The effect of noise on the accuracy of the results is investigated in some cases. A great unbraced frame with a lot of damaged element is considered to prove the ability of proposed method. More over BB-BC optimization method in damage detection is compared with particle swarm optimizer with passive congregation (PSOPC algorithm. This work shows that BB-BC optimization method is a feasible methodology to detect damage location and severity while introducing numerous advantages compared to referred method.

  4. On the inside of a marble from quantum mechanics to the Big Bang

    CERN Document Server

    Bascom, Gavin

    2017-01-01

    Keeping in mind that we can only see the universe from the comfort of our home galaxy, Bascom begins his text by meticulously laying the necessary groundwork to understand the Big Bang’s mathematics without using any equations. He then paints a freeze-frame picture of our universe as if we had taken a three-dimensional picture with a giant camera. Within this picture, he traces forces beginning with the smallest (a single atom) to the biggest (the cosmos), keeping in mind that in this frozen moment everything further away from the observer spatially is also further away from the observer in time; that is, older. Soon a very real and very vivid image of the Big Bang appears (especially in things that are loud or hot), echoing down through time and into our everyday lives, reflected in every atom during every measurement. Then, slowly but deliberately, Bascom unfreezes this picture, ratcheting each moment from one to the next, showing us how and why quantum particles are constantly in contact with the Big Ban...

  5. Georges Lemaître: The Priest Who Invented the Big Bang

    Science.gov (United States)

    Lambert, Dominique

    This contribution gives a concise survey of Georges Lemaître works and life, shedding some light on less-known aspects. Lemaître is a Belgian catholic priest who gave for the first time in 1927 the explanation of the Hubble law and who proposed in 1931 the "Primeval Atom Hypothesis", considered as the first step towards the Big Bang cosmology. But the scientific work of Lemaître goes far beyond Physical Cosmology. Indeed, he contributed also to the theory of Cosmis Rays, to the Spinor theory, to Analytical mechanics (regularization of 3- Bodies problem), to Numerical Analysis (Fast Fourier Transform), to Computer Science (he introduced and programmed the first computer of Louvain),… Lemaître took part to the "Science and Faith" debate. He defended a position that has some analogy with the NOMA principle, making a sharp distinction between what he called the "two paths to Truth" (a scientific one and a theological one). In particular, he never made a confusion between the theological concept of "creation" and the scientific notion of "natural beginning" (initial singularity). Lemaître was deeply rooted in his faith and sacerdotal vocation. Remaining a secular priest, he belonged to a community of priests called "The Friends of Jesus", characterized by a deep spirituality and special vows (for example the vow of poverty). He had also an apostolic activity amongst Chinese students.

  6. First life in primordial-planet oceans: the biological big bang

    CERN Document Server

    Gibson, Carl H; Schild, Rudolph E

    2010-01-01

    A scenario is presented for the formation of first life in the universe based on hydro-gravitational-dynamics (HGD) cosmology. From HGD, the dark matter of galaxies is H-He gas dominated planets (primordial-fog-particle PFPs) in million solar mass clumps (protoglobularstarcluster PGCs), which formed at the plasma to gas transition temperature 3000 K. Stars result from mergers of the hot-gas-planets. Over-accretion causes stars to explode as supernovae that scatter life-chemicals (C, N, O, P, S, Ca, Fe etc.) to other planets in PGC clumps and beyond. These chemicals were first collected gravitationally by merging PFPs to form H-saturated, high-pressure, dense oceans of critical-temperature 647 K water over iron-nickel cores at ~ 2 Myr. Stardust fertilizes the formation of first life in a cosmic hot-ocean soup kitchen comprised of all planets and their moons in meteoric communication, > 10^100 kg in total. Ocean freezing slows this biological big bang at ~ 8 Myr. HGD cosmology confirms that the evolving seeds o...

  7. A magnified young galaxy from about 500 million years after the Big Bang.

    Science.gov (United States)

    Zheng, Wei; Postman, Marc; Zitrin, Adi; Moustakas, John; Shu, Xinwen; Jouvel, Stephanie; Høst, Ole; Molino, Alberto; Bradley, Larry; Coe, Dan; Moustakas, Leonidas A; Carrasco, Mauricio; Ford, Holland; Benítez, Narciso; Lauer, Tod R; Seitz, Stella; Bouwens, Rychard; Koekemoer, Anton; Medezinski, Elinor; Bartelmann, Matthias; Broadhurst, Tom; Donahue, Megan; Grillo, Claudio; Infante, Leopoldo; Jha, Saurabh W; Kelson, Daniel D; Lahav, Ofer; Lemze, Doron; Melchior, Peter; Meneghetti, Massimo; Merten, Julian; Nonino, Mario; Ogaz, Sara; Rosati, Piero; Umetsu, Keiichi; van der Wel, Arjen

    2012-09-20

    Re-ionization of the intergalactic medium occurred in the early Universe at redshift z ≈ 6-11, following the formation of the first generation of stars. Those young galaxies (where the bulk of stars formed) at a cosmic age of less than about 500 million years (z ≲ 10) remain largely unexplored because they are at or beyond the sensitivity limits of existing large telescopes. Understanding the properties of these galaxies is critical to identifying the source of the radiation that re-ionized the intergalactic medium. Gravitational lensing by galaxy clusters allows the detection of high-redshift galaxies fainter than what otherwise could be found in the deepest images of the sky. Here we report multiband observations of the cluster MACS J1149+2223 that have revealed (with high probability) a gravitationally magnified galaxy from the early Universe, at a redshift of z = 9.6 ± 0.2 (that is, a cosmic age of 490 ± 15 million years, or 3.6 per cent of the age of the Universe). We estimate that it formed less than 200 million years after the Big Bang (at the 95 per cent confidence level), implying a formation redshift of ≲14. Given the small sky area that our observations cover, faint galaxies seem to be abundant at such a young cosmic age, suggesting that they may be the dominant source for the early re-ionization of the intergalactic medium.

  8. A universal, post Big-Bang Nucleo-synthesis, pre-Galactic, origin of the Lithium (Spite) Plateau

    CERN Document Server

    Ouyed, Rachid

    2012-01-01

    (Abridged abstract) We investigate the lithium plateau in the context of primordial dual-shock quark novae (dsQNe; i.e. a QN occurring a few days to a few weeks following the preceding SN explosion) going off in the wake of Pop. III stars. The neutron-rich relativistic QN ejecta leads to spallation of 56Ni processed in the ejecta of the preceding SN ejecta and thus to "iron impoverishment" of the primordial gas swept by dsQNe. We show that the generation of stars formed from fragmentation of pristine clouds swept-up by dsQNe acquire a metallicity with -7.5 2 (and up to [C/Fe] ~ 5) can be accounted for in our model for dsQNe with t_delay 10-11 days (i.e. [Fe/H] > -3). For shorter delays the temperature of the SN shell is too hot (> 2.5x10^6 K) for the spallated 7Li to survive. We find a corresponding 6Li plateau with 6Li/7Li < 0.3.

  9. Impact of Nuclear Reaction Uncertainties on AGB Nucleosynthesis Models

    CERN Document Server

    Bisterzo, S; Kaeppeler, F; Wiescher, M; Travaglio, C

    2012-01-01

    Asymptotic giant branch (AGB) stars with low initial mass (1 - 3 Msun) are responsible for the production of neutron-capture elements through the main s-process (main slow neutron capture process). The major neutron source is 13C(alpha, n)16O, which burns radiatively during the interpulse periods at about 8 keV and produces a rather low neutron density (10^7 n/cm^3). The second neutron source 22Ne(alpha, n)25Mg, partially activated during the convective thermal pulses when the energy reaches about 23 keV, gives rise to a small neutron exposure but a peaked neutron density (Nn(peak) > 10^11 n/cm^3). At metallicities close to solar, it does not substantially change the final s-process abundances, but mainly affects the isotopic ratios near s-path branchings sensitive to the neutron density. We examine the effect of the present uncertainties of the two neutron sources operating in AGB stars, as well as the competition with the 22Ne(alpha, gamma)26Mg reaction. The analysis is carried out on AGB the main-s process...

  10. The Astrophysical S-factor for the 2H(, )6Li Nuclear Reaction at Low-Energies

    Indian Academy of Sciences (India)

    H. Sadeghi; A. Moghadasi; M. Ghamary

    2014-12-01

    The alpha radiative capture reactions are the key to understand about primordial nucleosynthesis and the observed abundance of light nucleus in stars. The astrophysical S-factor for the process 2H(, )6Li has been calculated at the low-energies relevant to big-bang nucleosynthesis and in comparison with laboratory data. On the basis of the model, the alpha radiative capture process is studied by using the two-and three-body electromagnetic currents. The bound and resonance states of 6Li are calculated via an inverse process, deuteron- photodisintegration of a 6Li nucleus. In comparison with other theoretical approaches and available laboratory data, excellent agreement is achieved for the astrophysical S-factor of this process.

  11. Big History or the 13800 million years from the Big Bang to the Human Brain

    Science.gov (United States)

    Gústafsson, Ludvik E.

    2017-04-01

    Big History is the integrated history of the Cosmos, Earth, Life, and Humanity. It is an attempt to understand our existence as a continuous unfolding of processes leading to ever more complex structures. Three major steps in the development of the Universe can be distinguished, the first being the creation of matter/energy and forces in the context of an expanding universe, while the second and third steps were reached when completely new qualities of matter came into existence. 1. Matter comes out of nothing Quantum fluctuations and the inflation event are thought to be responsible for the creation of stable matter particles in what is called the Big Bang. Along with simple particles the universe is formed. Later larger particles like atoms and the most simple chemical elements hydrogen and helium evolved. Gravitational contraction of hydrogen and helium formed the first stars und later on the first galaxies. Massive stars ended their lives in violent explosions releasing heavier elements like carbon, oxygen, nitrogen, sulfur and iron into the universe. Subsequent star formation led to star systems with bodies containing these heavier elements. 2. Matter starts to live About 9200 million years after the Big Bang a rather inconspicous star of middle size formed in one of a billion galaxies. The leftovers of the star formation clumped into bodies rotating around the central star. In some of them elements like silicon, oxygen, iron and many other became the dominant matter. On the third of these bodies from the central star much of the surface was covered with an already very common chemical compound in the universe, water. Fluid water and plenty of various elements, especially carbon, were the ingredients of very complex chemical compounds that made up even more complex structures. These were able to replicate themselves. Life had appeared, the only occasion that we human beings know of. Life evolved subsequently leading eventually to the formation of multicellular

  12. Origin of matter and space-time in the big bang

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, G. J. [University of Notre Dame, Center for Astrophysics/JINA, Notre Dame, IN 46556, USA and Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Kajino, T. [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Yamazaki, D. [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Kusakabe, M. [School of Liberal Arts and Science, Korea Aerospace University, Goyang 412-791, Korea and Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of)

    2014-05-02

    We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory for the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type la supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse

  13. Origin of matter and space-time in the big bang

    Science.gov (United States)

    Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.

    2014-05-01

    We review the case for and against a bulk cosmic motion resulting from the quantum entanglement of our universe with the multiverse beyond our horizon. Within the current theory for the selection of the initial state of the universe from the landscape multiverse there is a generic prediction that pre-inflation quantum entanglement with other universes should give rise to a cosmic bulk flow with a correlation length of order horizon size and a velocity field relative to the expansion frame of the universe. Indeed, the parameters of this motion are are tightly constrained. A robust prediction can be deduced indicating that there should be an overall motion of of about 800 km/s relative to the background space time as defined by the cosmic microwave background (CMB). This talk will summarize the underlying theoretical motivation for this hypothesis. Of course our motion relative to the background space time (CMB dipole) has been known for decades and is generally attributed to the gravitational pull of the local super cluster. However, this cosmic peculiar velocity field has been recently deduced out to very large distances well beyond that of the local super cluster by using X-ray galaxy clusters as tracers of matter motion. This is achieved via the kinematic component of the Sunyaev-Zeldovich (KSZ) effect produced by Compton scattering of cosmic microwave background photons from the local hot intracluster gas. As such, this method measures peculiar velocity directly in the frame of the cluster. Similar attempts by our group and others have attempted to independently assess this bulk flow via Type la supernova redshifts. In this talk we will review the observation case for and against the existence of this bulk flow based upon the observations and predictions of the theory. If this interpretation is correct it has profound implications in that we may be observing for the first time both the physics that occurred before the big bang and the existence of the multiverse

  14. Codimension-Two Big-Bang Bifurcation in a ZAD-Controlled Boost DC-DC Converter

    Science.gov (United States)

    Amador, A.; Casanova, S.; Granada, H. A.; Olivar, G.; Hurtado, J.

    In this paper, we study some nonlinear behaviors in a two-dimensional system defined by a Boost Converter controlled by CPWM (Centered Pulse-Width Modulation) and a ZAD (Zero Average Dynamics) strategy. The dynamics was analyzed using a discrete-time map, which consists of a sampled system at each switching cycle. The structure of the two-parametric space is characterized analytically. This allows proving the existence and stability of an infinite number of codimension-one curves that intersect at the same point in the two-parametric space. This phenomenon has been called a big-bang bifurcation.

  15. 总星系局爆宇宙理论%Theory of Local Big Bang of Metagalaxy on Universe

    Institute of Scientific and Technical Information of China (English)

    殷业; 胡素辉

    2013-01-01

    大爆炸宇宙理论是一个非常成功的宇宙理论,它在经过古斯等人提出的暴涨理论修正后日趋完善。但即使这样也还存在几个难题无法解决:(1)欧洲普朗克望远镜揭示的宇宙背景辐射的不对称性;(2)宇宙中所有物质来源于大爆炸没有实验依据;(3)存在暴涨中宇宙膨胀的超光速问题。为了解释上述难题,本文提出了一种建立在大爆炸宇宙理论基础上的多宇宙模型:总星系局爆宇宙模型。该模型可以很好地解决上述难题,文中提出了检验理论模型新的实验方法,通过实验可以最终确认真实的宇宙到底更符合哪个模型。%Big Bang Theory is a very successful theory of the Universe, which is maturing after being cor-rected by Alan Guth proposed inflation theory. But even so, there are several problems can’t be solved:(a) European Planck telescope reveals the cosmic background radiation asymmetry; (b) Big Bang created all matter in the Universe there isn’t experimental evidence; (c) superluminal in inflation theory is contra-diction with relativistic invariance of light speed assumption. In order to explain these problems, this pa-per presents a new model of the Universe based on the Big Bang Theory: Model of Local Big Bang of Metagalaxy. The model can be a good solution to these problems, it is also proposed an experimental methods of tested theoretical model, the experiment can finally confirm which model is more in line with the real Universe in the end.

  16. A Study of the Subtitle Translation in“The Big Bang Theory”from Newmark’s Communicative Translation Theory

    Institute of Scientific and Technical Information of China (English)

    甄宽; 彭念凡; 甄顺

    2015-01-01

    The subtitle translation is very different from other forms of translation.We translators should meet the particular needs of the subtitle.This study is going to analyze the subtitle translation in“The Big Bang Theory” from Newmark’s Communicative Translation Theory in three main perspectives:the information transmission,the aesthetics effect and the emotional transmission.In the information transmission the study will put emphasis on the limited circumstance.In the aesthetics effect the study will explore the expression of the sense of beauty.In the emotional transmission this study will study the use of rhetoric to express different emotions.

  17. On the relation between boundary proposals and hidden symmetries of the extended pre-big bang quantum cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Jalalzadeh, S.; Rostami, T. [Shahid Beheshti University, Department of Physics, Tehran (Iran, Islamic Republic of); Moniz, P.V. [Centro de Matematica e Aplicacoes-UBI, Covilha (Portugal); Universidade da Beira Interior, Departamento de Fisica, Covilha (Portugal)

    2015-01-01

    A framework associating quantum cosmological boundary conditions to minisuperspace hidden symmetries has been introduced in Jalalzadeh and Moniz (Phys Rev D 89:083504, 2014). The scope of the application was, notwithstanding the novelty, restrictive because it lacked a discussion involving realistic matter fields. Therefore, in the present letter, we extend the framework scope to encompass elements from a scalar-tensor theory in the presence of a cosmological constant. More precisely, it is shown that hidden minisuperspace symmetries present in a pre-big bang model suggest a process from which boundary conditions can be selected. (orig.)

  18. A Study of the Subtitle Translation in “The Big Bang Theory” from Newmark’s Communicative Translation Theory

    Institute of Scientific and Technical Information of China (English)

    甄宽; 彭念凡; 甄顺

    2015-01-01

    The subtitle translation is very different from other forms of translation.We translators should meet the particular needs of the subtitle.This study is going to analyze the subtitle translation in "The Big Bang Theory" from Newmark’s Communicative Translation Theory in three main perspectives:the information transmission,the aesthetics effect and the emotional transmission.In the information transmission the study will put emphasis on the limited circumstance.In the aesthetics effect the study will explore the expression of the sense of beauty.In the emotional transmission this study will study the use of rhetoric to express different emotions.

  19. Nuclear Reaction Uncertainties, Massive Gravitino Decays and the Cosmological Lithium Problem

    CERN Document Server

    Cyburt, Richard H; Fields, Brian D; Luo, Feng; Olive, Keith A; Spanos, Vassilis C

    2010-01-01

    We consider the effects of uncertainties in nuclear reaction rates on the cosmological constraints on the decays of unstable particles during or after Big-Bang nucleosynthesis (BBN). We identify the nuclear reactions due to non-thermal hadrons that are the most important in perturbing standard BBN, then quantify the uncertainties in these reactions and in the resulting light-element abundances. These results also indicate the key nuclear processes for which improved cross section data would allow different light-element abundances to be determined more accurately, thereby making possible more precise probes of BBN and evaluations of the cosmological constraints on unstable particles. Applying this analysis to models with unstable gravitinos decaying into neutralinos, we calculate the likelihood function for the light-element abundances measured currently, taking into account the current experimental errors in the determinations of the relevant nuclear reaction rates. We find a region of the gravitino mass and...

  20. Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo

    CERN Document Server

    Tveten, G M; Schwengner, R; Naqvi, F; Larsen, A C; Eriksen, T K; Garrote, F L Bello; Bernstein, L A; Bleuel, D L; Campo, L Crespo; Guttormsen, M; Giacoppo, F; Görgen, A; Hagen, T W; Hadynska-Klek, K; Klintefjord, M; Meyer, B S; Nyhus, H T; Renstrøm, T; Rose, S J; Sahin, E; Siem, S; Tornyi, T G

    2016-01-01

    One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme, astrophysical environments. A particularly challenging part of that question is the creation of the so-called p-nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average strength function of $^{92}$Mo. State-of-the-art p-process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the $^{91}$Nb$(p,{\\gamma})^{92}$Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of $^{92}$Mo. Based on our results, we conclude that the $^{92}$Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations.

  1. Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo

    Science.gov (United States)

    Tveten, G. M.; Spyrou, A.; Schwengner, R.; Naqvi, F.; Larsen, A. C.; Eriksen, T. K.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Crespo Campo, L.; Guttormsen, M.; Giacoppo, F.; Görgen, A.; Hagen, T. W.; Hadynska-Klek, K.; Klintefjord, M.; Meyer, B. S.; Nyhus, H. T.; Renstrøm, T.; Rose, S. J.; Sahin, E.; Siem, S.; Tornyi, T. G.

    2016-08-01

    One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme astrophysical environments. A particularly challenging part of that question is the creation of the so-called p -nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average γ strength function of 92Mo. State-of-the-art p -process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the 91Nb(p ,γ )92Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of 92Mo. Based on our results, we conclude that the 92Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations.

  2. 'Big Bang' tomography as a new route to atomic-resolution electron tomography.

