International Nuclear Information System (INIS)
The paper concerns the 'Big Bang' theory of the creation of the Universe 15 thousand million years ago, and traces events which physicists predict occurred soon after the creation. Unified theory of the moment of creation, evidence of an expanding Universe, the X-boson -the particle produced very soon after the big bang and which vanished from the Universe one-hundredth of a second after the big bang, and the fate of the Universe, are all discussed. (U.K.)
International Nuclear Information System (INIS)
The precision of measurements in modern cosmology has made huge strides in recent years, with measurements of the cosmic microwave background and the determination of the Hubble constant now rivaling the level of precision of the predictions of big bang nucleosynthesis. However, these results are not necessarily consistent with the predictions of the Standard Model of big bang nucleosynthesis. Reconciling these discrepancies may require extensions of the basic tenets of the model, and possibly of the reaction rates that determine the big bang abundances
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.
Testing Big Bang Nucleosynthesis
Steigman, Gary
1996-01-01
Big Bang Nucleosynthesis (BBN), along with the cosmic background radiation and the Hubble expansion, is one of the pillars ofthe standard, hot, big bang cosmology since the primordial synthesis of the light nuclides (D, $^3$He, $^4$He, $^7$Li) must have occurred during the early evolution of a universe described by this model. The overall consistency between the predicted and observed abundances of the light nuclides, each of which spans a range of some nine orders of magnitude, provides impr...
International Nuclear Information System (INIS)
In these lectures I briefly review Big Bang baryosynthesis. In the first lecture I discuss the evidence which exists for the BAU, the failure of non-GUT symmetrical cosmologies, the qualitative picture of baryosynthesis, and numerical results of detailed baryosynthesis calculations. In the second lecture I discuss the requisite CP violation in some detail, further the statistical mechanics of baryosynthesis, possible complications to the simplest scenario, and one cosmological implication of Big Bang baryosynthesis. (orig./HSI)
Primordial Big Bang Nucleosynthesis
Olive, Keith A.
1999-01-01
Big Bang Nucleosynthesis is the theory of the production of the the light element isotopes of D, He3, He4, and Li7. After a brief review of the essential elements of the standard Big Bang model at a temperature of about 1 MeV, the theoretical input and predictions of BBN are discussed. The theory is tested by the observational determinations of the light element abundances and the current status of these observations is reviewed. Concordance of standard model and the related observations is f...
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.
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.
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.
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.
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.
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).
Big Bang Nucleosynthesis Calculation
Kurki-Suonio, H
2001-01-01
I review standard big bang nucleosynthesis and some versions of nonstandard BBN. The abundances of the primordial isotopes D, He-3, and Li-7 produced in standard BBN can be calculated as a function of the baryon density with an accuracy of about 10%. For He-4 the accuracy is better than 1%. The calculated abundances agree fairly well with observations, but the baryon density of the universe cannot be determined with high precision. Possibilities for nonstandard BBN include inhomogeneous and antimatter BBN and nonzero neutrino chemical potentials.
Craps, Ben; Sethi, Savdeep; Verlinde, Erik
2005-01-01
The light-like linear dilaton background represents a particularly simple time-dependent 1/2 BPS solution of critical type IIA superstring theory in ten dimensions. Its lift to M-theory, as well as its Einstein frame metric, are singular in the sense that the geometry is geodesically incomplete and the Riemann tensor diverges along a light-like subspace of codimension one. We study this background as a model for a big bang type singularity in string theory/M-theory. We construct the dual Matr...
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.
International Nuclear Information System (INIS)
We present an overview of the standard model of big bang nucleosynthesis (BBN), which describes the production of the light elements in the early universe. The theoretical prediction for the abundances of D, 3He, 4He, and 7Li is discussed. We emphasize the role of key nuclear reactions and the methods by which experimental cross section uncertainties are propagated into uncertainties in the predicted abundances. The observational determination of the light nuclides is also discussed. Particular attention is given to the comparison between the predicted and observed abundances, which yields a measurement of the cosmic baryon content. The spectrum of anisotropies in the cosmic microwave background (CMB) now independently measures the baryon density to high precision; we show how the CMB data test BBN, and find that the CMB and the D and 4He observations paint a consistent picture. This concordance stands as a major success of the hot big bang. On the other hand, 7Li remains discrepant with the CMB-preferred baryon density; possible explanations are reviewed. Finally, moving beyond the standard model, primordial nucleosynthesis constraints on early universe and particle physics are also briefly discussed
International Nuclear Information System (INIS)
The light-like linear dilaton background represents a particularly simple time-dependent 1/2 BPS solution of critical type-IIA superstring theory in ten dimensions. Its lift to M-theory, as well as its Einstein frame metric, are singular in the sense that the geometry is geodesically incomplete and the Riemann tensor diverges along a light-like subspace of codimension one. We study this background as a model for a big bang type singularity in string theory/M-theory. We construct the dual Matrix theory description in terms of a (1+1)-d supersymmetric Yang-Mills theory on a time-dependent world-sheet given by the Milne orbifold of (1+1)-d Minkowski space. Our model provides a framework in which the physics of the singularity appears to be under control
Craps, B; Verlinde, E; Craps, Ben; Sethi, Savdeep; Verlinde, Erik
2005-01-01
The light-like linear dilaton background represents a particularly simple time-dependent 1/2 BPS solution of critical type IIA superstring theory in ten dimensions. Its lift to M-theory, as well as its Einstein frame metric, are singular in the sense that the geometry is geodesically incomplete and the Riemann tensor diverges along a light-like subspace of codimension one. We study this background as a model for a big bang type singularity in string theory/M-theory. We construct the dual Matrix theory description in terms of a (1+1)-d supersymmetric Yang-Mills theory on a time-dependent world-sheet given by the Milne orbifold of (1+1)-d Minkowski space. Our model provides a framework in which the physics of the singularity appears to be under control.
Roy, Christelle
2006-01-01
Physiciens have been dreaming of it for 30 years; Thanks to huge particle accelerators, they were able to observe the matter such as it was some instants after the Big Bang (three different articles in 10 pages)
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.
Khoury, Justin; Ovrut, Burt A.; Seiberg, Nathan; Steinhardt, Paul J.(Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, 08544, USA); Turok, Neil
2001-01-01
We consider conditions under which a universe contracting towards a big crunch can make a transition to an expanding big bang universe. A promising example is 11-dimensional M-theory in which the eleventh dimension collapses, bounces, and re-expands. At the bounce, the model can reduce to a weakly coupled heterotic string theory and, we conjecture, it may be possible to follow the transition from contraction to expansion. The possibility opens the door to new classes of cosmological models. F...
Probing the pre-big bang universe
International Nuclear Information System (INIS)
Superstring theory suggests a new cosmology whereby a long inflationary phase preceded a non singular big bang-like event. After discussing how pre-big bang inflation naturally arises from an almost trivial initial state of the Universe, I will describe how present or near-future experiments can provide sensitive probes of how the Universe behaved in the pre-bang era
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…
Big Bang Nucleosynthesis: An Update
Olive, Keith A.; Scully, Sean T.
1995-01-01
WThe current status of big bang nucleosynthesis is reviewed with an emphasis on the comparison between the observational determination of the light element abundances of \\D, \\he3, \\he4 and \\li7 and the predictions from theory. In particular, we present new analyses for \\he4 and \\li7. Implications for physics beyond the standard model are also discussed. Limits on the effective number of neutrino flavors are also updated.
Dual of big bang and big crunch
International Nuclear Information System (INIS)
Starting from the Janus solution and its gauge theory dual, we obtain the dual gauge theory description of the cosmological solution by the procedure of double analytic continuation. The coupling is driven either to zero or to infinity at the big-bang and big-crunch singularities, which are shown to be related by the S-duality symmetry. In the dual Yang-Mills theory description, these are nonsingular as the coupling goes to zero in the N=4 super Yang-Mills theory. The cosmological singularities simply signal the failure of the supergravity description of the full type IIB superstring theory
Big bang nucleosynthesis: An update
International Nuclear Information System (INIS)
An update on the standard model of big bang nucleosynthesis (BBN) is presented. With the value of the baryon-tophoton ratio determined to high precision by WMAP, standard BBN is a parameter-free theory. In this context, the theoretical prediction for the abundances of D, 4He, and 7Li is discussed and compared to their observational determination. While concordance for D and 4He is satisfactory, the prediction for 7Li exceeds the observational determination by a factor of about four. Possible solutions to this problem are discussed
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!
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.
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.
Baryon symmetric big bang cosmology
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.
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.
Big Bang nucleosynthesis in crisis?
International Nuclear Information System (INIS)
A new evaluation of the constraint on the number of light neutrino species (Nν) from big bang nucleosynthesis suggests a discrepancy between the predicted light element abundances and those inferred from observations, unless the inferred primordial 4He abundance has been underestimated by 0.014±0.004 (1σ) or less than 10% (95% C.L.) of 3He survives stellar processing. With the quoted systematic errors in the observed abundances and a conservative chemical evolution parametrization, the best fit to the combined data is Nν=2.1±0.3 (1σ) and the upper limit is Nνν=3) at the 98.6% C.L. copyright 1995 The American Physical Society
Cosmic relics from the big bang
International Nuclear Information System (INIS)
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
Effective Dynamics of the Matrix Big Bang
Craps, Ben; Rajaraman, Arvind; Sethi, Savdeep
2006-01-01
We study the leading quantum effects in the recently introduced Matrix Big Bang model. This amounts to a study of supersymmetric Yang-Mills theory compactified on the Milne orbifold. We find a one-loop potential that is attractive near the Big Bang. Surprisingly, the potential decays very rapidly at late times, where it appears to be generated by D-brane effects. Usually, general covariance constrains the form of any effective action generated by renormalization group flow. However, the form ...
COBE looks back to the Big Bang
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.
'Big bang' of quantum universe
International Nuclear Information System (INIS)
The reparametrization-invariant generating functional for the unitary and causal perturbation theory in general relativity in a finite space-time is obtained. The classical cosmology of a Universe and the Faddeev-Popov-DeWitt functional correspond to different orders of decomposition of this functional over the inverse 'mass' of a Universe. It is shown that the invariant content of general relativity as a constrained system can be covered by two 'equivalent' unconstrained systems: the 'dynamic' (with 'dynamic' time as the cosmic scale factor and conformal field variables) and 'geometric' (given by the Levi-Civita type canonical transformation to the action-angle variables which determine initial cosmological states with the arrow of the proper time measured by the watch of an observer in the comoving frame). 'Big Bang', the Hubble evolution, and creation of 'dynamic' particles by the 'geometric' vacuum are determined by 'relations' between the dynamic and geometric systems as pure relativistic phenomena, like the Lorentz-type 'relation' between the rest and comoving frames in special relativity
Big-bang nucleosynthesis revisited
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.
Deuterium and big bang nucleosynthesis
International Nuclear Information System (INIS)
Measurements of deuterium absorption in high redshift quasar absorption systems provide a direct inference of the deuterium abundance produced by big bang nucleosynthesis (BBN). With measurements and limits from five independent absorption systems, we place strong constraints on the primordial ratio of deuterium to hydrogen, (D/H)p = 3.4 ± 0.3 x 10-5 [1,2]. We employ a direct numerical treatment to improve the estimates of critical reaction rates and reduce the uncertainties in BBN predictions of D/H and 7Li/H by a factor of three[3] over previous efforts[4]. Using our measurements of (D/H)p and new BBN predictions, we find at 95% confidence the baryon density ρb = (3.6 ± 0.4) x 10-31 g cm-3 (Ωbh265 = 0.045 ± 0.006 in units of the critical density), and cosmological baryon-photon ratio η = (5.1 ± 0.6) x 10-10
Big bang nucleosynthesis: Present status
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 Nνdata. In contrast with D/H and 4He, 7Li predictions continue to disagree with observations, perhaps pointing to new physics. This paper concludes with a look at future directions including key nuclear reactions, astronomical observations, and theoretical issues.
Turner, Michael S.
1995-01-01
The hot big-bang cosmology provides a reliable accounting of the Universe from about $10^{-2}\\sec$ after the bang until the present, as well as a robust framework for speculating back to times as early as $10^{-43}\\sec$. Cosmology faces a number of important challenges; foremost among them are determining the quantity and composition of matter in the Universe and developing a detailed and coherent picture of how structure (galaxies, clusters of galaxies, superclusters, voids, great walls, and...
From Big Bang to Big Crunch and Beyond
Elitzur, S.; Giveon, A.; Kutasov, D.; Rabinovici, E.
2002-01-01
We study a quotient Conformal Field Theory, which describes a 3+1 dimensional cosmological spacetime. Part of this spacetime is the Nappi-Witten (NW) universe, which starts at a ``big bang'' singularity, expands and then contracts to a ``big crunch'' singularity at a finite time. The gauged WZW model contains a number of copies of the NW spacetime, with each copy connected to the preceeding one and to the next one at the respective big bang/big crunch singularities. The sequence of NW spaceti...
International Nuclear Information System (INIS)
We confront the big bang for the beginning of the universe with an equivalent picture of a slow freeze — a very cold and slowly evolving universe. In the freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The freeze and big bang pictures both describe the same observations or physical reality. We present a simple “crossover model” without a big bang singularity. In the infinite past space–time is flat. Our model is compatible with present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy-dominated universe
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.
Pre-big bang cosmology and quantum fluctuations
International Nuclear Information System (INIS)
The quantum fluctuations of a homogeneous, isotropic, open pre-big bang model are discussed. By solving exactly the equations for tensor and scalar perturbations we find that particle production is negligible during the perturbative Pre-Big Bang phase
Big Bang riddles and their revelations
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 i...
New physics and the new big bang
International Nuclear Information System (INIS)
The old concept of the big bang is reviewed, and modifications that have recently occurred in the theory are described. The concept of the false vacuum is explained, and its role in the cosmic inflation scenario is shown. The way inflation solves critical problems of the old big bang scenario is indicated. The potential of supersymmetry and Kaluza-Klein theories for the development of a superunified theory of physical forces is discussed. Superstrings and their possible role in a superunified theory, including their usefulness in solving the problem of infinities, is considered
Effective dynamics of the matrix big bang
International Nuclear Information System (INIS)
We study the leading quantum effects in the recently introduced matrix big bang model. This amounts to a study of supersymmetric Yang-Mills theory compactified on the Milne orbifold. We find a one-loop potential that is attractive near the big bang. Surprisingly, the potential decays very rapidly at late times where it appears to be generated by D-brane effects. Usually, general covariance constrains the form of any effective action generated by renormalization group flow. However, the form of our one-loop potential seems to violate these constraints in a manner that suggests a connection between the cosmological singularity and long wavelength, late time physics
Effective Dynamics of the Matrix Big Bang
Craps, B; Sethi, S; Craps, Ben; Rajaraman, Arvind; Sethi, Savdeep
2006-01-01
We study the leading quantum effects in the recently introduced Matrix Big Bang model. This amounts to a study of supersymmetric Yang-Mills theory compactified on the Milne orbifold. We find a one-loop potential that decays near the Big Bang. More surprisingly, the potential decays very rapidly at late times where it appears to be generated by D-brane effects. Usually, general covariance constrains the form of any effective action generated by renormalization group flow. However, the form of our one-loop potential seems to violate these constraints in a manner that suggests a connection between the cosmological singularity and long wavelength, late time physics.
The big bang cosmology - enigmas and nostrums
International Nuclear Information System (INIS)
Some outstanding problems in connection with the big bang cosmology and relativity theory are reviewed under the headings: enigmas; nostrums and elixirs (the universe as Phoenix (an oscillating universe), the anthropomorphic universe (existence of observers in the present universe), reproducing universes (could a mini big bang bounce, perhaps adding entropy and matter and eventually developing into a suitable home for observers), variable strength of the gravitational interaction and oscillating universes (possible bounce models that have led eventually to the present hospitable environment). (U.K.)
Supernova bangs as a tool to study big bang
International Nuclear Information System (INIS)
Supernovae and gamma-ray bursts are the most powerful explosions in observed Universe. This educational review tells about supernovae and their applications in cosmology. It is explained how to understand the production of light in the most luminous events with minimum required energy of explosion. These most luminous phenomena can serve as primary cosmological distance indicators. Comparing the observed distance dependence on red shift with theoretical models one can extract information on evolution of the Universe from Big Bang until our epoch.
Big bang and big crunch in matrix string theory
International Nuclear Information System (INIS)
Following the holographic description of linear dilaton null cosmologies with a big bang in terms of matrix string theory put forward by Craps, Sethi, and Verlinde, we propose an extended background describing a universe including both big bang and big crunch singularities. This belongs to a class of exact string backgrounds and is perturbative in the string coupling far away from the singularities, both of which can be resolved using matrix string theory. We provide a simple theory capable of describing the complete evolution of this closed universe
Inhomogeneous Pre-Big Bang String Cosmology
Veneziano, G.
1997-01-01
An inhomogeneous version of pre--Big Bang cosmology emerges, within string theory, from quite generic initial conditions, provided they lie deeply inside the weak-coupling, low-curvature regime. Large-scale homogeneity, flatness, and isotropy appear naturally as late-time outcomes of such an evolution.
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).
Lifting gear crucial in Big Bang experiment
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)
"Big Bang" project put off to 2008
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)
Pre-big-bang in string cosmology
International Nuclear Information System (INIS)
We compute the amount of inflation required to solve the horizon problem of cosmology in the pre-big-bang scenario. First we give a quick overview of string cosmology as developed by Veneziano and collaborators. Then we show that the amount of inflation in this background solves the horizon problem. We discuss fine-tuning
From big bang to big crunch and beyond
International Nuclear Information System (INIS)
We study a quotient Conformal Field Theory, which describes a 3+1 dimensional cosmological spacetime. Part of this spacetime is the Nappi-Witten (NW) universe, which starts at a 'big bang' singularity, expands and then contracts to a 'big crunch' singularity at a finite time. The gauged WZW model contains a number of copies of the NW spacetime, with each copy connected to the preceding one and to the next one at the respective big bang/big crunch singularities. The sequence of NW spacetimes is further connected at the singularities to a series of non-compact static regions with closed timelike curves. These regions contain boundaries, on which the observables of the theory live. This suggests a holographic interpretation of the physics. (author)
Antigravity and the big crunch/big bang transition
Bars, Itzhak; Chen, Shih-Hung; Steinhardt, Paul J.(Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, 08544, USA); 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...
Quantum Fields in a Big Crunch/Big Bang Spacetime
Tolley, Andrew J.; Turok, Neil
2002-01-01
We consider quantum field theory on a spacetime representing the Big Crunch/Big Bang transition postulated in the ekpyrotic or cyclic cosmologies. We show via several independent methods that an essentially unique matching rule holds connecting the incoming state, in which a single extra dimension shrinks to zero, to the outgoing state in which it re-expands at the same rate. For free fields in our construction there is no particle production from the incoming adiabatic vacuum. When interacti...
Sailing through the big crunch-big bang transition
Bars, Itzhak; Steinhardt, Paul; Turok, Neil
2013-01-01
In a recent series of papers, we have shown that theories with scalar fields coupled to gravity (e.g., the standard model) can be lifted to a Weyl-invariant equivalent theory in which it is possible to unambiguously trace the classical cosmological evolution through the transition from big crunch to big bang. The key was identifying a sufficient number of finite, Weyl-invariant conserved quantities to uniquely match the fundamental cosmological degrees of freedom across the transition. In so ...
Big Bang Nucleosynthesis and Primordial Black Holes
Sivaram, C; Arun, Kenath
2010-01-01
There are ongoing efforts in detecting Hawking radiation from primordial black holes (PBH) formed during the early universe. Here we put an upper limit on the PBH number density that could have been formed prior to the big bang nucleosynthesis era, based on the constraint that the PBH evaporation energy consisting of high energy radiation not affect the observed abundances' of elements, by disintegrating the nuclei.
International Nuclear Information System (INIS)
The formation and evolution of the relics of the Big Bang are considered in detail. After considering the thermodynamics of the early universe, the author goes into various questions related to these relics such as the synthesis of helium and the characteristic features of the microwave background. The interplay between particle physics and cosmology is analyzed. Some problems related to the very early universe, including galaxy formation, are also touched upon. (author). 46 refs.; 1 fig.; 2 tabs
Quantum Gravity and the Big Bang
Bojowald, M.
2004-01-01
Quantum gravity has matured over the last decade to a theory which can tell in a precise and explicit way how cosmological singularities of general relativity are removed. A branch of the universe "before" the classical big bang is obtained which is connected to ours by quantum evolution through a region around the singularity where the classical space-time dissolves. We discuss the basic mechanism as well as applications ranging to new phenomenological scenarios of the early universe expansi...
Dark Radiation Emerging After Big Bang Nucleosynthesis?
Fischler, Willy; Meyers, Joel
2010-01-01
We show how recent data from observations of the cosmic microwave background may suggest the presence of additional radiation density which appeared after big bang nucleosynthesis. We propose a general scheme by which this radiation could be produced from the decay of non-relativistic matter, we place constraints on the properties of such matter, and we give specific examples of scenarios in which this general scheme may be realized.
Science Big Bang comes to the Alps
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.
Science: Big Bang comes to the Alps
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)
Five dimensional Gravity and Big Bang Singularity
Parthasarathy, R
2015-01-01
A 5-dimensional gravity theory, motivated by the brane world picture, with factorisable metric and with Kaluza scalar $G_{55}(r)$, is shown to give rise to a positive contribution to the Raychaudhuri equation. This inhibits the focusing of geodesics and possibly cause non-focusing of the geodesics. This feature is translated into the situation in which the universe has an infinite age and hence no beginning avoiding the big bang singularity.
Gravitation, phase transitions, and the big bang
International Nuclear Information System (INIS)
Introduced here is a model of the early universe based on the possibility of a first-order phase transition involving gravity, and arrived at by a consideration of instabilities in the semiclassical theory. The evolution of the system is very different from the standard Friedmann-Robertson-Walker big-bang scenario, indicating the potential importance of semiclassical finite-temperature gravitational effects. Baryosynthesis and monopole production in this scenario are also outlined
Big Bang Nucleosynthesis constraints on new physics
International Nuclear Information System (INIS)
Primordial Nucleosynthesis provides a probe of the physics of the early Universe when the temperature and particle densities are high. The Cosmic Nuclear Reactor may, thereby, lead to constraints on new physics which may be inaccessible to current accelerators. Current Big Bang Nucleosynthesis (BBN) bounds to the existence and/or properties of new particles are reviewed and used to constrain physics 'beyond the standard model.' (orig.)
Big bang models in string theory
International Nuclear Information System (INIS)
These proceedings are based on lectures delivered at the 'RTN Winter School on Strings, Supergravity and Gauge Theories', CERN, 16-20 January 2006. The school was mainly aimed at PhD students and young postdocs. The lectures start with a brief introduction to spacetime singularities and the string theory resolution of certain static singularities. Then they discuss attempts to resolve cosmological singularities in string theory, mainly focusing on two specific examples: the Milne orbifold and the matrix big bang
Laser interferometry for the Big Bang Observer
Harry, Gregory M.; Fritschel, Peter; Shaddock, Daniel A.; Folkner, William; Phinney, E. Sterl
2006-01-01
The Big Bang Observer is a proposed space-based gravitational-wave detector intended as a follow on mission to the Laser Interferometer Space Antenna (LISA). It is designed to detect the stochastic background of gravitational waves from the early universe. We discuss how the interferometry can be arranged between three spacecraft for this mission and what research and development on key technologies are necessary to realize this scheme.
Pre-Big Bang, vacuum and noncyclic cosmologies
Gonzalez-Mestres, L.
2011-01-01
WMAP and Planck open the way to unprecedented Big Bang phenomenology, potentially allowing to test the standard Big Bang model as well as less conventional approaches including noncyclic pre-Big Bang cosmologies that would incorporate a new fundamental scale beyond the Planck scale and, possibly, new ultimate constituents of matter. Alternatives to standard physics can be considered from a cosmological point of view concerning vacuum structure, the nature of space-time, the origin and evoluti...
Big Bang Day : The Great Big Particle Adventure - 3. Origins
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
The Big Bang and Cosmic Inflation
Guth, Alan H.
2014-03-01
A summary is given of the key developments of cosmology in the 20th century, from the work of Albert Einstein to the emergence of the generally accepted hot big bang model. The successes of this model are reviewed, but emphasis is placed on the questions that the model leaves unanswered. The remainder of the paper describes the inflationary universe model, which provides plausible answers to a number of these questions. It also offers a possible explanation for the origin of essentially all the matter and energy in the observed universe.
International Nuclear Information System (INIS)
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 ∼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
Nuclear Receptors, RXR, and the Big Bang.
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. PMID:24679540
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.
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.
International Nuclear Information System (INIS)
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 stregthening the conclusion that the cosmological baryon density is ∼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 than the favorite non-baryonic dark matter candidates of a few years ago. (author) 59 refs.; 5 figs.; 2 tabs
Reconciling sterile neutrinos with Big Bang nucleosynthesis
International Nuclear Information System (INIS)
We reexamine the big bang nucleosynthesis (BBN) bounds on the mixing of neutrinos with sterile species. These bounds depend on the assumption that the relic neutrino asymmetry Lν is very small. We show that for Lν large enough (greater than about 10endash5) the standard BBN bounds do not apply. We apply this result to the sterile neutrino solution to the atmospheric neutrino anomaly and show that for Lν approx-gt 7x10-5 it is consistent with BBN. The BBN bounds on sterile neutrinos mixing with electron neutrinos can also be weakened considerably. copyright 1995 The American Physical Society
Web Science Big Wins: Information Big Bang & Fundamental Constants
Carr, Les
2010-01-01
We take for granted a Web that provides free and unrestricted information exchange, but the Web is under pressure to change in order to respond to issues of security, commerce, criminality, privacy. Web Science needs to explain how the Web impacts society and predict the outcomes of proposed changes to Web infrastructure on business and society. Using the analogy of the Big Bang, this presentation describes how the Web spread the conditions of its initial creation throughout the whole of soci...
