Baryon symmetric big bang cosmology
International Nuclear Information System (INIS)
Stecker, F.W.
1978-01-01
It is stated that the framework of baryon symmetric big bang (BSBB) cosmology offers our greatest potential for deducting the evolution of the Universe because its physical laws and processes have the minimum number of arbitrary assumptions about 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. BSBB cosmology also provides the only acceptable explanation at present for the origin of the cosmic γ-ray background radiation. (author)
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.
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.
Pre-big bang cosmology: A long history of time?
International Nuclear Information System (INIS)
Veneziano, G.
1999-01-01
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)
The big bang cosmology - enigmas and nostrums
International Nuclear Information System (INIS)
Dicke, R.H.; Peebles, P.J.E.
1979-01-01
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.)
Baryon symmetric big-bang cosmology
Energy Technology Data Exchange (ETDEWEB)
Stecker, F.W.
1978-04-01
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.
Baryon symmetric big-bang cosmology
International Nuclear Information System (INIS)
Stecker, F.W.
1978-04-01
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
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.
International Nuclear Information System (INIS)
Gonzalez-Mestres, Luis
2016-01-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of “anomalies”. Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang
Gonzalez-Mestres, Luis
2016-11-01
A year ago, we wrote [1] that the field of Cosmology was undergoing a positive and constructive crisis. The possible development of more direct links between the Mathematical Physics aspects of cosmological patterns and the interpretation of experimental and observational results was particularly emphasized. Controversies on inflation are not really new, but in any case inflation is not required in pre-Big Bang models and the validity of the standard Big Bang + inflation + ΛCDM pattern has not by now been demonstrated by data. Planck has even explicitly reported the existence of "anomalies". Remembering the far-reaching work of Yoichiro Nambu published in 1959-61, it seems legitimate to underline the need for a cross-disciplinary approach in the presence of deep, unsolved theoretical problems concerning new domains of matter properties and of the physical world. The physics of a possible preonic vacuum and the associated cosmology constitute one of these domains. If the vacuum is made of superluminal preons (superbradyons), and if standard particles are vacuum excitations, how to build a suitable theory to describe the internal structure of such a vacuum at both local and cosmic level? Experimental programs (South Pole, Atacama, AUGER, Telescope Array…) and observational ones (Planck, JEM-EUSO…) devoted to the study of cosmic microwave background radiation (CMB) and of ultra-high energy cosmic rays (UHECR) are crucial to elucidate such theoretical interrogations and guide new phenomenological developments. Together with a brief review of the observational and experimental situation, we also examine the main present theoretical and phenomenological problems and point out the role new physics and alternative cosmologies can potentially play. The need for data analyses less focused a priori on the standard models of Particle Physics and Cosmology is emphasized in this discussion. An example of a new approach to both fields is provided by the pre-Big Bang pattern
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.
Challenges to the standard model of Big Bang nucleosynthesis
International Nuclear Information System (INIS)
Steigman, G.
1993-01-01
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 2 H, 3 He, 4 He, and 7 Li 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 ≤ η 10 ≤ 4.0. Increased accuracy in the estimate of primordial 4 he 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 (N ν BBN ≤ 3.0, where N ν is the number of equivalent light neutrinos). 23 refs
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.
Introduction to big bang nucleosynthesis and modern cosmology
Mathews, Grant J.; Kusakabe, Motohiko; Kajino, Toshitaka
Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the testing ground upon which many cosmological models must ultimately rest. It is our only probe of the universe during the important radiation-dominated epoch in the first few minutes of cosmic expansion. This paper reviews the basic equations of space-time, cosmology, and big bang nucleosynthesis. We also summarize the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measurements are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we analyze the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field.
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.
The universe before the Big Bang cosmology and string theory
Gasperini, Maurizio
2008-01-01
Terms such as "expanding Universe", "big bang", and "initial singularity", are nowadays part of our common language. The idea that the Universe we observe today originated from an enormous explosion (big bang) is now well known and widely accepted, at all levels, in modern popular culture. But what happens to the Universe before the big bang? And would it make any sense at all to ask such a question? In fact, recent progress in theoretical physics, and in particular in String Theory, suggests answers to the above questions, providing us with mathematical tools able in principle to reconstruct the history of the Universe even for times before the big bang. In the emerging cosmological scenario the Universe, at the epoch of the big bang, instead of being a "new born baby" was actually a rather "aged" creature in the middle of its possibly infinitely enduring evolution. The aim of this book is to convey this picture in non-technical language accessibile also to non-specialists. The author, himself a leading cosm...
A cosmological analogy between the big bang and a supernova
International Nuclear Information System (INIS)
Sen, S.
1983-01-01
The author presents an objection to Brown's (1981) analogy between a supernova and the Big Bang. According to Brown an expanding spherical shell is quite similar to an ejected supernova shell. However, the fragmented shell of a supernova moves outward in pre-existing space. The force of repulsion which makes the fragments of the shell drift apart can be regarded as equivalent to the force of attraction of the rest of the universe on the supernova. By definition, such a force of attraction is absent in the case of the Big Bang. Energy is supposed suddenly to appear simultaneously at all points throughout the universe at the time of the Big Bang. As the universe expands, space expands too. In the relativistic cosmology, the universe cannot expand in pre-existing space. (Auth.)
Cosmological analogy between the big bang and a supernova
Energy Technology Data Exchange (ETDEWEB)
Sen, S. (Hamburg, Germany, F.R.)
1983-10-01
The author presents an objection to Brown's (1981) analogy between a supernova and the Big Bang. According to Brown an expanding spherical shell is quite similar to an ejected supernova shell. However, the fragmented shell of a supernova moves outward in pre-existing space. The force of repulsion which makes the fragments of the shell drift apart can be regarded as equivalent to the force of attraction of the rest of the universe on the supernova. By definition, such a force of attraction is absent in the case of the Big Bang. Energy is supposed suddenly to appear simultaneously at all points throughout the universe at the time of the Big Bang. As the universe expands, space expands too. In the relativistic cosmology, the universe cannot expand in pre-existing space.
Big-bang nucleosynthesis in the new cosmology
International Nuclear Information System (INIS)
Fields, B.D.
2005-01-01
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 = n B /n γ 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)
String Theory and Pre-big bang Cosmology
Gasperini, M.
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...
Big Bang, Blowup, and Modular Curves: Algebraic Geometry in Cosmology
Manin, Yuri I.; Marcolli, Matilde
2014-07-01
We introduce some algebraic geometric models in cosmology related to the ''boundaries'' of space-time: Big Bang, Mixmaster Universe, Penrose's crossovers between aeons. We suggest to model the kinematics of Big Bang using the algebraic geometric (or analytic) blow up of a point x. This creates a boundary which consists of the projective space of tangent directions to x and possibly of the light cone of x. We argue that time on the boundary undergoes the Wick rotation and becomes purely imaginary. The Mixmaster (Bianchi IX) model of the early history of the universe is neatly explained in this picture by postulating that the reverse Wick rotation follows a hyperbolic geodesic connecting imaginary time axis to the real one. Penrose's idea to see the Big Bang as a sign of crossover from ''the end of previous aeon'' of the expanding and cooling Universe to the ''beginning of the next aeon'' is interpreted as an identification of a natural boundary of Minkowski space at infinity with the Big Bang boundary.
A philosophy for big-bang cosmology.
McCrea, W H
1970-10-03
According to recent developments in cosmology we seem bound to find a model universe like the observed universe, almost independently of how we suppose it started. Such ideas, if valid, provide fresh justification for the procedures of current cosmological theory.
Kantowski--Sachs cosmological models as big-bang models
International Nuclear Information System (INIS)
Weber, E.
1985-01-01
In the presence of a nonzero cosmological constant Λ, we classify the anisotropic cosmological models of the Kantowski--Sachs type by means of the quantities epsilon 2 0 , q 0 , summation 0 corresponding, respectively, to the relative root-mean-square deviation from isotropy, the deceleration parameter, and the density parameter of the perfect fluid at a given time t = t 0 . We obtain for Λ>0 a set of big-bang models of zero measure as well as a set of cosmological models of nonzero measure evolving toward the de Sitter solution
On the Cold Big Bang Cosmology
Directory of Open Access Journals (Sweden)
Assis A. V. D. B.
2011-04-01
Full Text Available We solve the general relativity (GR field equations under the cosmological scope via one extra postulate. The plausibility of the postulate resides within the Heisenberg indeterminacy principle, being heuristically analysed throughout the appendix. Under this approach, a negative energy density may provide the positive energy content of the universe via fluctuation, since the question of conservation of energy in cosmology is weakened, supported by the known lack of scope of the Noether's theorem in cosmology. The initial condition of the primordial universe turns out to have a natural cutoff such that the temperature of the cosmological substratum converges to the absolute zero, instead of the established divergence at the very beginning. The adopted postulate provides an explanation for the cosmological dark energy open question. The solution agrees with cosmological observations, including a 2.7K CMBT prediction.
On the Cold Big Bang Cosmology
Directory of Open Access Journals (Sweden)
Assis A. V. D. B.
2011-04-01
Full Text Available We solve the general relativity (GR field equations under the cosmological scope via one extra postulate. The plausibility of the postulate resides within the Heisenberg in- determinacy principle, being heuristically analysed throughout the appendix. Under this approach, a negative energy density may provide the positive energy content of the universe via fluctuation, since the question of conservation of energy in cosmol- ogy is weakened, supported by the known lack of scope of the Noether’s theorem in cosmology. The initial condition of the primordial universe turns out to have a natural cuto such that the temperature of the cosmological substratum converges to the ab- solute zero, instead of the established divergence at the very beginning. The adopted postulate provides an explanation for the cosmological dark energy open question. The solution agrees with cosmological observations, including a 2.7K CMBT prediction.
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.
General relativity cosmological models without the big bang
International Nuclear Information System (INIS)
Rosen, N.
1985-01-01
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
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).
Big bang nucleosynthesis: The standard model and alternatives
International Nuclear Information System (INIS)
Schramm, D.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 4 He at 24% by mass through 2 H and 3 He at parts in 10 5 down to 7 Li at parts in 10 10 . Furthermore, the recent LEP (and 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 conclusions on the baryonic density relative to the critical density, Ω b , remain approximately the same as in the standard homogeneous case, thus, adding to the robustness of the conclusion that Ω b ≅0.06. This latter point is the driving force behind the need for non-baryonic dark matter (assuming Ω total =1) and the need for dark baryonic matter, since Ω visible b . (orig.)
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.
Pre-big bang cosmology and quantum fluctuations
International Nuclear Information System (INIS)
Ghosh, A.; Pollifrone, G.; Veneziano, G.
2000-01-01
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
Solution of a braneworld big crunch/big bang cosmology
International Nuclear Information System (INIS)
McFadden, Paul L.; Turok, Neil; Steinhardt, Paul J.
2007-01-01
We solve for the cosmological perturbations in a five-dimensional background consisting of two separating or colliding boundary branes, as an expansion in the collision speed V divided by the speed of light c. Our solution permits a detailed check of the validity of four-dimensional effective theory in the vicinity of the event corresponding to the big crunch/big bang singularity. We show that the four-dimensional description fails at the first nontrivial order in (V/c) 2 . At this order, there is nontrivial mixing of the two relevant four-dimensional perturbation modes (the growing and decaying modes) as the boundary branes move from the narrowly separated limit described by Kaluza-Klein theory to the well-separated limit where gravity is confined to the positive-tension brane. We comment on the cosmological significance of the result and compute other quantities of interest in five-dimensional cosmological scenarios
``All that Matter ... in One Big Bang ...'', &Other Cosmological Singularities
Elizalde, Emilio
2018-02-01
The first part of this paper contains a brief description of the beginnings of modern cosmology, which, the author will argue, was most likely born in the Year 1912. Some of the pieces of evidence presented here have emerged from recent research in the history of science, and are not usually shared with the general audiences in popular science books. In special, the issue of the correct formulation of the original Big Bang concept, according to the precise words of Fred Hoyle, is discussed. Too often, this point is very deficiently explained (when not just misleadingly) in most of the available generalist literature. Other frequent uses of the same words, Big Bang, as to name the initial singularity of the cosmos, and also whole cosmological models, are then addressed, as evolutions of its original meaning. Quantum and inflationary additions to the celebrated singularity theorems by Penrose, Geroch, Hawking and others led to subsequent results by Borde, Guth and Vilenkin. And corresponding corrections to the Einstein field equations have originated, in particular, $R^2$, $f(R)$, and scalar-tensor gravities, giving rise to a plethora of new singularities. For completeness, an updated table with a classification of the same is given.