    Science.gov (United States)

    Van Dyck, Dirk; Jinschek, Joerg R; Chen, Fu-Rong

    2012-06-13

    Until now it has not been possible to image at atomic resolution using classical electron tomographic methods, except when the target is a perfectly crystalline nano-object imaged along a few zone axes. The main reasons are that mechanical tilting in an electron microscope with sub-ångström precision over a very large angular range is difficult, that many real-life objects such as dielectric layers in microelectronic devices impose geometrical constraints and that many radiation-sensitive objects such as proteins limit the total electron dose. Hence, there is a need for a new tomographic scheme that is able to deduce three-dimensional information from only one or a few projections. Here we present an electron tomographic method that can be used to determine, from only one viewing direction and with sub-ångström precision, both the position of individual atoms in the plane of observation and their vertical position. The concept is based on the fact that an experimentally reconstructed exit wave consists of the superposition of the spherical waves that have been scattered by the individual atoms of the object. Furthermore, the phase of a Fourier component of a spherical wave increases with the distance of propagation at a known 'phase speed'. If we assume that an atom is a point-like object, the relationship between the phase and the phase speed of each Fourier component is linear, and the distance between the atom and the plane of observation can therefore be determined by linear fitting. This picture has similarities with Big Bang cosmology, in which the Universe expands from a point-like origin such that the distance of any galaxy from the origin is linearly proportional to the speed at which it moves away from the origin (Hubble expansion). The proof of concept of the method has been demonstrated experimentally for graphene with a two-layer structure and it will work optimally for similar layered materials, such as boron nitride and molybdenum disulphide.

  3. The first three minutes - 1990 version. [of early universe after Big Bang

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    The present state of understanding of what occurred in the universe's first three minutes is reviewed. Emphasis is on the events that lead to potentially observable consequences and that are model-independent or at least generic to broad classes of models. Inflation, phase transitions, dark matter, and nucleosynthesis are summarized.

  4. Conference | The Big Bang and the interfaces of knowledge: towards a common understanding of Truth? | 25 June

    CERN Multimedia

    2014-01-01

    You are cordially invited to attend the concluding open session of the conference The Big Bang and the interfaces of knowledge: towards a common understanding of Truth?    Wednesday 25 June at 14.30 in the Main Auditorium Please register by Tuesday 24 June at: https://indico.cern.ch/event/325739/ In 2012, CERN and Wilton Park hosted the pioneering international conference “The Big Bank and the interfaces of knowledge: towards a common language?” The purpose of this conference was to enable scientists from a range of disciplines to dialogue with philosophers and theologians from the world religions about the nature of the Big Bang. What understandings might scientists and theologians share in common? How are their paradigms shaped and developed? Is it possible to develop a common framework or language. The conference gained global attention. A follow-up conference will be held on 23-25 June 2014 with the purpose of widening the spectrum of...

  5. p-process nucleosynthesis via proton-capture reactions in thermonuclear supernovae explosions

    Directory of Open Access Journals (Sweden)

    Endres Anne

    2015-01-01

    Full Text Available Model calculations within the framework of the so-called γ process show an underproduction of the p nucleus with the highest isotopic abundace 92Mo. This discrepancy can be narrowed by taking into account the alternative production site of a type Ia supernova explosion. Here, the nucleus 92Mo can be produced by a sequence of proton-capture reactions. The amount of 92Mo nuclei produced via this reaction chain is most sensitive to the reactions 90Zr(p,γ and 91Nb(p,γ. Both rates have to be investigated experimentally to study the impact of this nucleosynthesis aspect on the long-standing 92Mo-problem. We have already measured the proton-capture reaction on 90Zr using high-resolution in-beam γ-ray spectroscopy. In this contribution, we will present our preliminary results of the total cross sections as well as the partial cross sections. Furthermore, we plan to measure the 91Nb(p,γ reaction soon. Due to the radioactive target material, the 91Nb nuclei have to be produced prior to the experiment. The current status of this production will be presented in this contribution.

  6. Testing the Big Bang: Light elements, neutrinos, dark matter and large-scale structure

    Science.gov (United States)

    Schramm, David N.

    1991-01-01

    Several experimental and observational tests of the standard cosmological model are examined. In particular, a detailed discussion is presented regarding: (1) nucleosynthesis, the light element abundances, and neutrino counting; (2) the dark matter problems; and (3) the formation of galaxies and large-scale structure. Comments are made on the possible implications of the recent solar neutrino experimental results for cosmology. An appendix briefly discusses the 17 keV thing and the cosmological and astrophysical constraints on it.

  7. Ab initio many-body calculations of the (3)H(d,n)(4)He and (3)He(d,p)(4)He fusion reactions.

    Science.gov (United States)

    Navrátil, Petr; Quaglioni, Sofia

    2012-01-27

    We apply the ab initio no-core shell model combined with the resonating-group method approach to calculate the cross sections of the (3)H(d,n)(4)He and (3)He(d,p)(4)He fusion reactions. These are important reactions for the big bang nucleosynthesis and the future of energy generation on Earth. Starting from a selected similarity-transformed chiral nucleon-nucleon interaction that accurately describes two-nucleon data, we performed many-body calculations that predict the S factor of both reactions. Virtual three-body breakup effects are obtained by including excited pseudostates of the deuteron in the calculation. Our results are in satisfactory agreement with experimental data and pave the way for microscopic investigations of polarization and electron-screening effects, of the (3)H(d,γn)(4)He bremsstrahlung and other reactions relevant to fusion research.

  8. "Big Bang'' as a result of first-order phase transition driven by changing scalar curvature in expanding early Universe: "hyperinflation'' scenario

    CERN Document Server

    Pashitskii, E A

    2015-01-01

    We suggest that the "Big Bang" may be a result of the first-order phase transition driven by changing scalar curvature of the 4D space-time in expanding cold Universe, filled with nonlinear scalar field $\\phi $ and neutral matter with equation of state $p=\

  9. The Big Bang and Its Proofs%宇宙大爆炸:有什么证据?

    Institute of Scientific and Technical Information of China (English)

    白杉

    2003-01-01

    @@ 大爆炸理论是关于宇宙形成的最有影响的一种学说,英文说法为Big Bang,也称为大爆炸宇宙论.大爆炸理论诞生于20世纪20年代,在40年代得到补充和发展,但一直寂寂无闻.直到50年代,人们才开始广泛注意这个理论.大爆炸理论的主要观点是认为我们的宇宙诞生于140亿年前,并曾有一段从热到冷的演化史.迄今人类已经获得的宇宙大爆炸证据有下列内容.

  10. The new model of the Big Bang and the Universe expansion. A comparison with modern observational data and cosmological theories

    Science.gov (United States)

    Kraiko, A. N.; Valiyev, Kh. F.

    2016-10-01

    The new model of the Big Bang and the Universe expansion is constructed. It is based on solutions in classical and in relativistic statements of problem on the dispersion into the void of the gas compressed into a point or in a finite, but for further negligible, volume. If to restrict in relativistic statement gas speed value v by the speed of light (υ =| v |

  11. D-branes in a Big Bang/Big Crunch Universe: Nappi-Witten Gauged WZW Model

    CERN Document Server

    Hikida, Y; Panigrahi, K L; Hikida, Yasuaki; Nayak, Rashmi R.; Panigrahi, Kamal L.

    2005-01-01

    We study D-branes in the Nappi-Witten model, which is a gauged WZW model based on (SL(2,R) x SU(2)) / (U(1) x U(1)). The model describes a four dimensional space-time consisting of cosmological regions with big bang/big crunch singularities and static regions with closed time-like curves. The aim of this paper is to investigate by D-brane probes whether there are pathologies associated with the cosmological singularities and the closed time-like curves. We first classify D-branes in a group theoretical way, and then examine DBI actions for effective theories on the D-branes. In particular, we show that D-brane metric from the DBI action does not include singularities, and wave functions on the D-branes are well behaved even in the presence of closed time-like curves.

  12. 多模态下情景喜剧The Big Bang Theory的字幕翻译

    Institute of Scientific and Technical Information of China (English)

    王祥冰

    2010-01-01

    本文在多模态话语分析的理论框架下,探讨最近流行的美国电视情景喜剧The Big Bang Theory的字幕翻译方法,分析在新的观看方式和特殊的文化环境下,字幕与画面、音响等其他模态之问的关系比传统的辅助作用要更深入,直译的方式能更好发挥字幕的作用,使得该情景喜剧的"幽默交际"得以成功实现.

  13. New Cosmic Center Universe Model Matches Eight of Big Bang's Major Predictions Without The F-L Paradigm

    CERN Document Server

    Gentry, R V

    2003-01-01

    Accompanying disproof of the F-L expansion paradigm eliminates the basis for expansion redshifts, which in turn eliminates the basis for the Cosmological Principle. The universe is not the same everywhere. Instead the spherical symmetry of the cosmos demanded by the Hubble redshift relation proves the universe is isotropic about a nearby universal Center. This is the foundation of the relatively new Cosmic Center Universe (CCU) model, which accounts for, explains, or predicts: (i) The Hubble redshift relation, (ii) a CBR redshift relation that fits all current CBR measurements, (iii) the recently discovered velocity dipole distribution of radiogalaxies, (iv) the well-known time dilation of SNeIa light curves, (v) the Sunyaev-Zeldovich thermal effect, (vi) Olber's paradox, (vii) SN dimming for z 1 an enhanced brightness that fits SN 1997ff measurements, (ix) the existence of extreme redshift (z > 10) objects which, when observed, will further distinguish it from the big bang. The CCU model also plausibly expl...

  14. Testing the big bang: Light elements, neutrinos, dark matter and large-scale structure

    Energy Technology Data Exchange (ETDEWEB)

    Schramm, D.N. (Chicago Univ., IL (United States) Fermi National Accelerator Lab., Batavia, IL (United States))

    1991-06-01

    In this series of lectures, several experimental and observational tests of the standard cosmological model are examined. In particular, detailed discussion is presented regarding nucleosynthesis, the light element abundances and neutrino counting; the dark matter problems; and the formation of galaxies and large-scale structure. Comments will also be made on the possible implications of the recent solar neutrino experimental results for cosmology. An appendix briefly discusses the 17 keV thing'' and the cosmological and astrophysical constraints on it. 126 refs., 8 figs., 2 tabs.

  15. The 12C + 12C reaction and the impact on nucleosynthesis in massive stars

    CERN Document Server

    Pignatari, M; Wiescher, M; Gallino, R; Bennett, M; Beard, M; Fryer, C; Herwig, F; Rockefeller, G; Timmes, F X; 10.1088/0004-637X/762/1/31

    2012-01-01

    Despite much effort in the past decades, the C-burning reaction rate is uncertain by several orders of magnitude, and the relative strength between the different channels 12C(12C,alpha)20Ne, 12C(12C,p)23Na and 12C(12C,n)23Mg is poorly determined. Additionally, in C-burning conditions a high 12C+12C rate may lead to lower central C-burning temperatures and to 13C(alpha,n)16O emerging as a more dominant neutron source than 22Ne(alpha,n)25Mg, increasing significantly the s-process production. This is due to the rapid decrease of the 13N(gamma,p)12C with decreasing temperature, causing the 13C production via 13N(beta+)13C. Presented here is the impact of the 12C+12C reaction uncertainties on the s-process and on explosive p-process nucleosynthesis in massive stars, including also fast rotating massive stars at low metallicity. Using various 12C+12C rates, in particular an upper and lower rate limit of ~ 50000 higher and ~ 20 lower than the standard rate at 5*10^8 K, five 25 Msun stellar models are calculated. The...

  16. Primordial ${\\alpha} + d \\to {}^{6}{\\rm Li} + \\gamma$ reaction and second Lithium puzzle

    CERN Document Server

    Mukhamedzhanov, A M; Bertulani, C A

    2016-01-01

    During the Big Bang, ${}^{6}{\\rm Li}$ was synthesized via the ${}^{2}{\\rm H}(\\alpha,\\gamma){}^{6}{\\rm Li}$ reaction. After almost 25 years of the failed attempts to measure the ${}^{2}{\\rm H}(\\alpha,\\gamma){}^{6}{\\rm Li}$ reaction in the lab at the Big Bang energies, just recently the LUNA collaboration presented the first successful measurements at two different Big Bang energies [M. Anders {\\it et al.}, Phys. Rev. Lett. {\\bf 113}, 042501 (2014)]. In this paper we will discuss how to improve the accuracy of the direct experiment. To this end the photon's angular distribution is calculated in the potential model. It contains contributions from electric dipole and quadrupole transitions and their interference, which dramatically changes the photon's angular distribution. The calculated distributions at different Big Bang energies have a single peak at $\\sim 50^{\\circ}$. These calculations provide the best kinematic conditions to measure the ${}^{2}{\\rm H}(\\alpha,\\gamma){}^{6}{\\rm Li}$ reaction. The expressions...

  17. How to analyse a Big Bang of data: the mammoth project at the Cern physics laboratory in Geneva to recreate the conditions immediately after the universe began requires computing power on an unprecedented scale

    CERN Multimedia

    Thomas, Kim

    2005-01-01

    How to analyse a Big Bang of data: the mammoth project at the Cern physics laboratory in Geneva to recreate the conditions immediately after the universe began requires computing power on an unprecedented scale

  18. On the use of big-bang method to generate low-energy structures of atomic clusters modeled with pair potentials of different ranges.

    Science.gov (United States)

    Marques, J M C; Pais, A A C C; Abreu, P E

    2012-02-05

    The efficiency of the so-called big-bang method for the optimization of atomic clusters is analysed in detail for Morse pair potentials with different ranges; here, we have used Morse potentials with four different ranges, from long- ρ = 3) to short-ranged ρ = 14) interactions. Specifically, we study the efficacy of the method in discovering low-energy structures, including the putative global minimum, as a function of the potential range and the cluster size. A new global minimum structure for long-ranged ρ = 3) Morse potential at the cluster size of n= 240 is reported. The present results are useful to assess the maximum cluster size for each type of interaction where the global minimum can be discovered with a limited number of big-bang trials.

  19. Historia del modelo cosmológico estándar LCDM: la cosmología física tras del modelo del big bang

    OpenAIRE

    2015-01-01

    Desde que el big bang se asentara como modelo cosmológico estándar han pasado 50 años. En este periodo, la cosmología ha mantenido abierta la cuestión de cuál es la evolución del universo y a través de la teoría inflacionaria ha enfrentado el p

  20. New microwave background constraints on the cosmic matter budget: trouble for nucleosynthesis?

    Science.gov (United States)

    Tegmark; Zaldarriaga

    2000-09-11

    We compute the joint constraints on ten cosmological parameters from the latest cosmic microwave background measurements. The lack of a significant second acoustic peak in the new BOOMERANG and MAXIMA data favors models with more baryons than big bang nucleosynthesis predicts, almost independently of what prior information is included. The simplest flat inflation models with purely scalar scale-invariant fluctuations prefer a baryon density 0. 022

  1. A Rapidly Star-forming Galaxy 700 Million Years After the Big Bang at z=7.51

    CERN Document Server

    Finkelstein, S L; Dickinson, M; Song, M; Tilvi, V; Koekemoer, A M; Finkelstein, K D; Mobasher, B; Ferguson, H C; Giavalisco, M; Reddy, N; Ashby, M L N; Dekel, A; Fazio, G G; Fontana, A; Grogin, N A; Huang, J -S; Kocevski, D; Rafelski, M; Weiner, B J; Willner, S P

    2013-01-01

    Out of several dozen z > 7 candidate galaxies observed spectroscopically, only five have been confirmed via Lyman-alpha emission, at z=7.008, 7.045, 7.109, 7.213 and 7.215. The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium (IGM) rises quickly at z > 6.5, as Lyman-alpha is resonantly scattered by neutral gas. However, the small samples and limited depth of previous observations makes these conclusions tentative. Here we report the results of a deep near-infrared spectroscopic survey of 43 z > 6.5 galaxies. We detect only a single galaxy, confirming that some process is making Lyman-alpha difficult to detect. The detected emission line at 1.0343 um is likely to be Lyman-alpha emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colors are consistent with significant metal content, implying that galaxies become enriched rapidly. We measure a surprisingly high star formation rate of 330 Msol/yr,...

  2. Indeterministic Quantum Gravity and Cosmology; 7, Dynamical Passage through Singularities Black Hole and Naked Singularity, Big Crunch and Big Bang

    CERN Document Server

    Mashkevich, V S

    1997-01-01

    This paper is a continuation of the papers [gr-qc/9409010, gr-qc/9505034, gr-qc/9603022, gr-qc/9609035, gr-qc/9609046, gr-qc/9704033]. The aim of the paper is to incorporate singularities---both local (black hole and naked singularity) and global (big bang and big crunch)---into the dynamics of indeterministic quantum gravity and cosmology. The question is whether a singularity is dynamically passable, i.e., whether a dynamical process which ends with a singularity may be extended beyond the latter. The answer is yes. A local singularity is trivially passable, while the passableness for a global singularity may invoke CPT transformation. The passableness of the singularities implies pulsating black holes and the oscillating universe. For the local singularity, the escape effect takes place: In a vicinity of the singularity, quantum matter leaves the gravitational potential well. Keywords: tempered singularity, strong singularity, trivial passage, CPT passage, pulsating black hole, escape effect, oscillating u...

  3. Hydro-gravitational-dynamics cosmology is crucial to astrobiology and the biological big bang at two million years

    Science.gov (United States)

    Gibson, Carl H.

    2015-09-01

    Hydro-Gravitational-Dynamics (HGD) cosmology predicts that the 1012 s (30 Kyr) H-He4 plasma protogalaxies become, by viscous fragmentation, proto-globular-star-cluster PGC clumps of a trillion small planets, at the 1013 s transition to gas. Larger planets and stars result from mergers of these hot 3000 K hydrogen planets in the PGCs. Stardust oxides of life chemicals C, N, O, Fe, Si seed the planets when the stars explode as supernovae. Hydrogen reduces the metal oxides and silicates to metal and rocky planet cores with massive hot water oceans at critical water temperature 647 K in which organic chemistry and life can develop. Because information is continually exchanged between the merging planets, they form a cosmic soup. The biological big bang occurs between 2 Myr when liquid water rains hot deep oceans in the cooling cosmos, and 8 Myr when the oceans freeze6. Thus, HGD cosmology explains the Hoyle/Wickramasinghe concept of cometary panspermia by giving a vast, hot, nourishing, cosmological primordial soup for abiogenesis, and the means for transmitting the resulting life forms and their evolving RNA/DNA mechanisms widely throughout the universe. A primordial astrophysical basis is provided for astrobiology by HGD cosmology. Concordance ΛCDMHC cosmology is rendered obsolete by the observation of complex life on Earth.

  4. Discovery Of A Major Contradiction In Big Bang Cosmology Points To The New Cosmic Center Universe Model

    CERN Document Server

    Gentry, R V

    2003-01-01

    The BAL z=3.91 quasar's high Fe/O ratio has led to a reexamination of big bang's spacetime expansion postulate and the discovery that it predicts a CBR redshift of z>36000 instead of the widely accepted z~1000. This result leads an expansion-predicted CBR temperature of only T = 0.08K, which is contradicted by the experimental T = 2.73K. Contrary to long-held belief, these results strongly suggest that the F-L expanding spacetime paradigm, with its expansion redshifts, is not the correct relativistic description of the universe. This conclusion agrees with the earlier finding (gr-qc/9806061) that the universe is relativistically governed by the Einstein static spacetime solution of the field equations, not the F-L solution. Disproof of expansion redshifts removes the only support for the Cosmological Principle, thus showing that the spherical symmetry of the cosmos demanded by the Hubble redshift relation can no longer be attributed to the universe being the same everythere. The Cosmological Principle is flaw...

  5. Big Bang-Big Crunch Algorithm for Voltage Stability Limit Improvement by Coordinated Control of SVC Settings

    Directory of Open Access Journals (Sweden)

    S. Sakthivel

    2013-07-01

    Full Text Available Modern power system networks are operated under highly stressed conditions and there is a risk of voltage instability problems owing to increased load demand. A power system needs to be with sufficient voltage stability margin for secured operation. In this study, SVC parameters of location and size along with generator bus voltages, transformer tap settings are considered as control parameters for voltage stability limit improvement by minimizing loss and voltage deviation. The control parameters are varied in a coordinated manner for better results. The line based LQP voltage stability indicator is used for voltage stability assessment. The nature inspired meta heuristic Big Bang-Big Crunch (BB-BC algorithm is exploited for optimization of the control variables and the performance is compared with that of PSO algorithm. The effectiveness of the proposed algorithm is tested on the standard IEEE 30 bus system under normal and N-1 line outage contingency conditions. The results obtained from the simulation encourage the performances of the new algorithm.