Dual of Big-bang and Big-crunch
Bak, Dongsu
2006-01-01
Starting from the Janus solution and its gauge theory dual, we obtain the dual gauge theory description of the cosmological solution by procedure of the double anaytic continuation. The coupling is driven either to zero or to infinity at the big-bang and big-crunch singularities, which are shown to be related by the S-duality symmetry. In the dual Yang-Mills theory description, these are non singular at all as the coupling goes to zero in the N=4 Super Yang-Mills theory. The cosmological sing...
The Whole Shebang: How Science Produced the Big Bang Model.
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…
Standard Big-Bang nucleosynthesis after Planck
International Nuclear Information System (INIS)
Primordial or Big Bang nucleosynthesis (BBN) is one of the three historical strong evidences for the Big-Bang model together with the expansion of the Universe and the Cosmic Microwave Background radiation (CMB). The results by the Planck mission have changed the baryonic density Ωb compared to the previous WMAP values. We present the BBN predictions for the light elements using this new value of Ωb as well as an improvement of the nuclear network and new spectroscopic observations. The primordial D/H abundance ((2.57 - 2.72) X 10**-5 ) is narrower than recedently, to be compared to the recent observations in the light of sight of quasars, ((2.49 - 2.57) X 10**-5), at redshift z ∼ 3. The primordial Li/H abundance ((4.56 - 5.34) X 10**-10) is still 3 times larger than its observed spectroscopic abundance in halo stars of the Galaxy. Primordial Helium abundance is : Yp = 0.2461 - 0.2466, in a good agreement with the last He observations (0.2368 - 0.2562). (author)
Early universe and big bang nucleosynthesis
International Nuclear Information System (INIS)
This is a series of six one-hour lectures tuned to the level of a graduate course covering basically the background required for understanding the phenomenon of the big bang nucleosynthesis. It begins with a brief introduction to the geometry, dynamics and thermodynamics of the universe as a whole, followed by one lecture on the discovery, properties and implications of the 3 K microwave background radiation. Then we move on to the thermodynamical properties of the early universe, effects of pair annihilation, the role of the weak interactions in creating a neutrino background and freezing the ratio of the available free neutrons to protons. In the fourth lecture, we describe the process of the big bang nucleosynthesis leading to the formation of deuterium, helium and lithium. The methods of the observational estimations of these primordial abundances are discussed in the fifth lecture, and finally in the sixth, their comparison with the predictions of the standard model and the inadequacy of the standard model, if any. It is in this respect that primordial nucleosynthesis provides a testing ground for one of the possible cosmological consequences of the quark-hadron phase transition in the early universe. (orig.)
Quarks, leptons and the big bang
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.
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)
What's Next for Big Bang Nucleosynthesis?
International Nuclear Information System (INIS)
Big bang nucleosynthesis (BBN) plays an important role in the standard hot big bang cosmology. BBN theory is used to predict the primordial abundances of the lightest elements, hydrogen, helium and lithium. Comparison between the predicted and observationally determined light element abundances provides a general test of concordance and can be used to fix the baryon content in the universe. Measurements of the cosmic microwave background (CMB) anisotropies now supplant BBN as the premier baryometer, especially with the latest results from the WMAP satellite. With the WMAP baryon density, the test of concordance can be made even more precise. Any disagreement between theory predictions and observations requires careful discussion. Several possibilities exist to explain discrepancies; (1) observational systematics (either physical or technical) may not be properly treated in determining primordial light element abundances (2) nuclear inputs that determine the BBN predictions may have unknown systematics or may be incomplete, and (3) physics beyond that included in the standard BBN scenario may need to be included in the theory calculation. Before we can be absolutely sure new physics is warranted, points (1) and (2) must be addressed and ruled out. All of these scenarios rely on experimental or observational data to make definitive statements of their applicability and range of validity, which currently is not at the level necessary to discern between these possibilities with high confidence. Thus, new light element abundance observations and nuclear experiments are needed to probe these further. Assuming concordance is established, one can use the light element observations to explore the evolution from their primordial values. This can provide useful information on stellar evolution, cosmic rays and other nuclear astrophysics. When combined with detailed models, BBN, the CMB anisotropy and nuclear astrophysics can provide us with information about the populations
On the Initial Conditions for Pre-Big-Bang Cosmology
Borunda, M.; Ruiz-Altaba, M.
1998-01-01
The beautiful scenario of pre-big-bang cosmology is appealling not only because it is more or less derived from string theory, but also because it separates clearly the problem of the initial conditions for the universe from that of high curvatures. Recently, the pre-big-bang program was subject to attack from on the grounds that pre-big-bang cosmology does not solve the horizon and flatness problems in a ``natural'' way, as customary exponential ``new'' inflation does. In particular, it appe...
Big bang photosynthesis and pregalactic nucleosynthesis of light elements
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.
Antigravity and the big crunch/big bang transition
International Nuclear Information System (INIS)
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.
Solution of a braneworld big crunch/big bang cosmology
International Nuclear Information System (INIS)
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
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.
Antigravity and the big crunch/big bang transition
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.
Antigravity and the big crunch/big bang transition
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.
Global Fluctuation Spectra in Big Crunch/Big Bang String Vacua
Craps, Ben; Ovrut, Burt A.
2003-01-01
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...
Indian microchip for Big Bang research in Geneva
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)
Big Bang test delayed at CERN's LHC until 2008
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)
Estudiarán el Big Bang por Internet
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)
Pre-big bang geometric extensions of inflationary cosmologies
Klein, David
2016-01-01
Robertson-Walker cosmologies within a large class are geometrically extended to larger spacetimes that include spacetime points with zero and negative cosmological times. In the extended spacetimes, the big bang is lightlike, and though singular, it inherits some geometric structure from the original spacetime. Spacelike geodesics are continuous across the cosmological time zero submanifold which is parameterized by the radius of Fermi space slices, i.e, by the proper distances along spacelike geodesics from a comoving observer to the big bang. The continuous extension of the metric, and the continuously differentiable extension of the leading Fermi metric coefficient g{\\tau}{\\tau} of the observer, restrict the geometry of spacetime points with pre-big bang cosmological time coordinates. In our extensions the big bang is two di- mensional in a certain sense, consistent with some findings in quantum gravity.
Pre-big bang cosmology: A long history of time?
International Nuclear Information System (INIS)
The popular myth according to which the Universe - and time itself - started with/near a big bang singularity is questioned. After claiming that the two main puzzles of standard cosmology allow for two possible logical answers, I will argue that superstring theory strongly favours the the pre-big bang (PBB) alternative. I will then explain why PBB inflation is as generic as classical gravitational collapse, and why, as a result of symmetries in the latter problem, recent fine-tuning objections to the PBB scenario are unfounded. A hot big bang state naturally results from the powerful amplification of vacuum quantum fluctuations before the big bang, a phenomenon whose observable consequences will be briefly summarized. (author)
pp Wave Big Bangs: Matrix Strings and Shrinking Fuzzy Spheres
Das, Sumit R.; Michelson, Jeremy
2005-01-01
We find pp wave solutions in string theory with null-like linear dilatons. These provide toy models of big bang cosmologies. We formulate Matrix String Theory in these backgrounds. Near the big bang ``singularity'', the string theory becomes strongly coupled but the Yang-Mills description of the matrix string is weakly coupled. The presence of a second length scale allows us to focus on a specific class of non-abelian configurations, viz. fuzzy cylinders, for a suitable regime of parameters. ...
Effects of a torsion field on Big Bang nucleosynthesis
Brüggen, M.
1999-01-01
In this paper it is investigated whether torsion, which arises naturally in most theories of quantum gravity, has observable implications for the Big Bang nucleosynthesis. Torsion can lead to spin flips amongst neutrinos thus turning them into sterile neutrinos. In the early Universe they can alter the helium abundance which is tightly constrained by observations. Here I calculate to what extent torsion of the string theory type leads to a disagreement with the Big Bang nucleosynthesis predic...
Generating Ekpyrotic Curvature Perturbations Before the Big Bang
Lehners, Jean-Luc; McFadden, Paul; Turok, Neil; Steinhardt, Paul J.(Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, 08544, USA)
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 cosmol...
A numerical simulation of pre-big bang cosmology
International Nuclear Information System (INIS)
We analyse numerically the onset of pre-big bang inflation in an inhomogeneous, spherically symmetric Universe. Adding a small dilatonic perturbation to a trivial (Milne) background, we find that suitable regions of space undergo dilaton-driven inflation and quickly become spatially flat (Ω /to 1). Numerical calculations are pushed close enough to the big bang singularity to allow cross checks against previously proposed analytic asymptotic solutions. (author)
Inhomogeneous neutrino degeneracy and big bang nucleosynthesis
International Nuclear Information System (INIS)
We examine big bang nucleosynthesis (BBN) in the case of inhomogeneous neutrino degeneracy, in the limit where the fluctuations are sufficiently small on large length scales that the present-day element abundances are homogeneous. We consider two representative cases: degeneracy of the electron neutrino alone and equal chemical potentials for all three neutrinos. We use a linear programming method to constrain an arbitrary distribution of the chemical potentials. For the current set of (highly restrictive) limits on the primordial element abundances, homogeneous neutrino degeneracy barely changes the allowed range of the baryon-to-photon ratio η. Inhomogeneous degeneracy allows for little change in the lower bound on η, but the upper bound in this case can be as large as η=1.1x10-8 (only νe degeneracy) or η=1.0x10-9 (equal degeneracies for all three neutrinos). For the case of inhomogeneous neutrino degeneracy, we show that there is no BBN upper bound on the neutrino energy density, which is bounded in this case only by limits from structure formation and the cosmic microwave background. (c) 2000 The American Physical Society
Big Bang synthesis of nuclear dark matter
Hardy, Edward; Lasenby, Robert; March-Russell, John; West, Stephen M.
2015-06-01
We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. ≳ 108, may be synthesised, with the number distribution taking one of two characteristic forms. If small-nucleon-number fusions are sufficiently fast, the distribution of dark nuclei takes on a logarithmically-peaked, universal form, independent of many details of the initial conditions and small-number interactions. In the case of a substantial bottleneck to nucleosynthesis for small dark nuclei, we find the surprising result that even larger nuclei, with size ≫ 108, are often finally synthesised, again with a simple number distribution. We briefly discuss the constraints arising from the novel dark sector energetics, and the extended set of (often parametrically light) dark sector states that can occur in complete models of nuclear dark matter. The physics of the coherent enhancement of direct detection signals, the nature of the accompanying dark-sector form factors, and the possible modifications to astrophysical processes are discussed in detail in a companion paper.
Big-bang nucleosynthesis - observational aspects
International Nuclear Information System (INIS)
Extrapolation of observational data on the abundances of D, 3He, 4He and 7Li in various astrophysical objects to derive their primordial values leads to results in good accordance with calculations from Standard Big Bang nucleosynthesis theory over 9 orders of magnitude in abundance and has led to the following predictions: There are not more than 3 light neutrino species or other particles contributing relativistic degrees of freedom at temperatures of a few MeV; the neutron half-life is less than 10.4 minutes; and baryonic dark matter exists, but not in sufficient quantities to close the universe. (The first two of these predictions have been confirmed by laboratory experiments). Searches for a primordial component in the abundance of any other element heavier than hydrogen - such as might have resulted from inhomogeneities due to phase transitions in the early universe, notably the quark-hadron transition - have so far proved completely negative. The primordial helium abundance is found from observations of extragalactic ionized hydrogen clouds to be close to 0.230 by mass, a little lower than predicted, but the difference does not exceed likely errors. (orig.)
Big Bang Nucleosynthesis in the New Cosmology
International Nuclear Information System (INIS)
Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. We review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η = nB/nγ is measured to high precision. The confrontation between the BBN and CMB ''baryometers'' poses a new and stringent test of the standard cosmology; the status of this test are discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, are illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments are discussed, as is the lingering ''lithium problem.''
Big bang nucleosynthesis in the new cosmology
International Nuclear Information System (INIS)
Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. We review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η=nB/nγ is measured to high precision. The confrontation between the BBN and CMB ''baryometers'' poses a new and stringent test of the standard cosmology; the status of this test is discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, are illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments are discussed, as is the lingering ''lithium problem''. (orig.)
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...
pp wave big bangs: Matrix strings and shrinking fuzzy spheres
International Nuclear Information System (INIS)
We find pp wave solutions in string theory with null-like linear dilatons. These provide toy models of big bang cosmologies. We formulate matrix string theory in these backgrounds. Near the big bang 'singularity', the string theory becomes strongly coupled but the Yang-Mills description of the matrix string is weakly coupled. The presence of a second length scale allows us to focus on a specific class of non-Abelian configurations, viz. fuzzy cylinders, for a suitable regime of parameters. We show that, for a class of pp waves, fuzzy cylinders which start out big at early times dynamically shrink into usual strings at sufficiently late times
Passport to the Big Bang moves across the road
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...
Pre-Big Bang, vacuum and noncyclic cosmologies
Gonzalez-Mestres, Luis
2012-01-01
WMAP and Planck open the way to unprecedented Big Bang phenomenology, potentially allowing to test the standard Big Bang model as well as less conventional approaches including noncyclic pre-Big Bang cosmologies that would incorporate a new fundamental scale beyond the Planck scale and, possibly, new ultimate constituents of matter. Alternatives to standard physics can be considered from a cosmological point of view concerning vacuum structure, the nature of space-time, the origin and evolution of our Universe, the validity of quantum field theory and conventional symmetries, solutions to the cosmological constant problem, inflationary scenarios, dark matter and dark energy, the interpretation of string-like theories... Lorentz-like symmetries for the properties of matter (standard or superbradyonic) can then be naturally stable space-time configurations resulting from general cosmological scenarios that incorporate physics beyond the Planck scale and describe the formation and evolution of the present vacuum...
Generating ekpyrotic curvature perturbations before the big bang
International Nuclear Information System (INIS)
We analyze a general mechanism for producing a nearly scale-invariant spectrum of cosmological curvature perturbations during a contracting phase preceding a big bang, which 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 modeled 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 spectral tilt ns tends to range from slightly blue to red, with 0.97s<1.02 for the simplest models, a range compatible with current observations but shifted by a few percent towards the blue compared to the prediction of the simplest, large-field inflationary models
Challenges to the standard model of Big Bang nucleosynthesis
International Nuclear Information System (INIS)
Big Bang nucleosynthesis provides a unique probe of the early evolution of the Universe and a crucial test of the consistency of the standard hot Big Bang cosmological model. Although the primordial abundances of 2H, 3He, 4He, and 7Li inferred from current observational data are in agreement with those predicted by Big Bang nucleosynthesis, recent analysis has severely restricted the consistent range for the nucleon-to-photon ratio: 3.7 ≤ η10 ≤ 4.0. Increased accuracy in the estimate of primordial 4he and observations of Be and B in Pop II stars are offering new challenges to the standard model and suggest that no new light particles may be allowed (NνBBN ≤ 3.0, where Nν is the number of equivalent light neutrinos). 23 refs
Looking back in time beyond the big bang
Gasperini, M.
1999-01-01
String theory can (in principle) describe gravity at all curvature scales, and can be applied to cosmology to look back in time beyond the Planck epoch. The duality symmetries of string theory suggest a cosmological picture in which the imprint of a primordial, pre-big bang phase could still be accessible to present observations. The predictive power of such a scenario relies, however, on our ability to connect in a smooth way the pre-big bang to the present cosmological regime. Classical rad...
Big-bang Nucleosynthesis Enters the Precision Era
Schramm, David N.; Turner, Michael S.
1997-01-01
The last parameter of big-bang nucleosynthesis, the baryon density, is being pinned down by measurements of the deuterium abundance in high-redshift hydrogen clouds. When it is determined, it will fix the primeval light-element abundances. D, ^3He and ^7Li will become ``tracers'' for the study of Galactic and stellar chemical evolution, and big-bang nucleosynthesis will become an even sharper probe of particle physics, e.g., the bound to the number of light neutrino species will be tightened ...
Baryon symmetric big-bang cosmology. [matter-antimatter symmetry
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.
Capture reactions on C-14 in nonstandard big bang nucleosynthesis
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.
Nonuniversal scalar-tensor theories and big bang nucleosynthesis
International Nuclear Information System (INIS)
We investigate the constraints that can be set from big bang nucleosynthesis on two classes of models: extended quintessence and scalar-tensor theories of gravity in which the equivalence principle between standard matter and dark matter is violated. In the latter case, and for a massless dilaton with quadratic couplings, the phase space of theories is investigated. We delineate those theories where attraction toward general relativity occurs. It is shown that big bang nucleosynthesis sets more stringent constraints than those obtained from Solar System tests.
Film Presentation: The Big Bang Machine by BBC (2008)
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
On The Big Bang Singularity in $k=0$ FLRW Cosmologies
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.
BIG BANG NUCLEOSYNTHESIS WITH A NON-MAXWELLIAN DISTRIBUTION
International Nuclear Information System (INIS)
The abundances of light elements based on the big bang nucleosynthesis model are calculated using the Tsallis non-extensive statistics. The impact of the variation of the non-extensive parameter q from the unity value is compared to observations and to the abundance yields from the standard big bang model. We find large differences between the reaction rates and the abundance of light elements calculated with the extensive and the non-extensive statistics. We found that the observations are consistent with a non-extensive parameter q = 1-0.12+0.05, indicating that a large deviation from the Boltzmann-Gibbs statistics (q = 1) is highly unlikely.
Evolution of the early universe and big-bang nucleosynthesis
International Nuclear Information System (INIS)
Cosmological phase transition can create strongly inhomogeneous baryon density distribution. Inhomogeneous big-bang model for primordial nucleosynthesis allows higher universal mass density parameter of baryons than the standard model does, which is marginally consistent with recent astronomical suggestion that some kind of dark matter is made of baryons. Enhanced heavy-element abundances in halo dwarfs is shown to be an observational signature for the inhomogeneous big-bang model. The studies of radioactive nuclear reactions help predict the theoretical abundances of these elements more precisely. (author). 53 refs., 8 figs
Quantum Gravity Loses in the Big Bang and Black Holes
Rosenberg, David E.
2000-01-01
Applying the uncertainty principle to the stress-energy tensor, we investigate black holes, the big bang and galaxy formation. Dark energy, dark matter and other phenomena are readily explained using the principle of particle confinement. Evidence is presented that the universe results from a bounce and that black holes lose gravitational energy. PACS number 04.50Kd
Mapping the cold glow of the big bang
International Nuclear Information System (INIS)
The United States has recently launched a satellite solely dedicated to cosmology in an attempt to provide insight into the early formation of the Universe. The Cosmic Background Explorer (COBE) satellite is producing astonishing precise data which supports the Big Bang theory of the Universe's origins. Continued analysis of COBE data may provide clues as to how stars and galaxies formed. (UK)
HydraPower out to make a big bang
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."
Big Bang Nucleosynthesis and the Observed Abundances of Light Elements
Hogan, Craig J.
1996-01-01
The predictions of Standard Big Bang Nucleosynthesis are summarized and compared with observations of abundances of helium in HII regions, deuterium in quasar absorbers, deuterium and helium-3 in the Galaxy, and lithium in metal-poor stars. It is concluded that the prospects are good for a precise test of the theory.
Curing singularities: From the big bang to black holes
Levin, Janna
1998-01-01
Singular spacetimes are a natural prediction of Einstein's theory. Most memorable are the singular centers of black holes and the big bang. However, dilatonic extensions of Einstein's theory can support nonsingular spacetimes. The cosmological singularities can be avoided by dilaton driven inflation. Furthermore, a nonsingular black hole can be constructed in two dimensions.
Cavaglia, Marco
2001-01-01
We discuss a simple cosmological model derived from M-theory. Three assumptions lead naturally to a pre-big bang scenario: (a) 11-dimensional supergravity describes the low-energy world; (b) non-gravitational fields live on a three-dimensional brane; and (c) asymptotically past triviality.
Constraints on massive gravity theory from big bang nucleosynthesis
Lambiase, G.
2012-01-01
The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also discussed in the framework of the PAMELA experiment.
"Big Bang"test put off until May 2008
2007-01-01
"First tests in a scientific project aimed at solving mysteries of the universe and the "Big Bang" which created it have been put off from November to late april or early May next year, an official said yesterday." (2/3 page)
Leadership in the Big Bangs of European Integration
DEFF Research Database (Denmark)
? and, more importantly, what factors allowed specific actors to provide leadership in a given context? These conclusions provide a major step forward in the literature on the history-making bargains in the EU, allowing us to answer with more confidence the question of which actors have guided the big...... bangs in the European integration process in the past two decades, and why. ...
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 in...
Constructing "Nerdiness": Characterisation in "The Big Bang Theory"
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…
A Guided Inquiry on Hubble Plots and the Big Bang
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…
The Big Bang: UK Young Scientists' and Engineers' Fair 2010
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…
Cosmologie L'Univers avant le Big Bang
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
Film Presentation: Big Bang, mes ancêtres et moi
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...
Curing singularities From the big bang to black holes
Levin, J
1998-01-01
Singular spacetimes are a natural prediction of Einstein's theory. Most memorable are the singular centers of black holes and the big bang. However, dilatonic extensions of Einstein's theory can support nonsingular spacetimes. The cosmological singularities can be avoided by dilaton driven inflation. Furthermore, a nonsingular black hole can be constructed in two dimensions.
Recrean el Big Bang a nivel microscópico
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)
Small wormholes change our picture of the big bang
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)
Neutrino energy transport in weak decoupling and big bang nucleosynthesis
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 $\
Fisicos argentinos reproduciran el Big Bang
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)
Electron screening and its effects on big-bang nucleosynthesis
International Nuclear Information System (INIS)
We study the effects of electron screening on nuclear reaction rates occurring during the big-bang nucleosynthesis epoch. The sensitivity of the predicted elemental abundances on electron screening is studied in detail. It is shown that electron screening does not produce noticeable results in the abundances unless the traditional Debye-Hueckel model for the treatment of electron screening in stellar environments is enhanced by several orders of magnitude. This work rules out electron screening as a relevant ingredient to big-bang nucleosynthesis, confirming a previous study [see Itoh et al., Astrophys. J. 488, 507 (1997)] and ruling out exotic possibilities for the treatment of screening beyond the mean-field theoretical approach.
Big-Bang nucleosynthesis with updated nuclear data
International Nuclear Information System (INIS)
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 4He, D, 3He and 7Li 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.
Introduction to Big Bang nucleosynthesis: open and closed models, anisotropies
International Nuclear Information System (INIS)
A variety of observations suggest that the Universe had a hot dense origin and that the pregalactic composition of the Universe was determined by nuclear reactions that occurred in the first few minutes. There is no unique hot Big Bang theory, but the simplest version produces a primeval chemical composition that is in good qualitative agreement with the abundances deduced from observation. Whether or not any Big Bang theory will provide quantitative agreement with observations depends on a variety of factors in elementary particle physics (number and masses of stable or long-lived particles, half-life of neutron, structure of grand unified theories) and from observational astronomy (present mean baryon density of the Universe, the Hubble constant and deceleration parameter). The influence of these factors on the abundances is discussed, as is the effect of departures from homogeneity and isotropy in the early Universe. (author)
Post big bang processing of the primordial elements
Balbes, M J; Steigman, G; Thomas, D
1995-01-01
We explore the Gnedin-Ostriker suggestion that a post-Big-Bang photodissociation process may modify the primordial abundances of the light elements. We consider several specific models and discuss the general features that are necessary (but not necessarily sufficient) to make the model work. We find that with any significant processing, the final D and ^3He abundances, which are independent of their initial standard big bang nucleosynthesis (SBBN) values, rise quickly to a level several orders of magnitude above the observationally inferred primordial values. Solutions for specific models show that the only initial abundances that can be photoprocessed into agreement with observations are those that undergo virtually no processing and are already in agreement with observation. Thus it is unlikely that this model can work for any non-trivial case unless an artificial density and/or photon distribution is invoked.
Quantization of Big Bang in crypto-Hermitian Heisenberg picture
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) \
Big Bang Day: 5 Particles - 3. The Anti-particle
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.
Big-Bang Nucleosynthesis verifies classical Maxwell-Boltzmann distribution
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.
Kasner solutions, climbing scalars and big-bang singularity
International Nuclear Information System (INIS)
We elaborate on a recently discovered phenomenon where a scalar field close to big-bang is forced to climb a steep potential by its dynamics. We analyze the phenomenon in more general terms by writing the leading order equations of motion near the singularity. We formulate the conditions for climbing to exist in the case of several scalars and after inclusion of higher-derivative corrections and we apply our results to some models of moduli stabilization. We analyze an example with steep stabilizing potential and notice again a related critical behavior: for a potential steepness above a critical value, going backwards towards big-bang, the scalar undergoes wilder oscillations, with the steep potential pushing it back at every passage and not allowing the scalar to escape to infinity. Whereas it was pointed out earlier that there are possible implications of the climbing phase to CMB, we point out here another potential application, to the issue of initial conditions in inflation
Big-bang nucleosynthesis enters the precision era
International Nuclear Information System (INIS)
The last parameter of big-bang nucleosynthesis, the density of ordinary matter (baryons), is being pinned down by measurements of the deuterium abundance in high-redshift hydrogen clouds. When it is, the primeval abundances of the light elements D, 3He, 7Li, and 4He will be fixed. The first three will then become open-quotes tracersclose quotes in the study of Galactic and stellar chemical evolution. A precision determination of the 4He abundance will allow an important consistency test of big-bang nucleosynthesis and will sharpen nucleosynthesis as a probe of fundamental physics, e.g., the bound to the number of light neutrino species. An independent consistency test is on the horizon: a high-precision determination of the baryon density from measurements of the fluctuations of the cosmic background radiation temperature. copyright 1998 The American Physical Society
Brookhaven collider opens its quest for Big Bang conditions
Nadis, S
2000-01-01
The collision of two gold nuclei releasing 10 x 10 to the power 12 electron volts of energy, marked the debut of the Relativistic Heavy Ion Collider. Over the next few weeks, scientists hope to increase the accelerator's power to generate collisions 40 x 10 to the power 12 eVs of energy to simulate the conditions that existed immediately after the Big Bang (1 page).