Cosmological perturbations in the 5D big bang
International Nuclear Information System (INIS)
Garriga, Jaume; Tanaka, Takahiro
2002-01-01
Bucher has recently proposed an interesting brane-world cosmological scenario where the 'big bang' hypersurface is the locus of collision of two vacuum bubbles which nucleate in a five-dimensional flat space. This gives rise to an open universe, where the curvature can be very small provided that d/R 0 is sufficiently large. Here, d is the distance between bubbles and R 0 is their size at the time of nucleation. Quantum fluctuations develop on the bubbles as they expand towards each other, and these in turn imprint cosmological perturbations on the initial hypersurface. We present a simple formalism for calculating the spectrum of such perturbations and their subsequent evolution. We conclude that, unfortunately, the spectrum is very tilted, with a spectral index n s =3. The amplitude of fluctuations at the horizon crossing is given by 2 >∼(R 0 /d) 2 S E -1 k 2 , where S E >>1 is the Euclidean action of the instanton describing the nucleation of a bubble and k is the wave number in units of the curvature scale. The spectrum peaks on the smallest possible relevant scale, whose wave number is given by k∼d/R 0 . We comment on the possible extension of our formalism to more general situations where a big bang is ignited through the collision of 4D extended objects
Redshift structure of the big bang in inhomogeneous cosmological models. I. Spherical dust solutions
Energy Technology Data Exchange (ETDEWEB)
Hellaby, C.; Lake, K.
1984-07-01
The redshift from the big bang in the standard model is always infinite, but in inhomogeneous cosmological models infinite blueshifts are also possible. To avoid such divergent energy fluxes, we require that all realistic cosmological models must not display infinite blueshifts. We apply this requirement to the Tolman model (spherically symmetric dust), using the geometrical optics approximation, and assuming that the geodesic tangent vectors may be expanded in power series. We conclude that the bang time must be simultaneous. The stronger requirement, that only infinite redshifts from the big bang may occur, does not lead to a stronger condition on the metric. Further consequences of simultaneity are that no decaying mode fluctuations are possible, and that the only acceptable model which is homogeneous at late times is the Robertson-Walker model.
Redshift structure of the big bang in inhomogeneous cosmological models. I. Spherical dust solutions
International Nuclear Information System (INIS)
Hellaby, C.; Lake, K.
1984-01-01
The redshift from the big bang in the standard model is always infinite, but in inhomogeneous cosmological models infinite blueshifts are also possible. To avoid such divergent energy fluxes, we require that all realistic cosmological models must not display infinite blueshifts. We apply this requirement to the Tolman model (spherically symmetric dust), using the geometrical optics approximation, and assuming that the geodesic tangent vectors may be expanded in power series. We conclude that the bang time must be simultaneous. The stronger requirement, that only infinite redshifts from the big bang may occur, does not lead to a stronger condition on the metric. Further consequences of simultaneity are that no decaying mode fluctuations are possible, and that the only acceptable model which is homogeneous at late times is the Robertson-Walker model
International Nuclear Information System (INIS)
Boyd, Richard N.
2001-01-01
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
On the initial regime of pre-big bang cosmology
Energy Technology Data Exchange (ETDEWEB)
Gasperini, M., E-mail: gasperini@ba.infn.it [Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)
2017-09-01
The production of a background of super-horizon curvature perturbations with the appropriate (red) spectrum needed to trigger the cosmic anisotropies observed on large scales is associated, in the context of pre-big bang inflation, with a phase of growing string coupling. The extension towards the past of such a phase is not limited in time by the dynamical backreaction of the quantum perturbations of the cosmological geometry and of its sources. A viable, slightly red spectrum of scalar perturbations can thus be the output of an asymptotic, perturbative regime which is well compatible with an initial string-vacuum state satisfying the postulate of 'Asymptotic Past Triviality'.
International Nuclear Information System (INIS)
Narlikar, J.
1981-01-01
In discussing the viability of the big-bang model of the Universe relative evidence is examined including the discrepancies in the age of the big-bang Universe, the red shifts of quasars, the microwave background radiation, general theory of relativity aspects such as the change of the gravitational constant with time, and quantum theory considerations. It is felt that the arguments considered show that the big-bang picture is not as soundly established, either theoretically or observationally, as it is usually claimed to be, that the cosmological problem is still wide open and alternatives to the standard big-bang picture should be seriously investigated. (U.K.)
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...
Understanding big bang in loop quantum cosmology: Recent advances
Energy Technology Data Exchange (ETDEWEB)
Singh, Parampreet [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada)], E-mail: psingh@perimeterinstitute.ca
2008-11-01
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.
Understanding big bang in loop quantum cosmology: Recent advances
Singh, Parampreet
2008-11-01
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.
Understanding big bang in loop quantum cosmology: Recent advances
International Nuclear Information System (INIS)
Singh, Parampreet
2008-01-01
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.
A numerical simulation of pre-big bang cosmology
Maharana, J P; Veneziano, Gabriele
1998-01-01
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 ($\\Omega \\to 1$). Numerical calculations are pushed close enough to the big bang singularity to allow cross checks against previously proposed analytic asymptotic solutions.
Resolution of cosmological singularity and a plausible mechanism of the big bang
International Nuclear Information System (INIS)
Choudhury, D.C.
2002-01-01
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 ≅10 32 K at the beginning of the big bang is predicted
"Beyond the Big Bang: a new view of cosmology"
CERN. Geneva
2012-01-01
and parameters? Can one conceive of a completion of the scenario which resolves the big bang singularity and explains the dark energy now coming to dominate? Are we forced to resort to anthropic explanations? In this talk, I will develop an alternate picture, in which the big bang singularity is resolved and in which the value of the dark energy might be fixed by physical processes. The key is a resolution of the singularity. Using a combination of arguments,involving M theory and holography as well as analytic continuation in time within the low energy effective theory, I argue that there is a unique way to match cosmic evolution across the big bang singularity. The latter is no longer the beginning of time but is instead the gateway to an eternal, cyclical universe. If time permits, I shall describe new work c...
Pre-big-bang cosmology and circles in the cosmic microwave background
International Nuclear Information System (INIS)
Nelson, William; Wilson-Ewing, Edward
2011-01-01
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.
Kasner asymptotics of mixmaster Horava-Witten and pre-big-bang cosmologies
International Nuclear Information System (INIS)
Dabrowski, Mariusz P.
2001-01-01
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
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...
Inflationary and deflationary branches in extended pre-big-bang cosmology
International Nuclear Information System (INIS)
Lidsey, J.E.
1997-01-01
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 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
Inflationary and deflationary branches in extended pre-big-bang cosmology
Energy Technology Data Exchange (ETDEWEB)
Lidsey, J.E. [Astronomy Unit, School of Mathematical Sciences, Queen Mary Westfield, Mile End Road, London, E1 4NS (United Kingdom)
1997-03-01
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{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} {ital 1997} {ital The American Physical Society}
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...
Cosmological BCS mechanism and the big bang singularity
Alexander, Stephon; Biswas, Tirthabir
2009-07-01
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.
Observable gravitational waves in pre-big bang cosmology: an update
International Nuclear Information System (INIS)
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 suggest that this is possible in a string cosmology context, for a wide region of the parameter space of the so-called pre-big bang models. We also discuss the associated values of the tensor-to-scalar ratio relevant to the CMB polarization experiments. We conclude that future, cross-correlated results from CMB observations and GW detectors will be able to confirm or disprove pre-big bang models and—in any case—will impose new significant constraints on the basic string theory/cosmology parameters.
Observable gravitational waves in pre-big bang cosmology: an update
Energy Technology Data Exchange (ETDEWEB)
Gasperini, M., E-mail: gasperini@ba.infn.it [Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)
2016-12-01
In the light of the recent results concerning CMB observations and GW detection we address the question of whether it is possible, in a self-consistent inflationary framework, to simultaneously generate a spectrum of scalar metric perturbations in agreement with Planck data and a stochastic background of primordial gravitational radiation compatible with the design sensitivity of aLIGO/Virgo and/or eLISA. We suggest that this is possible in a string cosmology context, for a wide region of the parameter space of the so-called pre-big bang models. We also discuss the associated values of the tensor-to-scalar ratio relevant to the CMB polarization experiments. We conclude that future, cross-correlated results from CMB observations and GW detectors will be able to confirm or disprove pre-big bang models and—in any case—will impose new significant constraints on the basic string theory/cosmology parameters.
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...
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)
Faraoni, Valerio
2010-01-01
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.)
A criticism of big bang cosmological models based on interpretation of the red shift
Energy Technology Data Exchange (ETDEWEB)
Kierein, J.W. (Ball Aerospace Systems Div., Boulder, CO (USA))
1988-08-01
The interaction of light with the intergalactic plasma produces the Hubble red shift versus distance relationship. This interaction also produces an isotopic long wavelength background radiation from the plasma. Intrinsic red shifts in quasars and other objects are similarly explained, showing why they are exceptions to Hubble's law. Because the red shift is not doppler-shifted, big bang cosmological models should be replaced with static models. (author).
Directory of Open Access Journals (Sweden)
Paris Mark
2017-01-01
Full Text Available We introduce a new computational capability that moves toward a self-consistent calculation of neutrino transport and nuclear reactions for big bang nucleosynthesis (BBN. Such a self-consistent approach is needed to be able to extract detailed information about nuclear reactions and physics beyond the standard model from precision cosmological observations of primordial nuclides and the cosmic microwave background radiation. We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our approach allows the dissection of the relative contributions of each process responsible for evolving the dynamics of the early universe. Such an approach allows a detailed account of the evolution of the active neutrino energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and 'ow between the neutrino and photon/electron/positron/baryon plasma components. Our calculations reveal nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions. We discuss the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma. These e↑ects result in changes in the computed values of the BBN deuterium and helium-4 yields that are on the order of a half-percent relative to a baseline standard BBN calculation with no neutrino transport. This is an order of magnitude larger e↑ect than in previous estimates. For particular implementations of quantum corrections in plasma thermodynamics, our calculations show a 0.4% increase in deuterium and a 0.6% decrease in 4He over our baseline. The magnitude of these changes are on the order of uncertainties
Reheating and dangerous relics in pre-big-bang string cosmology
International Nuclear Information System (INIS)
Buonanno, Alessandra; Lemoine, Martin; Olive, Keith A.
2000-01-01
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
Lithium in Very Metal-poor Dwarf Stars -- Problems for Standard Big Bang Nucleosynthesis?
International Nuclear Information System (INIS)
Lambert, David L.
2004-01-01
The standard model of primordial nucleosynthesis by the Big Bang as selected by the WMAP-based estimate of the baryon density (Ωbh2) predicts an abundance of 7Li that is a factor of three greater than the generally reported abundance for stars on the Spite plateau, and an abundance of 6Li that is about a thousand times less than is found for some stars on the plateau. This review discusses and examines these two discrepancies. They can likely be resolved without major surgery on the standard model of the Big Bang. In particular, stars on the Spite plateau may have depleted their surface lithium abundance over their long lifetime from the WMAP-based predicted abundances down to presently observed abundances, and synthesis of 6Li (and 7Li) via α + α fusion reactions may have occurred in the early Galaxy. Yet, there remain fascinating ways in which to remove the two discrepancies involving aspects of a new cosmology, particularly through the introduction of exotic particles
Lithium isotopic abundances in metal-poor stars: a problem for standard big bang nucleosynthesis?
International Nuclear Information System (INIS)
Nissen, P.E.; Asplund, M.; Lambert, D.L.; Primas, F.; Smith, V.V.
2005-01-01
Spectral obtained with VLT/UVES suggest the existence of the 6 Li isotope in several metal-poor stars at a level that challenges ideas about its synthesis. The 7 Li abundance is, on the other hand, a factor of three lower than predicted by standard Big Bang nucleosynthesis theory. Both problems may be explained if decaying suppersymmetric particles affect the synthesis of light elements in the Big Bang. (orig.)
The Standard Model Higgs as the origin of the hot Big Bang
Figueroa, Daniel G.
2017-04-10
If the Standard Model (SM) Higgs is weakly coupled to the inflationary sector, the Higgs is expected to be universally in the form of a condensate towards the end of inflation. The Higgs decays rapidly after inflation -- via non-perturbative effects -- into an out-of-equilibrium distribution of SM species, which thermalize soon afterwards. If the post-inflationary equation of state of the universe is stiff, $w \\simeq +1$, the SM species eventually dominate the total energy budget. This provides a natural origin for the relativistic thermal plasma of SM species, required for the onset the `hot Big Bang' era. The viability of this scenario requires the inflationary Hubble scale $H_*$ to be lower than the instability scale for Higgs vacuum decay, the Higgs not to generate too large curvature perturbations at cosmological scales, and the SM dominance to occur before Big Bang Nucleosynthesis. We show that successful reheating into the SM can only be obtained in the presence of a non-minimal coupling to gravity $\\x...
The Role of Antimatter in Big-Bang Cosmology
Stecker, Floyd W.