  6. Enhancing Teachers' Awareness About Relations Between Science and Religion. The Debate Between Steady State and Big Bang Theories

    Science.gov (United States)

    Bagdonas, Alexandre; Silva, Cibelle Celestino

    2015-11-01

    Educators advocate that science education can help the development of more responsible worldviews when students learn not only scientific concepts, but also about science, or "nature of science". Cosmology can help the formation of worldviews because this topic is embedded in socio-cultural and religious issues. Indeed, during the Cold War period, the cosmological controversy between Big Bang and Steady State theory was tied up with political and religious arguments. The present paper discusses a didactic sequence developed for and applied in a pre-service science teacher-training course on history of science. After studying the historical case, pre-service science teachers discussed how to deal with possible conflicts between scientific views and students' personal worldviews related to religion. The course focused on the study of primary and secondary sources about cosmology and religion written by cosmologists such as Georges Lemaître, Fred Hoyle and the Pope Pius XII. We used didactic strategies such as short seminars given by groups of pre-service teachers, videos, computer simulations, role-play, debates and preparation of written essays. Along the course, most pre-service teachers emphasized differences between science and religion and pointed out that they do not feel prepared to conduct classroom discussions about this topic. Discussing the relations between science and religion using the history of cosmology turned into an effective way to teach not only science concepts but also to stimulate reflections about nature of science. This topic may contribute to increasing students' critical stance on controversial issues, without the need to explicitly defend certain positions, or disapprove students' cultural traditions. Moreover, pre-service teachers practiced didactic strategies to deal with this kind of unusual content.

  7. THE ANATOMY OF AN EXTREME STARBURST WITHIN 1.3 Gyr OF THE BIG BANG REVEALED BY ALMA

    Energy Technology Data Exchange (ETDEWEB)

    Carilli, C. L. [National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States); Riechers, D. [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Walter, F. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany); Maiolino, R.; Lentati, L. [Astrophysics Group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Wagg, J. [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19 (Chile); McMahon, R. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Wolfe, A., E-mail: ccarilli@aoc.nrao.edu [Department of Physics and Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA 92093 (United States)

    2013-02-15

    We present further analysis of the [C II] 158 {mu}m fine structure line and thermal dust continuum emission from the archetype extreme starburst/active galactic nucleus (AGN) group of galaxies in the early universe, BRI 1202-0725 at z = 4.7, using the Atacama Large Millimeter Array. The group has long been noted for having a closely separated (26 kpc in projection) FIR-hyperluminous quasar host galaxy and an optically obscured submillimeter galaxy (SMG). A short ALMA test observation reveals a rich laboratory for the study of the myriad processes involved in clustered massive galaxy formation in the early universe. Strong [C II] emission from the SMG and the quasar have been reported earlier by Wagg et al. based on these observations. In this paper, we examine in more detail the imaging results from the ALMA observations, including velocity channel images, position-velocity plots, and line moment images. We present detections of [C II] emission from two Ly{alpha}-selected galaxies in the group, demonstrating the relative ease with which ALMA can detect the [C II] emission from lower star formation rate galaxies at high redshift. Imaging of the [C II] emission shows a clear velocity gradient across the SMG, possibly indicating rotation or a more complex dynamical system on a scale {approx}10 kpc. There is evidence in the quasar spectrum and images for a possible outflow toward the southwest, as well as more extended emission (a {sup b}ridge{sup )}, between the quasar and the SMG, although the latter could simply be emission from Ly{alpha}-1 blending with that of the quasar at the limited spatial resolution of the current observations. These results provide an unprecedented view of a major merger of gas-rich galaxies driving extreme starbursts and AGN accretion during the formation of massive galaxies and supermassive black holes within 1.3 Gyr of the big bang.

  8. A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51.

    Science.gov (United States)

    Finkelstein, S L; Papovich, C; Dickinson, M; Song, M; Tilvi, V; Koekemoer, A M; Finkelstein, K D; Mobasher, B; Ferguson, H C; Giavalisco, M; Reddy, N; Ashby, M L N; Dekel, A; Fazio, G G; Fontana, A; Grogin, N A; Huang, J-S; Kocevski, D; Rafelski, M; Weiner, B J; Willner, S P

    2013-10-24

    Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.

  9. Coupled variations of fundamental couplings and primordial nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Coc, Alain [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, IN2P3/CNRS/UPS, Bat. 104, 91405 0rsay Campus (France); Nunes, Nelson J.; Olive, Keith A. [William I. Fine Theoretical Physics Institute, University of Minnesota, Minneapolis, MN 55455 (United States); Uzan, Jean-Philippe; Vangioni, Elisabeth [Institut d' Astrophysique de Paris, UMR-7095 du CNRS, Universite Pierre et Marie Curie, 98 bis bd Arago, 75014 Paris (France)

    2006-10-15

    The effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only {sup 4}He, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. These constraints are then translated into constraints on the time variation of the Yukawa couplings and the fine structure constant. Furthermore, we show that a variation of the deuterium binding energy is able to reconcile the {sup 7}Li abundance deduced from the WMAP analysis with its spectroscopically determined value while maintaining concordance with D and {sup 4}He. (authors)

  10. Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

    CERN Document Server

    Grohs, E; Kishimoto, C T; Paris, M W

    2015-01-01

    We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos.

  11. Galaxy formation from annihilation-generated supersonic turbulence in the baryon-symmetric big-bang cosmology and the gamma ray background spectrum

    Science.gov (United States)

    Stecker, F. W.; Puget, J. L.

    1972-01-01

    Following the big-bang baryon symmetric cosmology of Omnes, the redshift was calculated to be on the order of 500-600. It is show that, at these redshifts, annihilation pressure at the boundaries between regions of matter and antimatter drives large scale supersonic turbulence which can trigger galaxy formation. This picture is consistent with the gamma-ray background observations discussed previously. Gravitational binding of galaxies then occurs at a redshift of about 70, at which time vortical turbulent velocities of about 3 x 10 to the 7th power cm/s lead to angular momenta for galaxies comparable with measured values.

  12. HD 140283: A Star in the Solar Neighborhood that Formed Shortly After the Big Bang

    CERN Document Server

    Bond, Howard E; VandenBerg, Don A; Schaefer, Gail H; Harmer, Dianne; 10.1088/2041-8205/765/1/L12

    2013-01-01

    HD 140283 is an extremely metal-deficient and high-velocity subgiant in the solar neighborhood, having a location in the HR diagram where absolute magnitude is most sensitive to stellar age. Because it is bright, nearby, unreddened, and has a well-determined chemical composition, this star avoids most of the issues involved in age determinations for globular clusters. Using the Fine Guidance Sensors on the Hubble Space Telescope, we have measured a trigonometric parallax of 17.15 +/- 0.14 mas for HD 140283, with an error one-fifth of that determined by the Hipparcos mission. Employing modern theoretical isochrones, which include effects of helium diffusion, revised nuclear reaction rates, and enhanced oxygen abundance, we use the precise distance to infer an age of 14.46 +/- 0.31 Gyr. The quoted error includes only the uncertainty in the parallax, and is for adopted surface oxygen and iron abundances of [O/H] = -1.67 and [Fe/H] = -2.40. Uncertainties in the stellar parameters and chemical composition, especia...

  13. Criticize the Big-bang Cosmology%“大爆炸宇宙学”批评

    Institute of Scientific and Technical Information of China (English)

    黄志洵

    2015-01-01

    the big-bang cosmogony was based on the Hubble’ s astro-observation,he discovered that the remote celestial bodies are leaving far from us. It is the Hubble’ s theory of expanding cosmography. But this theory lacks sufficient proof,then it should be a product of subjective idealism. Another important argument of the theory of exploded cosmogony is that measurement data on microwave background radia-tion,but the data can’ t indicate that the temperature of microwave background radiation should be the re-sult of once exploding. It is never the spread ember at once exploding of an original celestrial body. Ac-cording to the definity of cosmos,people can’ t say “the age of cosmos”,because we only can say “the age of earth”,“the age of solar system” and“the age of star system”;etc. Then,we are against these ab-surd views of big-bang cosmology categorically,because such theoretical system is full of flaws that both science and philosophy all can’ t hold. Although it seems that the universe is riddled with in explicable forces,the theory of dark matter and dark energy just are two hypothesises. Another hypothesis is the exist of gravitational waves,it is just an estimate,but the actual situation might be different. The velocity of gravity in Newton’ s universal law is infinite,but the gravity propagation speed and the velocity of gravitational waves in Einstein’ s theory are the light speed c. The General relativity( GR) explains these features by suggesting that gravitation ( un-like electromagnetic forces) is a pure geometric effect of curved space-time,not a force of nature that propagates. Moreover,now different gravity models need to be considered. For example,if gravity is once again taken to be a propagating force of nature in flat space-time with the propagation speed indicated by observational evidence and experiments:not less than 2 × 1010c(c is the speed of light in vacuum). Al-though faster-than-light force propagation speeds do

  14. The Anatomy of an Extreme Starburst within 1.3 Gyr of the Big Bang Revealed by ALMA

    Science.gov (United States)

    Carilli, C. L.; Riechers, D.; Walter, F.; Maiolino, R.; Wagg, J.; Lentati, L.; McMahon, R.; Wolfe, A.

    2013-02-01

    We present further analysis of the [C II] 158 μm fine structure line and thermal dust continuum emission from the archetype extreme starburst/active galactic nucleus (AGN) group of galaxies in the early universe, BRI 1202-0725 at z = 4.7, using the Atacama Large Millimeter Array. The group has long been noted for having a closely separated (26 kpc in projection) FIR-hyperluminous quasar host galaxy and an optically obscured submillimeter galaxy (SMG). A short ALMA test observation reveals a rich laboratory for the study of the myriad processes involved in clustered massive galaxy formation in the early universe. Strong [C II] emission from the SMG and the quasar have been reported earlier by Wagg et al. based on these observations. In this paper, we examine in more detail the imaging results from the ALMA observations, including velocity channel images, position-velocity plots, and line moment images. We present detections of [C II] emission from two Lyα-selected galaxies in the group, demonstrating the relative ease with which ALMA can detect the [C II] emission from lower star formation rate galaxies at high redshift. Imaging of the [C II] emission shows a clear velocity gradient across the SMG, possibly indicating rotation or a more complex dynamical system on a scale ~10 kpc. There is evidence in the quasar spectrum and images for a possible outflow toward the southwest, as well as more extended emission (a "bridge"), between the quasar and the SMG, although the latter could simply be emission from Lyα-1 blending with that of the quasar at the limited spatial resolution of the current observations. These results provide an unprecedented view of a major merger of gas-rich galaxies driving extreme starbursts and AGN accretion during the formation of massive galaxies and supermassive black holes within 1.3 Gyr of the big bang. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA

  15. Instellar Gas Experiment (IGE): Testing interstellar gas particles to provide information on the processes of nucleosynthesis in the big bang stars and supernova

    Science.gov (United States)

    Lind, Don

    1985-01-01

    The Interstellar Gas Experiment (IGE) is designed to collect particles of the interstellar gas - a wind of interstellar media particles moving in the vicinity of the solar system. These particles will be returned to earth where the isotopic ratios of the noble gases among these particles will be measured. IGE was designed and programmed to expose 7 sets of six copper-beryllium metallic collecting foils to the flux of neutral interstellar gas particles which penetrate the heliosphere to the vicinity of the earth's orbit. These particles are trapped in the collecting foils and will be returned to earth for mass-spectrographic analysis when Long Duration Exposure Facility (LDEF) on which IGE was launched, is recovered.

  16. Nuclear reactions from lattice QCD

    Science.gov (United States)

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-02-01

    One of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, quantum chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three-nucleon (and higher) interactions in a consistent manner. Currently, lattice quantum chromodynamics (LQCD) provides the only reliable option for performing calculations of some of the low-energy hadronic observables. With the aim of bridging the gap between LQCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from LQCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

  17. Big Bang launch

    CERN Document Server

    2008-01-01

    Physicists from the University, along with scientists and engineers around the world, watched with fevered anticipation as the world's biggest scientific experiment was launched in September. (1/1 page)

  18. Jupiter's Big Bang.

    Science.gov (United States)

    McDonald, Kim A.

    1994-01-01

    Collision of a comet with Jupiter beginning July 16, 1994 will be observed by astronomers worldwide, with computerized information relayed to a center at the University of Maryland, financed by the National Aeronautics and Space Administration and National Science Foundation. Geologists and paleontologists also hope to learn more about earth's…

  19. A Big Bang Lab

    Science.gov (United States)

    Scheider, Walter

    2005-01-01

    The February 2005 issue of The Science Teacher (TST) reminded everyone that by learning how scientists study stars, students gain an understanding of how science measures things that can not be set up in lab, either because they are too big, too far away, or happened in a very distant past. The authors of "How Far are the Stars?" show how the…

  20. Lemaitre's Big Bang

    CERN Document Server

    Luminet, Jean-Pierre

    2015-01-01

    I give an epistemological analysis of the developments of relativistic cosmology from 1917 to 1966, based on the seminal articles by Einstein, de Sitter, Friedmann, Lemaitre, Hubble, Gamow and other historical figures of the field. It appears that most of the ingredients of the present-day standard cosmological model, including the acceleration of the expansion due to a repulsive dark energy, the interpretation of the cosmological constant as vacuum energy or the possible non-trivial topology of space, had been anticipated by Georges Lemaitre, although his articles remain mostly unquoted.

  1. The Big Bang machine

    CERN Multimedia

    Cox, Brian

    2009-01-01

    "At Cern in Geneva, 10'000 scientists form all over the world have gathered to discover the secrets of the universe. We drove there in a new Volvo C30 to watch the preparations for the second switch on" (12 pages)

  2. Clash over Big Bang

    CERN Multimedia

    Hawkes, N

    1999-01-01

    A recent announcement from Fermilab that they had discovered a precise value for the degree of CP Violation, has angered scientists at CERN who say the 'new' result is simply confirmation of results gained at CERN eleven years ago (1 page).

  3. Finding the Big Bang

    Science.gov (United States)

    Peebles, P. James E.; Page, Lyman A., Jr.; Partridge, R. Bruce

    2009-03-01

    1. Introduction; 2. A guide to modern cosmology; 3. Origins of the cosmology of the 1960s; 4. Recollections of the 1960s Dave Hogg, Neville Woolf, George B. Field, Patrick Thaddeus, Donald E. Osterbrock, Yuri Nikolaevich Smirnov, Igor Dmitriyevich Novikov, Andrei Georgievich Doroshkevich, Rashid Alievich Sunyaev, Malcolm S. Longair, Arno Penzias, Robert W. Wilson, Bernard F. Burke, Kenneth C. Turner, P. James E. Peebles, David T. Wilkinson, Peter G. Roll, R. Bruce Partridge, Malcolm S. Longair, John Faulkner, Robert V. Wagoner, Martin Rees, Geoffrey R. Burbidge, Jayant V. Narlikar, David Layzer, Michele Kaufman, Jasper V. Wall, John Shakeshaft, William Welch, Kazimir S. Stankevich, Paul Boynton, Robert A. Stokes, Martin Harwit, Judith L. Pipher, Kandiah Shivanandan, Rainer Weiss, Jer-tsang Yu, Rainer K. Sachs, Arthur M. Wolfe, Joe Silk, George F. R. Ellis, Ronald N. Bracewell, Edward K. Conklin, Stephen Boughn, Karl C. Davis, Paul S. Henry; 5. Cosmology and the CMBR since the 1960s Dick Bond; Appendixes; Glossary; References; Index.

  4. Primordial nucleosynthesis during the keV era

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, S.; Esmailzadeh, R.; Hall, L.J.; Starkman, G.D.

    1987-09-09

    Energetic hadronic and electromagnetic showers in the keV era of the hot big bang are produced by the decays of long lived particles. These showers initiate a new phase of nucleosynthesis. The abundance ratios of D, /sup 3/He, /sup 6/Li and /sup 7/Li are given by fixed points of rate equations, which are determined by nuclear physics not by the nature of the decaying particle. The fixed points are independent of prior abundances, so that constraints from the MeV era of nucleosynthesis evaporate, except for a requirement that /sup 4/He not be underproduced. For example, ..cap omega../sub B/ = 1 and many more than four neutrino species are both possible. Within the accuracy of our calculation (there are uncertainties of at least a factor of three), the abundances agree with those inferred from observations. Considerable /sup 6/Li is produced and must be depleted in both population II halo stars and in the galactic disk. We predict /sup 6/Li, /sup 3/He and D abundances in primordial material which are higher than conventional nucleosynthesis. 8 refs.

  5. On the Sensitivity of Massive Star Nucleosynthesis and Evolution to Solar Abundances and to Uncertainties in Helium Burning Reaction Rates

    CERN Document Server

    Tur, Clarisse; Austin, Sam M

    2007-01-01

    We explore the dependence of pre-supernova evolution and supernova nucleosynthesis yields on the uncertainties in helium burning reaction rates. Using the revised solar abundances of Lodders (2003) for the initial stellar composition, instead of those of Anders & Grevesse (1989), changes the supernova yields and limits the constraints that those yields place on the 12C(a,g)16O reaction rate. The production factors of medium-weight elements (A = 16 to 40) were found to be in reasonable agreement with observed solar ratios within the current experimental uncertainties in the triple alpha reaction rate. Simultaneous variations by the same amount in both reaction rates or in either of them separately, however, can induce significant changes in the central 12C abundance at core carbon ignition and in the mass of the supernova remnant. It therefore remains important to have experimental determinations of the helium burning rates so that their ratio and absolute values are known with an accuracy of 10% or better...

  6. Bayesian Estimation of Thermonuclear Reaction Rates

    Science.gov (United States)

    Iliadis, C.; Anderson, K. S.; Coc, A.; Timmes, F. X.; Starrfield, S.

    2016-11-01

    The problem of estimating non-resonant astrophysical S-factors and thermonuclear reaction rates, based on measured nuclear cross sections, is of major interest for nuclear energy generation, neutrino physics, and element synthesis. Many different methods have been applied to this problem in the past, almost all of them based on traditional statistics. Bayesian methods, on the other hand, are now in widespread use in the physical sciences. In astronomy, for example, Bayesian statistics is applied to the observation of extrasolar planets, gravitational waves, and Type Ia supernovae. However, nuclear physics, in particular, has been slow to adopt Bayesian methods. We present astrophysical S-factors and reaction rates based on Bayesian statistics. We develop a framework that incorporates robust parameter estimation, systematic effects, and non-Gaussian uncertainties in a consistent manner. The method is applied to the reactions d(p,γ)3He, 3He(3He,2p)4He, and 3He(α,γ)7Be, important for deuterium burning, solar neutrinos, and Big Bang nucleosynthesis.

  7. Big Bang, inflation, standard Physics… and the potentialities of new Physics and alternative cosmologies. Present statuts of observational and experimental Cosmology. Open questions and potentialities of alternative cosmologies

    Science.gov (United States)

    Gonzalez-Mestres, Luis

    2016-11-01

    A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of "anomalies". Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang pattern

  8. The analysis of irony through relevance theory in the big bang theory sitcom = A análise da ironia por meio da teoria da relevância na comédia de situação the big bang theory

    OpenAIRE

    2011-01-01

    Neste trabalho, será analisada a teoria da relevância proposta por Sperber e Wilson. Adicionalmente, a figura de linguagem ironia será descrita. Esse referencial teórico será utilizado para analisar um episódio da comédia de situação intitulado "The Big Bang Theory", em um esforço para demonstrar como enunciados são compreendidos entre os personagens e o público e como ironia é largamente utilizada como recurso humorístico

  9. The analysis of irony through relevance theory in the big bang theory sitcom = A análise da ironia por meio da teoria da relevância na comédia de situação the big bang theory

    Directory of Open Access Journals (Sweden)

    Izaias, Karla Camila Oliveira

    2011-01-01

    Full Text Available Neste trabalho, será analisada a teoria da relevância proposta por Sperber e Wilson. Adicionalmente, a figura de linguagem ironia será descrita. Esse referencial teórico será utilizado para analisar um episódio da comédia de situação intitulado "The Big Bang Theory", em um esforço para demonstrar como enunciados são compreendidos entre os personagens e o público e como ironia é largamente utilizada como recurso humorístico

  10. Innovación empresarial y desarrollo económico: De la destrucción creativa al big bang social coordinado

    Directory of Open Access Journals (Sweden)

    Carmen González Marsal

    2015-09-01

    Full Text Available El presente artículo parte de la distinción de Schumpeter entre innovación e invención en función de sus consecuencias económicas y analiza su conocido concepto de destrucción creativa provocada por la innovación empresarial. A continuación, se centra en el decisivo efecto de armonización social del ejercicio de la empresarialidad, sugiriendo la superación del concepto schumpeteriano a través de la idea de la creatividad coordinadora. De esta forma, se comprende que la innovación empresarial en vez de conducir a la autodestrucción del capitalismo, hace posible el desarrollo económico y social de manera ilimitada, proceso que ha sido denominado big bang social coordinado.