Adiabatic CMB perturbations in pre-big bang string cosmology
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 $-0.1 \\lesssim \\Delta n \\lesssim 0.3$.
The big-bang theory: construction, evolution and status
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 h...
The Quantum Big Bang in Global Time Theory
Burlankov, D. E.
2004-01-01
The it Global Time Theory (GTT) is the further development of the General Relativity (GR). GTT significantly differs from GR in the general physical concepts, but retains 90% of the mathematical structure and main results. The dynamics equations are derived from Lagrangian, and the Hamiltonian of gravitation is nonzero. The quantum theory of gravitation can be built on the basis of the Schroedinger equation, as for other fields. The quantum model of the Big Bang is demonstrated.
Gauge Approach to Gravitation and Regular Big Bang Theory
Minkevich, A. V.
2005-01-01
Field theoretical scheme of regular Big Bang in 4-dimensional physical space-time, built in the framework of gauge approach to gravitation, is discussed. Regular bouncing character of homogeneous isotropic cosmological models is ensured by gravitational repulsion effect at extreme conditions without quantum gravitational corrections. The most general properties of regular inflationary cosmological models are examined. Developing theory is valid, if energy density of gravitating matter is posi...
Review of Big Bang Nucleosynthesis and Primordial Abundances
Tytler, David; O'Meara, John M.; SUZUKI, Nao; Lubin, Dan
2000-01-01
Big Bang Nucleosynthesis (BBN) is the synthesis of the light nuclei, Deuterium, He3, He4 and Li7, 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. (abridged)
The big bang nucleosynthesis and finite temperature field theory
International Nuclear Information System (INIS)
We consider electromagnetic corrections at finite temperature and their effect on the nucleosynthesis in the standard Big Bang scenario. This requires discussing the finite, temperature dependent correction to the neutron-proton mass difference as well as making use of a previous result on the temperature correction to the mass of the electron. We find that these corrections do not affect the conventional results of e.g. the helium abundance to any appreciable extent. (orig.)
Constraints on massive gravity theory from big bang nucleosynthesis
International Nuclear Information System (INIS)
The massive gravity cosmology is studied in the scenario of big bang nucleosynthesis. By making use of current bounds on the deviation from the fractional mass, we derive the constraints on the free parameters of the theory. The cosmological consequences of the model are also analyzed in the framework of the PAMELA experiment, i.e. an excess of positron events, that the conventional cosmology and particle physics cannot explain
Generating a hot big bang via a change in topology
International Nuclear Information System (INIS)
This paper uses ideas developed recently in semiclassical quantum gravity to argue that many qualitative features of the hot big bang generally assumed in cosmology may be explained by the hypothesis that, interpreted semiclassically, the universe tunnelled into being via a quantum fluctuation from a small (Planck-sized), topologically complex entity to a topologically trivial entity (like a Friedmann universe) that rapidly grew to a more macroscopic size
Big Bang-Like Phenomenon in Multidimensional Data
Czech Academy of Sciences Publication Activity Database
Jiřina, Marcel
Wilmington: SDIWC, 2014 - (Malakooti, M.), s. 262-269 ISBN 978-0-9891305-5-4. [ICCTIM 2014. International Conference on Computing Technology and Information Management. Dubai (AE), 09.04.2014-11.04.2014] R&D Projects: GA MŠk(CZ) LG12020 Institutional support: RVO:67985807 Keywords : Big Bang * scaling * correlation dimension * expansion of distances * polynomial transformation Subject RIV: BB - Applied Statistics, Operational Research
Constraining big bang lithium production with recent solar neutrino data
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.
Inhomogeneous big bang nucleosynthesis with late-decaying massive particles
Lopez-Suarez, J.; Canal, R.
1998-01-01
We investigate the possibility of accounting for the currently inferred primordial abundances of D, 3He, 4He, and 7Li by big bang nucleosynthesis in the presence of baryon density inhomogeneities plus the effects of late-decaying massive particles (X), and we explore the allowed range of baryonic fraction of the closure density Omega_b in such context. We find that, depending on the parameters of this composite model (characteristic size and density contrast of the inhomogeneities; mass-densi...
Constraining Big Bang lithium production with recent solar neutrino data
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...
Cosmological nucleosynthesis in the Big-Bang and supernovae
International Nuclear Information System (INIS)
Recent observation of the power spectrum of Cosmic Microwave Background (CMB) Radiation has exhibited that the flat cosmology is most likely. This suggests too large universal baryon-density parameter Ωbh2≅0.022∼0.030 to accept a theoretical prediction, Ωbh2≤0.017, in the homogeneous Big-Bang model for primordial nucleosynthesis. Theoretical upper limit arises from the sever constraints on the primordial 7Li abundance. We propose two cosmological models in order to resolve the discrepancy; lepton asymmetric Big-Bang nucleosynthesis model, and baryon inhomogeneous Big-Bang nucleosynthesis model. In these cosmological models the nuclear processes are similar to those of the r-process nucleosynthesis in gravitational collapse supernova explosions. Massive stars≥10(solar mass) culminate their evolution by supernova explosions which are presumed to be the most viable candidate site for the r-process nucleosynthesis. Even in the nucleosynthesis of heavy elements, initial entropy and density at the surface of proto-neutron stars are so high that nuclear statistical equilibrium favors production of abundant light nuclei. In such explosive circumstances many neutron-rich radioactive nuclei of light-to-intermediate mass as well as heavy mass nuclei play the significant roles. (author)
Big bang nucleosynthesis: Non-standard models
International Nuclear Information System (INIS)
In spite of the success of the standard model for big band nucleosynthesis, it is always possible that a variant scenario was responsible for the production of the light element abundances, and while successfully predicting these abundances, it may be possible to alter some of the conclusions of the standard model. The most notable of these is the limit on the baryon density of the Universe, η10 = 1010(nB/nγ), 2.8 10 B, 0.01 Bh02 < 0.04. Given the importance of the conclusions of the standard model, an interest in nonstandard nucleosynthesis models remains high. In this contribution, the author briefly summarizes the current status of three non-standard scenarios: (1) Inhomogeneous Models; (2) Decaying Particle Scenarios; and (3) Lepton Degeneracies. 29 refs., 3 figs
Inflationary and Deflationary Branches in Extended Pre--Big Bang Cosmology
Lidsey, James E.
1996-01-01
The pre--big bang cosmological scenario is studied within the context of the Brans--Dicke theory of gravity. An epoch of superinflationary expansion may occur in the pre--big bang phase of the Universe's history in a certain region of parameter space. Two models are considered that contain a cosmological constant in the gravitational and matter sectors of the theory, respectively. Classical pre-- and post--big bang solutions are found for both models. The existence of a curvature singularity ...
Turning big bang into big bounce: II. Quantum dynamics
International Nuclear Information System (INIS)
We analyze the big bounce transition of the quantum Friedmann-Robertson-Walker model in the setting of the nonstandard loop quantum cosmology (LQC). Elementary observables are used to quantize composite observables. The spectrum of the energy density operator is bounded and continuous. The spectrum of the volume operator is bounded from below and discrete. It has equally distant levels defining a quantum of the volume. The discreteness may imply a foamy structure of spacetime at a semiclassical level which may be detected in astro-cosmo observations. The nonstandard LQC method has a free parameter that should be fixed in some way to specify the big bounce transition.
Big Bang à Genève - French version only
2005-01-01
C'est la dernière conférence du cycle organisé par la section de physique de l'Université de Genève à l'occasion de l'Année internationale de la physique. Pour le bouquet final, la section de physique a choisi le grand boum du Big Bang. Intitulée « Big Bang à Genève », la conférence donnée par Laurent Chevalier de l'institut français CEA Saclay évoquera les expériences qui se préparent au CERN avec le LHC. Leur but est de reproduire et d'analyser les conditions qui prévalaient à l'origine de l'Univers, juste après le Big Bang. L'exposé décrira de façon simple les techniques utilisées pour cette exploration, qui démarrera en 2007. Laurent Chevalier se demandera avec le public quels phénomènes nouveaux les physiciens espèrent découvrir dans ce monde inexploré. Comme les précédentes, la conférence débutera par une démonstration de détection de rayons cosmiques dans l'auditoire et l'utilisation de ces signaux pour créer une « musique cosmique », en collaboration avec le Pr...
H-dibaryons and the Big-Bang crisis
International Nuclear Information System (INIS)
An alternative solution for the apparent discrepancy between abundances of light nuclides predicted by the standard big bang and observational data is proposed, by assuming the presence of H dibaryons at the nucleosynthesis era. These dibaryons would be the consequence of a small fraction of strange quarks at the moment of the confinement transition. A relative abundance of H dibaryons of the order of nH/nB ∼ 0.07, decaying in a time-scale of the order of 105 s would be sufficient to explain differences in the 4 He abundance if the primordial deuterium abundance is of the order of 3 x 10-5. (authors)
Constraining Axion Dark Matter with Big Bang Nucleosynthesis
Kfir Blum; Raffaele Tito D'Agnolo; Mariangela Lisanti; Benjamin R. Safdi
2014-01-01
We show that Big Bang Nucleosynthesis (BBN) significantly constrains axion-like dark matter. The axion acts like an oscillating QCD $\\theta$ 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 4He during BBN and is thus excluded. The BBN bound overlaps with much of the parameter space that would be covered by proposed searches for time-varying ...
Constraining axion dark matter with Big Bang Nucleosynthesis
International Nuclear Information System (INIS)
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 4He 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
The case for the relativistic hot big bang cosmology
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.
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.
Cosmological BCS mechanism and the big bang singularity
International Nuclear Information System (INIS)
We provide a novel mechanism that resolves the big bang singularity present in Friedman-Lemaitre-Robertson-Walker space-times without the need for ghost fields. Building on the fact that a four-fermion interaction arises in general relativity when fermions are covariantly coupled, we show that at early times the decrease in scale factor enhances the correlation between pairs of fermions. This enhancement leads to a BCS-like condensation of the fermions and opens a gap dynamically driving the Hubble parameter H to zero and results in a nonsingular bounce, at least in some special cases.
Quark mass variation constraints from Big Bang nucleosynthesis
International Nuclear Information System (INIS)
We study the impact on the primordial abundances of light elements created by 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 a hierarchy of effective field theories. We find that the measured 4He abundances put a bound of -1% q/mq q/mq.
DLCQ and Plane Wave Matrix Big Bang Models
Blau, Matthias; O'Loughlin, Martin
2008-01-01
We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these c...
Relaxing the big-bang bound to the baryon density
International Nuclear Information System (INIS)
In the standard picture of big-bang nucleosynthesis the yields of D, 3He, 4He, and 7Li only agree with their inferred primordial abundances provided the fraction of critical density contributed by baryons is between 1% and 15%. If the τ neutrino has a mass between 20 MeV and 30 MeV and a lifetime between 200 sec and 3000 sec and its decay products include electron neutrinos this crucial bound is relaxed by a factor of 10. Experiments at e± colliders should soon test this possibility
The cosmological constant filter without big bang singularity
International Nuclear Information System (INIS)
In the recently proposed cosmological constant (CC) filter mechanism based on modified gravity in the Palatini formalism, gravity in the radiation, matter and late-time de Sitter eras is insensitive to energy sources with the equation of state -1. This implies that finite vacuum energy shifts from phase transitions are filtered out too. In this work, we investigate the CC filter model at very early times. We find that the initial big bang singularity is replaced by a cosmic bounce, where the matter energy density and the curvature are finite. In a certain case, this finiteness can be already observed on the algebraic level. (paper)
Big Bang Day : Afternoon Play - Torchwood: Lost Souls
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.
Big Bang Bifurcation Analysis and Allee Effect in Generic Growth Functions
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.
String Theory and Pre-big bang Cosmology
Gasperini, M
2007-01-01
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 si...
State of the Universe. If Not with a Big Bang, Then What?
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)
Light-like big bang singularities in string and matrix theories
International Nuclear Information System (INIS)
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.
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.
Big Bang pour le grand public - French version only
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 ...
Primordial alchemy: from the Big Bang to the present universe
Steigman, Gary
Of the light nuclides observed in the universe today, D, 3He, 4He, and 7Li are relics from its early evolution. The primordial abundances of these relics, produced via Big Bang Nucleosynthesis (BBN) during the first half hour of the evolution of the universe provide a unique window on Physics and Cosmology at redshifts ~1010. Comparing the BBN-predicted abundances with those inferred from observational data tests the consistency of the standard cosmological model over ten orders of magnitude in redshift, constrains the baryon and other particle content of the universe, and probes both Physics and Cosmology beyond the current standard models. These lectures are intended to introduce students, both of theory and observation, to those aspects of the evolution of the universe relevant to the production and evolution of the light nuclides from the Big Bang to the present. The current observational data is reviewed and compared with the BBN predictions and the implications for cosmology (e.g., universal baryon density) and particle physics (e.g., relativistic energy density) are discussed. While this comparison reveals the stunning success of the standard model(s), there are currently some challenge which leave open the door for more theoretical and observational work with potential implications for astronomy, cosmology, and particle physics.
Primordial Alchemy From The Big Bang To The Present Universe
Steigman, G
2002-01-01
Of the light nuclides observed in the universe today, D, 3He, 4He, and 7Li are relics from its early evolution. The primordial abundances of these relics, produced via Big Bang Nucleosynthesis (BBN) during the first half hour of the evolution of the universe provide a unique window on Physics and Cosmology at redshifts of order 10^10. Comparing the BBN-predicted abundances with those inferred from observational data tests the consistency of the standard model of cosmology over ten orders of magnitude in redshift, constrains the baryon and other particle content of the universe, and probes both Cosmology and Physics beyond their current standard models. These lectures are intended to introduce students, both of theory and observation, to those aspects of the evolution of the universe relevant to the production and evolution of the light nuclides from the Big Bang to the present. The current observational data is reviewed and compared with the BBN predictions and the implications for cosmology (e.g., universal ...
Re-evaluation of the immunological Big Bang.
Flajnik, Martin F
2014-11-01
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. PMID:25517375
Big bang nucleosynthesis: The standard model and alternatives
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).
Matrix membrane big bangs and D-brane production
International Nuclear Information System (INIS)
We construct matrix membrane theory in pp wave backgrounds that have a null linear dilaton in Type IIB string theory. Such backgrounds can serve as toy models of big bang cosmologies. At late times only Abelian degrees of freedom survive, and if the Kaluza-Klein modes along one of the directions of the membrane decouple, standard perturbative strings emerge. Near the 'big bang', non-Abelian configurations of fuzzy ellipsoids are present, as in the Type IIA theories. A generic configuration of these shrink to zero volume at late times. However, the Kaluza-Klein modes (which can be thought of as states of (p,q) strings in the original IIB theory) can be generically produced in pairs in both pp wave and flat backgrounds in the presence of time dependence. Indeed, if we require that at late times the theory evolves to the perturbative string vacuum, these modes must be prepared in a squeezed state with a thermal distribution at early times
The big-bang theory: construction, evolution and status
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...
Cosmic inflation and big bang interpreted as explosions
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...
Relationalism Evolves the Universe Through the Big Bang
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...
Dark/visible parallel universes and Big Bang nucleosynthesis
International Nuclear Information System (INIS)
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.
Horizons in matter: black hole hair vs. Null Big Bang
Bronnikov, K A
2009-01-01
It is shown that only particular kinds of matter (in terms of the "radial" pressure to density ratio $w$) can coexist with Killing horizons in black-hole or cosmological space-times. Thus, for arbitrary (not necessarily spherically symmetric) static black holes, admissible are vacuum matter ($w=-1$, i.e., the cosmological constant or some its generalization) and matter with certain values of $w$ between 0 and -1, in particular, a gas of disordered cosmic strings ($w=-1/3$). If the cosmological evolution starts from a horizon (the so-called Null Big Bang scenarios), this horizon can co-exist with vacuum matter and certain kinds of phantom matter with $w\\geq -3$. It is concluded that normal matter in such scenarios is entirely created from vacuum.
Big bang nucleosynthesis revisited via Trojan Horse method measurements
International Nuclear Information System (INIS)
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 2H(d, p)3H, 2H(d, n)3He, 7Li(p, α)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 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.
A Big Bang model of human colorectal tumor growth.
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. PMID:25665006
Big bang nucleosynthesis - The standard model and alternatives
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.
COBE's search for structure in the Big Bang
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.
Cosmologie l'univers avant le Big Bang
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.
Big bang nucleosynthesis and the quark-hadron transition
International Nuclear Information System (INIS)
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). 43 refs
Big bang nucleosynthesis and the quark-hadron transition
Energy Technology Data Exchange (ETDEWEB)
Kurki-Suonio, H.; Matzner, R.A.; Olive, K.A.; Schramm, D.N. (Drexel Univ., Philadelphia, PA (USA) Texas Univ., Austin (USA) Minnesota Univ., Minneapolis (USA) Chicago Univ., IL (USA))
1990-04-01
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). 43 refs.
Big Bang nucleosynthesis and the quark-hadron transition
Energy Technology Data Exchange (ETDEWEB)
Kurki-suonio, H.; Matzner, R.A.; Olive, K.A.; Schramm, D.N.
1989-12-01
An examination and brief review is made of the effects of quark-hadron transistion 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 much greater than 10(exp 3), whereas the simplest models for the transition seem to restrict R to less than approximately 10(exp 2).
Big bang nucleosynthesis and the quark-hadron transition
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).
Quantum Nature of the Big Bang: Improved dynamics
Ashtekar, A; Singh, P; Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet
2006-01-01
An improved Hamiltonian constraint operator is introduced in loop quantum cosmology. Quantum dynamics of the spatially flat, isotropic model with a massless scalar field is then studied in detail using analytical and numerical methods. The scalar field continues to serve as `emergent time', the big bang is again replaced by a quantum bounce, and quantum evolution remains deterministic across the deep Planck regime. However, while with the Hamiltonian constraint used so far in loop quantum cosmology the quantum bounce can occur even at low matter densities, with the new Hamiltonian constraint it occurs only at a Planck-scale density. Thus, the new quantum dynamics retains the attractive features of current evolutions in loop quantum cosmology but, at the same time, cures their main weakness.
DLCQ and plane wave matrix Big Bang models
Blau, Matthias; O'Loughlin, Martin
2008-09-01
We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.
Sharpening the Predictions of Big-Bang Nucleosynthesis
International Nuclear Information System (INIS)
We have reexamined the nuclear inputs to big-bang nucleosynthesis using Monte Carlo realization of the cross-section data to directly estimate theoretical uncertainties for the yields of D , 3He , and 7Li . Our results indicate that previous estimates of the uncertainties were too large by a factor of 2. Using the Burles - Tytler deuterium measurement, we infer a baryon density ΩBh2=0.019±0.0024 , predict a primeval 4He mass fraction YP=0.246±0.0014 , and obtain a limit to the equivalent number of neutrino species Nν<3.20 (all at 95% C.L.). We also identify key reactions and the energies, where improved data would allow further progress. copyright 1999 The American Physical Society
Big Bang Nucleosynthesis Revisited via Trojan Horse Method Measurements
Pizzone, R. G.; Spartá, R.; Bertulani, C. A.; Spitaleri, C.; La Cognata, M.; Lalmansingh, J.; Lamia, L.; Mukhamedzhanov, A.; Tumino, A.
2014-05-01
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 2H(d, p)3H, 2H(d, n)3He, 7Li(p, α)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 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.
DLCQ and Plane Wave Matrix Big Bang Models
Blau, Matthias
2008-01-01
We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.
DLCQ and plane wave matrix Big Bang models
International Nuclear Information System (INIS)
We study the generalisations of the Craps-Sethi-Verlinde matrix big bang model to curved, in particular plane wave, space-times, beginning with a careful discussion of the DLCQ procedure. Singular homogeneous plane waves are ideal toy-models of realistic space-time singularities since they have been shown to arise universally as their Penrose limits, and we emphasise the role played by the symmetries of these plane waves in implementing the flat space Seiberg-Sen DLCQ prescription for these curved backgrounds. We then analyse various aspects of the resulting matrix string Yang-Mills theories, such as the relation between strong coupling space-time singularities and world-sheet tachyonic mass terms. In order to have concrete examples at hand, in an appendix we determine and analyse the IIA singular homogeneous plane wave - null dilaton backgrounds.
Big Bang nucleosynthesis revisited via Trojan Horse Method measurements
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.
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.
Weak interaction rate Coulomb corrections in big bang nucleosynthesis
International Nuclear Information System (INIS)
We have applied a fully relativistic Coulomb wave correction to the weak reactions in the full Kawano/Wagoner big bang nucleosynthesis (BBN) code. We have also added the zero-temperature radiative correction. We find that using this higher accuracy Coulomb correction results in good agreement with previous work, giving only a modest ∼0.04% increase in helium mass fraction over correction prescriptions applied previously in BBN calculations. We have calculated the effect of these corrections on other light element abundance yields in BBN, and we have studied these yields as functions of electron neutrino lepton number. This has allowed insights into the role of the weak neutron-proton interconversion processes in the setting of the neutron-to-proton ratio during the BBN epoch. We find that the lepton capture processes' contributions to this ratio are only second order in the Coulomb correction.
Precise measurements of neutron lifetime and big bang nucleosynthesis
International Nuclear Information System (INIS)
In this talk, we review the current status of the relationships between measurements of neutron lifetime and predictions of light element abundances in big-bang nucleosynthesis (BBN). Performing the Monte Carlo simulation with experimental errors in neutron life-time and nuclear reaction rates in the computation, we can estimate the uncertainties of the prediction of primordial value of D, 4He and 7Li. In BBN, especially 4He is the most sensitive element to the neutron lifetime. Recently it was reported that neutron lifetime was measured within 0.1% (τn=885.7 ± 0.8) accuracy. In this situation, we can determine the primordial value of the 4He mass fraction within 0.1% accuracy. (author)
Constraints on neutrino oscillations from big bang nucleosynthesis
International Nuclear Information System (INIS)
We discuss in detail the effect of neutrino oscillations in Big Bang nucleosynthesis between active and sterile neutrinos as well as between active and active neutrinos. We calculate the constraints on mixings between active and sterile neutrinos from the present observation of the primordial helium abundance and discuss the potential implications on various astrophysical and cosmological problems of such oscillations. In particular, we show that large-angle sterile neutrino mixing seems to be excluded as a MSW solution to the solar neutrino situation or a solution to the atmospheric neutrino mixing hinted at in some underground experiments. We show how, with this constraint, the next generation of solar neutrino experiments should be able to determine the resolution of the solar neutrino problem. It is also shown how sterile neutrinos remain a viable dark matter candidate
Standard big bang nucleosynthesis and primordial CNO abundances after Planck
International Nuclear Information System (INIS)
Primordial or big bang nucleosynthesis (BBN) is one of the three historical strong evidences for the big bang model. The recent results by the Planck satellite mission have slightly changed the estimate of the baryonic density compared to the previous WMAP analysis. This article updates the BBN predictions for the light elements using the cosmological parameters determined by Planck, as well as an improvement of the nuclear network and new spectroscopic observations. There is a slight lowering of the primordial Li/H abundance, however, this lithium value still remains typically 3 times larger than its observed spectroscopic abundance in halo stars of the Galaxy. According to the importance of this ''lithium problem, we trace the small changes in its BBN calculated abundance following updates of the baryonic density, neutron lifetime and networks. In addition, for the first time, we provide confidence limits for the production of 6Li, 9Be, 11B and CNO, resulting from our extensive Monte Carlo calculation with our extended network. A specific focus is cast on CNO primordial production. Considering uncertainties on the nuclear rates around the CNO formation, we obtain CNO/H ≈ (5-30)×10-15. We further improve this estimate by analyzing correlations between yields and reaction rates and identified new influential reaction rates. These uncertain rates, if simultaneously varied could lead to a significant increase of CNO production: CNO/H∼10-13. This result is important for the study of population III star formation during the dark ages
Resolution of Cosmological Singularity and a Plausible Mechanism of the Big Bang
Choudhury, D. C.
2001-01-01
The initial cosmological singularity in the framework of the general theory of relativity is resolved by introducing the effect of the uncertainty principle of quantum theory without violating conventional laws of physics. A plausible account of the mechanism of the big bang, analogous to that of a nuclear explosion, is given and the currently accepted Planck temperature of about 10^(32)K at the beginning of the big bang is predicted. Subj-class: cosmology: theory-pre-big bang; mechanism of t...
The Quark Dirac Sea and the Contracted Universe cooperate to produce the Big Bang
Xu, Jiao-Lin
2009-01-01
The Big Bang theory cannot and does not provide any explanation for the primordial hot and dense initial condition. In order to give an explanation for the cause of the Big Bang, this paper expands the original Dirac sea (which includes only electrons) to the quark Dirac sea (QDS) including quarks (u and d) for producing the Big Bang with quark energy. The QDS is composed of "relatively infinite" u-quarks and d-quarks as well as electrons with negative energy in the vacuum. A huge number of d...
International Nuclear Information System (INIS)
We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of big bang nucleosynthesis. We calculate the magnitude of the amplification and show evidence of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification in big bang nucleosynthesis. It is shown that with a ∼1 eV νe, the amplification of its chemical potential by active-sterile neutrino oscillations can lower the effective number of neutrino species at big bang nucleosynthesis to significantly below three. copyright 1996 The American Physical Society
Cosmic Heritage Evolution from the Big Bang to Conscious Life
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...