1974-01-01
Discusses theories underlying man's conceptions of the universe, including Omnes' repulsive separation mechanism, the turbulence theory of galaxy formation, and the author's idea about gamma ray spectra in cosmological matter-antimatter annihilation. Indicates that the Apollo data provide encouraging evidence by fitting well with his theoretical…
Comparison of Plasma-Redshift Cosmology and Big-Bang Cosmology
Brynjolfsson, Ari
2009-05-01
Plasma redshift is derived theoretically from conventional axioms of physics by using more accurate methods than those conventionally used. The main difference is the proper inclusion of the dielectric constant. The force acting on the electron is proportional to E=D/ɛ and not D as is conventionally surmised. This correction is not important in ordinary laboratory plasmas; but in the hot sparse plasmas of the intergalactic space, it explains the gradual energy loss (the cosmological redshift) of photons. This energy loss of photons is transferred to the plasma and makes it very hot. The plasma redshift explains long range of phenomena, including the intrinsic redshift of Sun, stars, galaxies and quasars, and the cosmological redshift. It explains also the beautiful black body spectrum of the CMB, and it predicts the observed XRB, and much more. There is no need for Big Bang, Inflation, Dark Energy, Dark Matter, Black Holes and much more. The universe is quasi-static and can renew itself forever. There is no cosmic time dilation. In intergalactic space the average temperature is 2.7.10^6 K, and the average electron density (Ne)avg= 2 .10-4 cm-3.
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.
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.
Cosmological space-times with resolved Big Bang in Yang-Mills matrix models
Steinacker, Harold C.
2018-02-01
We present simple solutions of IKKT-type matrix models that can be viewed as quantized homogeneous and isotropic cosmological space-times, with finite density of microstates and a regular Big Bang (BB). The BB arises from a signature change of the effective metric on a fuzzy brane embedded in Lorentzian target space, in the presence of a quantized 4-volume form. The Hubble parameter is singular at the BB, and becomes small at late times. There is no singularity from the target space point of view, and the brane is Euclidean "before" the BB. Both recollapsing and expanding universe solutions are obtained, depending on the mass parameters.
Gamma rays and the case for baryon symmetric big-bang cosmology
International Nuclear Information System (INIS)
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 γ-ray background spectrum in the 1-200 MeV range, and a mechanism for galaxy formation. In the context of an open universe model, the value of Ω which best fits the present γ-ray data is Ω approximately equal to 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
International Nuclear Information System (INIS)
Turner, M.S.; Chicago Univ., IL
1983-01-01
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)
Through the big bang: Continuing Einstein's equations beyond a cosmological singularity
Koslowski, Tim A.; Mercati, Flavio; Sloan, David
2018-03-01
All measurements are comparisons. The only physically accessible degrees of freedom (DOFs) are dimensionless ratios. The objective description of the universe as a whole thus predicts only how these ratios change collectively as one of them is changed. Here we develop a description for classical Bianchi IX cosmology implementing these relational principles. The objective evolution decouples from the volume and its expansion degree of freedom. We use the relational description to investigate both vacuum dominated and quiescent Bianchi IX cosmologies. In the vacuum dominated case the relational dynamical system predicts an infinite amount of change of the relational DOFs, in accordance with the well known chaotic behaviour of Bianchi IX. In the quiescent case the relational dynamical system evolves uniquely though the point where the decoupled scale DOFs predict the big bang/crunch. This is a non-trivial prediction of the relational description; the big bang/crunch is not the end of physics - it is instead a regular point of the relational evolution. Describing our solutions as spacetimes that satisfy Einstein's equations, we find that the relational dynamical system predicts two singular solutions of GR that are connected at the hypersurface of the singularity such that relational DOFs are continuous and the orientation of the spatial frame is inverted.
Ashtekar, Abhay
2010-06-01
General relativity predicts that space-time comes to an end and physics comes to a halt at the big-bang. Recent developments in loop quantum cosmology have shown that these predictions cannot be trusted. Quantum geometry effects can resolve singularities, thereby opening new vistas. Examples are: The big bang is replaced by a quantum bounce; the `horizon problem' disappears; immediately after the big bounce, there is a super-inflationary phase with its own phenomenological ramifications; and, in presence of a standard inflation potential, initial conditions are naturally set for a long, slow roll inflation independently of what happens in the pre-big bang branch. As in my talk at the conference, I will first discuss the foundational issues and then the implications of the new Planck scale physics near the Big Bang.
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
Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN
Energy Technology Data Exchange (ETDEWEB)
Capozziello, S. [Universita di Napoli ' ' Federico II' ' , Complesso Universitario di Monte Sant' Angelo, Dipartimento di Fisica ' ' E. Pancini' ' , Napoli (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Napoli (Italy); Gran Sasso Science Institute, L' Aquila (Italy); Lambiase, G. [University of Salerno, Dipartimento di Fisica E.R. Cainaiello, Fisciano (Italy); INFN, Gruppo Collegato di Salerno, Sezione di Napoli, Fisciano (Italy); Saridakis, E.N. [National Technical University of Athens, Department of Physics, Athens (Greece); Baylor University, CASPER, Physics Department, Waco, TX (United States)
2017-09-15
We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)
Constraining f( T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN
Capozziello, S.; Lambiase, G.; Saridakis, E. N.
2017-09-01
We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f( T) gravity. The three most studied viable f( T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f( T) models can successfully satisfy the BBN constraints.
Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.
Capozziello, S; Lambiase, G; Saridakis, E N
2017-01-01
We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.
Constraining f(T) teleparallel gravity by big bang nucleosynthesis. f(T) cosmology and BBN
International Nuclear Information System (INIS)
Capozziello, S.; Lambiase, G.; Saridakis, E.N.
2017-01-01
We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f(T) gravity. The three most studied viable f(T) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f(T) models can successfully satisfy the BBN constraints. (orig.)
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.
International Nuclear Information System (INIS)
Flambaum, V.V.; Shuryak, E.V.
2002-01-01
Recent data on the cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of the possible variation of other constants. We discuss the variation of strong scale and quark masses. We derive limits on their relative change from (i) primordial big bang nucleosynthesis, (ii) the Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals
Pre-big-bang model on the brane
International Nuclear Information System (INIS)
Foffa, Stefano
2002-01-01
The equations of motion and junction conditions for a gravidilaton brane world scenario are studied in the string frame. It is shown that they allow Kasner-like solutions on the brane, which makes the dynamics of the brane very similar to the low curvature phase of pre-big-bang cosmology. Analogies and differences of this scenario with the Randall-Sundrum one and with the standard bulk pre-big-bang dynamics are also discussed
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.)
Entropy generation and inflation in collision induced pre-big-bang cosmology
Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.
2000-01-01
We study inflation and entropy generation in a recently proposed pre-big-bang model universe produced in a collision of gravitational and dilaton waves. It is shown that enough inflation occurs provided the incoming waves are sufficiently weak. We also find that entropy in this model is dynamically
Initial conditions and the structure of the singularity in pre-big-bang cosmology
Feinstein, A.; Kunze, K.E.; Vazquez-Mozo, M.A.
2000-01-01
We propose a picture, within the pre-big-bang approach, in which the universe emerges from a bath of plane gravitational and dilatonic waves. The waves interact gravitationally breaking the exact plane symmetry and lead generically to gravitational collapse resulting in a singularity with the
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.
Page, Lyman A; Partridge, R Bruce
2009-01-01
Cosmology, the study of the universe as a whole, has become a precise physical science, the foundation of which is our understanding of the cosmic microwave background radiation (CMBR) left from the big bang. The story of the discovery and exploration of the CMBR in the 1960s is recalled for the first time in this collection of 44 essays by eminent scientists who pioneered the work. Two introductory chapters put the essays in context, explaining the general ideas behind the expanding universe and fossil remnants from the early stages of the expanding universe. The last chapter describes how the confusion of ideas and measurements in the 1960s grew into the present tight network of tests that demonstrate the accuracy of the big bang theory. This book is valuable to anyone interested in how science is done, and what it has taught us about the large-scale nature of the physical universe.
Student Ideas About Cosmological Concepts: Age, Expansion, and the Big Bang
Trouille, Laura; Coble, K.; Camarillo, C.; Bailey, J.; Nickerson, M.; Cochran, G.; Hayes, V.; McLin, K.; Cominsky, L.
2012-05-01
Students enter introductory astronomy classes with ideas about the universe that are often misaligned with accepted scientific beliefs. In this presentation we will describe the results from a multi-semester study of urban minority students’ ideas in an introductory astronomy course. We use in-depth student interviews, homework assignments, lab responses, and exams to identify pre-instructional ideas. We also examine the resilience of alternate conceptions to modification through instruction. In this presentation we focus on students’ ideas with regards to the Big Bang, the age of the Universe, and the expansion of the Universe over time. We find that a significant fraction of students enter our astronomy courses with alternate conceptions, including that the Big Bang refers to an explosion from a small, single point in space, that there is no evidence for the Big Bang, that there is a center to our Universe, that the Universe expands into pre-existing matter, and that the Universe has either a much smaller or much larger age than its accepted age. Some of these alternate conceptions are relatively easy to overcome through active learning (for example, whether there is a center to the Universe), while others are more resistant to change (for example, whether the Universe expands into pre-existing matter). Also see our presentations on student ideas of structure and distances (Camarillo et al.) as well as the overview of our methodology (Coble et al.). This work was supported by NASA ROSES E/PO Grant #NNX1OAC89G, as well as by the Illinois Space Grant Consortium and National Science Foundation CCLI Grant #0632563 at Chicago State University and the Fermi E/PO program at Sonoma State University.
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.
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.
International Nuclear Information System (INIS)
Schramm, D.N.
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 ∼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
Probing the pre-big bang universe
International Nuclear Information System (INIS)
Veneziano, G.
2000-01-01
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
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.
Quantum Oscillations Can Prevent the Big Bang Singularity in an Einstein-Dirac Cosmology
Finster, Felix; Hainzl, Christian
2010-01-01
We consider a spatially homogeneous and isotropic system of Dirac particles coupled to classical gravity. The dust and radiation dominated closed Friedmann-Robertson-Walker space-times are recovered as limiting cases. We find a mechanism where quantum oscillations of the Dirac wave functions can prevent the formation of the big bang or big crunch singularity. Thus before the big crunch, the collapse of the universe is stopped by quantum effects and reversed to an expansion, so that the universe opens up entering a new era of classical behavior. Numerical examples of such space-times are given, and the dependence on various parameters is discussed. Generically, one has a collapse after a finite number of cycles. By fine-tuning the parameters we construct an example of a space-time which satisfies the dominant energy condition and is time-periodic, thus running through an infinite number of contraction and expansion cycles.
Evolution of the early universe and big-bang nucleosynthesis
International Nuclear Information System (INIS)
Kajino, T.
1995-01-01
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
Indian Academy of Sciences (India)
that the expansion started billions of years ago from an explosive Big Bang. Recent research sheds new light on the key cosmological question about the distant future: Will the universe expand forever or will it eventually revert to a contraction that ends in an apocalyptic "big crunch?" Our own galaxy, the Milky Way, has ...
Underground Study of Big Bang Nucleosynthesis in the Precision Era of Cosmology
Directory of Open Access Journals (Sweden)
Gustavino Carlo
2017-01-01
Full Text Available Big Bang Nucleosinthesis (BBN theory provides definite predictions for the abundance of light elements produced in the early universe, as far as the knowledge of the relevant nuclear processes of the BBN chain is accurate. At BBN energies (30 ≲ Ecm ≲ 300 MeV the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. For this reason it is convenient to perform the measurements deep underground. Presently the world’s only facility operating underground is LUNA (Laboratory for Undergound Nuclear astrophysics at LNGS (“Laboratorio Nazionale del Gran Sasso”, Italy. In this presentation the BBN measurements of LUNA are briefly reviewed and discussed. It will be shown that the ongoing study of the D(p, γ3He reaction is of primary importance to derive the baryon density of universe Ωb with high accuracy. Moreover, this study allows to constrain the existence of the so called “dark radiation”, composed by undiscovered relativistic species permeating the universe, such as sterile neutrinos.
Underground Study of Big Bang Nucleosynthesis in the Precision Era of Cosmology
Gustavino, Carlo
2017-03-01
Big Bang Nucleosinthesis (BBN) theory provides definite predictions for the abundance of light elements produced in the early universe, as far as the knowledge of the relevant nuclear processes of the BBN chain is accurate. At BBN energies (30 ≲ Ecm ≲ 300 MeV) the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. For this reason it is convenient to perform the measurements deep underground. Presently the world's only facility operating underground is LUNA (Laboratory for Undergound Nuclear astrophysics) at LNGS ("Laboratorio Nazionale del Gran Sasso", Italy). In this presentation the BBN measurements of LUNA are briefly reviewed and discussed. It will be shown that the ongoing study of the D(p, γ)3He reaction is of primary importance to derive the baryon density of universe Ωb with high accuracy. Moreover, this study allows to constrain the existence of the so called "dark radiation", composed by undiscovered relativistic species permeating the universe, such as sterile neutrinos.