  11. An Analysis of Humor of the Big Bang Theory (Season Six)%《生活大爆炸》第六季的幽默探析

    Institute of Scientific and Technical Information of China (English)

    邬贝贝; 潘文红

    2014-01-01

    This paper analyzes humor of The Big Bang Theory (Season Six) from the perspective of violation of the cooperative principle .The study helps enable English learners to have a better understanding of Grice ’ s cooperative principle and enhance their appreciation of English humor in situation comedies .%以《生活大爆炸》第六季的对话为语料,从违反合作原则的角度出发,探讨会话者因违反合作原则的四个准则而产生的幽默效果,从而加强英语学习者对格莱斯会话含义理论的理解,提高对情景喜剧中英语幽默的欣赏能力。

  12. 功能目的论视角下情景喜剧字幕翻译研究——以The Big Bang Theory为例

    Institute of Scientific and Technical Information of China (English)

    房晶

    2011-01-01

    德国功能主义目的论在行为理论、语篇语言学和交际理论的基础上,提出了翻译目的决定翻译策略,将译者从直译还是意译的两难处境中解放出来,增加了可供选择的翻译策略,为译者灵活处理源语文本提供了理论依据。本文以美国情景喜剧The Big Bang Theory为例,分别从目的论的"目的原则"、"连贯原则"和"忠诚原则"三方面,分析了该剧字幕的翻译方法和策略。

  13. Feynman Clocks, Casual Networks, and the Origin of Hierarchical "Arrows of Time" in Complex Systems from the Big Bang to the Brain

    CERN Document Server

    Hitchcock, S M

    2000-01-01

    A theory of 'time' as a form of 'information' is proposed. New tools such as Feynman Clocks, Collective Excitation Networks, Sequential Excitation Networks, Plateaus of Complexity, Causal Networks, and Quantum Computation methods are used to unify previously separate 'arrows of time'. The 'direction' and 'dimension' of 'time' are found to be secondary information structures created by the 'processing' of the information carried by signals connecting 'clocks' together in networks. The 'problem of time' may be solved by identification of a fundamental 'irreversible' Quantum Arrow of Time and 'reversible' Classical Arrows of Time. These 'arrows' can used to map information flow through complex causal networks from the Big Bang to the Brain. Keywords; unification of the fundamental interactions of matter, consciousness, entangled states, time reversal, time travel, and FTL or superluminal signals

  14. A Quantum Dynamic Cosmology Model Without Big Bang%一种无大爆炸量子动态宇宙模型

    Institute of Scientific and Technical Information of China (English)

    邵丹; 邵亮; 邵常贵

    2011-01-01

    According to the loop quantum gravity,calculates and obtains the results of the volume inflation and the metric fluctuation,and a creation way of gravity field is given,during the transition of the spacetime.Using finiteness of the representation of quantum group,a quantum dynamic cosmdogy model without singularity of spacetime is raised,and it is compared with the big bang cosmology model.%依据圈量子引力,计算出空时跃迁体积膨胀和度量起伏的结果,同时给出了引力场的一种生成途径.利用量子群SU 2 q表示的有限性,提出了一种不存在空时奇点的量子动态宇宙模型,并将其与大爆炸宇宙模型做了某些比较.

  15. The Study of Pedantic Language in the Big Bang Theory%《生活大爆炸》中学究语研究

    Institute of Scientific and Technical Information of China (English)

    王亚辉

    2014-01-01

    Variants vary via variable communities. Social dialect reflects in distinct speech communities caused by social factors. Pedantic language, a sort of academic style used by speech communities with high education background, is a language variety stylized with advanced terminologies and complex sentences. The TV The Big Bang Theory, with its unique script setting, cate-gorizes its dialogues into pedantic language. Its plays discernibly incarnate the use of pedantic language in specific registers, and dis-play the impacts of it with other varieties of speech communities to some extent. This paper tentatively studies the influence of ac-ademic style on inappropriate registers through the corpus of season two of The Big Bang Theory.%语言变体随社会网络变化而迥异。社群言语的抽象表现就是由社会因素造成的社会方言。“学究语”是受教育程度相当高的社会团体使用的学术性语体,话语中常包含高级术语和复杂长句,是语言变体的一种。美剧《生活大爆炸》中独特地剧本背景设定将角色语言划归为学究语,在不同程度上表现出学究语作为独特的语言变体在特定语域中的作用,以及与不同社群的其他语言变体的冲突。该文对该剧第二季语料中的语言变体进行分析,试解读固定语域下非恰当语体对听话人造成的影响。

  16. Coulomb screening in linear coasting nucleosynthesis

    CERN Document Server

    Singh, Parminder

    2015-01-01

    We investigate the impact of coulomb screening on primordial nucleosynthesis in a universe having scale factor that evolves linearly with time. Coulomb screening affects primordial nucleosynthesis via enhancement of thermonuclear reaction rates. This enhancement is determined by the solving Poisson equation within the context of mean field theory (under appropriate conditions during the primordial nucleosynthesis). Using these results, we claim that the mean field estimates of coulomb screening hardly affect the predicted element abundances and nucleosynthesis parameters$, \\{\\eta_9,\\xi_e\\}$. The deviations from mean field estimates are also studied in detail by boosting genuine screening results with the screening parameter ($\\omega_s$). These deviations show negligible effect on the element abundances and on nucleosynthesis parameters. This work thus rules out the coulomb screening effects on primordial nucleosynthesis in slow evolving models and confirms that constraints in ref.[7] on nucleosynthesis parame...

  17. Neutrino-nucleus reactions and their role for supernova dynamics and nucleosynthesis

    CERN Document Server

    Balasi, K G; Martínez-Pinedo, G

    2015-01-01

    The description of nuclear reactions induced by supernova neutrinos has witnessed significant progress during the recent years. At the energies and momentum transfers relevant for supernova neutrinos neutrino-nucleus cross sections are dominated by allowed transitions, however, often with non-negligible contributions from (first) forbidden transitions. For several nuclei allowed Gamow-Teller strength distributions could be derived from charge-exchange reactions and from inelastic electron scattering data. Importantly the diagonalization shell model has been proven to accurately describe these data and hence became the appropriate tool to calculate the allowed contributions to neutrino-nucleus cross sections for supernova neutrinos. Higher multipole contributions are usually calculated within the framework of the Quasiparticle Random Phase Approximation, which describes the total strength and the position of the giant resonances quite well. This manuscript reviews the recent progress achieved in calculating su...

  18. AGB nucleosynthesis: The 19F(α, p)22Ne reaction at astrophysical energies

    Science.gov (United States)

    D'Agata, G.; Pizzone, R. G.; Spitaleri, C.; Blagus, S.; Figuera, P.; Grassi, L.; Guardo, G. L.; Gulino, M.; Hayakawa, S.; Indelicato, I.; Kshetri, R.; La Cognata, M.; Lamia, L.; Lattuada, M.; Mijatović, T.; Milin, M.; Miljanic, D.; Prepolec, L.; Sergi, M. L.; Skukan, N.; Soic, N.; Tokic, V.; Tumino, A.; Uroic, M.

    2017-06-01

    Learning how 19F is produced and destructed in AGB-stars is crucial. Fluorine abundance is in fact important, given that it is strongly tied to standard and extra-mixing processes taking place in AGB-stars. This kind of objects are considered to be the main sources of fluorine in galactic environment, in which experimental abundances are far overestimated. For this reason the reaction 19F(α, p)22Ne, that represents the main destruction channel in He-rich environment, was studied at energies corresponding to T˜2.108 K. Such reaction has been studied with direct method at Ebeam = 1100 keV for alpha particles impinging on a fluorine target, corresponding to EC.M. ˜ 900 keV, still far from the Gamow window, placed at 390÷800 keV, below the Coulomb barrier (3.81 MeV). An experiment was performed at Rujer Boskovic Institut (Zagreb), applying the Trojan Horse Method. With this experimental procedure we were able to select the quasi-free contribution coming from 6Li(19F,p 22Ne)2H at Ebeam = 6 MeV at kinematically useful angles. We measured the 19F(α, p)22Ne at 0 MeV ≤ EC.M ≤ 0.9 MeV, extracting the two body cross-section in absolute units at energies of astrophysical interest.

  19. REACLIB: A Reaction Rate Library for the Era of Collaborative Science

    Science.gov (United States)

    Meisel, Zachary

    2008-10-01

    Thermonuclear reaction rates and weak decay rates are of great importance to modern nuclear astrophysics. They are critical in the study of many topics such as Big Bang Nucleosynthesis, X-ray bursts, Supernovae, and S-process element formation, among others. The Joint Institute for Nuclear Astrophysics (JINA) has been created to increase connectivity amongst nuclear astrophysicists in our modern age of highly collaborative science. Within JINA there has been an effort to create a frequently updated and readily accessible database of thermonuclear reactions and weak decay rates. This database is the REACLIB library, which can be accessed at the web address: http://www.nscl.msu.edu/˜nero/db/. Here I will discuss the JINA REACLIB Project, including a new procedure to fit reaction rates as a function of temperature that takes full advantage of physicality. With these updated reaction rates, astrophysical modelers will no longer have to worry about the adverse effects of using obsolete reaction rate libraries lacking physical behavior.

  20. The big bang of hemofiltration: the beginning of a new era in the third millennium for extra-corporeal blood purification!

    Science.gov (United States)

    Honore', P M; Joannes-Boyau, O; Merson, L; Boer, W; Piette, V; Galloy, A-C; Janvier, G

    2006-07-01

    Since the last decade, hemofiltration and especially high volume hemofiltration has rapidly evolved from a somewhat experimental treatment towards a potentially effective 'adjunctive' therapy in severe septic shock and especially refractory or catecholamine resistant hypodynamic septic shock. Nevertheless, this approach lacks prospective randomized studies (PRT'S) evaluating the critical role of early hemofiltration in sepsis. An important step forward which could be called the 'big bang' in term of hemofiltration was the publication of a PRT in patients with acute renal failure (ARF) (1). Before this study (2), nobody believed that hemofiltration could change the survival rate in intensive care. Since that big bang, many physicians consider that hemofiltration at a certain dose can change the survival rate in intensive care. So the world of hemofiltration in ICU is not a definitive world, it is still in expansion. Indeed, we now have to try to define what will be the exact dose we need in septic acute renal failure. This dose might well be 'higher' than 35 ml/kg/hour in the septic acute renal failure 'group' as suggested by many studies (2-5). At present, it is the issue of continuous dose of high volume hemofiltration that has to be tested in future randomized studies. Since the Vicenza study (2) has shown that 35 ml/kg/h is the best dose in terms of survival, dealing with non septic acute renal failure in ICU, several studies from different groups have shown that, in septic acute renal failure, a higher dose might correlate with better survival. This has also been shown in some way by the study of the 'Vicenza group' but not with a statistically significant value (2). New PRT'S have just started in Europe like the IVOIRE study (hIgh VOlume in Intensive caRE) (6) and the RENAL study. Another large study is looking more basically at dose in non septic acute renal failure in Australasia and is led by the group of Rinaldo Bellomo in Melbourne (7) as well as the ATN

  1. Transfer reaction measurements and the stellar nucleosynthesis of 26Al and 44Ti

    CERN Document Server

    AUTHOR|(CDS)2086831

    Progress in the description of stellar evolution is driven by the collaborative effort of nuclear physics, astrophysics and astronomy. Using those developments, the theory of the origin of elements in the Universe is challenged. This thesis addresses the problem behind the abundance of 44Ti and the origin of 26Al. The mismatch between the predicted abundance of 44Ti as produced by the only sites known to be able to create 44Ti, core collapse supernovae (CCSNe), and the observations, highlight the current uncertainty that exists in the physics of these stars. Several satellite based gamma-ray observations of the isotope 44Ti have been reported in recent times and conrm the disagreement. As the amount of this isotope in stellar ejecta is thought to critically depend on the explosion mechanism, the ability to accurately model the observed abundance would be a pivotal step towards validating that theory. The most in influential reaction to the amount of 44Ti in supernovae is 44Ti(alpha, p)47V. Here we report on a...

  2. Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenarios

    CERN Document Server

    Cyburt, Richard H; Fields, Brian D; Luo, Feng; Olive, Keith A; Spanos, Vassilis C

    2009-01-01

    The decays of massive gravitinos into neutralino dark matter particles and Standard Model secondaries during or after Big-Bang nucleosynthesis (BBN) may alter the primordial light-element abundances. We present here details of a new suite of codes for evaluating such effects, including a new treatment based on PYTHIA of the evolution of showers induced by hadronic decays of massive, unstable particles such as a gravitino. We also develop an analytical treatment of non-thermal hadron propagation in the early universe, and use this to derive analytical estimates for light-element production and in turn on decaying particle lifetimes and abundances. We then consider specifically the case of an unstable massive gravitino within the constrained minimal supersymmetric extension of the Standard Model (CMSSM). We present upper limits on its possible primordial abundance before decay for different possible gravitino masses, with CMSSM parameters along strips where the lightest neutralino provides all the astrophysical...

  3. An analysis of constraints on relativistic species from primordial nucleosynthesis and the cosmic microwave background

    CERN Document Server

    Nollett, Kenneth M

    2011-01-01

    We present constraints on the number of relativistic species from a joint analysis of cosmic microwave background (CMB) fluctuations and light element abundances (helium and deuterium) compared to big bang nucleosynthesis (BBN) predictions. Our BBN calculations include updates of nuclear rates in light of recent experimental and theoretical information, with the most significant change occuring for the d(p,gamma)^3He cross section. We calculate a likelihood function for BBN theory and observations that accounts for both observational errors and nuclear rate uncertainties and can be easily embedded in cosmological parameter fitting. We then demonstrate that CMB and BBN are in good agreement, suggesting that the number of relativistic species did not change between the time of BBN and the time of recombination. The level of agreement between BBN and CMB, as well as the agreement with the standard model of particle physics, depends somewhat on systematic differences among determinations of the primordial helium ...

  4. Nuclear halo effect on nucleon capture reaction rates at stellar energies

    Institute of Scientific and Technical Information of China (English)

    Liu Zu-Hua; Zhou Hong-Yu

    2005-01-01

    The capture cross sections at stellar energies are very difficult to measure directly. Hence, data are usually evaluated by using indirect methods or extrapolations from the experimental data obtained at the lowest possible energies. The asymptotic normalization coefficient (ANC) approach of the transfer reactions provides a reliable way for the determination of the capture cross sections at stellar energies. By virtue of its reliability, we have calculated the capture cross sections of the 10Be(n,γ)11Be reaction by using nuclear ANC method. 11Be is a well-known neutron halo nucleus with two weakly bound states. As a typical example, we have shown that the radiative cross sections for a nucleon captured into a halo state are obviously enhanced. The enormous enhancement of the capture cross section is just due to the large overlap of the incident neutron wave with the extended tail of the halo. The 10Be(n,γ)11Be capture reaction is involved in the inhomogeneous big-bang nucleosynthesis. We have evaluated its reaction rates at stellar energies with the nuclear ANC method.

  5. Characterization of big bang, a novel gene encoding for PDZ domain-containing proteins that are dynamically expressed throughout Drosophila development.

    Science.gov (United States)

    Kim, Sabrina Y; Renihan, Maia K; Boulianne, Gabrielle L

    2006-06-01

    PDZ (PSD-95, Discs-large, ZO-1) domain proteins often function as scaffolding proteins and have been shown to play important roles in diverse cellular processes such as the establishment and maintenance of cell polarity, and signal transduction. Here, we report the identification and cloning of a novel Drosophila melanogaster gene that is predicted to produce several different PDZ domain-containing proteins through alternative promoter usage and alternative splicing. This gene, that we have named big bang (bbg), was first identified as C96-GAL4, a GAL4 enhancer trap line that was generated in our lab. To further characterize bbg, its expression pattern was examined in ovaries, embryos, and late third instar larvae using UAS reporter gene constructs, in situ hybridization, or immunocytochemistry. In addition, the expression of alternatively spliced transcripts was examined in more detail using in situ hybridization. We find that during embryogenesis bbg is predominantly expressed in the developing gut, but it is also expressed in external sensory organs found in the epidermis. In the late third instar larva, bbg is expressed along the presumptive wing margin in the wing disc, broadly in the eye disc, and in other imaginal discs as well as in the brain. The expression patterns observed are dynamic and specific during development, suggesting that like other genes that encode for several different PDZ domain protein isoforms, bbg likely plays important roles in multiple developmental processes.

  6. Unsolved Mysteries of Science: A Mind-Expanding Journey through a Universe of Big Bangs, Particle Waves, and Other Perplexing Concepts

    Science.gov (United States)

    Malone, John

    2001-08-01

    A LIVELY EXPLORATION OF THE BIGGEST QUESTIONS IN SCIENCE How Did the Universe Begin? The Big Bang has been the accepted theory for decades, but does it explain everything? How Did Life on Earth Get Started? What triggered the cell division that started the evolutionary chain? Did life come from outer space, buried in a chunk of rock? What is Gravity? Newton's apple just got the arguments started, Einstein made things more complicated. Just how does gravity fit in with quantum theory? What Is the Inside of the Earth Like? What exactly is happening beneath our feet, and can we learn enough to help predict earthquakes and volcanic eruptions? How Do We Learn Language? Is language acquisition an inborn biological ability, or does every child have to start from scratch? Is There a Missing Link? The story of human evolution is not complete. In addition to hoaxes such as "Piltdown Man" and extraordinary finds such as "Lucy," many puzzles remain. What, in the end, do we mean by a "missing link"?

  7. 从合作原则分析《The Big Bang Theory》经典对白之幽默

    Institute of Scientific and Technical Information of China (English)

    向丽梅; 黎晓凤

    2015-01-01

    在交际中,为了保证会话的顺利进行,语用学中的合作原则要求交谈双方都必须遵守一些基本准则以期获得交际成功。但人们有时会故意违反合作原则中的某条或某几条准则,目的是想表达一定的会话含义,而这时幽默就会产生。本文以美国热播情景喜剧《The Big Bang Theory》典型对白为例,逐条分析其幽默产生机制,以期英语学习者能更好地理解合作原则,欣赏蕴藏在这些对白中的幽默。一、引言对幽默的研究实际上是对幽默的解读——幽默是怎么

  8. 将美剧引入高职英语课堂促进跨文化意识培养--以The Big Bang Theory为例

    Institute of Scientific and Technical Information of China (English)

    王梦君

    2015-01-01

    语言学习的最终目标是进行交际,学习者只在语言学层面学习语言,而缺乏跨文化意识,并不能够达到此目标。英语非母语国家的英语教学普遍存在的问题之一,是对英语学习者缺乏充分的跨文化意识输入和培养。传媒的全球化发展为语言教学者提供了一个很好的媒介来解决这一问题。The Big Bang Theory是广受国内大学生喜爱的美剧之一,全剧节奏明快,语言精炼地道,场景能够还原生活并有连续性,人物特征鲜明,将此剧引入课堂对学习者跨文化意识的输入和培养大有裨益。

  9. 基于粒子群优化的混合宇宙大爆炸算法%Hybrid Big Bang-Big Crunch Algorithm Based on Particle Swarm Optimization

    Institute of Scientific and Technical Information of China (English)

    吴伟民; 田龙; 林志毅

    2016-01-01

    宇宙大爆炸算法( Big Bang-Big Crunch,BB-BC)思想来源于宇宙大爆炸和大收缩理论。针对其在高维函数的寻优过程中,随迭代次数增加,爆炸生成的碎片解收缩速度慢,多样性快速减弱,质量变差,容易陷入局部最优解的缺点,提出一种混合型BB-BC算法( HBB-BC)。首先,将质心代入当代解中作为奇点解进行改进,提高算法收缩速度;其次,结合粒子群优化的路径优化,提高碎片解的质量;最后,引入宇宙大撕裂理论增加大爆炸阶段碎片解的多样性和跳出局部最优解的能力。通过9个新型测试函数进行测试,测试结果显示,HBB-BC算法在高维函数的寻优性能上更优于BB-BC算法和另一种改进的均匀大爆炸混沌大收缩( UBB-CBC)算法。%The Big Bang-Big Crunch ( BB-BC ) algorithm is based on the big bang and big contraction theory of the universe. With the increase of number of iterations in optimizing of high dimensional func-tions, the candidates shrink slowly, worsen in quality and weaken rapidly in diversity, as well as sink in-to a local optimal solution. In light of these features, an improved hybrid BB-BC algorithm ( HBB-BC) is proposed. This algorithm puts the center of mass into contemporary candidates computing as a singular point solution to increase the speed of contraction and improves the candidates’ quality and enhances its diversity by mean of Particle Swarm optimization (PSO). At last, Big Rip theory is introduced to in-crease the diversity of the big bang phase solutions and the ability to jump out of local optimal solution. The experimental results tested by 9 new benchmark test functions indicate that the improved algorithm performs better than the BB-BC and Uniform Big Bang-Chaotic Big Crunch ( UBB-CBC) on optimization of high dimensional functions.