String theory and pre-big bang cosmology
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.
Rebhan, E
2000-01-01
The solution for an inflationary universe without singularities is derived from the Einstein-Lemaitre equations. The present state of the universe evolved from a steady state solution for a tiny, but classical micro-universe with large cosmological constant or large equivalent vacuum energy density and with an equal energy density of radiation and/or some kind of relativistic primordial matter in the infinite past. An instability of this state outside the quantum regime caused a "soft bang" by triggering an expansion that smoothly started with zero expansion rate, continuously increased, culminated in an exponentially inflating phase and ended through a phase transition, the further evolution being a Friedmann-Lemaitre evolution as in big bang models. As a necessary implication of the model the universe must be closed. All other parameters of the model are very similar to those of big bang models and comply with observational constraints.
THE BIG BANG THEORY AND UNIVERSE MODELING. MISTAKES IN THE RELATIVITY THEORY
Javadov, Khaladdin; Javadli, Elmaddin
2014-01-01
This article is about Theory of Big Bang and it describes some details of Universe Modelling. It is Physical and Mathematical modeling of Universe formation. Application of mathematical and physical formulas for Universe Calculations.
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.
Regularization of the big bang singularity with a time varying equation of state $w > 1$
Xue, BingKan; Belbruno, Edward
2014-01-01
We study the classical dynamics of the universe undergoing a transition from contraction to expansion through a big bang singularity. The dynamics is described by a system of differential equations for a set of physical quantities, such as the scale factor $a$, the Hubble parameter $H$, the equation of state parameter $w$, and the density parameter $\\Omega$. The solutions of the dynamical system have a singularity at the big bang. We study if the solutions can be regularized at the singularit...
Resolution of cosmological singularity and a plausible mechanism of the big bang
International Nuclear Information System (INIS)
The initial cosmological singularity in the framework of the general theory of relativity is resolved by introducing the effect of the uncertainty principle of quantum theory without violating conventional laws of physics. A plausible account of the mechanism of the big bang, analogous to that of a nuclear explosion, is given and the currently accepted Planck temperature of ≅1032 K at the beginning of the big bang is predicted
Unified Description of Plausible Cause and Effect of the Big Bang
Choudhury, D. C.
2001-01-01
Plausible cause and effect of the big bang model are presented without violating conventional laws of physics. The initial cosmological singularity is resolved by introducing the uncertainty principle of quantum theory. We postulate that, preceding the big bang at the end of the gravitational collapse, the total observed mass including all forms of energy of the universe condensed into the primordial black hole (PBH) in a state of isotropic and minimal chaos (i.e., nearest to the absolute zer...
An Extension of Friedmann-Robertson-Walker Theory beyond Big Bang
Schroeter, Joachim
2009-01-01
Starting from the classic Friedmann–Robertson–Walker theory with big bang it is shown that the solutions of the field equations can be extended to negative times. Choosing a new cosmic time scale instead of proper time one achieves complete differentiability of the scale factor and of suitable thermodynamic quantities equivalent to pressure and energy density. Then, the singularity of big bang manifests itself only by the vanishing of the scale factor at time zero. Moreover,...
The Friedmann-Lemaître-Robertson-Walker Big Bang Singularities are Well Behaved
Stoica, Ovidiu Cristinel
2016-01-01
We show that the Big Bang singularity of the Friedmann-Lemaître-Robertson-Walker model does not raise major problems to General Relativity. We prove a theorem showing that the Einstein equation can be written in a non-singular form, which allows the extension of the spacetime before the Big Bang. The physical interpretation of the fields used is discussed. These results follow from our research on singular semi-Riemannian geometry and singular General Relativity.
Fate of classical tensor inhomogeneities in pre-big-bang string cosmology
International Nuclear Information System (INIS)
In pre-big-bang string cosmology one uses a phase of dilaton-driven inflation to stretch an initial (microscopic) spatial patch to the (much larger) size of the big-bang fireball. We show that the dilaton-driven inflationary phase does not naturally iron out the initial classical tensor inhomogeneities unless the initial value of the string coupling is smaller than gin∼-35
Mass-Boom Versus Big-Bang: An Alternative Model
Alfonso-Faus, Antonio
2006-03-01
In an effort to advance a first step in the long journey to harmonize Einstein's General Relativity with Quantum Mechanics, we interpret the gravitational field as a sea of gravity quanta. We calculate the value of the mass of these quanta by imposing the condition that their energy cannot be localized in the Universe (a General Relativity property of the gravitational field energy). These quanta have negative energy that is emitted in each quantum, one by one, from every fundamental particle with gravitational properties. It follows that the emitting positive masses increase their value linearly with cosmological time (this effect is what we call the Mass-Boom and is present in the entire Universe). In particular, it turns out that the mass of the Universe M is equivalent to its age t, and to its gravitational entropy S, (i.e. M = t = S), in a certain system of units that convert many fundamental laws to very simple relations. This is the Mass- Boom cosmological model, which we have published elsewhere under various points of view (all giving the same result). The Mass-Boom cosmological model is identical to the one that Einstein initially proposed: a static, finite, curved and unlimited model, that today we know is stable. The Hubble observation of the red shifts, as a possible indication of an expanding Universe, is here interpreted in a very different way: we consider our LAB systems not to be rigid, fixed in size. If the Universe is the static (rigid) general reference, as Einstein first saw, then the Hubble observations must be interpreted as a proof of a local shrinkage of the quantum world. Instead of an expanding Universe we get the picture of a contracting quantum world. This new view is very well justified because it explains many of the problems that have plagued the standard model (the big-bang). It also eliminates the need for additions/corrections to the standard model, like the addition of ``inflation'', to solve the inconsistencies of the model
Beyond Einstein: From the Big Bang to Black Holes
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
Classical propagation of strings across a big crunch/big bang singularity
International Nuclear Information System (INIS)
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).][P. J. Steinhardt and N. Turok, Science 296, 1436 (2002).][N. Turok, M. Perry, and P. J. Steinhardt, Phys. Rev. D 70, 106004 (2004).]. 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
Classical Propagation of Strings across a Big Crunch/Big Bang Singularity
Niz, Gustavo(Departamento de Física, Universidad de Guanajuato, DCI, Campus León, C.P. 37150, León, Guanajuato, México); Turok, Neil
2006-01-01
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 Z_2, the space-time represents two orbifold planes which collide and re-emerge, a process proposed as an explanation of the hot big bang. 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 suf...
The exact parity symmetric model and big bang nucleosynthesis
International Nuclear Information System (INIS)
The assumption of exact, unbroken parity symmetry leads directly to a simple predictive resolution of the atmospheric and solar neutrino puzzles. This is because the existence of this symmetry implies the existence of a set of mirror neutrinos which must mix maximally with the known neutrinos if neutrinos have mass. the maximal mixing of the electron neutrino with the mirror electron neutrino with 3 x 10-10 eV2 ≤ |δm2| ≤ 10-3 eV2 leads to a predicted reduction of the solar neutrino flux by-a factor of 2, which is in quite good agreement with the experiments. The maximal mixing of the muon neutrino with the mirror muon neutrino with |δm2| ∼ 10-2 eV2 also solves the atmospheric neutrino puzzle. We show that there is a significant range of parameters where these solutions are not in conflict with standard Big Bang Nucleosynthesis when the creation of lepton asymmetry due to neutrino oscillations is taken into account. (authors)
Big-bang nucleosynthesis in the new cosmology
International Nuclear Information System (INIS)
Big bang nucleosynthesis (BBN) describes the production of the lightest elements in the first minutes of cosmic time. I will review the physics of cosmological element production, and the observations of the primordial element abundances. The comparison between theory and observation has heretofore provided our earliest probe of the universe, and given the best measure of the cosmic baryon content. However, BBN has now taken a new role in cosmology, in light of new precision measurements of the cosmic microwave background (CMB). Recent CMB anisotropy data yield a wealth of cosmological parameters; in particular, the baryon-to-photon ratio η = nB/nγ is measured to high precision. The confrontation between the BBN and CMB 'baryometers' poses a new and stringent test of the standard cosmology; the status of this test will be discussed. Moreover, it is now possible to recast the role of BBN by using the CMB to fix the baryon density and even some light element abundances. This strategy sharpens BBN into a more powerful probe of early universe physics, and of galactic nucleosynthesis processes. The impact of the CMB results on particle physics beyond the Standard Model, and on non-standard cosmology, will be illustrated. Prospects for improvement of these bounds via additional astronomical observations and nuclear experiments will be discussed, as will the lingering 'lithium problem.' (author)
Big Bang Nucleosynthesis in Visible and Hidden-Mirror Sectors
International Nuclear Information System (INIS)
One of the still viable candidates for the dark matter is the so-called mirror matter. Its cosmological and astrophysical implications were widely studied, pointing out the importance to go further with research. In particular, the Big Bang nucleosynthesis provides a strong test for every dark matter candidate, since it is well studied and involves relatively few free parameters. The necessity of accurate studies of primordial nucleosynthesis with mirror matter has then emerged. I present here the results of accurate numerical simulations of the primordial production of both ordinary nuclides and nuclides made of mirror baryons, in presence of a hidden mirror sector with unbroken parity symmetry and with gravitational interactions only. These elements are the building blocks of all the structures forming in the Universe; therefore, their chemical composition is a key ingredient for astrophysics with mirror 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 7Li. For the mirror nuclides, instead, one observes an enhanced production of 4He, which becomes the dominant element for x≲0.5, and much larger abundances of heavier elements
Did something decay, evaporate, or annihilate during big bang nucleosynthesis?
International Nuclear Information System (INIS)
Results of a detailed examination of the cascade nucleosynthesis resulting from the putative hadronic decay, evaporation, or annihilation of a primordial relic during the big bang nucleosynthesis (BBN) era are presented. It is found that injection of energetic nucleons around cosmic time 103 s may lead to an observationally favored reduction of the primordial 7Li/H yield by a factor 2-3. Moreover, such sources also generically predict the production of the 6Li isotope with magnitude close to the as yet unexplained high 6Li abundances in low-metallicity stars. The simplest of these models operates at a fractional contribution to the baryon density Ωbh2 > or approx. 0.025, slightly larger than that inferred from standard BBN. Though further study is required, such sources, as, for example, due to the decay of the next-to-lightest supersymmetric particle into GeV gravitinos or the decay of an unstable gravitino in the TeV range of abundance ΩGh2∼5x10-4 show promise to explain both the 6Li and 7Li abundances in low-metallicity stars
big bang gene modulates gut immune tolerance in Drosophila.
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. PMID:23378635
The big bang and inflation united by an analytic solution
International Nuclear Information System (INIS)
Exact analytic solutions for a class of scalar-tensor gravity theories with a hyperbolic scalar potential are presented. Using an exact solution we have successfully constructed a model of inflation that produces the spectral index, the running of the spectral index, and the amplitude of scalar perturbations within the constraints given by the WMAP 7 years data. The model simultaneously describes the big bang and inflation connected by a specific time delay between them so that these two events are regarded as dependent on each other. In solving the Friedmann equations, we have utilized an essential Weyl symmetry of our theory in 3+1 dimensions which is a predicted remaining symmetry of 2T-physics field theory in 4+2 dimensions. This led to a new method of obtaining analytic solutions in the 1T field theory which could in principle be used to solve more complicated theories with more scalar fields. Some additional distinguishing properties of the solution includes the fact that there are early periods of time when the slow-roll approximation is not valid. Furthermore, the inflaton does not decrease monotonically with time; rather, it oscillates around the potential minimum while settling down, unlike the slow-roll approximation. While the model we used for illustration purposes is realistic in most respects, it lacks a mechanism for stopping inflation. The technique of obtaining analytic solutions opens a new window for studying inflation, and other applications, more precisely than using approximations.
General relativity cosmological models without the big bang
International Nuclear Information System (INIS)
Attention is given to the so-called standard model of the universe in the framework of the general theory of relativity. This model is taken to be homogeneous and isotropic and filled with an ideal fluid characterized by a density and a pressure. Taking into consideration, however, the assumption that the universe began in a singular state, it is found hard to understand why the universe is so nearly homogeneous and isotropic at present for a singularity represents a breakdown of physical laws, and the initial singularity cannot, therefore, predetermine the subsequent symmetries of the universe. The present investigation has the objective to find a way of avoiding this initial singularity, i.e., to look for a cosmological model without the big bang. The idea is proposed that there exists a limiting density of matter of the order of magnitude of the Planck density, and that this was the density of matter at the moment at which the universe began to expand
Understanding big bang in loop quantum cosmology: Recent advances
International Nuclear Information System (INIS)
We discuss the way non-perturbative quantization of cosmological spacetimes in loop quantum cosmology provides insights on the physics of Planck scale and the resolution of big bang singularity. In recent years, rigorous examination of mathematical and physical aspects of the quantum theory, have singled out a consistent quantization which is physically viable and various early ideas have been shown to be inconsistent. These include 'physical effects' originating from modifications to inverse scale factors in the flat models. The singularity resolution is understood to originate from the non-local nature of curvature in the quantum theory and the underlying polymer representation. Based on insights from extensive numerical simulations, an exactly solvable model involving a small approximation at the quantum level can be developed. The model predicts occurrence of bounce for a dense subspace of the Hilbert space and a supremum for the value of energy density. It also provides answers to the growth of fluctuations, showing that semi-classicality is preserved to an amazing degree across the bounce.
Constraint on slepton intergenerational mixing from big-bang nucleosynthesis
International Nuclear Information System (INIS)
We find constraint on intergenerational mixing of slepton from big-bang nucleosynthesis (BBN). Today, we know that there exist lepton flavor violation (LFV) from the observation of neutrino oscillation, though there do not exist LFV in the standard model of particle physics (SM). LFV in charged lepton sector (cLFV) have also been expected to exist. From theoretical point of view, the effects of long-lived stau on BBN have been investigated and it is known that the stau can solve the cosmological 7Li problem. However, in the study so far, tau flavor is exactly conserved and it contradict with the existence of cLFV. In this study, we generalize the flavor to be violated and call the stau as slepton. Even if the violation is tiny, it drastically changes the lifetime and the evolution of relic density of the slepton. Thus we analyze the effects of the long-lived slepton on BBN, and constrain the magnitude of the cLFV.
Big bang nucleosynthesis and physics beyond the standard model
International Nuclear Information System (INIS)
The Hubble expansion of galaxies, the 2.73 K black-body radiation background and the cosmic abundances of the light elements argue for a hot, dense origin of the universe - the standard big bang cosmology - and enable its evolution to be traced back fairly reliably to the nucleosynthesis era when the temperature was of O(1) MeV corresponding to an expansion age of O(1) s. All particles, known and hypothetical, would have been created at higher temperatures in the early universe and analyses of their possible effects on the abundances of the synthesized elements enable many interesting constraints to be obtained on particle properties. These arguments have usefully complemented laboratory experiments in guiding attempts to extend physics beyond the standard SU(3)cxSU(2)LxU(1)Y model, incorporating ideas such as supersymmetry, compositeness and unification. We first present a pedagogical account of relativistic cosmology and primordial nucleosynthesis, discussing both theoretical and observational aspects, and then proceed to examine such constraints in detail, in particular those pertaining to new massless particles and massive unstable particles. Finally, in a section aimed at particle physicists, we illustrate applications of such constraints to models of new physics. (author)
Constraining pre-big-bang nucleosynthesis expansion using cosmic antiprotons
International Nuclear Information System (INIS)
A host of dark energy models and nonstandard 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 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 nonstandard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model
Big bang nucleosynthesis and CMB constraints on dark energy
International Nuclear Information System (INIS)
Current observational data favor cosmological models which differ from the standard model due to the presence of some form of dark energy and, perhaps, by additional contributions to the more familiar dark matter. Primordial nucleosynthesis provides a window on the very early evolution of the universe and constraints from big bang nucleosynthesis (BBN) can bound the parameters of models for dark matter or energy at redshifts of the order of ten billion. The spectrum of temperature fluctuations imprinted on the cosmic microwave background (CMB) radiation opens a completely different window on the universe at epochs from redshifts of the order of ten thousand to nearly the present. The CMB anisotropy spectrum provides constraints on new physics which are independent of and complementary to those from BBN. Here we consider three classes of models for the dark matter or energy: extra particles which were relativistic during the early evolution of the universe ('X'); quintessence models involving a minimally coupled scalar field ('Q'); models with a non-minimally coupled scalar field which modify the strength of gravity during the early evolution of the universe ('G'). We constrain the parameters of these models using data from BBN and the CMB and identify the allowed regions in their parameter spaces consistent with the more demanding joint BBN and CMB constraints. For 'X' and 'Q' such consistency is relatively easy to find; it is more difficult for the 'G' models with an inverse power law potential for the scalar field
Brane big bang brought on by a bulk bubble
International Nuclear Information System (INIS)
We propose an alternative inflationary universe scenario in the context of Randall-Sundrum braneworld cosmology. In this new scenario the existence of extra dimension(s) plays an essential role. First, the brane universe is initially in the inflationary phase driven by the effective cosmological constant induced by a small mismatch between the vacuum energy in the five-dimensional bulk and the brane tension. This mismatch arises since the bulk is initially in a false vacuum. Then, false vacuum decay occurs, nucleating a true vacuum bubble with negative energy inside the bulk. The nucleated bubble expands in the bulk and consequently hits the brane, causing a hot big-bang brane universe of the Randall-Sundrum type. Here, the termination of the inflationary phase is due to the change of the bulk vacuum energy. The bubble kinetic energy heats up the universe. As a simple realization, we propose a model in which we assume an interaction between the brane and the bubble. We derive the constraints on the model parameters taking into account the following requirements: solving the flatness problem, no force which prohibits the bubble from colliding with the brane, a sufficiently high reheating temperature for the standard nucleosynthesis to work, and the recovery of Newton's law up to 1 mm. We find that a fine-tuning is needed in order to satisfy the first and the second requirements simultaneously, although the other constraints are satisfied in a wide range of the model parameters
Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons
International Nuclear Information System (INIS)
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.)
Quark-mass variation effect on big bang nucleosynthesis
International Nuclear Information System (INIS)
We calculate the effect of variation in the light-current quark mass, mq, on standard big bang nucleosynthesis. A change in mq at during the era of nucleosynthesis affects nuclear reaction rates, and hence primordial abundances, via changes the binding energies of light nuclei. It is found that a relative variation of δmq/mq = 0.016 ± 0.005 provides better agreement between observed primordial abundances and those predicted by theory. This is largely due to resolution of the existing discrepancies for 7Li. However this method ignores possible changes in the position of resonances in nuclear reactions. The predicted 7Li abundance has a strong dependence on the cross-section of the resonant reactions 3He (d, p) 4He and t (d, n) 4He. We show that changes in mq at the time of BBN could shift the position of these resonances away from the Gamow window and lead to an increased production of 7Li, exacerbating the lithium problem.
Big bang nucleosynthesis constraints on the tau neutrino mass
International Nuclear Information System (INIS)
We re-examine the effect of a massive τ neutrino on primordial nucleosynthesis. An improved calculation of the evolution of the total energy density is presented for both a stable τ neutrino, and for the case where the τ neutrino decays into a lighter neutrino and a scalar. The production of light elements in big bang nucleosynthesis is calculated for the stable τ neutrino and for the unstable case. Using observational limits on the abundances of 4He, D+3He, and 7Li, we constrain the allowed mass and lifetime of ντ. We find that the only range allowed for the mass and lifetime is either mντν> or ∼10-2 s and mντν/10-2 s) MeV for τν-2 s, or 5-10 MeVντ≤qslant31 MeV provided that τνντ from τ→5π±ντ. Tau neutrinos with lifetimes longer than 40 s are excluded by BBN in the mass interval 0.1 MeVντ< or ∼50 MeV. ((orig.))
Big bang nucleosynthesis constraints on massive, unstable neutrinos
International Nuclear Information System (INIS)
The tau-neutrino, if sufficiently massive, must be unstable. Big Bang Nucleosynthesis (BBN) can provide constraints on the ντ mass and lifetime. The modification to the energy density of the early Universe in the case of a massive τ-neutrino which decays via ντ→νμ+φ (where φ is a weakly coupled massless scalar) is described and the results of BBN production of the light elements is presented. Consistency with the primordial abundances of D, 3He, 7Li and, especially, 4He leads to constraints on the mass (mντ) and lifetime (τντ) of the tau-neutrino. Very massive ντ (mντ≥5-10MeV), up to the ARGUS bound of 31MeV, are only allowed for short lifetimes (≤qslant40sec). Much lighter (mντ≤qslant0.01MeV) ντ are permitted for lifetimes longer than similar 0.01sec but, mντ(MeV)≤qslant10τν(sec) for shorter lifetimes. ((orig.))
The B-Factory and the Big Bang
International Nuclear Information System (INIS)
A B-Factory, a virtual open-quotes time machineclose quotes back to the early moments of the Big Bang that created the universe, is not under construction at the Stanford Linear Accelerator Center (SLAC). The $300 million project to produce copious amounts of B mesons is a combined effort of SLAC, Lawrence Berkeley National Laboratory, and Lawrence Livermore National Laboratory. Scheduled for completion in early 1999, the facility will be one of the flagships of the US high-energy physics program. Nearly 200 Laboratory specialists, representing a broad range of disciplines, are contributing to the B-Factory effort. The B-Factory's two underground rings, each 2,200 meters (a mile and a half) in circumference, will generate B mesons by colliding electron and positrons (antimatter counterpart of electrons) at near the speed of light. A key feature of this collider is the fact that electrons and positrons will circulate and collide with unequal (or open-quotes asymmetricclose quotes) energies so that scientists can to better explore the particles generated in the collisions. In helping to design and manufacture many of the major components and detector systems for the B-Factory's twin particle beam rings and its three-story-tall detector, Lawrence Livermore is strengthening its reputation as a center of excellence for accelerator science and technology. In addition, many LLNL capabilities brought to bear on the technical challenges of the B-Factory are enhancing the Laboratory's efforts for the DOE Stockpile Stewardship Program
A few millionth of second after the big-bang
International Nuclear Information System (INIS)
In february 2000 CERN announced the existence of a new state of the matter: the quark and gluon plasma. This announcement was important because it means that we got a glimpse of what was the universe at the origin, for according to the big-bang theory such a plasma filled the universe a few millionth of second after its birth. The plasma of quarks and gluons appears when quarks and gluons are no longer confined in hadron particles and can interact with one another freely. This state is created in high energy ion collisions and lasts too little time to be detected so its existence is revealed through a series of hints called signatures. The first hint is the emission of an electromagnetic radiation whose spectrum is similar to that of a black body. The second hint is the decrease of the number of J/Ψ particles created at the moment of the collision when the energy of the colliding ion increases. The third hint is an increased production of strange quarks. Four months after this announcement RHIC entered into service, this ion collider allows to reach higher energies and the first preliminary results have confirmed the existence of a quark and gluon plasma. (A.C.)
Neutrino energy transport in weak decoupling and big bang nucleosynthesis
Grohs, E.; Fuller, G. M.; Kishimoto, C. T.; Paris, M. W.; Vlasenko, A.
2016-04-01
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 multienergy group Boltzmann neutrino energy transport scheme. The modular structure of our code provides the ability to dissect the relative contributions of each process responsible for evolving the dynamics of the early universe in the absence of neutrino flavor oscillations. Such an approach allows a detailed accounting of the evolution of the νe, ν¯e, νμ, ν¯μ, ντ, ν¯τ energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and flow between the neutrino and photon/electron/positron/baryon plasma components. This calculation reveals nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions (e.g., electron-positron pair densities), with implications for the phasing between scale factor and plasma temperature; the neutron-to-proton ratio; light-element abundance histories; and the cosmological parameter Neff. We find that our approach of following the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma results in changes in the computed value of the BBN deuterium yield. For example, for particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium. These changes are potentially significant in the context of anticipated improvements in observational and nuclear physics uncertainties.
Astrophysical Li-7 as a product of big bang nucleosynthesis and galactic cosmic-ray spallation
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.
Inflationary and deflationary branches in extended pre-big-bang cosmology
International Nuclear Information System (INIS)
The pre-big-bang cosmological scenario is studied within the context of the Brans-Dicke theory of gravity. An epoch of superinflationary expansion may occur in the pre-big-bang phase of the Universe close-quote s history in a certain region of parameter space. Two models are considered that contain a cosmological constant in the gravitational and matter sectors of the theory, respectively. Classical pre- and post-big-bang solutions are found for both models. The existence of a curvature singularity forbids a classical transition between the two branches. On the other hand, a quantum cosmological approach based on the tunneling boundary condition results in a nonzero transition probability. The transition may be interpreted as a spatial reflection of the wave function in minisuperspace. copyright 1997 The American Physical Society
Pre-big-bang cosmology and circles in the cosmic microwave background
International Nuclear Information System (INIS)
We examine the possibility that circles in the cosmic microwave background could be formed by the interaction of a gravitational wave pulse emitted in some pre-big-bang phase of the universe with the last scattering surface. We derive the expected size distribution of such circles, as well as their typical ring width and (for concentric circles) angular separation. We apply these results, in particular, to conformal cyclic cosmology, ekpyrotic cosmology as well as loop quantum cosmology with and without inflation in order to determine how the predicted geometric properties of these circles would vary from one model to the other, and thus, if detected, could allow us to differentiate between various pre-big-bang cosmological models. We also obtain a relation between the angular ring width and the angular radius of such circles that can be used in order to determine whether or not circles observed in the cosmic microwave background are due to energetic pre-big-bang events.
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.