Gentry, R V
2003-01-01
The BAL z=3.91 quasar's high Fe/O ratio has led to a reexamination of big bang's spacetime expansion postulate and the discovery that it predicts a CBR redshift of z>36000 instead of the widely accepted z~1000. This result leads an expansion-predicted CBR temperature of only T = 0.08K, which is contradicted by the experimental T = 2.73K. Contrary to long-held belief, these results strongly suggest that the F-L expanding spacetime paradigm, with its expansion redshifts, is not the correct relativistic description of the universe. This conclusion agrees with the earlier finding (gr-qc/9806061) that the universe is relativistically governed by the Einstein static spacetime solution of the field equations, not the F-L solution. Disproof of expansion redshifts removes the only support for the Cosmological Principle, thus showing that the spherical symmetry of the cosmos demanded by the Hubble redshift relation can no longer be attributed to the universe being the same everythere. The Cosmological Principle is flaw...
From big crunch to big bang: A quantum string cosmology perspective
International Nuclear Information System (INIS)
Maharana, Jnanadeva
2002-01-01
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
Possible evidence for dark radiation from Big Bang Nucleosynthesis data
International Nuclear Information System (INIS)
Flambaum, V.V.; Shuryak, E.V.
2006-01-01
We address the emerging discrepancy between the Big Bang Nucleosynthesis data and standard cosmology, which asks for a bit longer evolution time. If this effect is real, one possible implication (in a framework of brane cosmology model) is that there is a 'dark radiation' component which is negative and makes few percents of ordinary matter density. If so, all scales of this model can be fixed, provided brane-to-bulk leakage problem is solved. (authors)
Cosmology as relativistic particle mechanics: from big crunch to big bang
Energy Technology Data Exchange (ETDEWEB)
Russo, J G [Institucio Catalana de Recerca i Estudis Avancats, Departament ECM, Facultat de FIsica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain); Townsend, P K [Institucio Catalana de Recerca i Estudis Avancats, Departament ECM, Facultat de FIsica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona (Spain)
2005-02-21
Cosmology can be viewed as geodesic motion in an appropriate metric on an 'augmented' target space; here we obtain these geodesics from an effective relativistic particle action. As an application, we find some exact (flat and curved) cosmologies for models with N scalar fields taking values in a hyperbolic target space for which the augmented target space is a Milne universe. The singularities of these cosmologies correspond to points at which the particle trajectory crosses the Milne horizon, suggesting a novel resolution of them, which we explore via the Wheeler-DeWitt equation.
International Nuclear Information System (INIS)
Chown, Marcus.
1987-01-01
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)
Fields, Brian D.; Olive, Keith A.
2006-01-01
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, 3 He, 4 He, and 7 Li 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 4 He observations paint a consistent picture. This concordance stands as a major success of the hot big bang. On the other hand, 7 Li 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
Constraints on the production of primordial magnetic seeds in pre-big bang cosmology
Energy Technology Data Exchange (ETDEWEB)
Gasperini, M., E-mail: gasperini@ba.infn.it [Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)
2017-06-01
We study the amplification of the electromagnetic fluctuations, and the production of 'seeds' for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA.
New class of inhomogeneous cosmological perfect-fluid solutions without big-bang singularity
Energy Technology Data Exchange (ETDEWEB)
Senovilla, J.M.M. (Grupo de Fisica Teorica, Departamento de Fisica, Ingenieria y Radiologia Medica, Facultad de Ciencias, Universidad de Salamanca, 37008 Salmanaca (Spain))
1990-05-07
A new class of exact solutions to Einstein's field equations with a perfect-fluid source is presented. The solutions describe spatially inhomogeneous cosmological models and have a realistic equation of state {ital p}={rho}/3. The properties of the solutions are discussed. The most remarkable feature is the absence of an initial singularity, the curvature and matter invariants being regular and smooth everywhere. We also present an alternative interpretation of the solution as a globally regular cylindrically symmetric space-time.
Constraints on the production of primordial magnetic seeds in pre-big bang cosmology
Gasperini, M.
2017-06-01
We study the amplification of the electromagnetic fluctuations, and the production of "seeds" for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA.
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.
Neutrinos and Big Bang Nucleosynthesis
Directory of Open Access Journals (Sweden)
Gary Steigman
2012-01-01
Full Text Available According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders this neutrino background undetectable with current technology. The cosmic neutrino background can, however, be probed indirectly through its cosmological effects on big bang nucleosynthesis (BBN and the cosmic microwave background (CMB radiation. In this BBN review, focused on neutrinos and more generally on dark radiation, the BBN constraints on the number of “equivalent neutrinos” (dark radiation, on the baryon asymmetry (baryon density, and on a possible lepton asymmetry (neutrino degeneracy are reviewed and updated. The BBN constraints on dark radiation and on the baryon density following from considerations of the primordial abundances of deuterium and helium-4 are in excellent agreement with the complementary results from the CMB, providing a suggestive, but currently inconclusive, hint of the presence of dark radiation, and they constrain any lepton asymmetry. For all the cases considered here there is a “lithium problem”: the BBN-predicted lithium abundance exceeds the observationally inferred primordial value by a factor of ~3.
International Nuclear Information System (INIS)
Levy-Leblond, J.
1990-01-01
It is argued that the age of the universe may well be numerically finite (20 billion years or so) and conceptually infinite. A new and natural time scale is defined on a physical basis using group-theoretical arguments. An additive notion of time is obtained according to which the age of the universe is indeed infinite. In other words, never did the Big Bang begin. This new time scale is not supposed to replace the ordinary cosmic time scale, but to supplement it (in the same way as rapidity has taken a place by the side of velocity in Einsteinian relativity). The question is discussed within the framework of conventional (big-bang) and classical (nonquantum) cosmology, but could easily be extended to more elaborate views, as the purpose is not so much to modify present theories as to reach a deeper understanding of their meaning
The Big Bang Theory and the Nature of Science
Arthury, Luiz Henrique Martins; Peduzzi, Luiz O. Q.
2015-12-01
Modern cosmology was constituted, throughout the twentieth century to the present days, as a very productive field of research, resulting in major discoveries that attest to its explanatory power. The Big Bang Theory, the generic and popular name of the standard model of cosmology, is probably the most daring research program of physics and astronomy, trying to recreate the evolution of our observable universe. But contrary to what you might think, its conjectures are of a degree of refinement and corroborative evidence that make it our best explanation for the history of our cosmos. The Big Bang Theory is also an excellent field to discuss issues regarding the scientific activity itself. In this paper we discuss the main elements of this theory with an epistemological look, resulting in a text quite useful to work on educational activities with related goals.
International Nuclear Information System (INIS)
Kusakabe, Motohiko; Kajino, Toshitaka; Boyd, Richard N.; Yoshida, Takashi; Mathews, Grant J.
2008-01-01
Observations of metal poor halo stars exhibit a possible plateau of 6 Li abundance as a function of metallicity similar to that for 7 Li, suggesting a big bang origin. However, the inferred primordial abundance of 6 Li is ∼1000 times larger than that predicted by standard big bang nucleosynthesis (BBN) for the baryon-to-photon ratio inferred from the WMAP data. On the other hand, the inferred 7 Li primordial abundance is about 3 times smaller than the prediction. We study a possible simultaneous solution to both the problems of underproduction of 6 Li and overproduction of 7 Li in BBN. This solution involves a hypothetical massive, negatively-charged leptonic particle that would bind to the light nuclei produced in BBN, but would decay long before it could be detected. Because the particle gets bound to the existing nuclei after the cessation of the usual big bang nuclear reactions, a second longer epoch of nucleosynthesis can occur among X-nuclei which have reduced Coulomb barriers. We numerically carry out a fully dynamical BBN calculation, simultaneously solving the recombination and ionization processes of negatively-charged particles by normal and X-nuclei as well as many possible nuclear reactions among them. We confirm that a reaction in which the hypothetical particle is transferred can occur that greatly enhance the production of 6 Li while a reaction through an atomic excited state of X-nucleus depletes 7 Li. It is confirmed that BBN in the presence of these hypothetical particles, together with or without an event of stellar burning process, can simultaneously solve the two Li abundance problems
CERN. Geneva
2000-01-01
Most of the puzzles with standard big bang cosmology can be avoided if the big bang is NOT identified with the beginning of time. The short-distance cutoff and duality symmetries of superstring theory suggest a new (so-called pre-big bang) cosmology in which the birth of our Universe is the result of a long classical evolution characterized by a gravitational instability. I will motivate and describe this heretical scenario and compare its phenomenological implications with those of ortodox (post-big bang) inflation.
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.
Krnjaic, Gordan; Sigurdson, Kris
2015-12-01
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.
Wesson, Paul S.
We give a mathematically exact and physically faithful embedding of curved 4D cosmology in a flat 5D space, thereby enabling visualization of the big bang in a new and informative way. In fact, in unified theories of fields and particles with real extra dimensions, it is possible to dispense with the initial singularity.
Space Time Quantization and the Big Bang
Sidharth, B. G.
1998-01-01
A recent cosmological model is recapitulated which deduces the correct mass, radius and age of the universe as also the Hubble constant and other well known apparently coincidental relations. It also predicts an ever expanding accelerating universe as is confirmed by latest supernovae observations. Finally the Big Bang model is recovered as a suitable limiting case.
Quantum nature of the big bang.
Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet
2006-04-14
Some long-standing issues concerning the quantum nature of the big bang are resolved in the context of homogeneous isotropic models with a scalar field. Specifically, the known results on the resolution of the big-bang singularity in loop quantum cosmology are significantly extended as follows: (i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the "emergent time" idea; (ii) the physical Hilbert space, Dirac observables, and semiclassical states are constructed rigorously; (iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the nonperturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime.
Energy Technology Data Exchange (ETDEWEB)
Hata, N.; Scherrer, R.J.; Steigman, G.; Thomas, D.; Walker, T.P. [Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)
1996-02-01
We present new upper and lower bounds to the primordial abundances of deuterium and {sup 3}He based on observational data from the solar system and the interstellar medium. Independent of any model for the primordial production of the elements we find (at the 95{percent} C.L.): 1.5{times}10{sup {minus}5}{le}(D/H){sub {ital P}}{le}10.0{times}10{sup {minus}5} and ({sup 3}He/H){sub {ital P}}{le}2.6{times}10{sup {minus}5}. When combined with the predictions of standard big bang nucleosynthesis, these constraints lead to a 95{percent} C.L. bound on the primordial abundance deuterium: (D/H){sub best}=(3.5{sup +2.7}{sub {minus}1.8}){times}10{sup {minus}5}. Measurements of deuterium absorption in the spectra of high-redshift QSOs will directly test this prediction. The implications of this prediction for the primordial abundances of {sup 4}He and {sup 7}Li are discussed, as well as those for the universal density of baryons. {copyright} {ital 1996 The American Astronomical Society.}
What's Next for Big Bang Nucleosynthesis?
International Nuclear Information System (INIS)
Cyburt, R.H.
2005-01-01
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
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.
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.
Big bang nucleosynthesis: An update
Energy Technology Data Exchange (ETDEWEB)
Olive, Keith A. [William I. Fine Theoretical Physics Institute, School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
2013-07-23
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, {sup 4}He, and {sup 7}Li is discussed and compared to their observational determination. While concordance for D and {sup 4}He is satisfactory, the prediction for {sup 7}Li exceeds the observational determination by a factor of about four. Possible solutions to this problem are discussed.
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).
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.
Krnjaic, Gordan; Sigurdson, Kris
2014-01-01
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 generica...
10-35 seconds after the big bang
International Nuclear Information System (INIS)
Guth, A.H.
1982-01-01
The status of the inflationary model of the very early universe is summarized. In this model the universe supercools many orders of magnitude below the critical temperature of a grand unified theory phase transition, and in the process it expands by many orders of magnitude. The model can solve the monopole, horizon, and flatness problems of the standard hot big-bang cosmology, and at the same time it offers an explanation of the origin of all matter, energy, and entropy of the universe. There are still uncertainties concerning the mechanism which ends the inflationary era, but the new ending proposed by Linde and by Albrecht and Steinhardt appears very promising
Big bang nucleosynthesis - Predictions and uncertainties
International Nuclear Information System (INIS)
Krauss, L.M.; Romanelli, P.
1990-01-01
A detailed reexamination is made of primordial big-bang nucleosynthesis (BBN), concentrating on the data for the main nuclear reactions leading to the production of Li-7, He-3 and D, and on the neutron half-life, relevant for He-4 production. The new values for reaction rates and uncertainties are then used as input in a Monte Carlo analysis of big bang nucleosynthesis of light elements. This allows confidence levels for the predictions of the standard BBN model to be high. 70 refs
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...
Big bang and big crunch in matrix string theory
Bedford, J; Papageorgakis, C; Rodríguez-Gómez, D; Ward, J
2007-01-01
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...