  10. New Results on Nucleosynthesis in Massive Stars; Nuclear Data Needs for Nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, R; Rauscher, T; Heger, A; Woosley, S

    2001-11-09

    We review the current status of the nuclear reaction rates needed to study nucleosynthesis in massive stars. Results for the calculated nucleosynthesis of all stable species from Hydrogen to Bismuth in a completely evolved 25 M{sub {circle_dot}} star of initial solar metallicity will be presented. Special emphasis will be paid to two particular reactions, {sup 12}C({alpha}, {gamma}){sup 16}O and {sup 22}Ne({alpha},n){sup 25}Mg, and their effect on the structure of the star and resultant nucleosynthesis. Both have been measured many times, but the present range of experimental uncertainty translates into remarkable sensitivity of the calculated nucleosynthesis.

  11. BRUSLIB and NETGEN: the Brussels nuclear reaction rate library and nuclear network generator for astrophysics

    Science.gov (United States)

    Aikawa, M.; Arnould, M.; Goriely, S.; Jorissen, A.; Takahashi, K.

    2005-10-01

    Nuclear reaction rates are quantities of fundamental importance in astrophysics. Substantial efforts have been devoted in the last decades to measuring or calculating them. This paper presents a detailed description of the Brussels nuclear reaction rate library BRUSLIB and of the nuclear network generator NETGEN. BRUSLIB is made of two parts. The first one contains the 1999 NACRE compilation based on experimental data for 86 reactions with (mainly) stable targets up to Si. BRUSLIB provides an electronic link to the published, as well as to a large body of unpublished, NACRE data containing adopted rates, as well as lower and upper limits. The second part of BRUSLIB concerns nuclear reaction rate predictions to complement the experimentally-based rates. An electronic access is provided to tables of rates calculated within a statistical Hauser-Feshbach approximation, which limits the reliability of the rates to reactions producing compound nuclei with a high enough level density. These calculations make use of global and coherent microscopic nuclear models for the quantities entering the rate calculations. The use of such models makes the BRUSLIB rate library unique. A description of the Nuclear Network Generator NETGEN that complements the BRUSLIB package is also presented. NETGEN is a tool to generate nuclear reaction rates for temperature grids specified by the user. The information it provides can be used for a large variety of applications, including Big Bang nucleosynthesis, the energy generation and nucleosynthesis associated with the non-explosive and explosive hydrogen to silicon burning stages, or the synthesis of the heavy nuclides through the s-, α- and r-, rp- or p-processes.

  12. Low-energy d+d fusion reactions via the Trojan Horse Method

    Energy Technology Data Exchange (ETDEWEB)

    Tumino, A., E-mail: tumino@lns.infn.it [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Universita degli Studi di Enna ' Kore' , Enna (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mukhamedzhanov, A.M. [Cyclotron Institute Texas A and M University, College Station, TX (United States); Typel, S. [Excellence Cluster Universe, Technische Universitaet Muenchen, Garching (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH - Theorie, Darmstadt (Germany); Aliotta, M. [School of Physics and Astronomy, University of Edinburgh, Edinburgh, Scotland (United Kingdom); Scottish Universities Physics Alliance (United Kingdom); Burjan, V. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Gimenez del Santo, M. [Departamento de Fisica Nuclear, Universitade de Sao Paulo, Sao Paulo (Brazil); Kiss, G.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); ATOMKI, Debrecen (Hungary); Kroha, V.; Hons, Z. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); La Cognata, M.; Lamia, L. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Mrazek, J. [Nuclear Physics Institute of ASCR, Rez near Prague (Czech Republic); Pizzone, R.G. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy); Piskor, S. [Nuclear Physics Institute of ASCR, Rez (Czech Republic); Rapisarda, G.G.; Romano, S.; Sergi, M.L.; Sparta, R. [Laboratori Nazionali del Sud, INFN, and Dipartimento di Fisica e Astronomia, Universita di Catania, Catania (Italy)

    2011-06-06

    The bare nucleus S(E) factors for the {sup 2}H(d,p){sup 3}H and {sup 2}H(d,n){sup 3}He reactions have been measured for the first time via the Trojan Horse Method off the proton in {sup 3}He from 1.5 MeV down to 2 keV. This range overlaps with the relevant region for Standard Big Bang Nucleosynthesis as well as with the thermal energies of future fusion reactors and deuterium burning in the Pre-Main-Sequence phase of stellar evolution. This is the first pioneering experiment in quasi free regime where the charged spectator is detected. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from available direct data with new S(0) values of 57.4{+-}1.8 MeVb for {sup 3}H+p and 60.1{+-}1.9 MeVb for {sup 3}He+n. None of the existing fitting curves is able to provide the correct slope of the new data in the full range, thus calling for a revision of the theoretical description. This has consequences in the calculation of the reaction rates with more than a 25% increase at the temperatures of future fusion reactors.

  13. From the Big Bang to the life in the primitive seas. (Spanish Title: Desde la Gran Explosión hasta la vida en los mares primitivos)

    Science.gov (United States)

    Esteban, S. B.

    Man has always wondered about the origins of humanity, life, and the world around him. The Earth crust is a vast and natural archive, and its rocks represent the pages of the most documented events in the geological past. These rocks hold large amounts of information about the Earth history, whose age is estimated to be 4,600 million years. Historical Geology seeks to bring together the knowledge of the origin of the Universe as well as the origin of Earth as a member of the Solar System. The Big Bang theory supposes that the Universe began with a huge explosion. In the Earth's history it is possible to differentiate the biological events from the physical ones. The physical events are geographical and environmental transformations. The biological events are related to life on Earth. There are evidences of biological processes back to 3,500 million years ago. At the beginning, the conditions on Earth were catastrophic and unstable. At this stage, the first signs of life were the molecules that started to take energy from the sunlight and the chemical products. It was not a simple accumulation of gradual biological forms, but was accompanied by episodic innovations that allowed increasing complexity and greater use of ecospace. Some of these innovations are shown by certain groups of primitive arthropods adapted to live in oxygen-poor, deep marine environments. These arthropods have been found in 500 million-year-old rocks in northwestern Argentina (provinces of Jujuy and La Rioja), indicating the presence of oxygen-poor seas in that region.

  14. Big Bangs in Galaxy Clusters: Using X-ray Temperature Maps to Trace Merger Histories in Clusters with Radio Halos/Relics

    Science.gov (United States)

    Burns, Jack O.; Datta, Abhirup; Hallman, Eric J.

    2016-06-01

    Galaxy clusters are assembled through large and small mergers which are the most energetic events ("bangs") since the Big Bang. Cluster mergers "stir" the intracluster medium (ICM) creating shocks and turbulence which are illuminated by ~Mpc-sized radio features called relics and halos. These shocks heat the ICM and are detected in x-rays via thermal emission. Disturbed morphologies in x-ray surface brightness and temperatures are direct evidence for cluster mergers. In the radio, relics (in the outskirts of the clusters) and halos (located near the cluster core) are also clear signposts of recent mergers. Our recent ENZO cosmological simulations suggest that around a merger event, radio emission peaks very sharply (and briefly) while the x-ray emission rises and decays slowly. Hence, a sample of galaxy clusters that shows both luminous x-ray emission and radio relics/halos are good candidates for very recent mergers. We are in the early stages of analyzing a unique sample of 48 galaxy clusters with (i) known radio relics and/or halos and (ii) significant archival x-ray observations (>50 ksec) from Chandra and/or XMM. We have developed a new x-ray data analysis pipeline, implemented on parallel processor supercomputers, to create x-ray surface brightness, high fidelity temperature, and pressure maps of these clusters in order to study merging activity. The temperature maps are made using three different map-making techniques: Weighted Voronoi Tessellation, Adaptive Circular Binning, and Contour Binning. In this talk, we will show preliminary results for several clusters, including Abell 2744 and the Bullet cluster. This work is supported by NASA ADAP grant NNX15AE17G.

  15. A New Nucleosynthesis Constraint on the Variation of G

    CERN Document Server

    Copi, C J; Krauss, L M; Copi, Craig J.; Davis, Adam N.; Krauss, Lawrence M.

    2004-01-01

    Big Bang Nucleosynthesis can provide, via constraints on the expansion rate at that time, limits on possible variations in Newton's Constant, $G$. The original analyses were performed before an independent measurement of the baryon-to-photon ratio from the cosmic microwave background was available. Combining this with recent measurements of the primordial deuterium abundance in quasar absorption systems now allows one to derive a new tighter constraint on $G$ without recourse to considerations of helium or lithium abundances. We find that, compared to todays value, $G_0$, $G_{BBN}/G_0=1.01^{+0.20}_{-0.16}$ at the 68.3% confidence level. If we assume a monotonic power law time dependence, $G\\propto t^{-\\alpha}$, then the constraint on the index is $-0.004 < \\alpha < 0.005$. This would translate into $-3\\times10^{-13} \\textrm{yr}^{-1} < (\\dot G/G)_{\\textrm{today}} < 4 \\times 10^{-13} \\textrm{yr}^{-1}$.

  16. 7Be (n ,α )4He Reaction and the Cosmological Lithium Problem: Measurement of the Cross Section in a Wide Energy Range at n_TOF at CERN

    Science.gov (United States)

    Barbagallo, M.; Musumarra, A.; Cosentino, L.; Maugeri, E.; Heinitz, S.; Mengoni, A.; Dressler, R.; Schumann, D.; Käppeler, F.; Colonna, N.; Finocchiaro, P.; Ayranov, M.; Damone, L.; Kivel, N.; Aberle, O.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barros, S.; Bécares, V.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cristallo, S.; Diakaki, M.; Domingo-Pardo, C.; Dupont, E.; Duran, I.; Fernandez-Dominguez, B.; Ferrari, A.; Ferreira, P.; Furman, W.; Ganesan, S.; García-Rios, A.; Gawlik, A.; Glodariu, T.; Göbel, K.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Katabuchi, T.; Kavrigin, P.; Kimura, A.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lerendegui, J.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mazzone, A.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Nolte, R.; Oprea, A.; Pappalardo, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Piscopo, M.; Plompen, A.; Porras, I.; Praena, J.; Quesada, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P.; Rubbia, C.; Ryan, J.; Sabate-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Vollaire, J.; Wallner, A.; Warren, S.; Weigand, M.; Weiß, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.; n TOF Collaboration

    2016-10-01

    The energy-dependent cross section of the 7Be (n ,α )4He reaction, of interest for the so-called cosmological lithium problem in big bang nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of 7Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure 7Be, and a specifically designed experimental setup. Coincidences between the two alpha particles have been recorded in two Si -7Be -Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 1960s at a nuclear reactor. The energy dependence reported here clearly indicates the inadequacy of the cross section estimates currently used in BBN calculations. Although new measurements at higher neutron energy may still be needed, the n_TOF results hint at a minor role of this reaction in BBN, leaving the long-standing cosmological lithium problem unsolved.

  17. A study on verbal humor in The Big Bang Theory from the perspective of relevance theory%从关联理论视角解读《生活大爆炸》中的言语幽默

    Institute of Scientific and Technical Information of China (English)

    陈丽玉

    2013-01-01

    本文运用关联理论解读美国情景喜剧《生活大爆炸》中的幽默对白,探讨言语幽默的产生机制,以期更好地理解和欣赏言语幽默。%The present paper aims to study verbal humor in the American sitcom The Big Bang Theory from a perspective of Relevance Theory with a purpose of summarizing the generating mechanism of verbal humor and providing suggestions for better appreciation of verbal humor.

  18. On the Sensitivity of Massive Star Nucleosynthesis and Evolution to Solar Abundances and to Uncertainties in Helium-Burning Reaction Rates

    Science.gov (United States)

    Tur, Clarisse; Heger, Alexander; Austin, Sam M.

    2007-12-01

    We explore the dependence of presupernova evolution and supernova nucleosynthesis yields on the uncertainties in helium-burning reaction rates. Using the revised solar abundances of Lodders for the initial stellar composition, instead of those of Anders and Grevesse, changes the supernova yields and limits the constraints that those yields place on the 12C(α,γ)16O reaction rate. The production factors of medium-weight elements (A=16-40) were found to be in reasonable agreement with observed solar ratios within the current experimental uncertainties in the triple-α reaction rate. Simultaneous variations by the same amount in both reaction rates or in either of them separately, however, can induce significant changes in the central 12C abundance at core carbon ignition and in the mass of the supernova remnant. It therefore remains important to have experimental determinations of the helium-burning rates so that their ratio and absolute values are known with an accuracy of 10% or better.

  19. $^7Be(n,\\alpha)^4He$ reaction and the Cosmological Lithium Problem: measurement of the cross section in a wide energy range at n_TOF (CERN)

    CERN Document Server

    Barbagallo, M.; Cosentino, L.; Maugeri, E.; Heinitz, S.; Mengoni, A.; Dressler, R.; Schumann, D.; Käppeler, F.; Colonna, N.; Finocchiaro, P.; Ayranov, M.; Damone, L.; Kivel, N.; Aberle, O.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea-Correa, J.; Barros, S.; Bécares, V.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cristallo, S.; Diakaki, M.; Domingo-Pardo, C.; Dupont, E.; Duran, I.; Fernandez-Dominguez, B.; Ferrari, A.; Ferreira, P.; Furman, W.; Ganesan, S.; García-Rios, A.; Gawlik, A.; Glodariu, T.; Göbel, K.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Katabuchi, T.; Kavrigin, P.; Kimura, A.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lerendegui, J.; Lederer, C.; Leeb, H.; Lo Meo, S.; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mazzone, A.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Nolte, R.; Oprea, A.; Pappalardo, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Piscopo, M.; Plompen, A.; Porras, I.; Praena, J.; Quesada, J.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P.; Rubbia, C.; Ryan, J.; Sabate-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Vollaire, J.; Wallner, A.; Warren, S.; Weigand, M.; Weiß, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.

    2016-01-01

    The energy-dependent cross section of the 7Be(n,alpha)4He reaction, of interest for the so-called Cosmological Lithium Problem in Big Bang Nucleosynthesis, has been measured for the first time from 10 meV to 10 keV neutron energy. The challenges posed by the short half-life of 7Be and by the low reaction cross section have been overcome at n_TOF thanks to an unprecedented combination of the extremely high luminosity and good resolution of the neutron beam in the new experimental area (EAR2) of the n_TOF facility at CERN, the availability of a sufficient amount of chemically pure 7Be, and a specifically designed experimental setup. Coincidences between the two alpha-particles have been recorded in two Si-7Be-Si arrays placed directly in the neutron beam. The present results are consistent, at thermal neutron energy, with the only previous measurement performed in the 60's at a nuclear reactor. The energy dependence here reported clearly indicates the inadequacy of the cross section estimates currently used in ...

  20. Research on the Subtitle Translation of "The Big Bang Theory" from the Perspective of Functional Equivalence Theory%功能对等视角下《生活大爆炸》字幕翻译研究

    Institute of Scientific and Technical Information of China (English)

    蒋婷婷; 高圣兵

    2014-01-01

    "The Big Bang Theory"is a popular sitcom welcomed by a large audience. The features and limitations of the subtitles are fully showed in this sitcom, so the research can be done to this sitcom. In order to find out whether the subtitle translation have met the need of equivalence with different translating skills and methods and how they meet it, this paper presents a case study of American sitcom "The Big Bang Theory" within the framework of functionalism.%《生活大爆炸》是一个广受喜欢的情景喜剧。其字幕翻译中,包含了许多影视翻译的特征和制约因素,本文从语言和文体方面选取一些比较典型的对话片段,分析说明在翻译过程中是如何做到功能对等的,进而论证奈达的功能对等理论对字幕翻译具有实践性指导作用。

  1. Bugs and the big bang.

    Science.gov (United States)

    Parsons, Jenni

    2008-10-01

    Now that's a cheery thought! Somewhere more than 100 km below the Geneva countryside two parallel beams of subatomic particles are whizzing around a 27 km circuit in opposite directions at about 99% of the speed of light, doing over 11 000 laps per second. Physicists hope to create a 'bang' that won't end the world, but will unlock some of its mysteries. I confess I have never thought of physicists as poets, but they certainly come up with some evocative models to explain the unknown such as 'dark matter', the invisible skeleton stretching through space; or 'dark energy', which drives the expansion of the universe; or the grandiose 'God's particle' (officially named 'Higgs boson') postulated to endow other particles with mass. These are concepts both too large and too small to grasp.

  2. Big Bang Day: Engineering Solutions

    CERN Multimedia

    Lyn Evans; Austin Ball; Jim Virdee; Adam Hart-Davis

    2008-01-01

    CERN's Large Hadron Collider is the most complicated scientific apparatus ever built. Many of the technologies it uses hadn't even been invented when scientists started building it. Adam Hart-Davis discovers what it takes to build the world's most intricate discovery machine.

  3. Did the big bang boil?

    CERN Multimedia

    Wilczek, Frank

    2006-01-01

    "Standard theories tell us that, at some point in the Universe's evolution, free quarks and gluons must have become bound together into the hadronic matter we see today. But was this transition abrupt or smooth?

  4. Retour vers le Big Bang

    CERN Multimedia

    Pentier, Olivier

    2007-01-01

    A laboratory from Grenoble participated in the building of LHC (Large Hadron Collider) at CERN. This particle accelerator, operational at the end of 2007, will help to understand how the universe was born. (1 page)

  5. Big Bang Day : Physics Rocks

    CERN Multimedia

    Brian Cox; John Barrowman; Eddie Izzard

    2008-01-01

    Is particle physics the new rock 'n' roll? The fundamental questions about the nature of the universe that particle physics hopes to answer have attracted the attention of some very high profile and unusual fans. Alan Alda, Ben Miller, Eddie Izzard, Dara O'Briain and John Barrowman all have interests in this branch of physics. Brian Cox - CERN physicist, and former member of 90's band D:Ream, tracks down some very well known celebrity enthusiasts and takes a light-hearted look at why this subject can appeal to all of us.

  6. Scientists recreating the Big Bang

    CERN Multimedia

    Bagla, Pallava

    2007-01-01

    "Beneath the breathtaking alpine vineyards, work is on at a feverish pace to complete a machine nickmamed the "Lord of Rings". Otherwise called a particle accelerator, it will be switched on next summer." (1/2 page)

  7. Gauging away a big bang

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2017-08-01

    We argue that in the tensionless phase of string theory where the stringy gauge symmetries are unbroken, (at least some) cosmological singularities can be understood as gauge artefacts. We present two conceptually related, but distinct, pieces of evidence: one relying on spacetime and the other on worldsheet.

  8. Birmingham probes the Big Bang

    CERN Multimedia

    2007-01-01

    "The world's largest particle accelerator in Geneva is gearing up to begin work again. BBC Midlands Today science correspondent David Gregory went to see how scientists from the University of Birmingham are at the heart of trying to understand what makes our universe tick." (1 page)

  9. Measurement of the 2H(d ,p ) 3H reaction at astrophysical energies via the Trojan-horse method

    Science.gov (United States)

    Li, Chengbo; Wen, Qungang; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C.; Tumino, A.; Pizzone, R. G.; Lamia, L.