Inhomogeneous Big Bang Nucleosynthesis and the High Baryon Density Suggested by Boomerang and MAXIMA
Kurki-Suonio, Hannu; Sihvola, Elina
2000-01-01
The recent Boomerang and MAXIMA data on the cosmic microwave background suggest a large value for the baryonic matter density of the universe, omega_b = 0.03. This density is larger than allowed by standard big bang nucleosynthesis theory and observations on the abundances of the light elements. We explore here the possibility of accommodating this high density in inhomogeneous big bang nucleosynthesis (IBBN). It turns out that in IBBN the observed D and Y_p values are quite consistent with t...
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.
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.
The Big Bang and the Search for a Theory of Everything
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.
Kasner asymptotics of mixmaster Horava-Witten and pre-big-bang cosmologies
International Nuclear Information System (INIS)
We discuss various superstring effective actions and, in particular, their common sector which leads to the so-called pre-big-bang cosmology (cosmology in a weak coupling limit of heterotic superstring theory. Using the conformal relationship between these two theories we present Kasner asymptotic solutions of Bianchi type IX geometries within these theories and make predictions about possible emergence of chaos. Finally, we present a possible method of generating Horava-Witten cosmological solutions out of the well-known general relativistic or pre-big-bang solutions
Superhorizon curvaton amplitude in inflation and pre-big bang cosmology
DEFF Research Database (Denmark)
Sloth, Martin Snoager
2002-01-01
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...
Quantum Big Bang without fine-tuning in a toy-model
International Nuclear Information System (INIS)
The question of possible physics before Big Bang (or after Big Crunch) is addressed via a schematic non-covariant simulation of the loss of observability of the Universe. Our model is drastically simplified by the reduction of its degrees of freedom to the mere finite number. The Hilbert space of states is then allowed time-dependent and singular at the critical time t = tc. This option circumvents several traditional theoretical difficulties in a way illustrated via solvable examples. In particular, the unitary evolution of our toy-model quantum Universe is shown interruptible, without any fine-tuning, at the instant of its bang or collapse t = tc.
Beyond the Friedmann—Lemaître—Robertson—Walker Big Bang Singularity
International Nuclear Information System (INIS)
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—Lemaître—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.
Astrophysical S-factor for destructive reactions of lithium-7 in big bang nucleosynthesis
International Nuclear Information System (INIS)
One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for 4He. 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 7L(3He,p)9Be reaction
From big bang to bing bang - From the origin of the universe to the origin of the solar system
Lee, L.
An outline is given of the evolution of the Galaxy between the Big Bang and the Bing Bang (explosions of supernovae billions of years ago, providing materials and possibly the impetus for the formation of the solar system). During the long interval prior to the birth of the sun, the Galaxy evolved by converting gas to stars and by enriching the gas with heavy elements created in the stars. Some radioactive nuclides suggest that the interval between their production in stellar sources and the accumulation of planets of at least a few kilometers in size was only a few million years. The formation of the sun may have taken place in a stellar association and may have been preceded immediately by SN-type explosions, which may even have been the triggering mechanism of the formation process.
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.
From the big bang to the eureka moment
International Nuclear Information System (INIS)
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. Hawking told the meeting that he wants this simple equation (S
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
Licata, Ignazio; Chiatti, Leonardo
2008-01-01
This article proposes some cosmological reflections at the qualitative and conjectural level, suggested by the Fantappie & Arcidiacono projective relativity theory. The difference will firstly be discussed between two types of singularity in this theory: geometric (de Sitter horizon) and physical (big bang, big crunch). The reasons for the existence of geometric singularities are deeply rooted in the principle of inertia and in the principle of relativity, while physical singularities are ass...
Phenomenological Aspects of the Pre-Big-Bang Scenario in String Cosmology
Gasperini, M.
1994-01-01
I review various aspects of the pre-big-bang scenario and of its main open problems, with emphasis on the role played by the dilaton. Since the dilaton is a compelling consequence of string theory, tests of this scenario are direct tests of string theory and also, more generally, of Planck scale physics.
Entropy generation and inflation in collision induced pre-big-bang cosmology
A. Feinstein; K.E. Kunze; M.A. Vazquez-Mozo
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
Initial conditions and the structure of the singularity in pre-big-bang cosmology
A. Feinstein; K.E. Kunze; M.A. Vazquez-Mozo
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
After the Big Bang: What's Next in Design Education? Time to Relax?
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…
Limits to the primordial helium abundance in the baryon-inhomogeneous big bang
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.
From the Big Bang to the Nobel Prize and on to James Webb Space Telescope
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.
From the Big Bang to the Nobel Prize and on to the James Webb Space Telescope
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.
Occurrence of an iterative exponential function in cosmology without the big bang singularity
International Nuclear Information System (INIS)
Application of the 5-dimensional Projective Unified Field Theory of the author to a homogeneous isotropic and spherical-symmetric cosmological model leads to a regular solution of the field equations. On the way to this non-big-bang model iterative exponential functions occur, having never been met in this field of research. (authors)
Big bang nucleosynthesis constraints on the self-gravity of pressure
International Nuclear Information System (INIS)
Using big bang nucleosynthesis and present, high-precision measurements of light element abundances, we constrain the self-gravity of radiation pressure in the early universe. The self-gravity of pressure is strictly non-Newtonian, and thus the constraints we set provide a direct test of this prediction of general relativity and of the standard, Friedmann-Robertson-Walker cosmology
Pre-Big-Bang bubbles from the gravitational instability of generic string vacua
International Nuclear Information System (INIS)
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/inflation occurs, and, when it does, fix its characteristics, including anisotropies on the Big-Bang hypersurface whose imprint could have survived till now. Using Bayesian probability concepts, we finally attempt to answer some fine-tuning objections recently moved to the pre-Big-Bang scenario
Un experimento se acerca a las condiciones tras el Big Bang
Glanz, James
2001-01-01
A scientific team from the National Laboratory in Brookhaven, think to have reached with a particle accelerator the greatest density of matter created in an experiment. The scientists think that the last time such conditions occurred was some milliseconds after the Big Bang (0.5 page)
Big Bang Nucleosynthesis in the presence of sterile neutrinos with altered dispersion relations
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.
Dark matter relic abundance and big bang nucleosynthesis in Horava's gravity
International Nuclear Information System (INIS)
The cosmological consequences of Horava's gravity are reviewed in the frameworks of the PAMELA experiment (which has reported an excess of positron events that likely can be ascribed to weakly interacting massive particles dark matter) and of big bang nucleosynthesis. Constraints on parameters characterizing Horawa's cosmology are derived.
M theory model of a big crunch/big bang transition
International Nuclear Information System (INIS)
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 nonrelativistic 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 backreaction 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 inverse powers of α'. The conventional description of a crunch based on Einstein general relativity, involving Kasner or mixmaster behavior is misleading, we argue, because general relativity is only the leading order approximation to string theory in an expansion in positive powers of α'. In contrast, in the M theory setup we argue that interactions should be well behaved because of the smooth evolution of the fields combined with the fact that the string coupling tends to zero at the crunch. The production of massive Kaluza-Klein states should also be exponentially suppressed for small collision speeds. We contrast this good behavior with that found in previous studies of strings in Lorentzian orbifolds
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
Interview de l'astrophysicien Trinh Xuan Thuan: du Big Bang à la naissance de la vie
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
Gigantic particle collision machine does "mini Big Bangs"
2007-01-01
"The world's largest machine is reputed to be the Large Hadron Collider (LHC) at CERN in Geneva and everything about it is big. Designed to carry out high energy particle collisions, when completed next year, one of the collider's experiments includes a 10'000 ton detector." (1/2 page)
After the Big Bang? Obstacles to the emergence of the rule of law in post-communist societies
Hoff, Karla; STIGLITZ, Joseph E.
2002-01-01
With the collapse of communism in Eastern Europe and the Soviet Union in 1989-91, many economic reformers supported "Big Bang" privatization-the rapid transfer of state-owned enterprises to private individuals. It was hoped that Big Bang privatization would create the conditions for a demand-led evolution of legal institutions. But there was no theory to explain how this process of institu...
Big-Bang Nucleosynthesis from B^2FH to 21st-Century Cosmology
Fields, Brian
2007-04-01
In majestically laying out the case for element synthesis in stars, B^2FH deliberately avoided primordial nucleosynthesis; nevertheless, they identified stellar sources and sinks for the lightest elements and presciently laid out issues which have remained at the center of big-bang nucleosynthesis (BBN) through to the the present. We will briefly review the theory of cosmological nucleosynthesis (to which Hoyle and Fowler made pivotal contributions) and its broad concordance with observed light element abundances; this agreement not only marks a great success for the hot big bang, but also measures the cosmic baryon density. BBN takes a changing but still central role in the dawning era of precision cosmology: measurements of the cosmic baryon density by WMAP and large-scale structure observations provide an independent test of BBN and cosmology. The status of this test will be discussed, as will implications for dark matter and dark energy.
Superhorizon curvaton amplitude in inflation and pre-big bang cosmology
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.
Emergence of a Big Bang singularity in an exact string background
Hirano, Shinji
2007-01-01
The origin of Big Bang singularity in 3+1 dimensions can be understood in an exact string theory background obtained by an analytic continuation of a cigar like geometry with a nontrivial dilaton. In a T-dual conformal field theory picture there exists a closed string tachyon potential which excises the singular space-time of a strongly coupled regime to ensure that a higher dimensional universe has no curvature singularity. However in 3+1 dimensions the universe exhibits all the pathology of a standard Big Bang cosmology. The emergence of a singularity now owes to a higher dimensional orbifold singularity which does not have a curvature singularity in higher dimensions, suggesting that close to the compactification scale an effective description of 3+1 dimensions breaks down and bouncing universe emerges in 5 and higher dimensions.
Observable gravitational waves in pre-big bang cosmology: an update
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.
The music of the Big Bang the cosmic microwave background and the new cosmology
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...
Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis
International Nuclear Information System (INIS)
The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the high-intensity gamma-ray source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang nucleosynthesis. Our data are in excellent agreement with potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density ΩBh2 obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%
The structure of the big bang from higher-dimensional embeddings
International Nuclear Information System (INIS)
We give relations for the embedding of spatially-flat Friedmann-Robertson-Walker cosmological models of Einstein's theory in flat manifolds of the type used in Kaluza-Klein theory. We present embedding diagrams that depict different 4D universes as hypersurfaces in a higher-dimensional flat manifold. The morphology of the hypersurfaces is found to depend on the equation of state of the matter. The hypersurfaces possess a line-like curvature singularity infinitesimally close to the t 0+ 3-surface, where t is the time expired since the big bang. The family of timelike comoving geodesics on any given hypersurface is found to have a caustic on the singular line, which we conclude is the 5D position of the point-like big bang
Effects of variation of fundamental constants from big bang to atomic clocks
International Nuclear Information System (INIS)
Full text: 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 alpha=e2/h c, strong interaction and quark mass. The measurements of these variations cover lifespan of the Universe from few minutes after Big Bang to the present time and give controversial results. There are some hints for the variation 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 transition between accidentally degenerate atomic energy levels. Copyright (2005) Australian Institute of Physics
Time, space, stars and man the story of the Big Bang
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...
Sufficient conditions for a period incrementing big bang bifurcation in one-dimensional maps
International Nuclear Information System (INIS)
Typically, big bang bifurcation occurs for one (or higher)-dimensional piecewise-defined discontinuous systems whenever two border collision bifurcation curves collide transversely in the parameter space. At that point, two (feasible) fixed points collide with one boundary in state space and become virtual, and, in the one-dimensional case, the map becomes continuous. Depending on the properties of the map near the codimension-two bifurcation point, there exist different scenarios regarding how the infinite number of periodic orbits are born, mainly the so-called period adding and period incrementing. In our work we prove that, in order to undergo a big bang bifurcation of the period incrementing type, it is sufficient for a piecewise-defined one-dimensional map that the colliding fixed points are attractive and with associated eigenvalues of different signs
Reheating and dangerous relics in pre-big-bang string cosmology
International Nuclear Information System (INIS)
We discuss the mechanism of reheating in pre-big-bang string cosmology and we calculate the amount of moduli and gravitinos produced gravitationally and in scattering processes of the thermal bath. We find that this abundance always exceeds the limits imposed by big-bang nucleosynthesis, and significant entropy production is required. The exact amount of entropy needed depends on the details of the high curvature phase between the dilaton-driven inflationary era and the radiation era. We show that the domination and decay of the zero-mode of a modulus field, which could well be the dilaton, or of axions, suffices to dilute moduli and gravitinos. In this context, baryogenesis can be accommodated in a simple way via the Affleck-Dine mechanism and in some cases the Affleck-Dine condensate could provide both the source of entropy and the baryon asymmetry
Compilation and R-matrix analysis of Big Bang nuclear reaction rates
Descouvemont, Pierre; Adahchour, Abderrahim; Angulo, Carmen; Coc, Alain; Vangioni-Flam, Elisabeth
2004-01-01
We use the R-matrix theory to fit low-energy data on nuclear reactions involved in Big Bang nucleosynthesis. A special attention is paid to the rate uncertainties which are evaluated on statistical grounds. We provide S factors and reaction rates in tabular and graphical formats. Comment: 40 pages, accepted for publication at ADNDT, web site at http://pntpm3.ulb.ac.be/bigbang
Constraints on pre-big bang parameter space from CMBR anisotropies
Bozza, V.; Gasperini, M.; Giovannini, M.; Veneziano, G.
2002-01-01
The so-called curvaton mechanism --a way to convert isocurvature perturbations into adiabatic ones-- is investigated both analytically and numerically in a pre-big bang scenario where the role of the curvaton is played by a sufficiently massive Kalb--Ramond axion of superstring theory. When combined with observations of CMBR anisotropies at large and moderate angular scales, the present analysis allows us to constrain quite considerably the parameter space of the model: in particular, the ini...
The 'Big Bang' theory reconsidered: Some thoughts on the fabric of early Ghanaian history
Chouin, Gérard
2012-01-01
Paper presented at the 50th Anniversary Conference, Centre of African Studies, University of Edinburgh, 6-8 June 2012; Panel on 'Recent Research in the Early Modern History of Atlantic Africa' The 'big bang' theory - best articulated by Ivor Wilks in the late 1970s and recently revisited - is a complex heuristic monument that must be carefully deconstructed. Its claim that before the integration of forested West Africa into the European bullion market and the opening of the Atlantic trade,...
The Cold Big-Bang Cosmology as a Counter-example to Several Anthropic Arguments
Aguirre, Anthony
2001-01-01
A general Friedmann big-bang cosmology can be specified by fixing a half-dozen cosmological parameters such as the photon-to-baryon ratio Eta, the cosmological constant Lambda, the curvature scale R, and the amplitude Q of (assumed scale-invariant) primordial density fluctuations. There is currently no established theory as to why these parameters take the particular values we deduce from observations. This has led to proposed `anthropic' explanations for the observed value of each parameter,...
Effects of anisotropy and spatial curvature on the pre-big bang scenario
Clancy, D.; Lidsey, J. E.; Tavakol, R.
1998-01-01
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 VI_h models and the spatially isotropic, negatively curved Friedmann-Robertson-Walker universe. The effects of large anisotropy and spatial curvature are determined. In contrast to negatively curved Friedmann-Robertson-Walker model, there exist regions of the parameter space in whi...
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.
Le big bang n'est pas une théorie comme les autres
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...
Calixarenes and cations: a time-lapse photography of the big-bang.
Casnati, Alessandro
2013-08-01
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. PMID:23792898
Gamma-rays and the case for baryon symmetric big-bang cosmology
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.
Gauge-invariant gravitational wave modes in pre-big bang cosmology
International Nuclear Information System (INIS)
The t<0 branch of pre-big bang cosmological scenarios is subject to a gravitational wave instability. The unstable behaviour of tensor perturbations is derived in a very simple way in Hwang's covariant and gauge-invariant formalism developed for extended theories of gravity. A simple interpretation of this instability as the effect of an ''antifriction'' is given, and it is argued that a universe must eventually enter the expanding phase. (orig.)
Physics and the Making of ``The Big Bang'' TV Comedy Series
Saltzberg, David
2010-03-01
For the last three years I have served as the physics consultant for the popular television situation-comedy ``The Big Bang Theory'' which features physicists, astronomers, and engineers as its main characters. I will describe my role in the production. I will also describe the opportunities it has afforded for public outreach for physics and astronomy education. Based on my experience, I will discuss methods for interested scientists to get involved in the entertainment industry.
The moment of creation big bang physics from before the first millisecond to the present universe
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.
Can the Big Bang singularity be avoided by a single scalar field?
International Nuclear Information System (INIS)
In this paper, we investigate the possibility of avoiding the Big Bang singularity with a single scalar field which couples non-minimally to gravity. We show that in the case when gravity couples linearly to the field, some severe conditions on the field's potential have to be imposed. However, in the nonlinear case, it is quite generic to avoid the singularity with the single scalar field.
Hannaske, R.; Bemmerer, D.; Beyer, R.; Birgersson, E.; Ferrari, A.; Grosse, E.; Junghans, A. R.; Kempe, M.; Kögler, T.; Kosev, K.; Marta, M.; Massarczyk, R.; Matic, A.; Schilling, K. D.; Schramm, G.; Schwengner, R.; Wagner, A.; Yakorev, D.
2016-01-01
The photodissociation of the deuteron is a key reaction in Big Bang nucleosynthesis, but is only sparsely measured in the relevant energy range. To determine the cross section of the d(γ,n)p reaction we used pulsed bremsstrahlung and measured the time-of-flight of the neutrons. In this article, we describe how the efficiency of the neutron detectors was experimentally determined and how the modification of the neutron spectrum by parts of the experimental setup was simulated and corrected.
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.
The new Big Bang Theory according to dimensional continuous space-time theory
International Nuclear Information System (INIS)
This New View of the Big Bang Theory results from the Dimensional Continuous Space-Time Theory, for which the introduction was presented in [1]. This theory is based on the concept that the primitive Universe before the Big Bang was constituted only from elementary cells of potential energy disposed side by side. In the primitive Universe there were no particles, charges, movement and the Universe temperature was absolute zero Kelvin. The time was always present, even in the primitive Universe, time is the integral part of the empty space, it is the dynamic energy of space and it is responsible for the movement of matter and energy inside the Universe. The empty space is totally stationary; the primitive Universe was infinite and totally occupied by elementary cells of potential energy. In its event, the Big Bang started a production of matter, charges, energy liberation, dynamic movement, temperature increase and the conformation of galaxies respecting a specific formation law. This article presents the theoretical formation of the Galaxies starting from a basic equation of the Dimensional Continuous Space-time Theory.
Out of the white hole: a holographic origin for the Big Bang
International Nuclear Information System (INIS)
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
Novel big-bang element synthesis catalyzed by supersymmetric particle stau
International Nuclear Information System (INIS)
The extremely low isotope ratio of 6Li had remained as a drawback of the Big-Bang Nucleosynthesis (BBN) until Pospelov proposed the 6Li synthesis reaction catalyzed by negatively charged electroweak-scale particle X- in 2006. He remarked the catalytic enhancement of 6Li production by about 108 times, as well as the life and initial abundance of X-. The present authors classified BBN catalyzed reaction into six types, i.e. (1) non-resonant transfer, (2) resonant transfer, (3) non-resonant radiative capture, (4) resonant radiative capture, (5) three-body breakup and (6) charge transfer reactions to predict absolute values of cross sections which cannot be observed experimentally. Starting from the three-body treatment for those reactions, 6Li problems, the life-time and abundance of stau are discussed. Large change of element composition at 'late-time' big bang, generation of 9Be by stau catalyzed reaction, 7Li problem and stau catalyzed reactions are also discussed. Finally their relations with the supersymmetry theory and dark matter are mentioned. The basic nuclear calculations are providing quantitative base for the 'effect of nuclear reactions catalyzed by the supersymmetric particle stau on big bang nucleosynthesis'. (S. Funahashi)
Photo-nuclear reactions in the big-bang and supernovae
International Nuclear Information System (INIS)
Recent observation of the power spectrum of Cosmic Microwave Background Radiation has exhibited that the flat cosmology is most likely. This suggests too large universal baryon-density parameter Ωbh2 approx. = 0.022 - 0.030 to accept a theoretical prediction, Ωbh2 ≤ 0.017, in the homogeneous Big-Bang model for primordial nucleosynthesis. Theoretical upper limit arises from the sever constraints on the primordial 7Li abundance. We propose two cosmological models in order to resolve the discrepancy; lepton asymmetric Big-Bang nucleosynthesis model, and baryon inhomogeneous Big-Bang nucleosynthesis model. In these cosmological models the nuclear processes are similar to those of the r-process nucleosynthesis in gravitational collapse supernova explosions. Massive stars ≥ 10(solar mass) culminate their evolution by supernova explosions which are presumed to be the most viable candidate site for the r-process nucleosynthesis. Even in the nucleosynthesis of heavy elements, initial entropy and density at the surface of proto-neutron stars are so high that nuclear statistical equilibrium favors production of abundant light nuclei. In such explosive circumstances many neutron-rich radioactive nuclei of light-to-intermediate mass as well as heavy mass nuclei play the significant roles. (author)
The Passport to the Big Bang: a trail of discovery of CERN and its sites
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...
Regularization of the big bang singularity with a time varying equation of state w > 1
International Nuclear Information System (INIS)
We study the classical dynamics of the universe undergoing a transition from contraction to expansion through a big bang singularity. The dynamics is described by a system of differential equations for a set of physical quantities, such as the scale factor a, the Hubble parameter H, the equation of state parameter w, and the density parameter Ω. The solutions of the dynamical system have a singularity at the big bang. We study if the solutions can be regularized at the singularity in the sense of whether they have unique branch extensions through the singularity. In particular, we consider the model in which the contracting universe is dominated by a scalar field with a time varying equation of state w, which approaches a constant value wc near the singularity. We prove that, for wc>1, the solutions are regularizable only for a discrete set of wc values that satisfy a coprime number condition. Our result implies that the evolution of a bouncing universe through the big bang singularity does not have a continuous classical limit unless the equation of state is extremely fine-tuned. (paper)
Von Bertalanffy's dynamics under a polynomial correction: Allee effect and big bang bifurcation
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.
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.
International Nuclear Information System (INIS)
The Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory in the USA is a variable energy proton-proton and ion-ion collider that is the first accelerator capable of colliding heavy ions. RHIC was designed to do experiments that provide important information about the Standard Model of particle physics, Quantum Chromodynamics (QCD). QCD predicts that in the early part of the Universe just after the Big Bang the world consisted of a Quark Gluon Plasma, a weakly interacting collection of quarks and gluons. At RHIC we can recreate the conditions of the early Universe by colliding heavy ions at 200 GeV. This paper will give a general overview of the physics motivation for studying the QGP, how our experiments are designed to study the QGP, what we have learned over the last 9 years, and what the future holds.
Arizona State's Origins Project Starts with a Big Bang
Mangan, Katherine
2009-01-01
For 12 hours at Arizona State University, a sold-out crowd of 3,000 people gave a group of famous scientists a pop-star welcome, cheering their remarks and lining up for autographs after a day full of discussion about black holes, string theory, and evolutionary biology. At a time when program cuts and faculty layoffs dominate the headlines of…
Enigmatic Aspects of the Early Universe: Possibility of a 'Pre-Big Bang Phase'!
Sivaram, C; Arun, Kenath
2010-01-01
In this paper it is suggested that inclusion of mutual gravitational interactions among the particles in the early dense universe can lead to a 'pre-big bang' scenario, with particle masses greater than the Planck mass implying an accelerating phase of the universe, which then goes into the radiation phase when the masses fall below the Planck mass. The existence of towers of states of such massive particles (i.e. multiples of Planck mass) as implied in various unified theories, provides rapi...
The Theological Basis of Big Bang Cosmology and the Failure of General Relativity
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.
Emergence of a Big Bang singularity in an exact string background
Hirano, Shinji; mazumdar, Anupam
2007-01-01
The origin of Big Bang singularity in 3+1 dimensions can be understood in an exact string theory background obtained by an analytic continuation of a cigar like geometry with a nontrivial dilaton. In a T-dual conformal field theory picture there exists a closed string tachyon potential which excises the singular space-time of a strongly coupled regime to ensure that a higher dimensional universe has no curvature singularity. However in 3+1 dimensions the universe exhibits all the pathology of...
Quantum origin of pre-big bang collapse from Induced Matter theory of gravity
Bellini, Mauricio
2011-01-01
We revisit a collapsing pre-big-bang model of the universe to study with detail the non-perturbative quantum dynamics of the dispersal scalar field whose dynamics becomes from the dynamical foliation of test massless scalar field $\\phi$ on a 5D Riemann-flat metric, such that the extra space-like coordinate is noncompact. The important result here obtained is that the evolution of the system, which is described thorough the equation of state has the unique origin in the quantum contributions o...
Low-Energy Photodisintegration of the Deuteron and Big-Bang Nucleosynthesis
W. Tornow; Czakon, N. G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V. N.; Mikhailov, S.; Pinayev, I. V.; Weisel, G.J.; Witala, H
2003-01-01
The photon analyzing power for the photodisintegration of the deuteron was measured for seven gamma-ray energies between 2.39 and 4.05 MeV using the linearly polarized gamma-ray beam of the High-Intensity Gamma-ray Source at the Duke Free-Electron Laser Laboratory. The data provide a stringent test of theoretical calculations for the inverse reaction, the neutron-proton radiative capture reaction at energies important for Big-Bang Nucleosynthesis. Our data are in excellent agreement with pote...
On Big Bang Relics, the Neutrino Mass and the Cosmic Ray Spectrum
Wigmans, Richard
1998-01-01
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 a...
Quantum mechanics before the big bang in heterotic-M-theory
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 interpre...
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.
Gamma rays and the case for baryon symmetric big-bang cosmology
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.
Gravitationally induced adiabatic particle production: from big bang to de Sitter
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.