Fixing the Big Bang Theory's Lithium Problem
Kohler, Susanna
2017-02-01
How did our universe come into being? The Big Bang theory is a widely accepted and highly successful cosmological model of the universe, but it does introduce one puzzle: the cosmological lithium problem. Have scientists now found a solution?Too Much LithiumIn the Big Bang theory, the universe expanded rapidly from a very high-density and high-temperature state dominated by radiation. This theory has been validated again and again: the discovery of the cosmic microwave background radiation and observations of the large-scale structure of the universe both beautifully support the Big Bang theory, for instance. But one pesky trouble-spot remains: the abundance of lithium.The arrows show the primary reactions involved in Big Bang nucleosynthesis, and their flux ratios, as predicted by the authors model, are given on the right. Synthesizing primordial elements is complicated! [Hou et al. 2017]According to Big Bang nucleosynthesis theory, primordial nucleosynthesis ran wild during the first half hour of the universes existence. This produced most of the universes helium and small amounts of other light nuclides, including deuterium and lithium.But while predictions match the observed primordial deuterium and helium abundances, Big Bang nucleosynthesis theory overpredicts the abundance of primordial lithium by about a factor of three. This inconsistency is known as the cosmological lithium problem and attempts to resolve it using conventional astrophysics and nuclear physics over the past few decades have not been successful.In a recent publicationled by Suqing Hou (Institute of Modern Physics, Chinese Academy of Sciences) and advisorJianjun He (Institute of Modern Physics National Astronomical Observatories, Chinese Academy of Sciences), however, a team of scientists has proposed an elegant solution to this problem.Time and temperature evolution of the abundances of primordial light elements during the beginning of the universe. The authors model (dotted lines
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...
Light-like big bang singularities in string and matrix theories
International Nuclear Information System (INIS)
Craps, Ben; Evnin, Oleg
2011-01-01
Important open questions in cosmology require a better understanding of the big bang singularity. In string and matrix theories, light-like analogues of cosmological singularities (singular plane wave backgrounds) turn out to be particularly tractable. We give a status report on the current understanding of such light-like big bang models, presenting both solved and open problems.
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)
Wright, E.L.
1983-01-01
The author considers experiments to confirm the substantial deviations from a Planck curve in the Woody and Richards spectrum of the microwave background, and search for conducting needles in our galaxy. Spectral deviations and needle-shaped grains are expected for a cold Big Bang, but are not required by a hot Big Bang. (Auth.)
García-Bellido, J
2015-01-01
In these lectures I review the present status of the so-called Standard Cosmological Model, based on the hot Big Bang Theory and the Inflationary Paradigm. I will make special emphasis on the recent developments in observational cosmology, mainly the acceleration of the universe, the precise measurements of the microwave background anisotropies, and the formation of structure like galaxies and clusters of galaxies from tiny primordial fluctuations generated during inflation.
An atomic model of the Big Bang
Lasukov, V. V.
2013-03-01
An atomic model of the Big Bang has been developed on the basis of quantum geometrodynamics with a nonzero Hamiltonian and on the concept of gravitation developed by Logunov asymptotically combined with the Gliner's idea of a material interpretation of the cosmological constant. The Lemaître primordial atom in superpace-time, whose spatial coordinate is the so-called scaling factor of the Logunov metric of the effective Riemann space, acts as the Big Bang model. The primordial atom in superspace-time corresponds to spatialtime structures(spheres, lines, and surfaces of a level) of the Minkowski spacetime real within the Logunov gravitation theory, the foregoing structures being filled with a scalar field with a negative density of potential energy.
'Big bang' of quantum universe
International Nuclear Information System (INIS)
Pawlowski, M.; Pervushin, V.N.
2000-01-01
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 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.
Big bang photosynthesis and pregalactic nucleosynthesis of light elements
International Nuclear Information System (INIS)
Audouze, J.; Lindley, D.; Silk, J.; and Laboratoire Rene Bernas, Orsay, France)
1985-01-01
Two nonstandard scenarios for pregalactic synthesis of the light elements ( 2 H, 3 He, 4 He, and 7 Li) are developed. Big bang photosynthesis occurs if energetic photons, produced by the decay of massive neutrinos or gravitinos, partially photodisintegrate 4 He (formed in the standard hot big bang) to produce 2 H and 3 He. 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 4 He is synthesized by a later generation of massive stars
Gamma-ray Background Spectrum and Annihilation Rate in the Baryon-symmetric Big-bang Cosmology
Puget, J. L.
1973-01-01
An attempt was made to acquire experimental information on the problem of baryon symmetry on a large cosmological scale by observing the annihilation products. Data cover absorption cross sections and background radiation due to other sources for the two main products of annihilation, gamma rays and neutrinos. Test results show that the best direct experimental test for the presence of large scale antimatter lies in the gamma ray background spectrum between 1 and 70 MeV.
Craps, Ben; Sethi, Savdeep; Verlinde, Erik
2005-10-01
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.
Energy Technology Data Exchange (ETDEWEB)
McGuire, Austin D. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meade, Roger Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-09-13
As one of the very few people in the world to give the “go/no go” decision to detonate a nuclear device, Austin “Mac” McGuire holds a very special place in the history of both the Los Alamos National Laboratory and the world. As Commander of Joint Task Force Unit 8.1.1, on Christmas Island in the spring and summer of 1962, Mac directed the Los Alamos data collection efforts for twelve of the last atmospheric nuclear detonations conducted by the United States. Since data collection was at the heart of nuclear weapon testing, it fell to Mac to make the ultimate decision to detonate each test device. He calls his experience THE LAST BIG BANG, since these tests, part of Operation Dominic, were characterized by the dramatic displays of the heat, light, and sounds unique to atmospheric nuclear detonations – never, perhaps, to be witnessed again.
International Nuclear Information System (INIS)
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
Energy Technology Data Exchange (ETDEWEB)
Craps, Ben [Instituut voor Theoretische Fysica, Universiteit van Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands); Sethi, Savdeep [Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States); Verlinde, Erik [Instituut voor Theoretische Fysica, Universiteit van Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam (Netherlands)
2005-10-15
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.
Pre - big bang inflation requires fine tuning
Energy Technology Data Exchange (ETDEWEB)
Turner, Michael S. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Weinberg, Erick J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
1997-10-01
The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.
Strickland, Ken
2013-04-01
The Rate Change Big Bang Theory redefines the birth of the universe with a dramatic shift in energy direction and a new vision of the first moments. With rate change graph technology (RCGT) we can look back 13.7 billion years and experience every step of the big bang through geometrical intersection technology. The analysis of the Big Bang includes a visualization of the first objects, their properties, the astounding event that created space and time as well as a solution to the mystery of anti-matter.
Gravitino, dark matter candidate and implications for big bang nucleosynthesis
International Nuclear Information System (INIS)
Bailly, S.
2008-11-01
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)
Cosmology for high energy physicists
International Nuclear Information System (INIS)
Albrecht, A.
1987-11-01
The standard big bang model of cosmology is presented. Although not perfect, its many successes make it a good starting point for most discussions of cosmology. Places are indicated where well understood laboratory physics is incorporated into the big bang, leading to successful predictions. Much less established aspects of high energy physics and some of the new ideas they have introduced into the field of cosmology are discussed, such as string theory, inflation and monopoles. 49 refs., 5 figs
Generating ekpyrotic curvature perturbations before the big bang
International Nuclear Information System (INIS)
Lehners, Jean-Luc; Turok, Neil; McFadden, Paul; Steinhardt, Paul J.
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, 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 n s tends to range from slightly blue to red, with 0.97 s <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
Big Bang nucleosynthesis, microwave anisotropy, and the light element abundances
Energy Technology Data Exchange (ETDEWEB)
Coc, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS/IN2P3/UPS, Bat. 104, F-91405 Orsay Campus (France); Angulo, C. [Centre de Recherches du Cyclotron, Universite catholique de Louvain, Chemin du cyclotron 2, B-1348 Louvain-la-Neuve (Belgium); Vangioni-Flam, E. [lnstitut d' Astrophysique de Paris, CNRS, 98bis Bd. Arago, F-75014 Paris (France); Descouvemont, P. [Physique Nucleaire Theorique et Physique Mathematique, CP229, Universite Libre de Bruxelles, B-1050 Brussels (Belgium); Adahchour, A. [Physique Nucleaire Theorique et Physique Mathematique, CP229, Universite Libre de Bruxelles, B-1050 Brussels (Belgium)
2005-04-18
From the observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, the WMAP satellite has provided a determination of the baryonic density of the Universe, with an unprecedented precision: 4%. This imposes a careful reanalysis of the standard Big-Bang Nucleosynthesis (SBBN) calculations. In a recent paper, we used the R-matrix theory to fit S-factor data on nuclear reactions involved in Big Bang nucleosynthesis. We derived the reaction rates with associated uncertainties, which were evaluated on statistical grounds (available at http://pntpm3.ulb.ac.be/bigbang). Combining these BBN results with the {omega}bh2 value from WMAP, we deduced the light element ({sup 4}He, D, {sup 3}He and {sup 7}Li) primordial abundances and compare them with spectroscopic observations. There is a very good agreement with deuterium observed in cosmological clouds, which strengthens the confidence on the estimated baryonic density of the Universe. However, there is a discrepancy between the deduced {sup 7}Li abundance and the one observed in halo stars of our Galaxy, supposed, until now, to represent the primordial abundance of this isotope. The origin of this discrepancy, observational, nuclear or more fundamental remains to be clarified. The possible role of the up to now neglected {sup 7}Be(d,p)2{alpha} and {sup 7}Be(d,{alpha}){sup 5}Li reactions is considered and we present here a dedicated experiment performed at Louvain-la-Neuve to measure these cross sections.
Gravitation, phase transitions, and the big bang
International Nuclear Information System (INIS)
Krauss, L.M.
1982-01-01
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: Accelerator tests and can Ω/sub B/ really be large
International Nuclear Information System (INIS)
Schramm, D.N.
1987-10-01
The first collider tests of cosmological theory are now underway. The number of neutrino families in nature, N/sub nu/, plays a key role in elementary particle physics as well as in the synthesis of the light elements during the early evolution of the Universe. Standard Big Bang Nucleosynthesis argues for N/sub nu/ = 3 +- 1. Current limits on N/sub nu/ from the CERN anti pp collider and e + e - colliders are presented and compared to the cosmological bound. Supernova SN 1987A is also shown to give a limit on N/sub nu/ comparable to current accelerator bounds. All numbers are found to be small thus verifying the Big Bang model at an earlier epoch than is possible by traditional astronomical observations. Future measurements at SLC and LEP will further tighten this argument. Another key prediction of the standard Big Bang Nucleosynthesis is that the baryon density must be small (Ω/sub B/ ≤ 0.1). Recent attempts to try to subvert this argument using homogeneities of various types are shown to run afoul of the 7 Li abundance which has now become a rather firm constraint. 18 refs., 2 figs
Big bang models in string theory
Energy Technology Data Exchange (ETDEWEB)
Craps, Ben [Theoretische Natuurkunde, Vrije Universiteit Brussel and The International Solvay Institutes Pleinlaan 2, B-1050 Brussels (Belgium)
2006-11-07
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.
Gonzalez-Mestres, Luis
2015-05-01
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 further analyze
Superheavy magnetic monopoles and the standard cosmology
International Nuclear Information System (INIS)
Turner, M.S.
1984-10-01
The superheavy magnetic monopoles predicted to exist in grand unified theories (GUTs) are very interesting obsects, both from the point of view of particle physics, as well as from astrophysics and cosmology. Astrophysical and cosmological considerations have proved to be invaluable in studying the properties of GUT monopoles. Because of the glut of monopoles predicted in the standard cosmology for the simplest GUTs (so many that the Universe should have reached a temperature of 3 0 K at the tender age of approx. = 10,000 yrs), the simplest GUTs and the standard cosmology are not compatible. This is a very important piece of information about physics at unification energies (E greater than or equal to 10 14 GeV) and about the earliest moments (t less than or equal to 10 -34 s) of the Universe. In this talk the author reviews the cosmological consequences of GUT monopoles within the context of the standard hot big bang model. 46 references
Big-bang nucleosynthesis and the baryon density of the universe.
Copi, C J; Schramm, D N; Turner, M S
1995-01-13
For almost 30 years, the predictions of big-bang nucleosynthesis have been used to test the big-bang model to within a fraction of a second of the bang. The agreement between the predicted and observed abundances of deuterium, helium-3, helium-4, and lithium-7 confirms the standard cosmology model and allows accurate determination of the baryon density, between 1.7 x 10(-31) and 4.1 x 10(-31) grams per cubic centimeter (corresponding to about 1 to 15 percent of the critical density). This measurement of the density of ordinary matter is pivotal to the establishment of two dark-matter problems: (i) most of the baryons are dark, and (ii) if the total mass density is greater than about 15 percent of the critical density, as many determinations indicate, the bulk of the dark matter must be "non-baryonic," composed of elementary particles left from the earliest moments.