    2015-08-01

    The study of the 2H(d ,p ) 3H reaction is very important for the nucleosynthesis in both the standard Big Bang and stellar evolution, as well as for the future fusion reactor's planning of energy production. The 2H(d ,p ) 3H bare nucleus astrophysical S (E ) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan-horse method applied to the quasifree process 2H(6Li ,p t ) 4He induced at a lithium beam energy of 9.5 MeV, which is closer to the zero-quasifree-energy point. An accurate analysis leads to the determination of the Sbare(0 ) =56.7 ±2.0 keV b and of the corresponding electron screening potential Ue=13.2 ±4.3 eV. In addition, this work gives an updated test for the Trojan-horse nucleus invariance by comparing with previous indirect investigations using the 3He=(d +p ) breakup.

  10. Investigation of the impact of the $^{39}$Ar(n , $\\alpha)^{36}$S reaction on the nucleosynthesis of the rare isotope $^{36}$S

    CERN Multimedia

    Geltenbort, P

    2002-01-01

    The origin of the rare, neutron rich isotope $^{36}$S remains a debated question. One of the key reactions in the s-process nucleosynthesis network leading to $^{36}$S is $^{39}$Ar(n , $\\alpha) ^{36}\\!$S. This reaction has never been studied so far, which is due to the fact that $^{39}$Ar is a radioactive (T$_{1/2}$ = 269 y) gas, which is not commercially available. During a three days experimental campaign, an optimized $^{39}$Ar sample was prepared at ISOLDE. A dedicated titaniumoxide target (8 g/cm$^{2}$) was bombarded with 1 GeV protons from the PS Booster. In order to obtain a pure argon beam, a water-cooled transfer line was used to freeze-out less volatile isobars before they can reach the ion source. Adding stable argon with a calibrated leak to the ion source enabled to determine the ionization efficiency (3.5%). For the isotope separation, the low-mass side (GLM) of the General Purpose Separator was used. After magnetic separation, $^{39}$Ar ions (1+) were implanted at 60 keV in a 12 mm thick alumin...

  11. Neutrino Nucleosynthesis of radioactive nuclei in supernovae

    CERN Document Server

    Sieverding, A; Langanke, K; Martínez-Pinedo, G; Heger, A

    2015-01-01

    We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity and initial main sequence masses between 15 M$_\\odot$ and 40 M$_\\odot$. We improve previous investigations i) by using a global set of partial differential cross sections for neutrino-induced charged- and neutral-current reactions on nuclei with charge numbers $Z < 76 $ and ii) by considering modern supernova neutrino spectra which have substantially lower average energies compared to those previously adopted in neutrino nucleosynthesis studies. We confirm the production of $^7$Li, $^{11}$B, $^{138}$La, and $^{180}$Ta by neutrino nucleosynthesis, albeit at slightly smaller abundances due to the changed neutrino spectra. We find that for stars with a mass smaller than 20 M$_\\odot$, $^{19}$F is produced mainly by explosive nucleosynthesis while for higher mass stars it is produced by the $\

  12. New measurement of $\\rm S_{bare}(E)$ factor of the d(d,p)t reaction at astrophysical energies via the Trojan-horse method

    CERN Document Server

    Li, Chengbo; Fu, Yuanyong; Zhou, Jing; Zhou, Shuhua; Meng, Qiuying; Spitaleri, C; Tumino, A; Pizzone, R G; Lamia, L

    2015-01-01

    The study of d(d,p)t reaction is very important for the nucleosynthesis in both standard Big Bang and stellar evolution, as well as for the future fusion reactor planning of energy production. The d(d,p)t bare nucleus astrophysical S(E) factor has been measured indirectly at energies from about 400 keV down to several keV by means of the Trojan horse method applied to the quasi-free process $\\rm {}^2H({}^6Li,pt){}^4He$ induced at the lithium beam energy of 9.5 MeV, which is closer to the zero quasi-free energy point, in CIAE HI-13 tandem accelerator laboratory. An accurate analysis leads to the determination of the d(d,p)t $\\rm S(E)$ factor $\\rm S_{bare}(0)=56.7 \\pm 2.0 keV*b$ and of the corresponding electron screening potential $\\rm U_e = 13.2 \\pm 4.3 eV$. In addition, this work also gives an updated test for the Trojan horse nucleus invariance comparing with previous indirect investigations using $\\rm {}^3He=(d+p)$ breakup.

  13. 从英汉文化差异角度看2012年热播美剧Gossip Girl和The Big Bang Theory的字幕翻译

    Institute of Scientific and Technical Information of China (English)

    孟芸

    2013-01-01

    如今.不论电视剧还是电影领域,从美国引进的作品都占有重要一席。然而目前大部分中国人还不具备不依赖字幕直接欣赏英语片的能力,因此字幕翻译正日益受到影视爱好者和语言学习者的高度重视。本文主要从英汉文化差异看2012年热播关剧Gossip Girl和The Big Bang Theory的字幕翻译以及其对翻译策略选择的影响。

  14. Interpretation of Irony in the Big Bang Theory from the Perspective of Relevance%关联理论视角下《生活大爆炸》中的反语阐释

    Institute of Scientific and Technical Information of China (English)

    郑燕

    2013-01-01

    Irony study is drawing more and more attention from linguists. The basic claim in this article will be illustrated with these three prototypical cases by analyzing ironic utterances in the Big Bang Theory. The aim is to show how the relevance-theoret⁃ic framework of verbal irony describe and explain ironic communication in this comedy.%  反语研究正在受到越来越多语言学家的关注。此文将通过《生活大爆炸》里的三个典型的案例分析来阐释反语,其研究目的是研究关联理论如何描述和解释这部喜剧里的反语。

  15. 情景喜剧《生活大爆炸》中双关语的妙用%The using of puns in magical sitcom "the big bang"

    Institute of Scientific and Technical Information of China (English)

    张帆

    2013-01-01

      the pun is a common rhetorical device in English, but plays a decisive role in the sitcom. The paper discusses the classification of the pun in the sitcom "the big bang", and rhetorical effect, show the rich connotation and the artistic charm, and to improve the understanding of pun and appreciate level.%  双关是英语中一种常见的修辞手法,但是却在情景喜剧中起着举足轻重的作用。本文探讨情景喜剧《生活大爆炸》中双关的分类,及其修辞效果,展现双关丰富内涵及艺术魅力,并提高读者对双关的理解和欣赏水平。

  16. From God's particle to the world formula. Big Bang, Higgs, antimatter, and the mysterious shadow world; Vom Gottesteilchen zur Weltformel. Urknall, Higgs, Antimaterie und die raetselhafte Schattenwelt

    Energy Technology Data Exchange (ETDEWEB)

    Vaas, Ruediger

    2013-07-01

    Our knowledge about the elementary particles stands before a revolution: With the biggest machine of mankind the legendary Higgs boson was discovered - and for its prediction the Nobel prize awarded. Other researchers search for antiparticles from the universe and the shadow regime of the dark matter. What has be happened after the big bang? How the components of the universe have been arised? Of which consists the world - and why it exists at all? Science reporter and cosmology specialist Ruediger Vaas bends the bow from the smallest of all to the largest of all. He analyzes the actual state of knowledge and reports about the search for a ''world formula'', which explains, what holds the universe together in the innermost. A unique excursion to the fronts of research.

  17. Theoretical uncertainty of (α ,n ) reactions relevant for the nucleosynthesis of light r -process nuclei in neutrino-driven winds

    Science.gov (United States)

    Pereira, J.; Montes, F.

    2016-03-01

    Background: Neutrino-driven winds following core-collapse supernova explosions have been proposed as a possible site where light r -process nuclei (between Fe and Ag) might be synthesized. In these events, (α ,n ) reactions are key to moving matter towards the region of higher proton number. Abundance network calculations are very sensitive to the rates for this type of reactions. Purpose: The present work aims at evaluating the theoretical uncertainty of these (α ,n ) reactions calculated with reaction codes based on the Hauser-Feshbach model. Method: We compared several (α ,n ) rates taken from talys and the non-smoker database to determine the uncertainties owing to the existing technical differences between both codes. In addition, we evaluated the sensitivity of talys rates to variations in the α optical potentials, masses, level densities, optical potentials, preequilibrium intranuclear transition rates, level structure, radiative transmission coefficients, and width-fluctuation correction factors. Results: The main source of uncertainty at low temperature is mostly attributable to the use of different α optical potentials. Differences between talys and non-smoker at high temperatures arise from the energy-binning algorithm used by each code. We have also noticed that the (α ,n ) rates from the non-smoker database correspond to the inclusive reaction, instead of the exclusive (α ,1 n ) channel calculated in the present work and used in network calculations. Conclusions: Theoretical uncertainties in calculated reaction rates can be as high as one to two orders of magnitude and strongly dependent on the temperature of the environment. Besides direct measurements of the inclusive and exclusive (α ,1 n ) reaction rates, experimental studies of α optical potentials are crucial to improve the performance of reaction codes.

  18. Neutron Capture Nucleosynthesis

    CERN Document Server

    Kiss, Miklos

    2016-01-01

    Heavy elements (beyond iron) are formed in neutron capture nucleosynthesis processes. We have proposed a simple unified model to investigate the neutron capture nucleosynthesis in arbitrary neutron density environment. We have also investigated what neutron density is required to reproduce the measured abundance of nuclei assuming equilibrium processes. We found both of these that the medium neutron density has a particularly important role at neutron capture nucleosynthesis. About these results most of the nuclei can formed at medium neutron capture density environment e.g. in some kind of AGB stars. Besides these observations our model is capable to use educational purpose.

  19. Experimentally constrained (p ,γ )89Y and (n ,γ )89Y reaction rates relevant to p -process nucleosynthesis

    Science.gov (United States)

    Larsen, A. C.; Guttormsen, M.; Schwengner, R.; Bleuel, D. L.; Goriely, S.; Harissopulos, S.; Bello Garrote, F. L.; Byun, Y.; Eriksen, T. K.; Giacoppo, F.; Görgen, A.; Hagen, T. W.; Klintefjord, M.; Renstrøm, T.; Rose, S. J.; Sahin, E.; Siem, S.; Tornyi, T. G.; Tveten, G. M.; Voinov, A. V.; Wiedeking, M.

    2016-04-01

    The nuclear level density and the γ -ray strength function have been extracted for 89Y by using the Oslo method on 89Y(p ,p'γ )89Y coincidence data. The γ -ray strength function displays a low-energy enhancement consistent with previous observations in this mass region (Mo-9893). Shell-model calculations support the conclusion that the observed enhancement is due to strong, low-energy M 1 transitions at high excitation energies. The data were further used as input for calculations of the 88Sr(p ,γ )89Y and 88Y(n ,γ )89Y cross sections with the talys reaction code. Comparison with cross-section data, where available, as well as with values from the BRUSLIB library, shows a satisfying agreement.

  20. Nucleosynthesis Basics and Applications to Supernovae

    CERN Document Server

    Thielemann, F K; Freiburghaus, C; Nomoto, K; Hashimoto, M; Pfeiffer, B; Kratz, K L

    1998-01-01

    This review concentrates on nucleosynthesis processes in general and their applications to massive stars and supernovae. A brief initial introduction is given to the physics in astrophysical plasmas which governs composition changes. We present the basic equations for thermonuclear reaction rates and nuclear reaction networks. The required nuclear physics input for reaction rates is discussed, i.e. cross sections for nuclear reactions, photodisintegrations, electron and positron captures, neutrino captures, inelastic neutrino scattering, and beta-decay half-lives. We examine especially the present state of uncertainties in predicting thermonuclear reaction rates, while the status of experiments is discussed by others in this volume (see M. Wiescher). It follows a brief review of hydrostatic burning stages in stellar evolution before discussing the fate of massive stars, i.e. the nucleosynthesis in type II supernova explosions (SNe II). Except for SNe Ia, which are explained by exploding white dwarfs in binary...

  1. New Determination of the 2H(d,p)3H and 2H(d,n)3He Reaction Rates at Astrophysical Energies

    Science.gov (United States)

    Tumino, A.; Spartà, R.; Spitaleri, C.; Mukhamedzhanov, A. M.; Typel, S.; Pizzone, R. G.; Tognelli, E.; Degl'Innocenti, S.; Burjan, V.; Kroha, V.; Hons, Z.; La Cognata, M.; Lamia, L.; Mrazek, J.; Piskor, S.; Prada Moroni, P. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.

    2014-04-01

    The cross sections of the 2H(d,p)3H and 2H(d,n)3He reactions have been measured via the Trojan Horse method applied to the quasi-free 2H(3He,p 3H)1H and 2H(3He,n 3He)1H processes at 18 MeV off the proton in 3He. For the first time, the bare nucleus S(E) factors have been determined from 1.5 MeV, across the relevant region for standard Big Bang nucleosynthesis, down to the thermal energies of deuterium burning in the pre-main-sequence (PMS) phase of stellar evolution, as well as of future fusion reactors. Both the energy dependence and the absolute value of the S(E) factors deviate by more than 15% from the available direct data and existing fitting curves, with substantial variations in the electron screening by more than 50%. As a consequence, the reaction rates for astrophysics experience relevant changes, with a maximum increase of up to 20% at the temperatures of the PMS phase. From a recent primordial abundance sensitivity study, it turns out that the 2H(d,n)3He reaction is quite influential on 7Li, and the present change in the reaction rate leads to a decrease in its abundance by up to 10%. The present reaction rates have also been included in an updated version of the FRANEC evolutionary code to analyze their influence on the central deuterium abundance in PMS stars with different masses. The largest variation of about 10%-15% pertains to young stars (=1 M ⊙.

  2. Spectra for the A = 6 reactions calculated from a three-body resonance model

    Directory of Open Access Journals (Sweden)

    Paris Mark W.

    2016-01-01

    Full Text Available We develop a resonance model of the transition matrix for three-body breakup reactions of the A = 6 system and present calculations for the nucleon observed spectra, which are important for inertial confinement fusion and Big Bang nucleosynthesis (BBN. The model is motivated by the Faddeev approach where the form of the T matrix is written as a sum of the distinct Jacobi coordinate systems corresponding to particle configurations (α, n-n and (n; n-α to describe the final state. The structure in the spectra comes from the resonances of the two-body subsystems of the three-body final state, namely the singlet (T = 1 nucleon-nucleon (NN anti-bound resonance, and the Nα resonances designated the ground state (Jπ = 3−2${{{3^ - }} \\over 2}$ and first excited state (Jπ = 1−2${{{1^ - }} \\over 2}$ of the A = 5 systems 5He and 5Li. These resonances are described in terms of single-level, single-channel R-matrix parameters that are taken from analyses of NN and Nα scattering data. While the resonance parameters are approximately charge symmetric, external charge-dependent effects are included in the penetrabilities, shifts, and hard-sphere phases, and in the level energies to account for internal Coulomb differences. The shapes of the resonance contributions to the spectrum are fixed by other, two-body data and the only adjustable parameters in the model are the combinatorial amplitudes for the compound system. These are adjusted to reproduce the observed nucleon spectra from measurements at the Omega and NIF facilities. We perform a simultaneous, least-squares fit of the tt neutron spectra and the 3He3He proton spectra. Using these amplitudes we make a prediction of the α spectra for both reactions at low energies. Significant differences in the tt and 3He3He spectra are due to Coulomb effects.

  3. Spectra for the A = 6 reactions calculated from a three-body resonance model

    Science.gov (United States)

    Paris, Mark W.; Hale, Gerald M.

    2016-06-01

    We develop a resonance model of the transition matrix for three-body breakup reactions of the A = 6 system and present calculations for the nucleon observed spectra, which are important for inertial confinement fusion and Big Bang nucleosynthesis (BBN). The model is motivated by the Faddeev approach where the form of the T matrix is written as a sum of the distinct Jacobi coordinate systems corresponding to particle configurations (α, n-n) and (n; n-α) to describe the final state. The structure in the spectra comes from the resonances of the two-body subsystems of the three-body final state, namely the singlet (T = 1) nucleon-nucleon (NN) anti-bound resonance, and the Nα resonances designated the ground state (Jπ = {{{3^ - }} over 2}) and first excited state (Jπ = {{{1^ - }} over 2}) of the A = 5 systems 5He and 5Li. These resonances are described in terms of single-level, single-channel R-matrix parameters that are taken from analyses of NN and Nα scattering data. While the resonance parameters are approximately charge symmetric, external charge-dependent effects are included in the penetrabilities, shifts, and hard-sphere phases, and in the level energies to account for internal Coulomb differences. The shapes of the resonance contributions to the spectrum are fixed by other, two-body data and the only adjustable parameters in the model are the combinatorial amplitudes for the compound system. These are adjusted to reproduce the observed nucleon spectra from measurements at the Omega and NIF facilities. We perform a simultaneous, least-squares fit of the tt neutron spectra and the 3He3He proton spectra. Using these amplitudes we make a prediction of the α spectra for both reactions at low energies. Significant differences in the tt and 3He3He spectra are due to Coulomb effects.

  4. Astrophysical S-factor of T(4He, γ)7Li reaction at E cm = 15.7 keV

    Science.gov (United States)

    Bystritsky, V. M.; Dudkin, G. N.; Emets, E. G.; Filipowicz, M.; Krylov, A. R.; Nechaev, B. A.; Nurkin, A.; Padalko, V. N.; Philippov, A. V.; Sadovsky, A. B.

    2017-07-01

    The astrophysical S-factor of the reaction T(4He, γ)7Li is measured for the first time at the center of mass energy E cm = 15.7 keV, lower than the energy range of the Standard Big Bang Nucleosynthesis (SBBN) model. The experiment is performed on a Hall pulsed accelerator (TPU, Tomsk). An acceleration pulse length of 10 μs allows one to suppress the background of cosmic radiation and the ambient medium by five orders of magnitude. A beam intensity of 5 × 1014 4He+ ions per pulse allows one to measure an extremely low reaction yield. The yield of γ-quanta with the energies E γ 0 = 2483.7 keV and E γ 1 = 2006.1 keV is registered by NaI(Tl) detectors with the efficiency ɛ = 0.331 ± 0.026. A method for direct measurement of the background from the chain of reactions T(4He, 4He)T→T(T, 2 n)X→( n, γ) and/or ( n, n'γ) which ends by neutron activation of materials surrounding the target is proposed and implemented in this study. The value of the astrophysical S-factor of the reaction T(4He, γ)7Li S αt ( E cm = 15.7 keV) = 0.091 ± 0.032 keV b provides the choice from the set of experimental data for the astrophysical S αt -factor in favor of experimental data [4] with S αt ( E cm = 0) = 0.1067 ± 0.0064 keV b.

  5. ECM and Verbal Humor—Take Big Bang Theory as an Example%事件域认知模型与言语幽默——以美剧《生活大爆炸》为例

    Institute of Scientific and Technical Information of China (English)

    高文璐

    2012-01-01

      以王寅教授提出的事件域认知模型(ECM)为理论基础,从认知的角度对美国情景喜剧《生活大爆炸》中的言语幽默进行动态分析.ECM对言语幽默具有很强的解释力,通过ECM中的事件(Event)、行为/事体(A/B)、特征性或分类性特征(D/C)三个层面探究《生活大爆炸》中言语幽默产生的动态机制.%  Event-domain Cognitive Model (ECM), proposed by Chinese professor Wang Yin, is applied to dynamically the cog⁃nitive analysis of verbal humor in an American sitcom Big Bang Theory. It affords a strong explanatory power for the formation of verbal humor. The ECM theory tries to explore the dynamic mechanism of verbal humor on the EVENT, ACTION, BEING and D/C levels.

  6. The origin of the Universe by the Big Bang theory applied in the classroom, following the proposal of the school curriculum of the State of São Paulo

    Science.gov (United States)

    Oliveira, Janes Ferreira dos Reis

    2017-07-01

    The purpose of this work is show to a bibliographic study based on the analysis made to the content applied in the first year of High School, through the booklet primer of the educational curriculum of the state of São Paulo, as predicted: "Natural Sciences and their Technologies" (São Paulo, 2010), implemented since 2008 in the public education network. The analysis made compares from the content addressed by the "Student Notebook" versus "Teacher's Notebook", an indispensable tool in the teaching network on the approach of theory of the emergence of the universe. An essential theme for educational knowledge in this cycle, revealing a hypothetical model of the Big Bang, and also curved space and cosmic inflation. Possibly this model may still be a controversial subject for some groups, because it involves belief, religion, science or another perspective of universe. The field of research was carried out in a group of 40 first year students of the High School, at the State School "Professor Rômulo Pero", in the city of São Paulo, supervised by the State Board of Education - Central Region. The completion of this task presents an important tool to be used by the teacher, a Conceptual Map, in order to raise previous knowledge and probing for the established topic, in the teaching of Physics.