Right-handed sneutrino dark matter and big-bang nucleosynthesis
International Nuclear Information System (INIS)
We study the light-element abundances in supersymmetric model where the right-handed sneutrino is the lightest superparticle (LSP), assuming that the neutrino masses are purely Dirac-type. In such a scenario, the lightest superparticle in the minimal supersymmetric standard model sector (which we call MSSM-LSP) becomes long-lived, and thermal relic MSSM-LSP may decay after the big-bang nucleosynthesis starts. We calculate the light-element abundances including non-standard nuclear reactions induced by the MSSM-LSP decay, and derive constraints on the scenario of right-handed sneutrino LSP.
Majorana Neutrino Magnetic Moment and Neutrino Decoupling in Big Bang Nucleosynthesis
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.
Big bang nucleosynthesis constraints on scalar-tensor theories of gravity
International Nuclear Information System (INIS)
We investigate Big bang nucleosynthesis (BBN) in scalar-tensor theories of gravity with arbitrary matter couplings and self-interaction potentials. We first consider the case of a massless dilaton with a quadratic coupling to matter. We perform a full numerical integration of the evolution of the scalar field and compute the resulting light element abundances. We demonstrate in detail the importance of particle mass thresholds on the evolution of the scalar field in a radiation dominated universe. We also consider the simplest extension of this model including a cosmological constant in either the Jordan or Einstein frame
Quantum origin of pre-big-bang collapse from induced matter theory of gravity
International Nuclear Information System (INIS)
We revisit a collapsing pre-big-bang model of the universe to study with detail the non-perturbative quantum dynamics of the dispersal scalar field whose dynamics becomes from the dynamical foliation of test massless scalar field φ on a 5D Riemann-flat metric, such that the extra space-like coordinate is noncompact. The important result here obtained is that the evolution of the system, which is described thorough the equation of state has the unique origin in the quantum contributions of the effective 4D scalar field φ¯.
Revisiting big-bang nucleosynthesis constraints on dark-matter annihilation
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.
Should price reform proceed gradually or in a"big bang?"
van Wijnbergen, Sweder
1991-01-01
Should countries such as Poland or the USSR move toward more flexible prices gradually or in a"big bang?"Why is it that governments committed to eventual price flexibility so often seem to be unable to let go of"temporary"controls? Why, after price increases early in a program of price controls, does output often rise at the same time that shortages seem to increase? Theauthor argues that intertemporal speculation, hoarding, and the political economy of price control help explain these puzzle...
International Nuclear Information System (INIS)
The standard scenario of big bang nucleosynthesis (BBN) is generalized to take into account nonthermal nuclear reactions in the primordial plasma. These reactions are naturally triggered in the BBN epoch by fast particles generated in various exoergic processes. It is found that, although such particles can appreciably enhance the rates of some individual reactions, their influence on the whole process of element production is not significant. The nonthermal corrections to element abundances are obtained to be 0.1% (3H), −0.03% (7Li), and 0.34 %-0.63% (CNO group).
Neutrino-driven nucleon fission reactors: Supernovae, quasars, and the big bang
International Nuclear Information System (INIS)
The purpose of this work is to establish the existence of naturally occurring celestial neutrino-driven nucleon fission chain reaction reactors as the first step in the development of controlled nucleon fission reactors on Earth. Celestial nucleon fission reactors provide functioning models that serve as starting points for reactor development. Recognizing supernovae, quasars, and the Big Bang as functioning neutrino-driven nucleon fission reactors presents the nuclear industry with a new and significant challenge. That challenge is our technological prowess to achieve a controlled nucleon fission chain reaction using the Earth's resources
Licata, Ignazio
2008-01-01
This article proposes some cosmological reflections at the qualitative and conjectural level, suggested by the Fantappie & Arcidiacono projective relativity theory. The difference will firstly be discussed between two types of singularity in this theory: geometric (de Sitter horizon) and physical (big bang, big crunch). The reasons for the existence of geometric singularities are deeply rooted in the principle of inertia and in the principle of relativity, while physical singularities are associated with the creation or destruction of matter. In this framework, quantum mechanics is introduced through a particular interpretation of Bohm holomovement. Finally, a possible mechanism is discussed for the genesis of the cosmological term. No form of inflation appears in the scenario described.
A large neutral fraction of cosmic hydrogen a billion years after the Big Bang.
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. PMID:14985754
Gonzalez-Mestres, L.
2014-04-01
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.
Could there have been a single origin of life in a big bang universe?
Gordon, Richard; Hoover, Richard B.
2007-09-01
Frank Tipler, in The Physics of Immortality, wrote about how to spread a form of traveling artificial life throughout the known, expanding universe, prior to collapse. The key is to make the ALife self-reproducing, permitting exponential growth, like life itself, but faster. We ask whether microbial extremophiles could have originated in a single location at an early phase of a big bang universe, and spread throughout the cosmos, as is commonly assumed in discussions of the panspermia hypothesis? Since the universe was much smaller when the first condensed matter appeared, this hypothesis merits consideration. In comparing particle horizons with biohorizons, we find that the answer is no: at our earliest estimated time for the origin of life, 500x10 6 years after the big bang, if life started everywhere it could, there would have had to have been at least 50,000 origins of life. In the course of our rough calculations, we introduce the concepts of the generations of life (from microorganisms to consciousness), the Biocosmological Principle that life is spread throughout the universe, life as a wave in an active medium, and the speed of life, i.e., the speed of ejecta from galaxies and lesser bodies on which life could be transported.
Molecular evolution of colorectal cancer: from multistep carcinogenesis to the big bang.
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. PMID:26947218
The Standard Model Higgs as the origin of the hot Big Bang
Figueroa, Daniel G
2016-01-01
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, $w \\simeq +1$, 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...
STANDARD BIG BANG NUCLEOSYNTHESIS UP TO CNO WITH AN IMPROVED EXTENDED NUCLEAR NETWORK
Energy Technology Data Exchange (ETDEWEB)
Coc, Alain [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse (CSNSM), CNRS/IN2P3, Universite Paris Sud, UMR 8609, Batiment 104, F-91405 Orsay Campus (France); Goriely, Stephane; Xu, Yi [Institut d' Astronomie et d' Astrophysique, Universite Libre de Bruxelles, CP 226, Boulevard du Triomphe, B-1050 Bruxelles (Belgium); Saimpert, Matthias; Vangioni, Elisabeth [Institut d' Astrophysique de Paris, UMR 7095 CNRS, Universite Pierre et Marie Curie, 98 bis Boulevard Arago, Paris 75014 (France)
2012-01-10
Primordial or big bang nucleosynthesis (BBN) is one of the three strong pieces of evidence for the big bang model together with the expansion of the universe and cosmic microwave background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and enlarge the nuclear network up to sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including Almost-Equal-To 270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial beryllium, boron, carbon, nitrogen, and oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, {sup 9}Be, and boron nucleosynthesis. We re-evaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial beryllium abundance increase by a factor of four compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 Multiplication-Sign 10{sup -15}. On the other hand, the extension of the nuclear network has not changed the {sup 7}Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.
Why the Big Bang Model Cannot Describe the Observed Universe Having Pressure and Radiation
Directory of Open Access Journals (Sweden)
Abhas Mitra
2011-12-01
Full Text Available It has been recently shown that, since in general relativity (GR, given one time label t, one can choose any other time label t → t_{*}= f(t, the pressure of a homogeneous and isotropic fluid is intrinsically zero (Mitra, Astrophys. Sp. Sc. 333, 351, 2011. Here we explore the physical reasons for the inevitability of this mathematical result. The essential reason is that the Weyl Postulate assumes that the test particles in a homogeneous and isotropic spacetime undergo pure geodesic motion without any collisions amongst themselves. Such an assumed absence of collisions corresponds to the absence of any intrinsic pressure. Accordingly, the “Big Bang Model” (BBM which assumes that the cosmic fluid is not only continuous but also homogeneous and isotropic intrinsically corresponds to zero pressure and hence zero temperature. It can be seen that this result also follows from the relevant general relativistic first law of thermodynamics (Mitra, Found. Phys. 41, 1454, 2011. Therefore, the ideal BBM cannot describe the physical universe having pressure, temperature and radiation. Consequently, the physical universe may comprise matter distributed in discrete non-continuous lumpy fashion (as observed rather than in the form of a homogeneous continuous fluid. The intrinsic absence of pressure in the “Big Bang Model” also rules out the concept of a “Dark Energy”.
The amazing unity of the Universe and its origin in the Big Bang
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 ...
Don’t miss the Passport to the Big Bang event this Sunday!
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...
Pre-big bang bubbles from the gravitational instability of generic string vacua
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...
SUSY-catalyzed big bang nucleosynthesis as a solution of lithium problems
International Nuclear Information System (INIS)
6Li abundances observed in metal-poor stars appear to exhibit a plateau as a function of metallicity similar to that for 7Li. This suggests a big bang origin for 6Li. However, since the radiative capture of a deuteron by an alpha particle during the big bang nucleosynthesis (BBN) is suppressed, it is difficult to explain the observed 6Li abundance in the framework of standard BBN. The 6Li problem is thus a nagging puzzle in nuclear astrophysics. In addition, observed 7Li abundances is smaller than expected in standard BBN (SBBN). In this paper we show that there is a possible simultaneous solution to both of the lithium problems in the paradigm of catalyzed BBN by negatively charged supersymmetric particle. We also show that there is no observable signature of the particle on primordial abundances of light nuclei with mass number larger than 8. We study effects of rates for important reactions on resulting final abundances of light nuclei, and show the importance of precise theoretical calculation of reaction rates involving supersymmetric particles using a few-body model. We discuss implications of this model to constraining the mass of dark matter particles to be measured with direct detection experiments such as CDMS II.
STANDARD BIG BANG NUCLEOSYNTHESIS UP TO CNO WITH AN IMPROVED EXTENDED NUCLEAR NETWORK
International Nuclear Information System (INIS)
Primordial or big bang nucleosynthesis (BBN) is one of the three strong pieces of evidence for the big bang model together with the expansion of the universe and cosmic microwave background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and enlarge the nuclear network up to sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including ≈270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial beryllium, boron, carbon, nitrogen, and oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9Be, and boron nucleosynthesis. We re-evaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial beryllium abundance increase by a factor of four compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 × 10–15. On the other hand, the extension of the nuclear network has not changed the 7Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.
Lyons, Daniel
2006-01-01
"It will be the world's largest machine. It could explain the origins of the universe. But first a team of engineers has the gargantuan logistic challenge of putting the Large Hadron Collider together" (2 pages)
No ``explosion'' in Big Bang cosmology: teaching kids the truth of what cosmologists really know
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
Relic gravitons from the pre-big bang: what we know and what we do not know
Gasperini, M.
1996-01-01
I discuss the status of present knowledge about a possible background of relic gravitons left by an early, pre-big bang cosmological epoch, whose existence in the past of our Universe is suggested by the duality symmetries of string theory.
sup 3 He( sub 3 H,. gamma. ) sup 6 Li; Source of sup 6 Li production in the big bang
Energy Technology Data Exchange (ETDEWEB)
Funck, C.; Langanke, K. (Inst. fur Theoretisch Physik I, Univ. Munster, D-4400 Munster (DE))
1990-01-10
The authors have calculated the {sup 3}He({sup 3}H,{gamma}){sup 6}Li reaction rate at big bang temperatures based on a microscopic study in the framework of the Generator Coordinate Method. It is discussed whether {sup 6}Li could be made by {sup 3}He + {sup 3}H fusion in the early epoch of our universe.
From big crunch to big bang: A quantum string cosmology perspective
International Nuclear Information System (INIS)
The scenario that the Universe contracts towards a big crunch and then undergoes a transition to an expanding universe is envisaged in the quantum string cosmology approach. The Wheeler-DeWitt (WDW) equation is solved exactly for an exponential dilaton potential. An S-duality invariant cosmological effective action for type IIB theory is considered to derive classical solutions and solve WDW equations
From Big Crunch to Big Bang: A Quantum String Cosmology Perspective
Maharana, Jnanadeva
2001-01-01
The scenario that the Universe contracts towards a big crunch and then undergoes a transition to expanding Universe in envisaged in the quantum string cosmology approach. The Wheeler-De Witt equation is solved exactly for an exponential dilaton potential. S-duality invariant cosmological effective action, for type IIB theory, is considered to derive classical solutions and solve WDW equations.
Geneva Festival, 2004: Opened with the Big Bang, closed with Creation
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...
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.
178th International School of Physics "Enrico Fermi" : From the Big Bang to the Nucleosynthesis
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...
The Big Bang, COBE, and the Relic Radiation of Creation (LBNL Science at the Theater)
Energy Technology Data Exchange (ETDEWEB)
Smoot, George
2007-03-05
Berkeley Lab's George Smoot won the 2006 Physics Nobel Prize, together with John Mather of NASA Goddard Space Flight Center, for "the discovery of the blackbody form and anisotropy of the cosmic microwave background radiation." The anisotropy showed as small variations in the map of the early universe. This research looks back into the infant universe and provides a better understanding of the origin of galaxies and stars. The cosmic background radiation is a tool to understand the structure and history of the universe and the structure of space-time. These observations have provided increased support for the big bang theory of the universe's origin. The Cosmic Background Explorer (COBE) NASA satellite, launched in 1989, carries instruments that measured various aspects of cosmic microwave background radiation, and produced the data for these compelling scientific results, which opened up a field that continues very actively today.
Low-lying Resonances and Relativistic Screening in Big Bang Nucleosynthesis
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.
The main path to C, N, O elements in big bang nucleosynthesis
International Nuclear Information System (INIS)
The production of C, N, O elements in a standard big bang nucleosynthesis scenario is investigated. Using the up-to-date data of nuclear reactions in BBN, in particular the 8Li (n, γ) 9Li which has been measured in China Institute of Atomic Energy, a full nucleosynthesis network calculation of BBN is carried out. Our calculation results show that the abundance of 12C is increased for an order of magnitude after addition of the reaction chain 8Li (n, γ) 9Li (α, n) 12B (β) 12C, which was neglected in previous studies. We find that this sequence provides the main channel to convert the light elements into C, N, O in standard BBN. (authors)
“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.
From the Big Bang to the Nobel Prize and the JWST
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.
Low-lying resonances and relativistic screening in Big Bang nucleosynthesis
Famiano, M. A.; Balantekin, A. B.; Kajino, T.
2016-04-01
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,γ ) 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.
Quantum mechanics before the big bang in heterotic-M-theory
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.
Dust production 0.7-1.5 billion years after the Big Bang
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.
Jedamzik, K
2006-01-01
Big Bang nucleosynthesis in the presence of decaying relic particles is examined in detail. All non-thermal processes important for the determination of light-element abundance yields of 2H, 3H, 3He, 4He, 6Li, and 7Li are coupled to the thermonuclear fusion reactions to obtain comparatively accurate results. Predicted light-element yields are compared to observationally inferred limits on primordial light-element abundances to infer constraints on the abundances and properties of relic decaying particles with decay times in the interval 0.01 sec < tau < 10^(12) sec. Decaying particles are typically constrained at early times by 4He or 2H, at intermediate times by 6Li, and at large times by the 3He/2H ratio. Constraints are shown for a large number of hadronic branching ratios and decaying particle masses and may be applied to constrain the evolution of the early Universe.
International Nuclear Information System (INIS)
The classical model of the development of the universe starting from the Big Bang has some shortcomings, such as the problem of the horizon, the problem of nonhomogeneity, and the problem of the critical density of the universe. Some shortcomings are explained in the inflanationary model of Guth and Steinhardt of 1984. The principle of the new model is the period of 10-45 to 10-30s following the beginning of the universe during which the universe got exponentially inflated due to repulsive gravitational force. The increase by a factor of 1050 has its justification in the idea of the large negative pressure of a false vacuum. (M.D.). 1 fig
The great adventure of the LHC - From big bang to the Higgs boson
International Nuclear Information System (INIS)
This book presents what has been the biggest scientific equipment ever designed on earth: the LHC (large hadron collider) and its associated experiments (ATLAS, CMS, LHCb and ALICE) that led to the discovery of the Higgs boson in 2012. About 10.000 physicists and engineers from 50 countries have taken part into the project that began in 1989. This book is composed of the following chapters: 1) the standard model (SM) of particle physics, 2) the experimental success of SM, 3) the shortfalls of SM, 4) the new physics, 5) the original big bang, 6) the LHC, 7) particle detection, 8) ATLAS and CMS experiments, 9) the first data from LHC, 10) data analysis, 11) the quest for the Higgs boson, 12) the search for new physics, 13) LHCb and ALICE experiments, and 14) future prospects
Neutrino mass in elementary-particle physics and in big bang cosmology
International Nuclear Information System (INIS)
Some theoretical aspects of a nonzero value for the neutrino rest mass and its possible implications for physics are discussed. The nature of the neutrino mass is analyzed, as well as the physical consequences that may derive from the existence of new helicity states for the neutrino or from lepton charge nonconservation if the mass is of Dirac or Majorana character, respectively. Massive neutrinos are examined in the context of grand unified theories combining the weak, strong, and electromagnetic interactions. Searches for neutrino-mass effects in β decay and for neutrino oscillations are reviewed. Several astrophysical effects of the neutrino mass are described: solar-neutrino oscillations, the decay of primordial neutrinos, the feasibility of detecting massive primordial neutrinos experimentally. The predictions of big bang theory regarding the neutrino number density in the universe are analyzed, and a discussion is given of the influence neutrino oscillations might have on the neutrino density and on cosmological nucleosynthesis
Sneutrino condensate as a candidate for the hot big bang cosmology
International Nuclear Information System (INIS)
If the inflationary paradigm is correct, then it must create conditions for the hot big bang model with all observed matter, baryons, and the seed perturbations for 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 Trh≤109 GeV and finally generating the lepton/baryon asymmetry nB/s∼10-10 with no lepton/baryon-isocurvature fluctuations
On big bang relics, the neutrino mass and the spectrum of cosmic rays
International Nuclear Information System (INIS)
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/c2. 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/α ratio
Majorana neutrino magnetic moment and neutrino decoupling in big bang nucleosynthesis
Vassh, N.; Grohs, E.; Balantekin, A. B.; Fuller, G. M.
2015-12-01
We examine the physics of the early universe when Majorana neutrinos (νe, νμ, ντ) 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 abundances and other cosmological parameters are sensitive to magnetic couplings on the order of 1 0-10μB. Given the recent analysis of sub-MeV Borexino data which constrains Majorana moments to the order of 1 0-11μB or less, we find that changes in cosmological parameters from magnetic contributions to neutrino decoupling temperatures are below the level of upcoming precision observations.
Radiative decay of a long-lived particle and big-bang nucleosynthesis
International Nuclear Information System (INIS)
The effects of radiatively decaying, long-lived particles on big-bang nucleosynthesis (BBN) are discussed. If high-energy photons are emitted after BBN, they may change the abundances of the light elements through photodissociation processes, which may result in a significant discrepancy between the BBN theory and observation. We calculate the abundances of the light elements, including the effects of photodissociation induced by a radiatively decaying particle, but neglecting the hadronic branching ratio. Using these calculated abundances, we derive a constraint on such particles by comparing our theoretical results with observations. Taking into account the recent controversies regarding the observations of the light-element abundances, we derive constraints for various combinations of the measurements. We also discuss several models which predict such radiatively decaying particles, and we derive constraints on such models. copyright 1999 The American Physical Society
Underground nuclear astrophysics for the Sun, and for the Big Bang
International Nuclear Information System (INIS)
After the resolution of the solar neutrino problem in 2002, the study of the Sun has now entered a precision era, and an entirely new dilemma has come up: New elemental abundance data from Fraunhofer line analyses are in contradiction with helioseismological observables. Observations of 13N and 15O neutrinos from the Sun may address this socalled solar abundance problem, but their interpretation will require precise nuclear reaction data. Due to the low cross sections involved, such data can only be provided by experiments in an underground low-background setting. Work at the world's only underground accelerator, the 0.4 MV LUNA machine in Gran Sasso (Italy), on solar fusion reactions and on the Big Bang production of 6,7Li will be reviewed. Higher-energy underground accelerators are planned in Italy and also at the Dresden Felsenkeller in Germany. (author)
Toward a self-consistent and unitary reaction network for big bang nucleosynthesis
International Nuclear Information System (INIS)
Unitarity, the mathematical expression of the conservation of probability in multichannel reactions, is an essential ingredient in the development of accurate nuclear reaction networks appropriate for nucleosynthesis in a variety of environments. We describe our ongoing program to develop a 'unitary reaction network' for the big-bang nucleosynthesis environment and look at an example of the need and power of unitary parametrizations of nuclear scattering and reaction data. Recent attention has been focused on the possible role of the 9B compound nuclear system in the resonant destruction of 7Li during primordial nucleosynthesis. We have studied reactions in the 9B compound system with a multichannel, two-body unitary R-matrix code (EDA) using the known elastic and reaction data, in a four-channel treatment. The data include elastic 6Li(3He,3He)6Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for 6Li(3He,p)8Be* and from 0.4 to 5.0 MeV for the 6Li(3He,γ)7Be reaction. Capture data have been added to the previous analysis with integrated cross section measurements from 0.7 to 0.825 MeV for 6Li(3He,γ)9B. The resulting resonance parameters are compared with tabulated values from TUNL Nuclear Data Group analyses. Previously unidentified resonances are noted and the relevance of this analysis and a unitary reaction network for big-bang nucleosynthesis are emphasized. (author)
Nobel Lecture: From the Big Bang to the Nobel Prize and beyond
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.
Multiple main sequence of globular clusters as a result of inhomogeneous big bang nucleosynthesis
International Nuclear Information System (INIS)
A new mechanism for enhancing the helium abundance in the blue main sequence stars of ω Centauri and NGC 2808 is investigated. We suggest that helium enhancement was caused by the inhomogeneous big bang nucleosynthesis. Regions with extremely high baryon-to-photon ratios are assumed to be caused by the baryogenesis. Its mass scale is also assumed to be 106M·. An example of the mechanisms to realize these two things was already proposed as the Affleck-Dine baryogenesis. As the baryon-to-photon ratio becomes larger, the primordial helium abundance is enhanced. We calculated the big bang nucleosynthesis and found that there exists a parameter region yielding enough helium to account for the split of the main sequence in the aforementioned globular clusters while keeping the abundance of other elements compatible with observations. Our mechanism predicts that heavy elements with the mass number of around 100 is enhanced in the blue main sequence stars. We estimate the time scales of diffusion of the enhanced helium and mass accretion in several stages after the nucleosynthesis to investigate whether these processes diminish the enhancement of helium. We found that the diffusion does not influence the helium content. A cloud with a sufficiently large baryon-to-photon ratio to account for the multiple main sequence collapsed immediately after the recombination. Subsequently, the cloud accreted the ambient matter with the normal helium content. If the star formation occurred both in the collapsed core and the accreted envelope, then the resultant star cluster has a double main sequence.
International Nuclear Information System (INIS)
A scenario of the big-bang nucleosynthesis is analyzed within the minimal supersymmetric standard model, which is consistent with a stau-neutralino coannihilation scenario to explain the relic abundance of dark matter. We find that we can account for the possible discrepancy of the abundance of 7Li between the observation and the prediction of the big-bang nucleosynthesis by taking the mass of the neutralino as 300 GeV and the mass difference between the stau and the neutralino as (100-120) MeV. We can therefore simultaneously explain the abundance of the dark matter and that of 7Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.
Big Bang nucleosynthesis and the results of the 2H(α,γ)6Li experiment at LUNA
International Nuclear Information System (INIS)
Observations of the 6Li abundance in very metal-poor stars, if confirmed, show a level of 6Li that is several orders of magnitude larger than the production of this nuclide in standard Big Bang nucleosynthesis. The 2H(α,γ)6Li nuclear reaction is believed to dominate 6Li production in the Big Bang, but there are no directly measured data at relevant energies yet. The reaction has been studied at the LUNA 0.4 MV accelerator, deep underground in the Gran Sasso laboratory in Italy, using an intensive He+ beam and a windowless deuterium gas target. The conclusions from the final data analysis of the experiment are presented.
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
Ellman, Roger
2000-01-01
There is general agreement that the universe began with an "explosion" of matter and energy at a "singularity", the "Big Bang". This paper analyses the mechanics of that beginning and two alternative theories related to it: - The Hubble-Einstein theory that that beginning created space itself, expanding and carrying the universe's matter and energy with it, and - The Universal Decay theory that the length, (L), dimensional aspect of all quantities in the universe is exponentially decaying whi...
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。
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.
Are Dark Matter and Dark Energy the Residue of the Expansion-Reaction to the Big Bang ?
Ringermacher, Harry I.; Mead, Lawrence R.
2006-01-01
We derive the phenomenological Milgrom square-law acceleration, describing the apparent behavior of dark matter, as the reaction to the Big Bang from a model based on the Lorentz-Dirac equation of motion traditionally describing radiation reaction in electromagnetism but proven applicable to expansion reaction in cosmology. The model is applied within the Robertson-Walker hypersphere, and suggests that the Hubble expansion exactly cancels the classical reaction imparted to matter following th...
An Accurate Calculation of the Big-Bang Prediction for the Abundance of Primordial Helium
López, R E; Lopez, Robert E.; Turner, Michael S.
1999-01-01
Within the standard model of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of Helium to a theoretical uncertainty of $0.1 \\pct$ $(\\delta Y_P = \\pm 0.0002)$. At this accuracy the uncertainty in the abundance is dominated by the experimental uncertainty in the neutron mean lifetime, $\\tau_n = 885.3 \\pm 2.0 \\rm{sec}$. The following physical effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon mass corrections to the weak rates; order-$\\alpha$ quantum-electrodynamic correction to the plasma density, electron mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosynthesis code to control numerical errors to less than 0.1\\pct. Our predictions for the \\EL[4]{He} abundance are summarized with an accurate fitting formula. Summarizing our work...