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. [Departments of Physics and of Astronomy & Astrophysics, Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637-1433 (United States)]|[NASA/Fermilab Astrophysics Center, Fermi National Accelerator Laboratory, Batavia, Illinois 60510-0500 (United States)
1995-08-01
The hot big-bang cosmology provides a reliable accounting of the Universe from about 10{sup {minus}2} sec after the bang until the present, as well as a robust framework for speculating back to times as early as 10{sup {minus}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 so on) developed. At present there is a working hypothesis{emdash}cold dark matter{emdash}which is based upon inflation and which, if correct, would extend the big bang model back to 10{sup {minus}32} sec and cast important light on the unification of the forces. Many experiments and observations, from CBR anisotropy experiments to Hubble Space Telescope observations to experiments at Fermilab and CERN, are now putting the cold dark matter theory to the test. At present it appears that the theory is viable only if the Hubble constant is smaller than current measurements indicate (around 30 km s{sup {minus}1} Mpc{sup {minus}1}), or if the theory is modified slightly, e.g., by the addition of a cosmological constant, a small admixture of hot dark matter (5 eV {open_quote}{open_quote}worth of neutrinos{close_quote}{close_quote}), more relativistic particle or a tilted spectrum of density perturbations.
Big bang and big crunch in matrix string theory
International Nuclear Information System (INIS)
Bedford, J.; Ward, J.; Papageorgakis, C.; Rodriguez-Gomez, D.
2007-01-01
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
pp wave big bangs: Matrix strings and shrinking fuzzy spheres
International Nuclear Information System (INIS)
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. 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
Accessibility of the pre-big-bang models to LIGO
International Nuclear Information System (INIS)
Mandic, Vuk; Buonanno, Alessandra
2006-01-01
The recent search for a stochastic background of gravitational waves with LIGO interferometers has produced a new upper bound on the amplitude of this background in the 100 Hz region. We investigate the implications of the current and future LIGO results on pre-big-bang models of the early Universe, determining the exclusion regions in the parameter space of the minimal pre-big-bang scenario. Although the current LIGO reach is still weaker than the indirect bound from big bang nucleosynthesis, future runs by LIGO, in the coming year, and by Advanced LIGO (∼2009) should further constrain the parameter space, and in some parts surpass the Big Bang nucleosynthesis bound. It will be more difficult to constrain the parameter space in nonminimal pre-big bang models, which are characterized by multiple cosmological phases in the yet not well understood stringy phase, and where the higher-order curvature and/or quantum-loop corrections in the string effective action should be included
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.
Mapping the cold glow of the big bang
International Nuclear Information System (INIS)
Bennett, Charles
1991-01-01
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)
Fields, Brian D.; Sarkar, Subir
2014-01-01
A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, η, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of η from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range η=(5.7−6.7)×10−10 at 95% CL (corresponding to a cosmological baryon density ΩBh2=0.021−0.025). The D and He-4 abundances, when combined with the CMB determination of η, provide the bound Nν=3.28±0.28 on the effective number of neutrino species. Other constraints on new physics are discussed briefly.
Vaas, Ruediger
2004-01-01
Our universe appears to have been created not out of nothing but from a strange space-time dust. Quantum geometry (loop quantum gravity) makes it possible to avoid the ominous beginning of our universe with its physically unrealistic (i.e. infinite) curvature, extreme temperature, and energy density. This could be the long sought after explanation of the big-bang and perhaps even opens a window into a time before the big-bang: Space itself may have come from an earlier collapsing universe tha...
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.
Endless universe beyond the big bang
Steinhardt, Paul J
2007-01-01
The Big Bang theory—widely regarded as the leading explanation for the origin of the universe—posits that space and time sprang into being about 14 billion years ago in a hot, expanding fireball of nearly infinite density. Over the last three decades the theory has been repeatedly revised to address such issues as how galaxies and stars first formed and why the expansion of the universe is speeding up today. Furthermore, an explanation has yet to be found for what caused the Big Bang in the first place. In Endless Universe, Paul J. Steinhardt and Neil Turok, both distinguished theoretical physicists, present a bold new cosmology. Steinhardt and Turok “contend that what we think of as the moment of creation was simply part of an infinite cycle of titanic collisions between our universe and a parallel world” (Discover). They recount the remarkable developments in astronomy, particle physics, and superstring theory that form the basis for their groundbreaking “Cyclic Universe” theory. According to t...
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.
Big Bang or vacuum fluctuation
International Nuclear Information System (INIS)
Zel'dovich, Ya.B.
1980-01-01
Some general properties of vacuum fluctuations in quantum field theory are described. The connection between the ''energy dominance'' of the energy density of vacuum fluctuations in curved space-time and the presence of singularity is discussed. It is pointed out that a de-Sitter space-time (with the energy density of the vacuum fluctuations in the Einstein equations) that matches the expanding Friedman solution may describe the history of the Universe before the Big Bang. (P.L.)
Energy Technology Data Exchange (ETDEWEB)
Allen, A.D.
1976-02-01
Recent computer simulations indicate that a system of n gravitating masses breaks up, even when the total energy is negative. As a result, almost any initial phase-space distribution results in a universe that eventually expands under the Hubble law. Hence Hubble expansion implies little regarding an initial cosmic state. Especially it does not imply the singularly dense superpositioned state used in the big bang model.
Constraining pre big-bang-nucleosynthesis expansion using cosmic antiprotons
Energy Technology Data Exchange (ETDEWEB)
Schelke, M. [Istituto Nazionale di Fisica Nucleare, Torino (Italy); Catena, R. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Fornengo, N. [Torino Univ. (Italy). Dipt. di Fisica Teorica]|[Istituto Nazionale di Fisica Nucleare, Torino (Italy); Masiero, A. [Pavoa Univ. (Italy). Dipt. di Fisica]|[Istituto Nazionale di Fisica Nucleare, Padova (Italy); Pietroni, M. [Istituto Nazionale di Fisica Nucleare, Padova (Italy)
2006-06-15
A host of dark energy models and non-standard cosmologies predict an enhanced Hubble rate in the early Universe: perfectly viable models, which satisfy Big Bang Nucleosynthesis (BBN), cosmic microwave background and general relativity tests, may nevertheless lead to enhancements of the Hubble rate up to many orders of magnitude. In this paper we show that strong bounds on the pre-BBN evolution of the Universe may be derived, under the assumption that dark matter is a thermal relic, by combining the dark matter relic density bound with constraints coming from the production of cosmic-ray antiprotons by dark matter annihilation in the Galaxy. The limits we derive can be sizable and apply to the Hubble rate around the temperature of dark matter decoupling. For dark matter masses lighter than 100 GeV, the bound on the Hubble-rate enhancement ranges from a factor of a few to a factor of 30, depending on the actual cosmological model, while for a mass of 500 GeV the bound falls in the range 50-500. Uncertainties in the derivation of the bounds and situations where the bounds become looser are discussed. We finally discuss how these limits apply to some specific realizations of non-standard cosmologies: a scalar-tensor gravity model, kination models and a Randall-Sundrum D-brane model. (Orig.)
Nonuniversal scalar-tensor theories and big bang nucleosynthesis
International Nuclear Information System (INIS)
Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth
2009-01-01
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.
Nonuniversal scalar-tensor theories and big bang nucleosynthesis
Coc, Alain; Olive, Keith A.; Uzan, Jean-Philippe; Vangioni, Elisabeth
2009-05-01
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.
Generating a hot big bang via a change in topology
International Nuclear Information System (INIS)
Kandvup, H.E.
1990-01-01
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
The gravitino-stau scenario after catalyzed big bang nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Kersten, Joern [The Abdus Salam ICTP, Strada Costiera 11, 34014 Trieste (Italy); Schmidt-Hoberg, Kai, E-mail: jkersten@ictp.it, E-mail: kai.schmidt-hoberg@ph.tum.de, E-mail: kai.schmidt.hoberg@desy.de [Physik-Department T30, Technische Universitaet Muenchen, James-Franck-Strasse, 85748 Garching (Germany)
2008-01-15
We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m{sub 1/2}. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.
The gravitino-stau scenario after catalyzed big bang nucleosynthesis
Kersten, Jörn; Schmidt-Hoberg, Kai
2008-01-01
We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m1/2. As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints.
Generating a hot big bang via a change in topology
Energy Technology Data Exchange (ETDEWEB)
Kandvup, H.E. (Florida Univ., Gainesville, FL (USA). Space Astronomy Lab.); Masur, P.O. (Institute for Fundamental Theory, Univ. of Florida, Gainesville, FL (US))
1990-08-01
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.
Mapping the cold glow of the big bang
Energy Technology Data Exchange (ETDEWEB)
Bennett, Charles (National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center)
1991-08-10
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).
The gravitino–stau scenario after catalyzed big bang nucleosynthesis
International Nuclear Information System (INIS)
Kersten, Jörn; Schmidt-Hoberg, Kai
2008-01-01
We consider the impact of catalyzed big bang nucleosynthesis on theories with a gravitino lightest superparticle and a charged slepton next-to-lightest superparticle. In models where the gravitino to gaugino mass ratio is bounded from below, such as gaugino-mediated supersymmetry breaking, we derive a lower bound on the gaugino mass parameter m 1/2 . As a concrete example, we determine the parameter space of gaugino mediation that is compatible with all cosmological constraints
Inhomogeneous Big Bang Nucleosynthesis Revisited
Lara, J. F.; Kajino, T.; Mathews, G. J.
2006-01-01
We reanalyze the allowed parameters for inhomogeneous big bang nucleosynthesis in light of the WMAP constraints on the baryon-to-photon ratio and a recent measurement which has set the neutron lifetime to be 878.5 +/- 0.7 +/- 0.3 seconds. For a set baryon-to-photon ratio the new lifetime reduces the mass fraction of He4 by 0.0015 but does not significantly change the abundances of other isotopes. This enlarges the region of concordance between He4 and deuterium in the parameter space of the b...
International Nuclear Information System (INIS)
Davies, P.
1991-01-01
The main concepts of cosmology are discussed, and some of the misconceptions are clarified. The features of big bang cosmology are examined, and it is noted that the existence of the cosmic background radiation provides welcome confirmation of the big bang theory. Calculations of relative abundances of the elements conform with observations, further strengthening the confidence in the basic ideas of big bang cosmology
Brane big bang brought on by a bulk bubble
International Nuclear Information System (INIS)
Gen, Uchida; Ishibashi, Akihiro; Tanaka, Takahiro
2002-01-01
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
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.
From big bang to big crunch and beyond
International Nuclear Information System (INIS)
Elitzur, Shmuel; Rabinovici, Eliezer; Giveon, Amit; Kutasov, David
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 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)
Negative-mass lagging cores of the big bang
International Nuclear Information System (INIS)
Miller, B.D.
1976-01-01
Examples are given of spherically symmetric cosmological models containing space-sections with the following properties: at large values of the geometrically defined coordinate R, the mass is positive, while at small values of R, the mass is negative. The negative-mass region of spacetime has local properties similar to those of the negative-mass Schwarzschild solution. The big bang in these models is partially spacelike and partially timelike, so the spacetimes do not obey the strong form of the cosmic censorship hypothesis. The timelike, negative-mass segments of the big bang are unlimited sources of electromagnetic and gravitational radiation, and as such may be attractive as ''lagging core'' models of highly energetic astrophysical phenomena
Negative-mass lagging cores of the big bang
Energy Technology Data Exchange (ETDEWEB)
Miller, B.D.
1976-09-01
Examples are given of spherically symmetric cosmological models containing space-sections with the following properties: at large values of the geometrically defined coordinate R, the mass is positive, while at small values of R, the mass is negative. The negative-mass region of spacetime has local properties similar to those of the negative-mass Schwarzschild solution. The big bang in these models is partially spacelike and partially timelike, so the spacetimes do not obey the strong form of the cosmic censorship hypothesis. The timelike, negative-mass segments of the big bang are unlimited sources of electromagnetic and gravitational radiation, and as such may be attractive as ''lagging core'' models of highly energetic astrophysical phenomena. (AIP)
Big-Bang nucleosynthesis and lithium abundance
International Nuclear Information System (INIS)
Singh, Vinay; Lahiri, Joydev; Bhowmick, Debasis; Basu, D.N.
2017-01-01
The predictions of the standard big-bang nucleosynthesis (BBN) theory depend on the astrophysical nuclear reaction rates and on additional three parameters, the number of flavours of light neutrinos, the neutron lifetime and the baryon-to-photon ratio in the uni- verse. The effect of the modification of thirty-five reaction rates on light element abundance yields in BBN was investigated earlier by us. In the present work we have replaced the neutron lifetime, baryon-to-photon ratio by the most recent values and further modified 3 He( 4 He,γ) 7 Be reaction rate which is used directly for estimating the formation of 7 Li as a result of β + decay by the most recent equation. We find that these modifications reduce the calculated abundance of 7 Li by ∼ 12%
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!
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)
Hata, N.; Scherrer, R.J.; Steigman, G.; Thomas, D.; Walker, T.P.; Bludman, S.; Langacker, P.
1995-01-01
A new evaluation of the constraint on the number of light neutrino species (N ν ) from big bang nucleosynthesis suggests a discrepancy between the predicted light element abundances and those inferred from observations, unless the inferred primordial 4 He abundance has been underestimated by 0.014±0.004 (1σ) or less than 10% (95% C.L.) of 3 He 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 N ν =2.1±0.3 (1σ) and the upper limit is N ν ν =3) at the 98.6% C.L. copyright 1995 The American Physical Society
Wetterich, C.