  7. Challenges in nucleosynthesis of trans-iron elements

    CERN Document Server

    Rauscher, T

    2014-01-01

    Nucleosynthesis beyond Fe poses additional challenges not encountered when studying astrophysical processes involving light nuclei. Astrophysical sites and conditions are not well known for some of the processes involved. On the nuclear physics side, different approaches are required, both in theory and experiment. The main differences and most important considerations are presented for a selection of nucleosynthesis processes and reactions, specifically the $s$-, $r$-, $\\gamma$-, and $\

  8. An Analysis of Humorous Effects of Turn-taking---A Case Study of The Big Bang Theory%以《生活大爆炸》为例分析话轮转换的幽默效果

    Institute of Scientific and Technical Information of China (English)

    刘馨林

    2014-01-01

    In daily conversation , turn-taking is a very common phenomenon .Turn-taking is first proposed by the founders of conversational analysis ,Harvey Sacks , Emanuel Schegolff and Gail Jefferson .They summarize the turn-taking rules in personal communication so that the rules can help people to analyze different effects as a result of turn-taking mechanism , such as humorous effects of expressions .This paper attempts to expound what turn-taking is, what turn-taking strategies are , and analyze how to use turn-taking strategies to produce humorous conversations by taking the sitcom , The Big Bang Theory , as an example .%在日常会话中,话轮转换是一种普遍现象。话轮转换最初是由话语分析学派的开创者Harvey Sacks ,Emanuel Schegolff和Gail Jefferson提出的。他们总结了在交流中话轮转换的规则,从而帮助人们分析由话轮转换机制产生的不同表达效果,例如通过话轮转换产生幽默的会话效果。主要阐述话轮转换概念,话轮转换策略,并以《生活大爆炸》为例,揭示如何利用话轮转换策略表达出幽默的会话效果。

  9. 从语境角度分析《生活大爆炸》中的幽默言语%Analysis of the Humorous Discourse in The Big Bang Theory from the Perspective of Cognitive Environment

    Institute of Scientific and Technical Information of China (English)

    张黎

    2014-01-01

    该文以关联理论为基础,从认知语境的角度对《生活大爆炸》中幽默话语进行了分析,阐述了认知语境产生幽默所应具备的条件,以及影响个人认知语境的几个因素。以往的幽默研究着重强调交流双方在具有共同的认知语境之下产生的幽默,这篇文章指出交际双方在认知语境方面存在的差异很多时候是幽默制造的必需品;研究突破了传统的对语境的研究,从不同的角度阐述了认知语境与幽默之间存在着的的关系。%Based on Relevance Theory, This paper analyzed the humorous dialogues in American sitcom The Big Bang Theory from the perspective of cognitive environment to elaborate the necessary conditions of cognitive environment for humor genera-tion as well as the factors which influence people’s cognitive environment. Previous studies of humor always emphasize the hu-mor generated when two parties of communication have the same cognitive environment. This paper pointed out that the differ-ences of cognitive environment between both sides of communication are often the necessities for humor manufacturing;besides, the research broken through the traditional single general study of cognitive environment, and fully elaborated the varied and complicated relationship between cognitive environment and humor from a new perspective.

  10. Study of Humorous Language in Sitcom TheBigBangTheoryunder Skopostheory%目的论视角下《生活大爆炸》中幽默语的翻译

    Institute of Scientific and Technical Information of China (English)

    方欣

    2013-01-01

    Humor is the carrier of language and culture. With the development of intercultural communication, there are more studies on humor, most of which are from the perspectives of literature, arts or psychology. Very few studies on humor are taken in view of translation. Some scholars even consider humor as untranslatable. The translation of humor enables people from differ⁃ent cultures to share joy with one another. This essay takes Skopostheory as theoretical basis, analyzing the humorous language in the popular American sitcom TheBigBangTheoryand evaluating different translation strategies adopted.%  幽默是一种语言和文化内涵的载体,随着跨文化交流的日益频繁,越来越多的人对幽默有所探索。目前对幽默的研究大都是从文学、艺术、心理学等角度,但是从翻译的侧面对幽默的研究并不多,有些学者甚至认为幽默是不可翻译的。幽默语的翻译可以使来自不同文化背景人们相互之间更好地分享幽默。该文以功能翻译目的论为理论依据,选取时下流行的美国情景喜剧《生活大爆炸》中的幽默语言为案例,分析译者在翻译幽默语时所采取的具体策略及其得失。

  11. Pygmy resonances and nucleosynthesis

    CERN Document Server

    Tsoneva, Nadia

    2014-01-01

    A microscopic theoretical approach based on a self-consistent density functional theory for the nuclear ground state and QRPA formalism extended with multi-phonon degrees of freedom for the nuclear excited states is implemented in investigations of new low-energy modes called pygmy resonances. Advantage of the method is the unified description of low-energy multiphonon excitations, pygmy resonances and core polarization effects. This is found of crucial importance for the understanding of the fine structure of nuclear response functions at low energies. Aspects of the precise knowledge of nuclear response functions around the neutron threshold are discussed in a connection to nucleosynthesis.

  12. 范畴层次视域下的美国情景剧《生活大爆炸》中的言语幽默%Interpretation of Verbal Humor in Sitcom the Big Bang Theory from the Perspective of Categorization Levels

    Institute of Scientific and Technical Information of China (English)

    雷丽岚; 周蓓

    2011-01-01

    《生活大爆炸》是最近热播的情景喜剧,讲述四个情商极低的科学家和一个美女邻居之间的故事。试图运用范畴层次理论来阐释其特有的言语幽默。%The big bang theory is a very popular sitcom telling what happened between four scientists with a low EQ and a neighbor beauty.The paper tries to interpret its special verbal humor from the perspective of categorization levels.

  13. Translating strategy of cultural defaults of subtitles ---Taking The Big Bang Theory for example%影视字幕中文化缺省的翻译策略——以《生活大爆炸》为例

    Institute of Scientific and Technical Information of China (English)

    章程

    2012-01-01

    Many cultural defauhs exist in audiovisuals. Subtitle translation, as a new kind of art translation, has its own characteristics. This paper, taking American audiovisual The Big Bang Theory for example, explores translation strategies of cultural defaults.%在影视作品中存在大量的文化缺省现象。字幕翻译作为一种新的文学翻译形式有着它自身的特点。以美剧《生活大爆炸》为例,探讨影视作品中文化缺省的翻译策略。

  14. 3He(α,γ7Be cross section measured using complementary techniques

    Directory of Open Access Journals (Sweden)

    Carmona-Gallardo M.

    2014-03-01

    Full Text Available The astrophysical S-factor for the 3He(α,γ7Be reaction plays an important role in the Solar Standard Model and in the Big Bang Nucleosynthesis scenario. The advances from two recent experiments performed using complementary techniques at center of mass (C.M. energies between 1 and 3 MeV are discussed.

  15. Experimental investigation of the reactions {sup 25}Mg({alpha},n){sup 28}Si, {sup 26}Mg({alpha},n){sup 29}Si, {sup 18}O({alpha},n){sup 21}Ne and their impact on stellar nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Falahat, Sascha

    2010-06-10

    In the present dissertation, the nuclear reactions {sup 25}Mg({alpha},n){sup 28}Si, {sup 26}Mg({alpha},n){sup 29}Si, {sup 18}O({alpha},n){sup 21}Ne are investigated in the astrophysically interesting energy region from E{sub {alpha}}=1000 keV to E{sub {alpha}}=2450 keV. The experiments were performed at the Nuclear Structure Laboratory of the University of Notre Dame (USA) with the Van-de-Graaff accelerator KN. Solid state targets with evaporated magnesium or anodized oxygen were bombarded with {alpha}-particles and the released neutrons detected. For the detection of the released neutrons, computational simulations were used to construct a neutron detector based on {sup 3}He counters. Because of the strong occurrence of background reactions, different methods of data analysis were employed. Finally, the impact of the reactions {sup 25}Mg({alpha},n){sup 28}Si, {sup 26}Mg({alpha},n){sup 29}Si, {sup 18}O({alpha},n){sup 21}Ne on stellar nucleosynthesis is investigated by means of network calculations. (orig.)

  16. The AGB star nucleosynthesis in the light of the recent {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reaction rate determinations

    Energy Technology Data Exchange (ETDEWEB)

    Palmerini, S.; Sergi, M. L.; La Cognata, M.; Pizzone, R. G. [INFN-Laboratori Nazionali del Sud, Catania (Italy); Lamia, L. [Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy); Spitaleri, C. [INFN-Laboratori Nazionali del Sud, Catania, Italy and Dipartimento di Fisica e Astronomia, Universitá degli Studi di Catania (Italy)

    2015-02-24

    Presolar grains form in the cold and dusty envelopes of Asymptotic Giant Branch (AGB) stars. These solides, once that have been ejected by stellar winds, come to us as inclusions in meteorites providing invaluable benchmarks and constraints for our knowledge of low temeperature H-burning in stars. The Trojan Horse Method (THM) has been used to investigate the low-energy cross sections of the {sup 17}O(p,α){sup 14}N and {sup 18}O(p,α){sup 15}N reactions. Moreover, the strength of the 65 keV resonance in the {sup 17}O(p,α){sup 14}N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the {sup 17}O+p radiative capture channel. The new estimates of the reaction rates have been introduced into calculations of AGB star nucleosynthesis and the results have been compared with geochemical analysis of 'presolar' grains to determine their impact on astrophysical environments.

  17. Analysis of The Big Bang Theory's Subtitle Translationfrom the Perspective of Eco-translatology%生态翻译学视角下情景喜剧字幕翻译的研究--以《生活大爆炸》为例

    Institute of Scientific and Technical Information of China (English)

    杨喆

    2014-01-01

    生态翻译学是近年来兴起的一个根植于中国的翻译理论,它是一个完整的理论系统,解决了“何为译”、“如何译”、“为何译”等一系列问题。而《生活大爆炸》作为一部吸引了无数中国人眼球的情景喜剧,其成功的字幕翻译无疑为其在中国的传播起到了举足轻重的作用。本文试从生态翻译学“如何译”的角度,即“三维”转换角度来分析《生活大爆炸》中的字幕翻译。%Eco-translatology is a newly developed translation theory that rooted in China. It's a comprehensive theory system which deals with many important translation questions such as what is translation, how to translate, why do people translate and so on. The Big Bang Theory is a popular sitcom among Chinese. And its success is closely related to its subtitle translation. This paper will mainly analyze the subtitle translation of The Big Bang Theory with three-dimensional transformations.

  18. Pooling resources to decypher the Big Bang

    CERN Multimedia

    Harvey, Fiona

    2003-01-01

    " Work has started on a "virtual supercomputer" that will be the world's second most powerful data processor. The virtual computer will take the form of a "grid", a technology that links many smaller computers to make one huge computing resource" (1/2 page.

  19. The Meta-Analytic Big Bang

    Science.gov (United States)

    Shadish, William R.; Lecy, Jesse D.

    2015-01-01

    This article looks at the impact of meta-analysis and then explores why meta-analysis was developed at the time and by the scholars it did in the social sciences in the 1970s. For the first problem, impact, it examines the impact of meta-analysis using citation network analysis. The impact is seen in the sciences, arts and humanities, and on such…

  20. From the Big Bang to the Brain.

    Science.gov (United States)

    Boliek, Carol A.; Lohmeier, Heather

    1999-01-01

    Summarizes research findings that challenge long-standing theories of infant cognition and motor development and proposes alternative theoretical models to describe skill acquisition during the first several years of life. Findings are discussed with respect to research in the area of infant speech physiology and production. (Author/CR)

  1. 革命者BIG BANG

    Institute of Scientific and Technical Information of China (English)

    刘岩

    2015-01-01

    <正>在鄂尔多斯的繁荣时代,我遇见了那里的一位"意见领袖",因为他从美国回来,见过外面的世界,有着对奢侈品辽阔的见识和独到的品味。他引领着那座神秘财富城市中一个小圈子的购物风潮,他们一块接一块儿地购入Big Bang。那个时候,我并不太清楚他们迷恋这款腕表的原因,直到我一次次地去到巴塞尔表展,一次次地了解到Big Bang的想象力。是的,Big Bang的确充满了魅力。Big Bang进化史2005年Big Bang系列诞生2006年Big Bang全黑"全黑"理念使Big Bang更加纯粹和简洁。Big Bang全黑腕表从表壳到表盘浑然天成的亚光质感和多层次、不同材料融合起来的黑色,蕴含"不可见的可见"之禅意。

  2. Oceanic turbulence - Big bangs or continuous creation?

    Science.gov (United States)

    Caldwell, D. R.

    1983-01-01

    A hypothesis concerning the turbulence characteristics of 'microstructure' patches in the ocean is proposed in which a turbulence field is driven at the same time and scale at which it is observed. The driving energy is converted into turbulence kinetic energy in such a way that the observed overturning thickness scale is linearly related to the length scale. This hypothesis is contrasted with that of Gibson (1982), in which the 'patches' are produced by rare, powerful turbulence generators that have 'fossilized' prior to their observation. Careful attention is given to the sampling process and its assumptions.

  3. Critical geometry of a thermal big bang

    Science.gov (United States)

    Afshordi, Niayesh; Magueijo, João

    2016-11-01

    We explore the space of scalar-tensor theories containing two nonconformal metrics, and find a discontinuity pointing to a "critical" cosmological solution. Due to the different maximal speeds of propagation for matter and gravity, the cosmological fluctuations start off inside the horizon even without inflation, and will more naturally have a thermal origin (since there is never vacuum domination). The critical model makes an unambiguous, nontuned prediction for the spectral index of the scalar fluctuations: nS=0.96478 (64 ) . Considering also that no gravitational waves are produced, we have unveiled the most predictive model on offer. The model has a simple geometrical interpretation as a probe 3-brane embedded in an E AdS2×E3 geometry.

  4. Big Bang and context-driven collapse.

    Science.gov (United States)

    Robertson-Tessi, Mark; Anderson, Alexander R A

    2015-03-01

    Heterogeneity is the single most important factor driving cancer progression and treatment failure, yet little is understood about how and when this heterogeneity arises. A new study shows that colorectal cancers acquire their dominant mutations early in development and that subsequent mutations, even if they confer greater fitness, are unlikely to sweep through the tumor.

  5. Tracking Back to the Big Bang.

    Science.gov (United States)

    Peat, David

    1983-01-01

    Traces some astronomical history and considers how astronomers have arrived at their current knowledge of distance, size, and time as it applies to objects in the night sky. The information is provided as background to a discussion of the Hubble constant and its relationship to the age of the universe. (JN)

  6. Motivating Reluctant Learners with a Big Bang

    Science.gov (United States)

    Lochner, James C.; Cvetic, Geraldine A.; Hall, Jonathan B.

    2007-01-01

    We present results of a collaboration between a media specialist, a science teacher, and an astronomer to bring a modern astronomy topic to at-risk, emotionally disabled students who have experienced little success. These normally unengaged students became highly motivated because they were given an authentic task of presenting research on an intriguing science topic, and because they witnessed a collaboration brought together on their behalf This experience demonstrates that sophisticated astronomy topics can be used to motivate at-risk students.

  7. Del Big Bang al Big Bounce

    OpenAIRE

    2010-01-01

    39 transp.-- Presentación incluida entre las actividades de divulgación y comunicación social de la Semana de la Ciencia y la Tecnología en el CSIC (Consejo Superior de Investigaciones Científicas, Nov 2010)

  8. From pop to the Big Bang

    CERN Multimedia

    Sutherland, Paul

    2007-01-01

    "An amazing new movie takes us to the brink of the end of the world. Sunshine whisks us to a moment 50 years in the future when the sun is about to die, attacked by rogue particles made at the start of time." (2 pages)

  9. Still waiting for that Big Bang...

    CERN Multimedia

    2009-01-01

    "It has been called the greatest and most ambitious science experiment ever built by man. When operating at full power, the Large Hadron Collider - Europe's 3.2 billion (pounds) particle accelerator - will hurl beams of protons around its rings at a fraction of a per cent less than the speed of light" (2 pages)

  10. Dal Big Bang infiniti universi nascosti

    CERN Multimedia

    Valsecchi, Maria Cristina

    2005-01-01

    The intensity of the gravitational force, the speed with which the universe expands, the electric power of the electron, the speed of the light. That's some fundamental constants, some values which determine the characteristics of the universe surrounding us (½ page)

  11. Pa spaning efter Big Bang i underjorden

    CERN Multimedia

    Granström, Helena

    2008-01-01

    The LHC will start this summer; an accelerator placed in a 27km long annel. The machine will collide particles in order to test the theory of dark matter, dark energy and supersymmetry. We will get to know much more, but maybe understand even less. (4 pages)

  12. A fully quantum model of Big Bang

    CERN Document Server

    Maydanyuk, Sergei P; Olkhovsky, Vladislav S

    2013-01-01

    In the paper the closed Friedmann-Robertson-Walker model with quantization in the presence of the positive cosmological constant and radiation is studied. For analysis of tunneling probability for birth of an asymptotically deSitter, inflationary Universe as a function of the radiation energy a new definition of a "free" wave propagating inside strong fields is proposed. On such a basis, tunneling boundary condition is corrected, penetrability and reflection concerning to the barrier are calculated in fully quantum stationary approach. For the first time non-zero interference between the incident and reflected waves has been taken into account which turns out to play important role inside cosmological potentials and could be explained by non-locality of barriers in quantum mechanics. Inside whole region of energy of radiation the tunneling probability for the birth of the inflationary Universe is found to be close to its value obtained in semiclassical approach. The reflection from the barrier is determined f...

  13. Testing out the Big bang theory

    CERN Multimedia

    Rumford, Alex

    2007-01-01

    "Bristol University academics are among some of the finest minds in the world toiling in a mind-blowingly massive laboratory to find answers to some of the biggest questions that can be asked - about life, the universe and everything. Lucy Parkinson travelled to Switzerland to find out what they are doing there." (2 pages)

  14. On the Cold Big Bang Cosmology

    Directory of Open Access Journals (Sweden)

    Assis A. V. D. B.

    2011-04-01

    Full Text Available We solve the general relativity (GR field equations under the cosmological scope via one extra postulate. The plausibility of the postulate resides within the Heisenberg indeterminacy principle, being heuristically analysed throughout the appendix. Under this approach, a negative energy density may provide the positive energy content of the universe via fluctuation, since the question of conservation of energy in cosmology is weakened, supported by the known lack of scope of the Noether's theorem in cosmology. The initial condition of the primordial universe turns out to have a natural cutoff such that the temperature of the cosmological substratum converges to the absolute zero, instead of the established divergence at the very beginning. The adopted postulate provides an explanation for the cosmological dark energy open question. The solution agrees with cosmological observations, including a 2.7K CMBT prediction.

  15. A la poursuite du Big Bang

    CERN Multimedia

    Bois, Jérome

    2008-01-01

    Hundred meters under the Pays de Gex, at the end of July, billions of particles are going to be throwed at 99,99% of the speed of the light to recreate the conditions having existed at the origin of the Universe. (1 page)

  16. UH team expands big-bang theory

    CERN Multimedia

    Creamer, B

    2002-01-01

    After six months of research at a new underground neutrino detector near the central Japan city of Toyama, an international research team announced yesterday that neutrinos have mass and are capable of morphing from one type to another (1 page).