Constraints on Ωb from nucleosynthesis of 7Li in the standard big bang model
International Nuclear Information System (INIS)
We update standard big bang nucleosynthesis (SBBN) calculations on the basis of recent nuclear physics compilations (NACRE in particular), experimental and theoretical works. By a Monte Carlo technique, we calculate the uncertainties on the light element yields (4He, D, 3He and 7Li) related to nuclear reactions. The results are compared to observations that are thought to be representative of the corresponding primordial abundances. It is found that 7Li could lead to more stringent constraints on the baryonic density of the universe (Ωbh2) than deuterium, because of much higher observation statistics and an easier extrapolation to primordial values. The confrontation of SBBN results with 7Li observations is of special interest since other independent approaches have also recently provided Ωbh2 values: (i) the anisotropies of the cosmic microwave background by the BOOMERANG, CBI, DASI and MAXIMA experiments and (ii) the Lyman-α forest at high redshift. A comparison between these results obtained by different methods provides a test of their consistency and could provide a better determination of the baryonic density in the universe. However, the agreement between Ωbh2 values deduced from SBBN calculation and 7Li observation on the one hand and CMB observations on the other hand is only marginal
Implication of the proton-deuteron radiative capture for Big Bang Nucleosynthesis
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...
Georges Lemaître: The Priest Who Invented the Big Bang
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.
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.
A class of transient acceleration models consistent with Big Bang cosmology
International Nuclear Information System (INIS)
Is it possible that the current cosmic accelerating expansion will turn into a decelerating one? Can this transition be realized by some viable theoretical model that is consistent with the standard Big Bang cosmology? We study a class of phenomenological models with a transient acceleration, based on a dynamical dark energy with a very general form of equation of state pde = βρde − βρdem. It mimics the cosmological constant ρde → const for a small scale factor a, and behaves as a barotropic gas with ρde → a−3(α+1) with α ≥ 0 for large a. The cosmic evolution of four models in the class has been examined in detail, and all yield a smooth transient acceleration. Depending on the specific model, the future universe may be dominated by either dark energy or by matter. In two models, the dynamical dark energy can be explicitly realized by a scalar field with an analytical potential V(φ). Moreover, a statistical analysis shows that the models can be as robust as ΛCDM in confronting the observational data of Type Ia supernovae, cosmic microwave background (CMB) and baryon acoustic oscillation. As improvements over previous studies, our models overcome the problem of over-abundance of dark energy during early eras, and satisfy the constraints on dark energy from WMAP observations of CMB
Revisiting constraints on small scale perturbations from big-bang nucleosynthesis
Inomata, Keisuke; Tada, Yuichiro
2016-01-01
We revisit the constraints on the small scale density perturbations ($10^4\\,\\mathrm{Mpc}^{-1}\\lesssim k \\lesssim10^5\\,\\mathrm{Mpc}^{-1}$) from the modification of the freeze-out value of the neutron-proton ratio at big-bang nucleosynthesis era. Around the freeze-out temperature $T\\sim 0.5\\,\\mathrm{MeV}$, the universe can be divided into several local patches which have different temperatures since any perturbation which 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 use of the latest observed $^4$He abundance, we obtain the constraint on the power spectrum of the curvature perturbations as $\\Delta^2_\\mathcal{R}\\lesssim 0.018$ on $10^4\\,\\mathrm{Mpc}^{-1}\\lesssim k \\lesssim 10^5\\,\\mathrm{Mpc}^{-1}$.
Precision prediction for the big-bang abundance of primordial 4He
International Nuclear Information System (INIS)
Within the standard models of particle physics and cosmology we have calculated the big-bang prediction for the primordial abundance of 4He to a theoretical uncertainty of less than 0.1% (δYPn=885.4±2.0 sec. The following physical effects were included in the calculation: the zero and finite-temperature radiative, Coulomb and finite-nucleon-mass corrections to the weak rates; order-α quantum-electrodynamic correction to the plasma density, electron mass, and neutrino temperature; and incomplete neutrino decoupling. New results for the finite-temperature radiative correction and the QED plasma correction were used. In addition, we wrote a new and independent nucleosynthesis code designed to control numerical errors to be less than 0.1%. Our predictions for the 4He abundance are presented in the form of an accurate fitting formula. Summarizing our work in one number, YP(η=5x10-10)=0.2462±0.0004 (expt)±Bh2=0.019±0.001, leads to the prediction YP=0.2464±0.0005 (D/H)±4He abundance will allow an important consistency test of primordial nucleosynthesis. copyright 1999 The American Physical Society
Big-Bang Nucleosynthesis: lithium problems and scalar-tensor theories of gravity
International Nuclear Information System (INIS)
The observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, by the WMAP satellite, has provided a determination of the baryonic density of the Universe (Ωbh2) with an unprecedented precision. Using this value, the primordial abundances of the light elements can be calculated in the framework of the Standard Big-Bang Nucleosynthesis model (SBBN). While the agreement is excellent for D and good for 4He, there is a difference of a factor of ≅3 for 7Li. In addition, in a few halo stars, 6Li has also been observed at a level well above SBBN predictions. To enable a more reliable calculation of these 7Li and 6Li yields, two nuclear reactions important for the nucleosynthesis of 7Li and 6Li have been studied experimentally: D(α, γ)6Li and 7Be(d,p)2α. Even though, the lithium primordial production is not well understood, BBN can be used to constrain theories beyond the standard model, for instance, scalar-tensor theories of gravity
Big bang nucleosynthesis constraints on universal extra dimensions and varying fundamental constants
International Nuclear Information System (INIS)
The successful prediction of light element abundances from big bang nucleosynthesis (BBN) has been a pillar of the standard model of cosmology. Because many of the relevant reaction rates are sensitive to the values of fundamental constants, such as the fine structure constant and the strong coupling constant, BBN is a useful tool to probe and to put constraints on possible cosmological variations of these constants, which arise naturally from many versions of extra-dimensional theories. In this paper, we study the dependences of fundamental constants on the radion field of the universal extra-dimension model, and calculate the effects of such varying constants on BBN. We also discuss the possibility that the discrepancy between BBN and the Wilkinson Microwave Anisotropy Probe (WMAP) data on the baryon-to-photon ratio can be reduced if the volume of the extra dimensions was slightly larger--by O(10-3)--at the BBN era compared to its present value, which would result in smaller gauge couplings at BBN by the same factor
Kernan, P J; Vachaspati, T; Kernan, Peter J.; Starkman, Glenn D.; Vachaspati, Tanmay
1996-01-01
Recently Cheng, Olinto, Schramm and Truran (COST) reexamined the constraints from big bang nucleosynthesis (BBN) on the strength of primordial magnetic fields. Their bottom line agreed with that of an earlier recent paper on the subject (Kernan, Starkman and Vachaspati (KSV)), both in its final limit on the magnetic field during BBN, and in its conclusion that for allowed values of the magnetic field the dominant factor for BBN is the increased expansion rate at a given temperature caused by the energy density of the magnetic field, $B^2/8\\pi$. However, their conclusion that weak interaction rates increased with increasing B-field at these low field values contradicted the earlier results of KSV. In this comment we point out that the Taylor series expansion of the weak interaction rate about B=0 used in COST is not well-defined, while the Euler-McLaurin expansion of KSV is well-behaved and reliable. Using the Euler-McLaurin expansion we find that the weak interaction rates decrease rather than increase with i...
An Educational Look at an Alternative to the Simple Big Bang Model
Kriske, Richard
2009-10-01
The author often toys with a Positively Curved surface resembling a globe as an alternative to the simple Big Bang model on a flat surface. When one looks at the Horizon of the earth, say at the ocean, masts in the distance tip away from the observer. If three dimensions of space where curved with a perpendicular mast at each vertex, those time masts would tip away from the observer and be cut-off. A new optical effect would be observed, in which vertices in the distance, say pair annihilation, would result in gamma rays appearing to be redshifted, since by parallel displacement, their time axis would progressively tilt away from the observer and give them a red shift until they reached a distance were they where non- magnifiable. Just as the Earth's Horizon is a non-magnifiable line (since the objects are tilted over and cut-off), so should be the Universe's Horizon be tilted and cut-off (but like a Black-Hole, the Horizon will be an area). The tilt and cut-off can be used to calculate the size and mass of the Universe,given that the cutoff is taken to be 2.725K, the CMBR. This model turns out to be a model of constants and gives absolute meaning to spin. Since this is a brand new theory developed solely by the author at his coffee breaks, looking out the window, he presents it as an exercise.
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.)
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...
Constraints on the strength of a primordial magnetic field from big bang nucleosynthesis
International Nuclear Information System (INIS)
The effects of magnetic fields on big bang nucleosynthesis (BBN) are calculated, and the impact on the abundances of the light elements are investigated numerically. An upper limit on the strength of primordial magnetic fields compatible with observations of light element abundances is thus obtained. In the framework of standard BBN theory, the maximum strength of the primordial magnetic fields, on scales greater than 104 cm but smaller than the event horizon at the BBN epoch (∼1 min, ∼2x1012 cm), is ≤1011 G. This limit is shown to allow magnetic fields at the time of recombination no stronger than ∼0.1 G on scales ≥1011 cm. Our results also strongly indicate that, at the BBN epoch, and for field strengths B≤1013 G, the effects of magnetic fields on the primordial abundances of light elements are dominated by effects from reaction rates in the presence of primeval magnetic fields rather than by magnetic density effects on the expansion rate
The holography hypothesis in pre-big-bang cosmology with string sources
International Nuclear Information System (INIS)
The holographic ratio in Pre-big bang string cosmology is obtained in the presence string sources. An iterative procedure is adopted to solve the equations of motion and derive the ratio in four dimensional world. First the zeroth order ratio is computed in the remote past, i.e. at t=-∞, then the holographic ratio is obtained taking into account the evolution of the backgrounds following the iterative procedure. The corrections to the zeroth order value of the ratio depends on the form of the initial number distribution of the strings chosen. Moreover, we estimate the holographic ratio in the recent past (i.e. when gamma=-frac(1)(d)) and in the remote past (i.e. when gamma=0), gamma vertical bar equiv vertical bar frac(p)(vertical bar varrho), in different dimensions in the Einstein frame and in the string frame. We find that in the first case it has similar time dependences in both the frames, especially in four dimensions the ratio is explicitly computed to be the same in the two cases, whereas for gamma=0 case the time dependence is different. (author)
Radioactive nuclear beam studies of reactions important to big bang nucleosynthesis
International Nuclear Information System (INIS)
The primordal element abundances provide one of the basic tests of models of big bang nucleosynthesis. Unfortunately, many of the most important reactions for the inhomogeneous models involve short-lived nuclides, so their study requires radioactive nuclear beams. Thus, the authors have used facilities which generate such beams at RIKEN and the Univ. of Notre Dame to study the 8Li(4He,n)11B reaction, several reactions associated with 2H+8Li, and the 18C(n,γ)19C reaction. 8Li(4He,n)11B is important for producing all nuclides heavier than mass 10 amu over much of the inhomogeneous model parameter space, whereas the 2H+8Li reactions serve primarily to destroy 8Li, and hence to limit heavy element production. Because of theoretical uncertainties involving Li, Be, and B, nuclides heavier than 20 amu may provide important test cases. 18C(n,γ)19C may be important in producing such nuclides. Theoretical motivation, experimental techniques, and results are presented
International Nuclear Information System (INIS)
It has been proposed that the apparent discrepancies between the inferred primordial abundances of 6Li and 7Li and the predictions of big bang nucleosynthesis (BBN) can be resolved by the existence of a negatively charged massive unstable supersymmetric particle (X-) during the BBN epoch. Here, we present new BBN calculations with an X- particle utilizing an improved nuclear reaction network including captures of nuclei by the particle, nuclear reactions and β decays of normal nuclei and nuclei bound to the X- particles (X nuclei), and new reaction rates derived from recent rigorous quantum many-body dynamical calculations. We find that this is still a viable model to explain the observed 6Li and 7Li abundances. We also show that with the new rates the production of heavier nuclei is suppressed and there is no signature on abundances of nuclei heavier than Be in the X--particle catalyzed BBN model as has been previously proposed. We also consider the version of this model whereby the X- particle decays into the present cold dark matter. We analyze this paradigm in light of the recent constraints on the dark-matter mass deduced from the possible detected events in the CDMS-II experiment. We conclude that based upon the inferred range for the dark-matter mass, only X- decay via the weak interaction can achieve the desired 7Li destruction while also reproducing the observed 6Li abundance.
Constraints on modified Gauss-Bonnet gravity during big bang nucleosynthesis
Kusakabe, Motohiko; Koh, Seoktae; Kim, K. S.; Cheoun, Myung-Ki
2016-02-01
Modified gravity is considered to be one of the possible explanations of the accelerated expansions of the present and the early universe. We study the effects of modified gravity on big bang nucleosynthesis (BBN). If the effects of modified gravity are significant during the BBN epoch, they should be observed as changes of primordial light element abundances. We assume a f (G ) term with the Gauss-Bonnet term G , during the BBN epoch. A power-law relation of d f /d G ∝tp where t is the cosmic time was assumed for the function f (G ) as an example case. We solve time evolutions of physical variables during BBN in the f (G ) gravity model numerically, and we analyzed the calculated results. It is found that a proper solution for the cosmic expansion rate can be lost in some parameter region. In addition, we show that calculated results of primordial light element abundances can be significantly different from observational data. Especially, observational limits on the primordial D abundance leads to the strongest constraint on the f (G ) gravity. We then derive constraints on parameters of the f (G ) gravity taking into account the existence of the solution of expansion rate and final light element abundances.
Radiative neutron capture on a proton at big-bang nucleosynthesis energies
International Nuclear Information System (INIS)
The total cross section for radiative neutron capture on a proton, np→dγ, is evaluated at big-bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to-leading-order within the framework of pionless effective field theory with dibaryon fields. We also calculate the dγ→np cross section and the photon analyzing power for the dγ(vector sign)→np process from the amplitudes. The values of low-energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low-energy experimental data. Our result agrees well with those of other theoretical calculations except for the np→dγ cross section at some energies estimated by an R-matrix analysis. We also study the uncertainties in our estimation of the np→dγ cross section at relevant BBN energies and find that the estimated cross section is reliable to within ∼1% error
Origin of matter and space-time in the big bang
International Nuclear Information System (INIS)
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
Implication of the Proton-Deuteron Radiative Capture for Big Bang Nucleosynthesis
Marcucci, L. E.; Mangano, G.; Kievsky, A.; Viviani, M.
2016-03-01
The astrophysical S factor for the radiative capture d (p ,γ ) 3He 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 v18 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 /m3. 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 /m3 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 )3He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for 2H/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 Neff=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.
Using Big Bang Nucleosynthesis to extend CMB probes of neutrino physics
International Nuclear Information System (INIS)
We present calculations showing that upcoming Cosmic Microwave Background (CMB) experiments will have the power to improve on current constraints on neutrino masses and provide new limits on neutrino degeneracy parameters. The latter could surpass those derived from Big Bang Nucleosynthesis (BBN) and the observationally-inferred primordial helium abundance. These conclusions derive from our Monte Carlo Markov Chain (MCMC) simulations which incorporate a full BBN nuclear reaction network. This provides a self-consistent treatment of the helium abundance, the baryon number, the three individual neutrino degeneracy parameters and other cosmological parameters. Our analysis focuses on the effects of gravitational lensing on CMB constraints on neutrino rest mass and degeneracy parameter. We find for the PLANCK experiment that total (summed) neutrino mass Mν > 0.29 eV could be ruled out at 2σ or better. Likewise neutrino degeneracy parameters ξνe > 0.11 and |ξνμ/τ| > 0.49 could be detected or ruled out at 2σ confidence, or better. For POLARBEAR we find that the corresponding detectable values are Mν > 0.75 eV, ξνe > 0.62, and |ξνμ/τ| > 1.1, while for EPIC we obtain Mν > 0.20 eV, ξνe > 0.045, and |ξνμ/τ| > 0.29. Our forcast for EPIC demonstrates that CMB observations have the potential to set constraints on neutrino degeneracy parameters which are better than BBN-derived limits and an order of magnitude better than current WMAP-derived limits
An update on the big bang nucleosynthesis prediction for 7Li: the problem worsens
International Nuclear Information System (INIS)
The lithium problem arises from the significant discrepancy between the primordial 7Li abundance as predicted by big bang nucleosynthesis (BBN) theory and the Wilkinson Microwave Anisotropy Probe (WMAP) baryon density, and the pre-Galactic lithium abundance inferred from observations of metal-poor (Population II) stars. This problem has loomed for the past decade, with a persistent discrepancy of a factor of 2–3 in 7Li/H. Recent developments have sharpened all aspects of the Li problem. Namely: (1) BBN theory predictions have sharpened due to new nuclear data; in particular, the uncertainty on the reaction rate for3He(α,γ)7Be has reduced to 7.4%, nearly a factor of 2 tighter than previous determinations. (2) The WMAP five-year data set now yields a cosmic baryon density with an uncertainty reduced to 2.7%. (3) Observations of metal-poor stars have tested for systematic effects. With these, we now find that the BBN+WMAP predicts7Li/H = (5.24−0.67+0.71) × 10−10. The central value represents an increase by 23%, most of which is due to the upward shift in the3He(α,γ)7Be rate. More significant is the reduction in the7Li/H uncertainty by almost a factor of 2, tracking the reduction in the3He(α,γ)7Be error bar. These changes exacerbate the Li problem; the discrepancy is now a factor 2.4 or 4.2σ (from globular cluster stars) to 4.3 or 5.3σ (from halo field stars). Possible resolutions to the lithium problem are briefly reviewed, and key experimental and astronomical measurements highlighted
A magnified young galaxy from about 500 million years after the Big Bang.
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. PMID:22996554
From the Big Bang to the stars: The genesis of matter
International Nuclear Information System (INIS)
After the second World War, it was believed that the whole chemical elements of the Universe were produced in the heart of the stars by successive nuclear fusion reactions. However, the relative abundance of some elements, such as deuterium, helium, lithium, beryllium or bore, are more abundant than expected by this simple theory. In 1970, the spallation mechanism was proposed to explain the formation of anomalous abundances of lithium, beryllium and bore in the interstellar medium by the splitting of heavy nuclei under the action of cosmic rays. However, this process cannot explain the observed quantities of deuterium, helium 3 and 4, and lithium 7. The explanation must be found in the first steps of the Universe creation. This paper describes the first minutes of the evolution of the primordial Universe and the successive chain reactions between neutrons, protons, and neutrinos, and then between neutrons and protons to produce deuterium and progressively heavier nuclei. This standard model of the Big Bang does not show any major contradiction between the observed relative abundance of elements and a common value for the baryonic number. However, the stellar activity has continuously modified the primordial abundance of the elements, in particular deuterium could have been ten times more abundant in the primitive matter than today. The observation and analysis of stellar matter, meteorites, stars and young galaxies indicate that the baryonic number cannot be greater than 5 10-10 and that today the Universe's baryonic density is lower than 3 10-31 g/cm3. This value is 15 to 30 times lower than the critical density on which our Universe evolution depends. Our Universe seems to be in a perpetual expansion as far as the existence of a huge quantity of non-baryonic matter (the famous missing mass) has not been demonstrated. (J.S.). 12 refs, 3 figs, 1 photo
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...
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.
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.)
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.
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.
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.
Andersson Happe, Emma
2015-01-01
Since 2007 the American sitcom the Big Bang Theory has spread throughout the world. With its twenty million watchers it is one of the most popular sitcoms of our time. The starting point for this essay is that the humourus series with the more or less geeky main characters is more than just entertainment - it is a part of the mediatization of religion. This means that media is affecting the recipients’ view on religion in general and the personal religion. As we watch TV, we get socialized in...
International Nuclear Information System (INIS)
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.)
International Nuclear Information System (INIS)
We extend the Induced Matter Theory of gravity (IMT) to 5D curved spacetimes by using the Weitzenboeck representation of connections on a 5D curved spacetime. In this representation the 5D curvature tensor becomes null, so that we can make a static foliation on the extra non-compact coordinate to induce in the Weitzenboeck representation the Einstein equations. Once we have done it, we can rewrite the effective 4D Einstein equations in the Levi-Civita representation. This generalization of IMT opens a huge window of possible applications for this theory. A pre-big bang collapsing scenario is explored as an example. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Romero, Jesus Martin [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Mar del Plata (Argentina); Bellini, Mauricio [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Mar del Plata (Argentina); Universidad Nacional de Mar del Plata, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Funes 3350, C.P. 7600, Mar del Plata (Argentina)
2013-02-15
We extend the Induced Matter Theory of gravity (IMT) to 5D curved spacetimes by using the Weitzenboeck representation of connections on a 5D curved spacetime. In this representation the 5D curvature tensor becomes null, so that we can make a static foliation on the extra non-compact coordinate to induce in the Weitzenboeck representation the Einstein equations. Once we have done it, we can rewrite the effective 4D Einstein equations in the Levi-Civita representation. This generalization of IMT opens a huge window of possible applications for this theory. A pre-big bang collapsing scenario is explored as an example. (orig.)
Rate of 3H(7Li,n0)9Be and big-bang nucleosynthesis
International Nuclear Information System (INIS)
The differential cross sections for the 3H(7Li,n0)9Be reaction measured at 5 angles in the energy range E(c.m.)=0.2-0.9 MeV using a pulsed 7Li beam and time-of-flight technique. Absolute values of the cross section were obtained by comparison with the well-known cross section of 3H(d,n)4He at Ed=1.0 MeV. The resulting reaction rates are obtained at temperatures relevant to big-bang nucleosynthesis, and consequences for primordial 9Be abundances are discussed. (orig.)
Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Mangano, Gianpiero; Miele, Gennaro; Pisanti, Ofelia; Sarikas, Srdjan [Istituto Nazionale di Fisica Nucleare – Sezione di Napoli, Complesso Universitario di Monte S. Angelo, I-80126 Napoli (Italy); Pastor, Sergio, E-mail: mangano@na.infn.it, E-mail: miele@na.infn.it, E-mail: pastor@ific.uv.es, E-mail: pisanti@na.infn.it, E-mail: sarikas@na.infn.it [Instituto de Física Corpuscular (CSIC-Universitat de València), Ed. Institutos de Investigación, Apdo. correos 22085, E-46071 Valencia (Spain)
2011-03-01
The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N{sub eff}. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N{sub eff} from primordial neutrino-antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, η{sub ν} = η{sub ν{sub e}}+η{sub ν{sub μ}}+η{sub ν{sub τ}} and the initial electron neutrino asymmetry η{sub ν{sub e}{sup in}}, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the ν{sub e}−ν-bar {sub e} asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial {sup 2}H/H density ratio and {sup 4}He mass fraction. Note that taking the baryon fraction as measured by WMAP, the {sup 2}H/H abundance plays a relevant role in constraining the allowed regions in the η{sub ν}−η{sub ν{sub e}{sup in}} plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N{sub eff} as a function of the mixing parameter θ{sub 13}, and point out the upper bound N{sub eff}∼<3.4. Comparing these results with the forthcoming measurement of N{sub eff} by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.
'Big Bang' tomography as a new route to atomic-resolution electron tomography.
Van Dyck, Dirk; Jinschek, Joerg R; Chen, Fu-Rong
2012-06-14
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
Zylstra, Alex; Herrmann, Hans; Kim, Yongho; Hale, Gerry; Paris, Mark; McEvoy, Aaron; Gatu Johnson, Maria; Frenje, Johan; Li, Chikang; Seguin, Fredrick; Sio, Hong; Petrasso, Richard; McNabb, Dennis; Sayre, Dan; Pino, Jesse; Brune, Carl; Bacher, Andy; Forrest, Chad; Glebov, Vladimir; Stoeckl, Christian; Janezic, Roger; Sangster, Craig
2015-11-01
The 3He+3He, T+3He, and p +D reactions directly relevant to Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using high-temperature low-density `exploding pusher' implosions. The advantage of using these plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments. Measured proton spectra from the 3He3He reaction are used to constrain nuclear R-matrix modeling. The resulting T+3He gamma-ray data rule out an anomalously-high 6Li production during the Big Bang as an explanation to the high observed values in metal poor first generation stars. The proton spectrum from the T+3He reaction is also being used to constrain the R-matrix model. Recent experiments have probed the p +D reaction for the first time in a plasma; this reaction is relevant to energy production in protostars, brown dwarfs and at higher CM energies to BBN. This work was partially supported by the US DOE, NLUF, LLE, and GA.