2014-09-01
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.
A Quantum Universe Before the Big Bang(s)?
Veneziano, Gabriele
2017-08-01
The predictions of general relativity have been verified by now in a variety of different situations, setting strong constraints on any alternative theory of gravity. Nonetheless, there are strong indications that general relativity has to be regarded as an approximation of a more complete theory. Indeed theorists have long been looking for ways to connect general relativity, which describes the cosmos and the infinitely large, to quantum physics, which has been remarkably successful in explaining the infinitely small world of elementary particles. These two worlds, however, come closer and closer to each other as we go back in time all the way up to the big bang. Actually, modern cosmology has changed completely the old big bang paradigm: we now have to talk about (at least) two (big?) bangs. If we know quite something about the one closer to us, at the end of inflation, we are much more ignorant about the one that may have preceded inflation and possibly marked the beginning of time. No one doubts that quantum mechanics plays an essential role in answering these questions: unfortunately a unified theory of gravity and quantum mechanics is still under construction. Finding such a synthesis and confirming it experimentally will no doubt be one of the biggest challenges of this century’s physics.
Cosmic relics from the big bang
Energy Technology Data Exchange (ETDEWEB)
Hall, L.J.
1988-12-01
A brief introduction to the big bang picture of the early universe is given. Dark matter is discussed; particularly its implications for elementary particle physics. A classification scheme for dark matter relics is given. 21 refs., 11 figs., 1 tab.
Detection of pristine gas two billion years after the Big Bang.
Fumagalli, Michele; O'Meara, John M; Prochaska, J Xavier
2011-12-02
In the current cosmological model, only the three lightest elements were created in the first few minutes after the Big Bang; all other elements were produced later in stars. To date, however, heavy elements have been observed in all astrophysical environments. We report the detection of two gas clouds with no discernible elements heavier than hydrogen. These systems exhibit the lowest heavy-element abundance in the early universe, and thus are potential fuel for the most metal-poor halo stars. The detection of deuterium in one system at the level predicted by primordial nucleosynthesis provides a direct confirmation of the standard cosmological model. The composition of these clouds further implies that the transport of heavy elements from galaxies to their surroundings is highly inhomogeneous.
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.
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.
Experimentally testing the standard cosmological model
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N. (Chicago Univ., IL (USA) Fermi National Accelerator Lab., Batavia, IL (USA))
1990-11-01
The standard model of cosmology, the big bang, is now being tested and confirmed to remarkable accuracy. Recent high precision measurements relate to the microwave background; and big bang nucleosynthesis. This paper focuses on the latter since that relates more directly to high energy experiments. In particular, the recent LEP (and SLC) results on the number of neutrinos are discussed as a positive laboratory test of the standard cosmology scenario. Discussion is presented on the improved light element observational data as well as the improved neutron lifetime data. alternate nucleosynthesis 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 conclusions 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 standard model conclusion that {Omega}{sub b} {approximately} 0.06. This latter point is the deriving 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} < {Omega}{sub b}. Recent accelerator constraints on non-baryonic matter are discussed, showing that any massive cold dark matter candidate must now have a mass M{sub x} {approx gt} 20 GeV and an interaction weaker than the Z{sup 0} coupling to a neutrino. It is also noted that recent hints regarding the solar neutrino experiments coupled with the see-saw model for {nu}-masses may imply that the {nu}{sub {tau}} is a good hot dark matter candidate. 73 refs., 5 figs.
Distortions in the cosmic background radiation and big-bang 4He nucleosynthesis
International Nuclear Information System (INIS)
Mathews, G.J.; Alhassid, Y.; Fuller, G.M.
1981-01-01
The observed distortion of the cosmic background radiation is analyzed in the framework of information theory to derive a simple form of the photon occupation probability. Taking this distribution function as indicative of the Lagrange parameters which might characterize the era of nucleosynthesis during the big bang, and assuming equilibrium among the constituents present, we find that the primordial 4 He abundance may be reduced by as much as 15% from the standard big-bang prediction
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.
Quantum fields in a big-crunch-big-bang spacetime
International Nuclear Information System (INIS)
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 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 reexpands at the same rate. For free fields in our construction there is no particle production from the incoming adiabatic vacuum. When interactions are included the particle production for fixed external momentum is finite at the tree level. We discuss a formal correspondence between our construction and quantum field theory on de Sitter spacetime
Particle physics catalysis of thermal big bang nucleosynthesis.
Pospelov, Maxim
2007-06-08
We point out that the existence of metastable, tau>10(3) s, negatively charged electroweak-scale particles (X-) alters the predictions for lithium and other primordial elemental abundances for A>4 via the formation of bound states with nuclei during big bang nucleosynthesis. In particular, we show that the bound states of X- with helium, formed at temperatures of about T=10(8) K, lead to the catalytic enhancement of 6Li production, which is 8 orders of magnitude more efficient than the standard channel. In particle physics models where subsequent decay of X- does not lead to large nonthermal big bang nucleosynthesis effects, this directly translates to the level of sensitivity to the number density of long-lived X- particles (tau>10(5) s) relative to entropy of nX-/s less, approximately <3x10(-17), which is one of the most stringent probes of electroweak scale remnants known to date.
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.
International Nuclear Information System (INIS)
Wetterich, C.
2014-01-01
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
Energy Technology Data Exchange (ETDEWEB)
Wetterich, C.
2014-09-07
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.
Directory of Open Access Journals (Sweden)
C. Wetterich
2014-09-01
Full Text Available 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.
Adiabatic perturbations in pre-big bang models: Matching conditions and scale invariance
International Nuclear Information System (INIS)
Durrer, Ruth; Vernizzi, Filippo
2002-01-01
At low energy, the four-dimensional effective action of the ekpyrotic model of the universe is equivalent to a slightly modified version of the pre-big bang model. We discuss cosmological perturbations in these models. In particular we address the issue of matching the perturbations from a collapsing to an expanding phase. We show that, under certain physically motivated and quite generic assumptions on the high energy corrections, one obtains n=0 for the spectrum of scalar perturbations in the original pre-big bang model (with a vanishing potential). With the same assumptions, when an exponential potential for the dilaton is included, a scale invariant spectrum (n=1) of adiabatic scalar perturbations is produced under very generic matching conditions, both in a modified pre-big bang and ekpyrotic scenario. We also derive the resulting spectrum for arbitrary power law scale factors matched to a radiation-dominated era
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.
Horizons in Matter:. Black Hole Hair Versus Null Big Bang
Bronnikov, K. A.; Zaslavskii, Oleg B.
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 its generalization with the same value of w) 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 coexist with vacuum matter and certain kinds of phantom matter with w ≤ -3. It is concluded that normal matter in such scenarios is entirely created from vacuum.
Antigravity and the big crunch/big bang transition
International Nuclear Information System (INIS)
Bars, Itzhak; Chen, Shih-Hung; Steinhardt, Paul J.; Turok, Neil
2012-01-01
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.
Big-bang nucleosynthesis - observational aspects
International Nuclear Information System (INIS)
Pagel, B.E.J.
1990-01-01
Extrapolation of observational data on the abundances of D, 3 He, 4 He and 7 Li 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.)
Bojowald, Martin
2008-06-06
When quantum gravity is used to discuss the big bang singularity, the most important, though rarely addressed, question is what role genuine quantum degrees of freedom play. Here, complete effective equations are derived for isotropic models with an interacting scalar to all orders in the expansions involved. The resulting coupling terms show that quantum fluctuations do not affect the bounce much. Quantum correlations, however, do have an important role and could even eliminate the bounce. How quantum gravity regularizes the big bang depends crucially on properties of the quantum state.
New physics and the new big bang
International Nuclear Information System (INIS)
Davies, P.
1985-01-01
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
Revisiting big-bang nucleosynthesis constraints on long-lived decaying particles
Kawasaki, Masahiro; Kohri, Kazunori; Moroi, Takeo; Takaesu, Yoshitaro
2018-01-01
We study the effects of long-lived massive particles, which decayed during the big-bang nucleosynthesis (BBN) epoch, on the primordial abundance of light elements. Compared to previous studies, (i) the reaction rates of standard BBN reactions are updated, (ii) the most recent observational data on the light element abundance and cosmological parameters are used, (iii) the effects of the interconversion of energetic nucleons at the time of inelastic scattering with background nuclei are considered, and (iv) the effects of the hadronic shower induced by energetic high-energy antinucleons are included. We compare the theoretical predictions on the primordial abundance of light elements with the latest observational constraints, and we derive upper bounds on the relic abundance of the decaying particle as a function of its lifetime. We also apply our analysis to an unstable gravitino, the superpartner of a graviton in supersymmetric theories, and obtain constraints on the reheating temperature after inflation.
Planck 2015 results: XIII. Cosmological parameters
DEFF Research Database (Denmark)
Ade, P. A R; Aghanim, N.; Arnaud, M.
2016-01-01
is constrained to w =-1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints...
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).
Teoria del Big Bang e buchi neri
Wald, Robert M
1980-01-01
Un giovane fisico americano delinea con chiarezza in questo volume le attuali concezioni dello spazio, del tempo e della gravitazione, cosi come si sono andate delineando dopo e innovazioni teoriche aperte da Einstein. Esse investono problemi affascinanti, come la teoria del big bang, da cui avrebbe avuto origine l'universo, e l'enigma dei buchi neri.
Strange matter and Big Bang helium synthesis
International Nuclear Information System (INIS)
Madsen, J.; Riisager, K.
1985-01-01
Stable strange quark matter produced in the QCD phase transition in the early universe will trap neutrons and repel protons, thus reducing primordial helium production, Ysub(p). For reasonable values of Ysub(p), the radius of strange droplets must exceed 10 -6 cm if strange matter shall solve the dark-matter problem without spoiling Big Bang helium synthesis. (orig.)
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)
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
Axion cold dark matter in nonstandard cosmologies
International Nuclear Information System (INIS)
Visinelli, Luca; Gondolo, Paolo
2010-01-01
We study the parameter space of cold dark matter axions in two cosmological scenarios with nonstandard thermal histories before big bang nucleosynthesis: the low-temperature reheating (LTR) cosmology and the kination cosmology. If the Peccei-Quinn symmetry breaks during inflation, we find more allowed parameter space in the LTR cosmology than in the standard cosmology and less in the kination cosmology. On the contrary, if the Peccei-Quinn symmetry breaks after inflation, the Peccei-Quinn scale is orders of magnitude higher than standard in the LTR cosmology and lower in the kination cosmology. We show that the axion velocity dispersion may be used to distinguish some of these nonstandard cosmologies. Thus, axion cold dark matter may be a good probe of the history of the Universe before big bang nucleosynthesis.
Global fluctuation spectra in big-crunch-big-bang string vacua
International Nuclear Information System (INIS)
Craps, Ben; Ovrut, Burt A.
2004-01-01
We study big-crunch-big-bang cosmologies that correspond to exact world-sheet superconformal field theories of type II strings. The string theory spacetime contains a big crunch and a big bang cosmology, as well as additional 'whisker' asymptotic and intermediate regions. Within the context of free string theory, we compute, unambiguously, the scalar fluctuation spectrum in all regions of spacetime. Generically, the big crunch fluctuation spectrum is altered while passing through the bounce singularity. The change in the spectrum is characterized by a function Δ, which is momentum and time dependent. We compute Δ explicitly and demonstrate that it arises from the whisker regions. The whiskers are also shown to lead to 'entanglement' entropy in the big bang region. Finally, in the Milne orbifold limit of our superconformal vacua, we show that Δ→1 and, hence, the fluctuation spectrum is unaltered by the big-crunch-big-bang singularity. We comment on, but do not attempt to resolve, subtleties related to gravitational back reaction and light winding modes when interactions are taken into account
Narlikar, Jayant Vishnu
2002-01-01
The third edition of this successful textbook is fully updated and includes important recent developments in cosmology. It begins with an introduction to cosmology and general relativity, and goes on to cover the mathematical models of standard cosmology. The physical aspects of cosmology, including primordial nucleosynthesis, the astroparticle physics of inflation, and the current ideas on structure formation are discussed. Alternative models of cosmology are reviewed, including the model of Quasi-Steady State Cosmology, which has recently been proposed as an alternative to Big Bang Cosmology.
Krishnan, Chethan; Raju, Avinash
2017-08-01
We argue that in the tensionless phase of string theory where the stringy gauge symmetries are unbroken, (at least some) cosmological singularities can be understood as gauge artefacts. We present two conceptually related, but distinct, pieces of evidence: one relying on spacetime and the other on worldsheet.