  17. Scientists hope collider makes a big bang

    CERN Multimedia

    Nickerson, Colin

    2007-01-01

    "In a 17-ile circular tunnel curving beneath the Swiss-French border, scientists are poised to recreate the universe's first trillionth of a second. The aim of the audacious undertaking is to solve one of the most perturbing puzzles of physics: How did matter attain mass and form the cosmos? (2 pages)

  18. Re-creating the big bang

    CERN Multimedia

    Mung, Adrienne

    2007-01-01

    "Deep beneath the Swiss-French border near Geneva, thousands of physicists rushed to build the world's largest and most expensive science experiment that they hope will bring them one step closer toward unlocking some of the universe's oldest secrets." (1,5 page)

  19. Inside the big-bang machine

    CERN Multimedia

    Boyle, Alan

    2007-01-01

    "The future of particle physics is being built below ground, in a setting that's more appropriate for construction hardhats than lab coats. To get to the caverns where the world's most powerful particle collider is taking shape, you have to take an industrial-issue elevator down just one floor. But that floor is a doozy: it's about 100 meters below ground, roughly as deep as a 30-story building is tall." (2 pages)

  20. Dal Big Bang ai buchi neri

    CERN Document Server

    Hawking, Stephen W

    1988-01-01

    "Che cosa sappiamo sull'universo, e come lo sappiamo? Da dove è venuto, e dove sta andando? L'universo ebbe un inizio e, in tal caso cosa c'era prima? Il tempo avrà mai una fine?" Con questi quesiti Stephen Hawking introduce il lettore in una straordinaria avventura: un'emozionante cavalcata nel tempo. L'espansione dell'universo, il principio di indeterminazione, le particelle elementari e le forze della natura, l'origine e la sorte dell'universo, l'unificazione della fisica sono le grandi tappe di questo viaggio indimenticabile. Ma oltre a riassumere le conoscenze tradizionali Hawking illustra le ultime teorie sulla fisica dei buchi neri, il principio antropico, la teoria dell'universo inflazionario, l'universo contenuto in una bolla. Il titolo viene ripubblicato in una nuova veste editoriale, con la copertina che per l'occasione è stata realizzata da Hennie Haworth.

  1. Pooling resources to decypher the Big Bang

    CERN Multimedia

    Harvey, F

    2003-01-01

    "Work has started on a "virtual supercomputer" that will be the world's second most powerful data processor. The virtual computer will take the form of a "grid", a technology that links many smaller computers to make one huge computing resource" (1/2 page)

  2. Museum makes room for the Big Bang

    CERN Multimedia

    Pinnell, Heather

    2007-01-01

    "Heather Pinnell discovers that a small exhibition about the Large Hadron Collider scored very highly for its impact." The museum has plans to add a spark chamber into the gallery to show that the experiments done at CERM are safe. (2/3 page)

  3. Seeking nature of God in Big Bang

    CERN Multimedia

    2008-01-01

    ""The most exciting thing of all," says Professor Peter Watkins with a smile, "is we have absolutely no idea what will happen until we switch it on." When you realise that the University of Birmingham academic is referring to the world's largest particle physics experiment, it is a little disconcerting. After 13 years of planning and construction, the Large Hadron Collider (LHC), is due to begin its work in the spring of 2008."

  4. Big Bang as a critical point

    CERN Document Server

    Mielczarek, Jakub

    2014-01-01

    This essay addresses the issue of gravitational phase transitions in the early universe. We suggest that a second order phase transition observed in the Causal Dynamical Triangulations approach to quantum gravity may have a cosmological relevance. The phase transition interpolates between a non-geometric crumpled phase of gravity, and an extended phase with classical properties. Transitions of this kind have been postulated earlier in the context of geometrogenesis in Quantum Graphity. We show that critical behavior may also be associated with a signature change event in Loop Quantum Cosmology. In both cases, classical spacetime originates at the critical point associated with a second order phase transition.

  5. Big Bang as a Critical Point

    Directory of Open Access Journals (Sweden)

    Jakub Mielczarek

    2017-01-01

    Full Text Available This article addresses the issue of possible gravitational phase transitions in the early universe. We suggest that a second-order phase transition observed in the Causal Dynamical Triangulations approach to quantum gravity may have a cosmological relevance. The phase transition interpolates between a nongeometric crumpled phase of gravity and an extended phase with classical properties. Transition of this kind has been postulated earlier in the context of geometrogenesis in the Quantum Graphity approach to quantum gravity. We show that critical behavior may also be associated with a signature change in Loop Quantum Cosmology, which occurs as a result of quantum deformation of the hypersurface deformation algebra. In the considered cases, classical space-time originates at the critical point associated with a second-order phase transition. Relation between the gravitational phase transitions and the corresponding change of symmetry is underlined.

  6. On the Cold Big Bang Cosmology

    Directory of Open Access Journals (Sweden)

    Assis A. V. D. B.

    2011-04-01

    Full Text Available We solve the general relativity (GR field equations under the cosmological scope via one extra postulate. The plausibility of the postulate resides within the Heisenberg in- determinacy principle, being heuristically analysed throughout the appendix. Under this approach, a negative energy density may provide the positive energy content of the universe via fluctuation, since the question of conservation of energy in cosmol- ogy is weakened, supported by the known lack of scope of the Noether’s theorem in cosmology. The initial condition of the primordial universe turns out to have a natural cuto such that the temperature of the cosmological substratum converges to the ab- solute zero, instead of the established divergence at the very beginning. The adopted postulate provides an explanation for the cosmological dark energy open question. The solution agrees with cosmological observations, including a 2.7K CMBT prediction.

  7. Fisicos argentinos reproduciran el Big Bang

    CERN Multimedia

    De Ambrosio, Martin

    2008-01-01

    Two groups of argentine physicists from La Plata and Buenos Aires Universities work in a sery of experiments who while recreate the conditions of the big explosion that was at the origin of the universe. (1 page)

  8. Neutrinos and nucleosynthesis in supernova

    Energy Technology Data Exchange (ETDEWEB)

    Solis, U [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); D' Olivo, J C [Instituto de Ciencias Nucleares, Departamento de Fisica de Altas EnergIas, Universidad Nacional Autonoma de Mexico (ICN-UNAM). Apartado Postal 70-543, 04510 Mexico, D.F. (Mexico); Cabral-Rosetti, L G [Departamento de Posgrado, Centro Interdisciplinario de Investigacion y Docencia en Educacion Tecnica (CIIDET), Av. Universidad 282 Pte., Col. Centro, A. Postal 752, C.P. 76000, Santiago de Queretaro, Qro. (Mexico)

    2006-05-15

    The type II supernova is considered as a candidate site for the production of heavy elements. The nucleosynthesis occurs in an intense neutrino flux, we calculate the electron fraction in this environment.

  9. Role of clusters in nuclear astrophysics with Cluster Nucleosynthesis Diagram (CND)

    Science.gov (United States)

    Kubono, S.; Binh, Dam N.; Hayakawa, S.; Hashimoto, H.; Kahl, D.; Yamaguchi, H.; Wakabayashi, Y.; Teranishi, T.; Iwasa, N.; Komatsubara, T.; Kato, S.; Chen, A.; Cherubini, S.; Choi, S. H.; Hahn, I. S.; He, J. J.; Khiem, Le Hong; Lee, C. S.; Kwon, Y. K.; Wanajo, S.; Janka, H.-T.

    2013-04-01

    The role of nuclear clustering in stellar reactions is discussed, with Cluster Nucleosynthesis Diagram (CND) proposed before, for nucleosynthesis in stellar evolution and explosive stellar phenomena. Special emphasis is placed on α-induced stellar reactions. We report here the first experimental evidence that a cluster resonances dominate the (α,p) stellar reaction cross sections that is crucial for the vp-process in core-collapse supernovae.

  10. REACTION RATES OF {sup 64}Ge(p,γ){sup 65}As AND {sup 65}As(p,γ){sup 66}Se AND THE EXTENT OF NUCLEOSYNTHESIS IN TYPE I X-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Y. H.; He, J. J.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Xu, H. S. [Key Laboratory of High Precision Nuclear Spectroscopy, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Parikh, A. [Departament de Física i Enginyeria Nuclear, EUETIB, Universitat Politècnica de Catalunya, Barcelona E-08036 (Spain); Schatz, H.; Brown, B. A. [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Guo, B., E-mail: jianjunhe@impcas.ac.cn, E-mail: anuj.r.parikh@upc.edu, E-mail: schatz@nscl.msu.edu [China Institute of Atomic Energy, P.O. Box 275(10), Beijing 102413 (China)

    2016-02-10

    The extent of nucleosynthesis in models of type I X-ray bursts (XRBs) and the associated impact on the energy released in these explosive events are sensitive to nuclear masses and reaction rates around the {sup 64}Ge waiting point. Using the well known mass of {sup 64}Ge, the recently measured {sup 65}As mass, and large-scale shell model calculations, we have determined new thermonuclear rates of the {sup 64}Ge(p,γ){sup 65}As and {sup 65}As(p,γ){sup 66}Se reactions with reliable uncertainties. The new reaction rates differ significantly from previously published rates. Using the new data, we analyze the impact of the new rates and the remaining nuclear physics uncertainties on the {sup 64}Ge waiting point in a number of representative one-zone XRB models. We find that in contrast to previous work, when all relevant uncertainties are considered, a strong {sup 64}Ge rp-process waiting point cannot be ruled out. The nuclear physics uncertainties strongly affect XRB model predictions of the synthesis of {sup 64}Zn, the synthesis of nuclei beyond A = 64, the energy generation, and the burst light curve. We also identify key nuclear uncertainties that need to be addressed to determine the role of the {sup 64}Ge waiting point in XRBs. These include the remaining uncertainty in the {sup 65}As mass, the uncertainty of the {sup 66}Se mass, and the remaining uncertainty in the {sup 65}As(p,γ){sup 66}Se reaction rate, which mainly originates from uncertain resonance energies.

  11. First stars evolution and nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bahena, D. [Institute of Astronomy of the Academy of Sciences, Bocni II 1401, 14131 Praha 4, (Czech Republic); Klapp, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico); Dehnen, H. [Fachbereich Physik, Universitat Konstanz, 78457 Konstanz (Germany)]. e-mail: bahen@hotmail.com

    2007-12-15

    The first stars in the universe were massive and luminous with typical masses M {>=} 100M. Metal-free stars have unique physical characteristics and exhibit high effective temperatures and small radii. These so called Population III stars were responsible for the initial enrichment of the intergalactic medium with heavy elements. In this work, we study the structure, evolution and nucleosynthesis of 100, 200, 250 and 300M galactic and pregalactic Population III mass losing stars with metallicities Z 10{sup -6} and Z = 10{sup -9}, during the hydrogen and helium burning phases. Using a stellar evolution code, a system of 10 structure and evolution equations together with boundary conditions, and a set of 30 nuclear reactions, are solved simultaneously, obtaining the star's structure, evolution, isotopic abundances and their ratios. Motivated by recent stability analysis, almost all very massive star (VMS) calculations during the past few years have been performed with no mass loss. However, it has recently been claimed that VMS should have strong mass loss. We present in this work new VMS calculations that includes mass loss. The main difference between zero-metal and metal-enriched stars lies in the nuclear energy generation mechanism. For the first stars, nuclear burning proceeds in a non-standard way. Since Population III stars can reach high central temperatures, this leads to the first synthesis of primary carbon through the 3 {alpha} reaction activating the CNO-cycles. Zero-metal stars produce light elements, such as He, C, N and O. Thus, very massive pregalactic Population III stars experienced self-production of C, either at the zero-age main sequence or in later phases of central hydrogen burning. In advanced evolutionary phases, these stars contribute to the chemical enrichment of the intergalactic medium through supernova explosions. (Author)

  12. A treatment of excited states in nucleosynthesis

    Science.gov (United States)

    Gupta, Sanjib Shankar

    2002-10-01

    Many isotopes of importance to nucleosynthesis have metastable states whose decay to the ground state is strongly inhibited by a high angular momentum difference. Traditionally, excited states of a nucleus have been treated by assuming attainment of thermal equilibrium; a Hauser-Feshbach calculation is then performed on the whole nucleus to determine nuclear reaction rates. A description of the nucleus when it is not in equilibrium, and a method for computing reaction rates that does not presume thermalization are presented in this work. In nucleosynthesis calculations, we may characterize the internal electromagnetic transitions of a nucleus as a Markov process. This allows us to decompose the interaction of radiation with nucleons into effective interactions between ensembles. Rather than consider a single isotope, we construct the canonical ensembles which are the true nuclear species of interest. We are then in a position to specify nonequilibrium occupations of the ensembles by discretizing the Nuclear Level Density function. The generality of the stochastic process identified at the outset now permits the description of nucleosynthesis as Markov flows in networks of suitably populated ensembles. This allows us to use as many excited states as we wish in nucleosyn thesis while tracking their nonequilibrium evolution as substochastic processes. A website utilizing these principles is discussed in some detail. It accesses the theoretical NLD database from the Brussels Intitute of Astrophysics to supplement adopted experimental data from the ENSDF database (maintained by Brookhaven National Laboratories). The composite is processed by a CGI (Common Gateway Interface) application to dynamically obtain plots and tables of rates on a specified temperature grid. Beta-decay rates are discussed for an isotope important to nuclear astrophysics ( 180TA) as a test-bed for the techniques implemented.

  13. On Comic Effect of The Big Bang Theory from the Perspective of Violating Politeness Maxim%从违反礼貌原则的角度浅析《生活大爆炸》对白的幽默效果

    Institute of Scientific and Technical Information of China (English)

    章丹

    2014-01-01

    Humor is a key feature of the sitcoms. The Big Bang Theory is recently hitting ratings high in America. The sitcom is well written and features an endearing cast who provides viewers with lots of humorous moments. This essay focuses on pragmatic analysis of the dialogues in Season 6 which have comic effect emerged by violating the six maxims of politeness principles.%幽默是情景喜剧的精髓所在。《生活大爆炸》是近几年热播的一美剧。剧情幽默风趣,经常让观众捧腹大笑。本文以本片第六季为蓝本分别从违反礼貌原则的六个准则角度分析其对白的幽默效果。

  14. ExpIanation of the Humorous Utterances Based on the ReIevance Theory---Take The Big Bang Theory for ExampIe%从关联理论角度解释话语幽默--以美剧《生活大爆炸》为例

    Institute of Scientific and Technical Information of China (English)

    史岩

    2015-01-01

    Selecting large quantities of humorous utterances from the American TV series The Big Bang Theory,this paper aims to explore how the humor is produced and understood based on the Relevance Theory. The fact proved that the Relevance Theory can ex-plain the humorous utterances forcefully and it paves a new way for the research on humorous utterances.%选取《生活大爆炸》中大量幽默言语,从关联理论出发,探究幽默是如何产生的,又是怎样被理解的。事实证明关联理论对幽默言语具有很强的解释力,为幽默话语研究开拓了新领域。

  15. Reviews Book: Nucleus Book: The Wonderful World of Relativity Book: Head Shot Book: Cosmos Close-Up Places to Visit: Physics DemoLab Book: Quarks, Leptons and the Big Bang EBook: Shooting Stars Equipment: Victor 70C USB Digital Multimeter Web Watch

    Science.gov (United States)

    2012-09-01

    WE RECOMMEND Nucleus: A Trip into the Heart of Matter A coffee-table book for everyone to dip into and learn from The Wonderful World of Relativity A charming, stand-out introduction to relativity The Physics DemoLab, National University of Singapore A treasure trove of physics for hands-on science experiences Quarks, Leptons and the Big Bang Perfect to polish up on particle physics for older students Victor 70C USB Digital Multimeter Equipment impresses for usability and value WORTH A LOOK Cosmos Close-Up Weighty tour of the galaxy that would make a good display Shooting Stars Encourage students to try astrophotography with this ebook HANDLE WITH CARE Head Shot: The Science Behind the JKF Assassination Exploration of the science behind the crime fails to impress WEB WATCH App-lied science for education: a selection of free Android apps are reviewed and iPhone app options are listed

  16. 从文化翻译论看美剧《生活大爆炸》的字幕翻译策略%On the Subtitle Translation of the US TV series The Big Bang Theory, with Reference to the Cultural Translation Theory

    Institute of Scientific and Technical Information of China (English)

    齐佳宁; 田翠芸; 刘颖

    2014-01-01

    随着国际化的逐步加深,影视作品作为一种文化传播媒介在人们的日常生活中扮演着越来越重要的角色。而字幕翻译作为国际交流的工具,在国际影视作品传播过程中发挥着关键的作用。运用文化翻译论分析了美剧《生活大爆炸》的字幕翻译,并结合其制造的视听效果,初步总结了影视字幕的翻译方法和翻译策略,为影视字幕翻译提供一些借鉴。%with the general deepening of the current trend towards internationalization , films and TV programs have become increasingly more important in cultural communication .Subtitle translation , which is an important tool of international communication , is quite crucial in the world-wide spread of films and TV programs .Referring to the Cultural Translation Theory , the US TV series The Big Bang Theory is analyzed in this thesis .With a comprehen-sive consideration of the visual and sound effects projected by the Big Bang Theory program , some subtitle transla-tion methods and strategies have been summarized , which, it is hoped, will provide some guidance for effective subtitle translation .

  17. 科学与影视娱乐交融的科普模式——以美国电视剧《生活大爆炸》为案例%Science and Entertainment: A Case Study on the American TV Series The Big Bang Theory

    Institute of Scientific and Technical Information of China (English)

    王一鸣

    2012-01-01

    随着当代科学与社会及公众的联系更加紧密,借助于资讯与传媒的发达,产生了科学与影视娱乐交融的科普模式。美国电视剧《生活大爆炸》即是一部成功实践这种模式的生活情景喜剧,在娱乐中传播与普及科学知识,获得较大社会反响。分析了《生活大爆炸》的成功的运行机制和特点,并与中国现状进行了对比,同时在此基础上对科学传播与影视娱乐结合的科普方式进行了思考。%With the connection between contemporary science, society and people, and also by the progress of information and communication, the new method of science popularization through the integration of science and entertainment was generated. The American TV series The Big Bang Theory was one of that and obtained great social responding by communicating and popularizing the science through entertainment. The operating mechanism and features of The Big Bang Theory are analyzed. The current status of China is also discussed. Furthermore, the method of science popularization through the integration of science and entertainment is pondered.

  18. The cosmological lithium problem revisited

    Science.gov (United States)

    Bertulani, C. A.; Mukhamedzhanov, A. M.; Shubhchintak

    2016-07-01

    After a brief review of the cosmological lithium problem, we report a few recent attempts to find theoretical solutions by our group at Texas A&M University (Commerce & College Station). We will discuss our studies on the theoretical description of electron screening, the possible existence of parallel universes of dark matter, and the use of non-extensive statistics during the Big Bang nucleosynthesis epoch. Last but not least, we discuss possible solutions within nuclear physics realm. The impact of recent measurements of relevant nuclear reaction cross sections for the Big Bang nucleosynthesis based on indirect methods is also assessed. Although our attempts may not able to explain the observed discrepancies between theory and observations, they suggest theoretical developments that can be useful also for stellar nucleosynthesis.

  19. The Cosmological Lithium Problem Revisited

    CERN Document Server

    Bertulani, C A; Shubhchintak,

    2016-01-01

    After a brief review of the cosmological lithium problem, we report a few recent attempts to find theoretical solutions by our group at Texas A&M University (Commerce & College Station). We will discuss our studies on the theoretical description of electron screening, the possible existence of parallel universes of dark matter, and the use of non-extensive statistics during the Big Bang nucleosynthesis epoch. Last but not least, we discuss possible solutions within nuclear physics realm. The impact of recent measurements of relevant nuclear reaction cross sections for the Big Bang nucleosynthesis based on indirect methods is also assessed. Although our attempts may not able to explain the observed discrepancies between theory and observations, they suggest theoretical developments that can be useful also for stellar nucleosynthesis.

  20. Explosive Nucleosynthesis in Magnetohydrodynamical Jets from Collapsars II. Heavy-element nucleosynthesis of s, r, p-processes

    CERN Document Server

    Ono, Masaomi; Fujimoto, Shin-ichiro; Kotake, Kei; Yamada, Shoichi

    2012-01-01

    We investigate the nucleosynthesis in a massive star of 70 M_solar with solar metallicity in the main sequence stage. The helium core mass after hydrogen burning corresponds to 32 M_solar. Nucleosynthesis calculations have been performed during the stellar evolution and the jet-like supernova explosion of a collapsar model. We focus on the production of heavier elements than iron. Nucleosynthesis calculations have been done by using large nuclear reaction networks, where the weak s-, p-, and r-processes are taken into account. We confirm that s-elements of 60 90 are produced via photodisintegrations of seed s-elements. However, the produced p-elements are destructed in later stages except for ^{180}Ta. In the explosive nucleosynthesis, elements of 90 50) are overproduced relative to the solar values via the p-process because of the low peak temperatures in the oxygen and neon-rich layers. We confirm primary synthesis of light p-elements in the ejected matter of high peak temperature. The ejected matter has ...