International Nuclear Information System (INIS)
In this paper, a multi-objective framework is proposed for simultaneous optimal network reconfiguration and DG (distributed generation) power allocation. The proposed method encompasses objective functions of power losses, voltage stability, DG cost, and greenhouse gas emissions and it is optimized subject to power system operational and technical constraints. In order to solve the optimization problem, the HBB-BC (Hybrid Big Bang-Big Crunch) algorithm as one of the most recent heuristic tools is modified and employed here by introducing a mutation operator to enhance its exploration capability. To resolve the scaling problem of differently-scaled objective functions, a fuzzy membership is used to bring them into a same scale and then, the fuzzy fitness of the final objective function is utilized to measure the satisfaction level of the obtained solution. The proposed method is tested on balanced and unbalanced test systems and its results are comprehensively compared with previous methods considering different scenarios. According to results, the proposed method not only offers an enhanced exploration capability but also has a better converge rate compared with previous methods. In addition, the simultaneous network reconfiguration and DG power allocation leads to a more optimal result than separately doing tasks of reconfiguration and DG power allocation. - Highlights: • Hybrid Big Bang-Big Crunch algorithm is applied to network reconfiguration problem. • Joint reconfiguration and DG power allocation leads to a more optimal solution. • A mutation operator is used to improve the exploration capability of HBB-BC method. • The HBB-BC has a better convergence rate than the compared algorithms
Most Distant X-Ray Jet Yet Discovered Provides Clues To Big Bang
2003-11-01
The most distant jet ever observed was discovered in an image of a quasar made by NASA's Chandra X-ray Observatory. Extending more than 100,000 light years from the supermassive black hole powering the quasar, the jet of high-energy particles provides astronomers with information about the intensity of the cosmic microwave background radiation 12 billion years ago. The discovery of this jet was a surprise to the astronomers, according to team members. Astronomers had previously known the distant quasar GB1508+5714 to be a powerful X-ray source, but there had been no indication of any complex structure or a jet. "This jet is especially significant because it allows us to probe the cosmic background radiation 1.4 billion years after the Big Bang," said Aneta Siemiginowska of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of a report on this research in the November 20th Astrophysical Journal Letters. Prior to this discovery, the most distant confirmed X-ray jet corresponded to a time about 3 billion years after the Big Bang. Quasars are thought to be galaxies that harbor an active central supermassive black hole fueled by infalling gas and stars. This accretion process is often observed to be accompanied by the generation of powerful high-energy jets. Radio image of GB1508 Radio Image of GB1508 As the electrons in the jet fly away from the quasar at near the speed of light, they move through the sea of cosmic background radiation left over from the hot early phase of the universe. When a fast-moving electron collides with one of these background photons, it can boost the photon's energy up into the X-ray band. The X-ray brightness of the jet depends on the power in the electron beam and the intensity of the background radiation. "Everyone assumes that the background radiation will change in a predictable way with time, but it is important to have this check on the predictions," said Siemiginowska. "This jet is hopefully just the
Montemayor-Aldrete, J. A.; Morones-Ibarra, J. R.; Morales-Mori, A.; Ugalde-Velez, P.; Mendoza-Allende, A.; Cabrera-Bravo, E.; Montemayor-Varela, A.
2013-03-01
It is shown that the entropy of the low density monochromatic gravitational waves which stabilize gravitationally the crystalline structure of vacuum cosmic space varies with the volume in the same way as the entropy of an ideal gas formed by particles. This implies that close enough to the local Big-Bang event the energy of all the gravitational waves which stabilizes the crystalline structure of vacuum space behaves thermodynamically as though it is consisted of a number of independent energy or matter quanta (neutrons). Also it is shown that the diminishing in the gravitational energy of the waves which stabilize the crystalline vacuum space structure is the source of energy required to produce the electromagnetic radiation which is responsible for the hot matter expansion through a preexisting infinite cosmic space. Matter and antimatter is produced in equal quantities at the Big Bang region and there are no annihilation events between them during their initial stage of expansion through vacuum cosmic space due to the gravitational stress gradient pattern existing around the source region which has zero gravitational stress all the matter travels globally in one direction (For instance pointing to the long range tension gravitational stress cell-region) and all the antimatter corresponding to the contiguous compressed cell-region travels in the opposite direction. The obtained expression for the volumetric electromagnetic energy density resembles the classical one proportional to , obtained for the black body radiation in equilibrium conditions at temperature ; and at thermal equilibrium with baryons for the decoupling temperature between photons and matter, , electromagnetic energy of radiation has a value of photons per baryon. Also the evaluation of the Gibbs ´s free energy for the adiabatic compression process of transformation of gravitational stabilization waves of the crystalline vacuum space into baryons at the Big Bang gives a value of zero for the
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=\
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.
First direct measurement of the 2H(α,γ)6Li cross section at Big Bang energies at LUNA
International Nuclear Information System (INIS)
The amount of 6Li produced during the Big Bang Nucleosynthesis (BBN) era can be theoretically estimated on the basis of cosmological and nuclear astrophysics knowledge. The latter strongly depends on the measurement of the nuclear cross section of the processes involved in the production and destruction of 6Li during the first stages of the Universe. Whereas the destruction process cross sections are well known, the reaction that dominates the 6Li production, the 2H(α,γ)6Li, has never been directly measured in the BBN energy range and only upper limits coming from indirect measurements are available till now. Here we report the first direct measurement of the 2H(α,γ)6Li cross section at BBN energies obtained at LUNA (Laboratory for Underground Nuclear Astrophysics, LNGS, Italy). (author)
International Nuclear Information System (INIS)
This talk has been prepared for the Symposium on Novel Approaches to Nuclear Astrophysics hosted by the ACS Division of Nuclear Chemistry and Technology for the San Diego ACS meeting. This talk indeed describes a truly novel approach. It discusses a proposal for the construction of the National Ignition Facility which could provide the most powerful concentration of laser energy yet attempted. The energy from such a facility could be concentrated in such a way as to reproduce, for the first time in a terrestrial laboratory, an environment which nearly duplicates that which occurs within stars and during the first few moments of cosmic creation during the big bang. These miniature versions of cosmic explosions may allow us to understand better the tumultuous astrophysical environments which have profoundly influenced the origin and evolution of the universe
International Nuclear Information System (INIS)
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.
Alexeev, Boris V
2010-01-01
Quantum solitons are discovered with the help of generalized quantum hydrodynamics. The solitons have the character of the stable quantum objects in the self consistent electric field. The delivered theory demonstrates the great possibilities of the generalized quantum hydrodynamics in investigation of the quantum solitons. The theory leads to solitons as typical formations in the generalized quantum hydrodynamics. The principle of universal antigravitation is considered from positions of the Newtonian theory of gravitation and non-local kinetic theory. It is found that explanation of Hubble effect in the Universe and peculiar features of the rotational speeds of galaxies need not in introduction of new essence like dark matter and dark energy. Problems of antimatter after Big Bang are considered from positions of non-local physics. The origin of difficulties consists in total Oversimplification following from principles of local physics and reflects the general shortenings of the local kinetic transport theo...
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...
International Nuclear Information System (INIS)
Ordinary-sterile neutrino oscillations can generate significant neutrino asymmetry in the early Universe. In this paper we extend this work by computing the evolution of neutrino asymmetries and light element abundances during the big bang nucleosynthesis (BBN) epoch. We show that a significant electron-neutrino asymmetry can be generated in a way that is approximately independent of the oscillation parameters δm2 and sin22θ for a range of parameters in an interesting class of models. The numerical value of the asymmetry leads to the prediction that the effective number of neutrino flavors during BBN is either about 2.5 or 3.4, depending on the sign of the asymmetry. Interestingly, one class of primordial deuterium abundance data favors an effective number of neutrino flavors during the epoch of BBN of less than 3. copyright 1997 The American Physical Society
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
Bid to recreate the Big Bang and unlock the secrets of life hits a
Morgan, James
2007-01-01
"It was not the kind of "big band" they were hopint for - but the explosion at the new £6.81 bn particle accelerator in Switzerland on Saturday, was "not a major setback", says a British scientist who is leading the project." (1 page)
Large hadron collider will get us closer to the Big Bang
Khadilkar, Dhananjay
2006-01-01
The LHC consists of a 27 km tunnel located 100 meters under the ground near Geneva in Switzerland, lined with hundreds of superconducting magnets which will accelerate protons and subsequently collide them at mind-boggling energies of 14 terra electorn Volts. The result will be conditions prevalent just microseconds after the Big Band 15 billion years ago (1/2 page)
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.
Marques, J M C; Pais, A A C C; Abreu, P E
2012-02-01
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. PMID:22131287
Historia del modelo cosmológico estándar LCDM: la cosmología física tras del modelo del big bang
Luis Peña, Pilar Francisca
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
Reynès, Janie
2015-01-01
This research focuses on two American TV shows, Friends and The Big Bang Theory. The analysis and comparison of translation segments of both shows in the original version in English and the dubbed version in Spanish enable the translation of humor in general to be studied, and, most specifically, culture-related humor. Some translation mistakes are also described. For each translation segment considered improvable a solution has been proposed. Both shows feature cultural references although F...
Tsujikawa, S; Finelli, F; Tsujikawa, Shinji; Brandenberger, Robert; Finelli, Fabio
2002-01-01
We consider the construction of nonsingular Pre-Big-Bang and Ekpyrotic type cosmological models realized by the addition to the action of specific higher-order terms stemming from quantum corrections. We study models involving general relativity coupled to a single scalar field with a potential motivated by the Ekpyrotic scenario. We find that the inclusion of the string loop and quantum correction terms in the string frame makes it possible to obtain solutions of the variational equations which are nonsingular and bouncing in the Einstein frame, even when a negative exponential potential is present, as is the case in the Ekpyrotic scenario. We analyze the spectra of perturbations produced during the bouncing phase and find that the spectrum of curvature fluctuations in the model proposed originally to implement the Ekpyrotic scenario has a large blue tilt (n_R = 3). Except for instabilities introduced on small scales, the result agrees with what is obtained by imposing continuity of the induced metric and of...
Big-Bang Nucleosynthesis and Gamma-Ray Constraints on Cosmic Strings with a large Higgs condensate
Mota, H F Santana
2014-01-01
We consider constraints on cosmic strings from their emission of Higgs particles, in the case that the strings have a Higgs condensate with amplitude of order the string mass scale, assuming that a fraction of the energy of condensate can be turned into radiation near cusps. The injection of energy by the decaying Higgs particles affects the light element abundances predicted by standard Big-Bang Nucleosynthesis (BBN), and also contributes to the Diffuse Gamma-Ray Background (DGRB) in the universe today. We examine the two main string scenarios (Nambu-Goto and field theory), and find that the primordial Helium abundance strongly constrains the string tension and the efficiency of the emission process. The Fermi-LAT measurement of the DGRB constrains the field theory scenario (but not the NG scenario) even more strongly, requiring that the product of the string tension {\\mu} and Newton's constant G is bounded by G{\\mu} < 3x10^{-11}{\\beta}_{ft}^{-2}, where {\\beta}_{ft}^2 is the fraction of the strings' energ...
International Nuclear Information System (INIS)
The standard model of big bang nucleosynthesis (BBN) relies on a nuclear reaction network operating with thermal reactivities for Maxwellian plasma. In the primordial plasma, however, a number of non-thermal processes triggered by energetic particles of various origins can take place. In the present work we examine in-flight nuclear reactions induced in the plasma by MeV protons generated in D(d, p)T and 3He(d, p)4He fusions. We particularly focus on several low threshold endoergic processes. These are reactions omitted in the standard network—proton-induced break-ups of loosely bound D, 7Li, 7Be nuclei—and the 3H(p, n)3He charge-exchange reaction important for the interconversion of A = 3 nuclei in the early universe. It is found that the break-up processes in the plasma take the form of Maxwellian processes at temperatures T>70 keV, while in the lower temperature range they proceed as non-thermal reactions. It is shown that at Tp = 0.2457, D/H = 2.542 × 10−5, 3He/H = 1.004 × 10−5, 7Li/H = 4.444 × 10−10. Future steps in the study of non-thermal processes in the primordial plasma are briefly discussed
International Nuclear Information System (INIS)
Data from future high precision cosmic microwave background measurements will be sensitive to the primordial helium abundance Yp. At the same time, this parameter can be predicted from big bang nucleosynthesis (BBN) as a function of the baryon and radiation densities, as well as a neutrino chemical potential. We suggest using this information to impose a self-consistent BBN prior on Yp and determining its impact on parameter inference from simulated planck data. We find that this approach can significantly improve bounds on cosmological parameters compared to an analysis which treats Yp as a free parameter, if the neutrino chemical potential is taken to vanish. We demonstrate that fixing the helium fraction at an arbitrary value can seriously bias parameter estimates. Under the assumption of degenerate BBN (i.e., letting the neutrino chemical potential ξ vary), the BBN prior's constraining power is somewhat weakened, but nevertheless allows us to constrain ξ with an accuracy that rivals that for bounds inferred from present data on light element abundances
Biological Review of Wapanocca and Big Lake National Wildlife Refuges
US Fish and Wildlife Service, Department of the Interior — This report covers and summarizes a biological review of Wapanocca and Big Lake National Wildlife Refuge in 1999. Topics include Wapanocca Lake, cropland,...
THE ANATOMY OF AN EXTREME STARBURST WITHIN 1.3 Gyr OF THE BIG BANG REVEALED BY ALMA
International Nuclear Information System (INIS)
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.
A galaxy rapidly forming stars 700 million years after the Big Bang at redshift 7.51.
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. PMID:24153304
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.
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.
Cortes, Eduardo; Vanoli, Verónica; Casas, Sandra
2006-01-01
El proceso de enseñanza y aprendizaje de los cursos iniciales de nivel superior que tienen por objeto introducir al estudiante en el diseño e implementación de algoritmos, puede ser favorecido mediante el uso de herramientas específicas que den soporten tanto a los temas conceptuales como a las técnicas utilizadas. BIG BANG es una herramienta construida y utilizada como recurso didáctico-pedagógico en estos contextos, cuyo objetivo es facilitar la complementación de las prácticas habitualm...
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
S-factor measurement of the 2H(α,γ)6Li reaction at energies relevant for Big-Bang nucleosynthesis
International Nuclear Information System (INIS)
For about 20 years now, observations of 6Li in several old metal-poor stars inside the halo of our galaxy have been reported, which are largely independent of the stars' metallicity, and which point to a possible primordial origin. The observations exceed the predictions of the Standard Big-Bang Nucleosynthesis model by a factor of 500. In the relevant energy range, no directly measured S-factors were available yet for the main production reaction 2H(α,γ)6Li, while different theoretical estimations have an uncertainty of up to two orders of magnitude. The very small cross section in the picobarn range has been measured with a deuterium gas target at the LUNA accelerator (Laboratory for Underground Nuclear Astrophysics), located deep underground inside Laboratori Nazionali del Gran Sasso in Italy. A beam-induced, neutron-caused background in the γ-detector occurred which had to be analyzed carefully and subtracted in an appropriate way, to finally infer the weak signal of the reaction. For this purpose, a method to parameterize the Compton background has been developed. The results are a contribution to the discussion about the accuracy of the recent 6Li observations, and to the question if it is necessary to include new physics into the Standard Big-Bang Nucleosynthesis model.
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. PMID:25105610
International Nuclear Information System (INIS)
The homogeneous standard big-bang nucleosynthesis (SBBN) yields of D, 3He, 4He, and 7Li are computed allowing independent variations of μ1, the chemical potential for electron neutrinos, and μ2, the chemical potential of μ neutrinos (or equivalently of GgR, the product of Newton's constant and the number of effective relativistic degrees of freedom at the epoch of nucleosynthesis). This follows up previous investigations of chemical-potential variations, which however considered only [7Li]/[H]congruent 10-9. It is found that even with a primordial 7Li abundance of 10-10 the hydrogen abundance ΩBh02∼0.1 is permitted as is ΩBh02∼1; however, the required chemical potential for the νe is μ1∼T. The required chemical potential for νμ and/or ντ is μ2∼(5--25)T (for ΩBh02 congruent 0.1 and 1, respectively), or equivalently (GgR)∼(few--103)(GgR)SBBN. Thus baryonic dark matter may be incorporated into the standard big-bang nucleosynthesis model albeit with dramatic requirements for lepto-genesis and/or the constancy of the gravitational coupling. It is also found that the ''lithium dip'' tracks the primordial deuterium abundance and thus may not be an independent measure of the parameters of the SBBN model
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.
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)
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…
International Nuclear Information System (INIS)
The development of a new well stimulation technique that uses propellant technology was discussed. The enhanced oil production process involves igniting a cylinder of solid rocket propellant positioned across a perforated zone to disrupt clogging sand. The StimGun assembly is a hybrid method of perforating with simultaneous propellant stimulation. High pressure gas enters the perforated zone and breaks through damage around the tunnel creating fractures. Data recorders can also run with the StimGun to record downhole pressure and provide a data model for estimating rock properties and propellant penetration. The StimGun assembly was developed by Marathon Oil, Computalog Ltd., Owen Oil Tools, and HTH Technical Services Inc., and is available in Canada from Computalog. 1 fig
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.
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).
Izaias, Karla Camila Oliveira
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.
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
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。
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。
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.
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)
International Nuclear Information System (INIS)
In a recent analysis of Wilkinson Microwave Anisotropy Probe (WMAP) seven-year temperature maps, Gurzadyan and Penrose claim to find concentric circular patterns in the sky with anomalously low variances. These circles are presented as observational evidence for violent processes in a universe preceding our big bang as predicted by Penrose's Conformal Cyclic Cosmology. We reassess the statistical significance of the detection of the claimed concentric low-variance circles by comparing the WMAP data with Monte Carlo simulations of the cosmic microwave background (CMB) sky plus realistic modeling of WMAP's anisotropic noise. We find no anomaly in the variances compared with the ΛCDM cosmological model. The observed variances in the data are consistent with a Gaussian CMB sky as predicted by the inflationary cosmology model at better than 3σ.
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。
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.
Towards the study of 2H(p, γ)3He reaction in the Big Bang Nucleosynthesis energy range in LUNA
Kochanek, Izabela
2016-04-01
The Big Bang Nucleosynthesis began a few minutes after the Big Bang, when the Universe was sufficiently cold to allow deuterium nuclei to survive photo-disintegration. The total amount of deuterium produced in the Universe during the first minutes depends on the cosmological parameters (like the energy density in baryons, Ω bh 2, and the effective neutrino number, Neff ) and on the nuclear cross sections of the relevant reactions. The main source of uncertainty in the deuterium estimation comes from the 2H(p, γ)3He cross section. Measurements of Cosmic Microwave Background (CMB) anisotropies obtained by the Planck satellite are in very good agreement with the theoretical predictions of the minimal ΛCDM cosmological model, significantly reducing the uncertainty on its parameters. The Planck data allows to indirectly deduce with very high precision the abundances of primodial nuclides, such as the primodial deuterium fraction 2H/H = (2.65 ± 0.07) .10-5 (68% C.L.). The astrophysical observations in damped Lyman-a systems at high redshifts provide a second high accuracy measurement of the primodial abundance of deuterium 2H/H = (2.53 ± 0.04) · 10-5 (68% C.L.). The present experimental status on the astrophysical S-factor of the 2H(p, γ)3He reaction in the BBN energy range, gives a systematic uncertainties of 9%. Also the difference between ab-initio calculations and experimental values of S12 is at the level of 10%. In order to clarify the actual scenario, a measurement of 2H(p, γ)3He cross section with a precision of a few percent in the 70-400 keV energy range is planned at LUNA in 2016. A feasibility test of the measurement has been performed in October 2014, giving the preliminary results on the cross section. The experimental setup for the test and final measurement campaign will be presented.
Overbye, Dennis
2007-01-01
"At a news conference in Beijing this Thursday, an international consortium of physicists released the first detailed design of what they believe will be the Next Big Thing in physics: a machine 20 miles long that will slam together electrons and their evil-twin opposites, positrons, to produce fireballs of energy recreating conditions when the universe was only a trillionth of a second old." (1.5 page)
Expanding protein universe and its origin from the biological Big Bang
Dokholyan, Nikolay V.; Shakhnovich, Boris; Shakhnovich, Eugene I.
2002-01-01
The bottom-up approach to understanding the evolution of organisms is by studying molecular evolution. With the large number of protein structures identified in the past decades, we have discovered peculiar patterns that nature imprints on protein structural space in the course of evolution. In particular, we have discovered that the universe of protein structures is organized hierarchically into a scale-free network. By understanding the cause of these patterns, we attempt to glance at the v...
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。
International Nuclear Information System (INIS)
The 3He(α,γ)7Be reaction plays an important role both in determining the predicted fluxes of 7Be and 8B neutrinos from our Sun, and in the calculation of primordial 7Li production. In light of the highly precise determination of the baryon-to-photon ratio from the cosmic microwave background data, it is necessary to re-determine primordial 7Li production. Recent experimental nuclear astrophysics work has led to an improved determination of the 3He(α,γ)7Be cross section, with several experiments clustered at E = 0.5 MeV center-of-mass energy and above [2, and references therein]. On the other hand, precisely calibrated 7Be and 8B neutrino fluxes from the Sun are now available. Assuming the accepted solar central temperature to be correct, the neutrino flux data can be used to determine the 3He(α,γ)7Be cross section at the solar Gamow peak, E = 0.03 MeV. The energy range relevant for Big Bang 7Li production lies just between 0.03 and 0.5 MeV. The poster aims to use the two above described levels in order to improve the precision of the predicted primordial abundance of 7Li. It updates a previous work that appeared before the new cross section, solar neutrino and microwave background data were available. (author)
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.
International Nuclear Information System (INIS)
Continuing the analysis of non-thermal effects in standard big bang nucleosynthesis (JCAP05(2008)010), we examine the role of suprathermal nuclear reactions induced in the early universe plasma by energetic nucleons of various origins. The processes of present interest are break-ups of D, 7Li, 7Be nuclei induced by 14-MeV neutrons generated in the plasma via the T(d, n)4He reaction. It is shown that this reaction forms the ensemble of fast neutrons whose fraction in the plasma neutron component is at the level of 0.01 %. In spite of the small percentage, such neutrons can effectively destroy the loosely bound D, 7Li, 7Be nuclei. It is found that at temperatures T9 7Li dominate over other reactions occurring in the n+D and n+7Li systems. However, the non-thermal neutronic effects prove to be insufficiently strong to modify the standard picture of nucleosynthesis. The D, 3He, 4He abundances are obtained to remain unchanged, and only a little effect is marked for primordial 7Li. The 0.01 % fraction of plasma neutrons (fast DT neutrons) reduces the 7Li abundance by 0.02 %
2007-01-01
The entrails of the universe, the keys of the biological clock, diseases like Alzheimer and the processes that govern our brain, the mother celles, the physic of materials, the survival of the lynx, the fight against cancer, etc...(2,5 pages)
Kusakabe, Motohiko; Kim, K. S.; Cheoun, Myung-Ki; Kajino, Toshitaka; Kino, Yasushi; Mathews, Grant. J.
2014-09-01
We extensively reanalyze the effects of a long-lived, negatively charged massive particle, X -, on big bang nucleosynthesis (BBN). The BBN model with an X - particle was originally motivated by the discrepancy between the 6, 7Li abundances predicted in the standard BBN model and those inferred from observations of metal-poor stars. In this model, 7Be is destroyed via the recombination with an X - particle followed by radiative proton capture. We calculate precise rates for the radiative recombinations of 7Be, 7Li, 9Be, and 4He with X -. In nonresonant rates, we take into account respective partial waves of scattering states and respective bound states. The finite sizes of nuclear charge distributions cause deviations in wave functions from those of point-charge nuclei. For a heavy X - mass, mX >~ 100 GeV, the d-wave → 2P transition is most important for 7Li and 7, 9Be, unlike recombination with electrons. Our new nonresonant rate of the 7Be recombination for mX = 1000 GeV is more than six times larger than the existing rate. Moreover, we suggest a new important reaction for 9Be production: the recombination of 7Li and X - followed by deuteron capture. We derive binding energies of X nuclei along with reaction rates and Q values. We then calculate BBN and find that the amount of 7Be destruction depends significantly on the charge distribution of 7Be. Finally, updated constraints on the initial abundance and the lifetime of the X - are derived in the context of revised upper limits to the primordial 6Li abundance. Parameter regions for the solution to the 7Li problem and the primordial 9Be abundances are revised.
International Nuclear Information System (INIS)
We extensively reanalyze the effects of a long-lived, negatively charged massive particle, X –, on big bang nucleosynthesis (BBN). The BBN model with an X – particle was originally motivated by the discrepancy between the 6, 7Li abundances predicted in the standard BBN model and those inferred from observations of metal-poor stars. In this model, 7Be is destroyed via the recombination with an X – particle followed by radiative proton capture. We calculate precise rates for the radiative recombinations of 7Be, 7Li, 9Be, and 4He with X –. In nonresonant rates, we take into account respective partial waves of scattering states and respective bound states. The finite sizes of nuclear charge distributions cause deviations in wave functions from those of point-charge nuclei. For a heavy X – mass, mX ≳ 100 GeV, the d-wave → 2P transition is most important for 7Li and 7, 9Be, unlike recombination with electrons. Our new nonresonant rate of the 7Be recombination for mX = 1000 GeV is more than six times larger than the existing rate. Moreover, we suggest a new important reaction for 9Be production: the recombination of 7Li and X – followed by deuteron capture. We derive binding energies of X nuclei along with reaction rates and Q values. We then calculate BBN and find that the amount of 7Be destruction depends significantly on the charge distribution of 7Be. Finally, updated constraints on the initial abundance and the lifetime of the X – are derived in the context of revised upper limits to the primordial 6Li abundance. Parameter regions for the solution to the 7Li problem and the primordial 9Be abundances are revised
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.
Contreras Radovic, Cristian
2005-01-01
My doctoral thesis studies the Big Bang Theory about the origin of the universe and his relationship with the doctrine of the buddhist philosopher Nagarjuna (India s.II-III), founder of Buddhism of the Middle Way, in accord with his genuine work, titled: Mûla-mâdhyamaka-kârik_; an authentic text, opus magna of this author in accord with the india, chinese and tibetan tradition, clear probe of the history of his figure. Nagarjuna, one of the four suns witch illuminated the world in the four di...
From Darwin to the Census of Marine Life: Marine Biology as Big Science
Vermeulen, N.
2013-01-01
With the development of the Human Genome Project, a heated debate emerged on biology becoming ‘big science’. However, biology already has a long tradition of collaboration, as natural historians were part of the first collective scientific efforts: exploring the variety of life on earth. Such mappings of life still continue today, and if field biology is gradually becoming an important subject of studies into big science, research into life in the world's oceans is not taken into account yet....
Suwa, Tomomi; Williamson, Brad
2014-01-01
We present a guided-inquiry biology lesson, using the plant-rhizobium symbiosis as a model system. This system provides a rich environment for developing connections between the big ideas in biology as outlined in the College Board's new AP Biology Curriculum. Students gain experience with the practice of scientific investigation, from…
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。
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?