Zero Kelvin Big Bang, an Alternative Paradigm: I. Logic and the Cosmic Fabric
Haynes, Royce
2011-11-01
This is the first of three papers describing an alternative paradigm of cosmogony, the beginning and evolution of the universe. The Zero Kelvin Big Bang (ZKBB) theory is compared to the prevailing Standard Big Bang (SBB) paradigm, and challenges the notion that our universe is "all there is." Logic suggests that the Big Bang was not a creation event, but that the universe did have a beginning: a "cosmic fabric" of pre- existing matter, in pre-existing space. Instead, the Zero Kelvin Big Bang was a transitional event between that "beginning" and what would become our universe. Extrapolating entropy back in time (as SBB does for matter and energy), and applying simple logic, suggests a "cosmic fabric" of the simplest, stable particles of matter, at the lowest energy state possible: singlet state, spin-oriented atomic hydrogen at zero kelvin, at a density of, at most, only a few atoms per cubic meter of space, infinite and (almost) eternal. Papers II and III describe the condensation of part of the cosmic fabric into a Bose-Einstein condensate (BEC) as Lemaître's primeval atom, followed by an implosion- explosion Big Bang.
Colloquium spectroscopicum internationale XXIV: From big bang to unsolved problems
International Nuclear Information System (INIS)
Schrader, B.
1985-01-01
Brief report on the Colloquium Spectroscopicum Internationale 1985, held in Garmisch-Partenkirchen (FRG). The opening lecture, ''From Big Bang to Black Holes'', unfolded the current knowledge of the universe, whereas two thirds of the following 61 plenary lectures dealt with problems of atomic spectroscopy and the remaining papers with molecular spectroscopy. In 40 poster sessions 350 posters were briefly discussed, and the conference was accompanied by an exhibition of latest spectrometric equipment. Experimental methods were the centre of discussions of atomic spectroscopy experts, whereas in the field of moclecular spectroscopy issues such as standards for digitised spectra, databases and information exchange via data networks met with great interest. (RB) [de
Laser interferometry for the Big Bang Observer
International Nuclear Information System (INIS)
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
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)
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.
Laser interferometry for the Big Bang Observer
Energy Technology Data Exchange (ETDEWEB)
Harry, Gregory M [LIGO Laboratory, Massachusetts Institute of Technology, NW17-161, Cambridge, MA 02139 (United States); Fritschel, Peter [LIGO Laboratory, Massachusetts Institute of Technology, NW17-161, Cambridge, MA 02139 (United States); Shaddock, Daniel A [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Folkner, William [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Phinney, E Sterl [California Institute of Technology, Pasadena, CA 91125 (United States)
2006-08-07
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.
Shaposhnikov, Mikhail
2015-01-01
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
The Higgs boson and cosmology.
Shaposhnikov, Mikhail
2015-01-13
I will discuss how the Higgs field of the Standard Model may have played an important role in cosmology, leading to the homogeneity, isotropy and flatness of the Universe; producing the quantum fluctuations that seed structure formation; triggering the radiation-dominated era of the hot Big Bang; and contributing to the processes of baryogenesis and dark matter production.
Big bang nucleosynthesis: The strong nuclear force meets the weak anthropic principle
International Nuclear Information System (INIS)
MacDonald, J.; Mullan, D. J.
2009-01-01
Contrary to a common argument that a small increase in the strength of the strong force would lead to destruction of all hydrogen in the big bang due to binding of the diproton and the dineutron with a catastrophic impact on life as we know it, we show that provided the increase in strong force coupling constant is less than about 50% substantial amounts of hydrogen remain. The reason is that an increase in strong force strength leads to tighter binding of the deuteron, permitting nucleosynthesis to occur earlier in the big bang at higher temperature than in the standard big bang. Photodestruction of the less tightly bound diproton and dineutron delays their production to after the bulk of nucleosynthesis is complete. The decay of the diproton can, however, lead to relatively large abundances of deuterium.
Rotational inhomogeneities from pre-big bang?
International Nuclear Information System (INIS)
Giovannini, Massimo
2005-01-01
The evolution of the rotational inhomogeneities is investigated in the specific framework of four-dimensional pre-big bang models. While minimal (dilaton-driven) scenarios do not lead to rotational fluctuations, in the case of non-minimal (string-driven) models, fluid sources are present in the pre-big bang phase. The rotational modes of the geometry, coupled to the divergenceless part of the velocity field, can then be amplified depending upon the value of the barotropic index of the perfect fluids. In the light of a possible production of rotational inhomogeneities, solutions describing the coupled evolution of the dilaton field and of the fluid sources are scrutinized in both the string and Einstein frames. In semi-realistic scenarios, where the curvature divergences are regularized by means of a non-local dilaton potential, the rotational inhomogeneities are amplified during the pre-big bang phase but they decay later on. Similar analyses can also be performed when a contraction occurs directly in the string frame metric
Rotational inhomogeneities from pre-big bang?
Energy Technology Data Exchange (ETDEWEB)
Giovannini, Massimo [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland)
2005-01-21
The evolution of the rotational inhomogeneities is investigated in the specific framework of four-dimensional pre-big bang models. While minimal (dilaton-driven) scenarios do not lead to rotational fluctuations, in the case of non-minimal (string-driven) models, fluid sources are present in the pre-big bang phase. The rotational modes of the geometry, coupled to the divergenceless part of the velocity field, can then be amplified depending upon the value of the barotropic index of the perfect fluids. In the light of a possible production of rotational inhomogeneities, solutions describing the coupled evolution of the dilaton field and of the fluid sources are scrutinized in both the string and Einstein frames. In semi-realistic scenarios, where the curvature divergences are regularized by means of a non-local dilaton potential, the rotational inhomogeneities are amplified during the pre-big bang phase but they decay later on. Similar analyses can also be performed when a contraction occurs directly in the string frame metric.
Pre-Big-Bang bubbles from the gravitational instability of generic string vacua
International Nuclear Information System (INIS)
Buonanno, A.; Damour, T.; Veneziano, G.
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/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
Pre-Big-Bang bubbles from the gravitational instability of generic string vacua
Energy Technology Data Exchange (ETDEWEB)
Buonanno, A.; Damour, T.; Veneziano, G
1999-03-22
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.
Big Bang nucleosynthesis and the quark-hadron transition
International Nuclear Information System (INIS)
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).
The Sounds of the Little and Big Bangs
Shuryak, Edward
2017-11-01
Studies of heavy ion collisions have discovered that tiny fireballs of new phase of matter -- quark gluon plasma (QGP) -- undergoes explosion, called the Little Bang. In spite of its small size, it is not only well described by hydrodynamics, but even small perturbations on top of the explosion turned to be well described by hydrodynamical sound modes. The cosmological Big Bang also went through phase transitions, the QCD and electroweak ones, which are expected to produce sounds as well. We discuss their subsequent evolution and hypothetical inverse acoustic cascade, amplifying the amplitude. Ultimately, collision of two sound waves leads to formation of gravity waves, with the smallest wavelength. We briefly discuss how those can be detected.
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.
The Sounds of the Little and Big Bangs
Directory of Open Access Journals (Sweden)
Edward Shuryak
2017-11-01
Full Text Available Studies on heavy ion collisions have discovered that tiny fireballs of a new phase of matter—quark gluon plasma (QGP—undergo an explosion, called the Little Bang. In spite of its small size, not only is it well described by hydrodynamics, but even small perturbations on top of the explosion turned out to be well described by hydrodynamical sound modes. The cosmological Big Bang also went through phase transitions, related with Quantum Chromodynamics (QCD and electroweak/Higgs symmetry breaking, which are also expected to produce sounds. We discuss their subsequent evolution and hypothetical inverse acoustic cascade, amplifying the amplitude. Ultimately, the collision of two sound waves leads to the formation of one gravity waves. We briefly discuss how these gravity waves can be detected.
Higher spin resolution of a toy big bang
Krishnan, Chethan; Roy, Shubho
2013-08-01
Diffeomorphisms preserve spacetime singularities, whereas higher spin symmetries need not. Since three-dimensional de Sitter space has quotients that have big-bang/big-crunch singularities and since dS3-gravity can be written as an SL(2,C) Chern-Simons theory, we investigate SL(3,C) Chern-Simons theory as a higher-spin context in which these singularities might get resolved. As in the case of higher spin black holes in AdS3, the solutions are invariantly characterized by their holonomies. We show that the dS3 quotient singularity can be desingularized by an SL(3,C) gauge transformation that preserves the holonomy: this is a higher spin resolution the cosmological singularity. Our work deals exclusively with the bulk theory, and is independent of the subtleties involved in defining a CFT2 dual to dS3 in the sense of dS/CFT.
Cosmology and Cosmogony in a Cyclic Universe Jayant V. Narlikar ...
Indian Academy of Sciences (India)
Key words. Cosmology—cosmogony—high energy phenomena. 1. Introduction. 1.1 Cosmological models. The standard cosmological model accepted by the majority at present is centered about the big bang which involves the creation of matter and energy in an initial explosion. Since we have overwhelming evidence that ...
International Nuclear Information System (INIS)
Hansen, S.H.; Melchiorri, A.; Mangano, G.; Miele, G.; Pisanti, O.
2002-01-01
We perform a likelihood analysis of the recent results on the anisotropy of cosmic microwave background radiation from the BOOMERanG and DASI experiments to show that they single out an effective number of neutrinos in good agreement with standard big bang nucleosynthesis. We also consider degenerate big bang nucleosynthesis to provide new bounds on effective relativistic degrees of freedom N ν and, in particular, on the neutrino chemical potential ξ α . When including supernova type Ia data we find, at 2σ, N ν ≤7 and -0.01≤ξ e ≤0.22, vertical bar ξ μ,τ vertical bar ≤2.6
Big bang nucleosynthesis with a varying fine structure constant and nonstandard expansion rate
International Nuclear Information System (INIS)
Ichikawa, Kazuhide; Kawasaki, Masahiro
2004-01-01
We calculate the primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take nonstandard values. We compare them with the recent values of observed D, 4 He, and 7 Li abundances, which show a slight inconsistency among themselves in the standard big bang nucleosynthesis scenario. This inconsistency is not solved by considering either a varying fine structure constant or a nonstandard expansion rate separately but solutions are found by their simultaneous existence
Beyond the Friedmann—Lemaître—Robertson—Walker Big Bang Singularity
International Nuclear Information System (INIS)
Stoica, Cristi
2012-01-01
Einstein's equation, in its standard form, breaks down at the Big Bang singularity. A new version, equivalent to Einstein's whenever the latter is defined, but applicable in wider situations, is proposed. The new equation remains smooth at the Big Bang singularity of the Friedmann—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.
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.
Out of the white hole: a holographic origin for the Big Bang
Pourhasan, Razieh; Afshordi, Niayesh; Mann, Robert B.
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.
Out of the white hole: a holographic origin for the Big Bang
International Nuclear Information System (INIS)
Pourhasan, Razieh; Afshordi, Niayesh; Mann, Robert B.
2014-01-01
While most of the singularities of General Relativity are expected to be safely hidden behind event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical Big Bang singularity, whose resolution constitutes the active field of early universe cosmology. Could the Big Bang be also hidden behind a causal horizon, making us immune to the decadent impacts of a naked singularity? We describe a braneworld description of cosmology with both 4d induced and 5D bulk gravity (otherwise known as Dvali-Gabadadze-Porati, or DGP model), which exhibits this feature: the universe emerges as a spherical 3-brane out of the formation of a 5D Schwarzschild black hole. In particular, we show that a pressure singularity of the holographic fluid, discovered earlier, happens inside the white hole horizon, and thus need not be real or imply any pathology. Furthermore, we outline a novel mechanism through which any thermal atmosphere for the brane, with comoving temperature of ∼20% of the 5D 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
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?
International Nuclear Information System (INIS)
Partridge, R.B.
1977-01-01
Some sixty years after the development of relativistic cosmology by Einstein and his colleagues, observations are finally beginning to have an important impact on our views of the Universe. The available evidence seems to support one of the simplest cosmological models, the hot Big Bang model. The aim of this paper is to assess the observational support for certain assumptions underlying the hot Big Bang model. These are that the Universe is isobaric and homogeneous on a large scale; that it is expanding from an initial state of high density and temperature; and that the proper theory to describe the dynamics of the Universe is unmodified General Relativity. The properties of the cosmic microwave background radiation and recent observations of the abundance of light elements, in particular, support these assumptions. Also examined here are the data bearing on the related questions of the geometry and the future of the Universe (is it ever-expanding, or fated to recollapse). Finally, some difficulties and faults of the standard model are discussed, particularly various aspects of the 'initial condition' problem. It appears that the simplest Big Bang cosmological model calls for a highly specific set of initial conditions to produce the presently observed properties of the Universe. (Auth.)
Pregeometric origin of the big bang
International Nuclear Information System (INIS)
Akama, K.; Terazawa, H.; Tokyo Univ., Tanashi
1981-07-01
The temperature-dependent effective action for gravity is calculated in pregeometry. It indicates that the effective potential for the space-time metric has the minimum at the origin for extremely high temperature. The origin of the big bang can be taken as a local and spontaneous phase transition of the space-time from the pregeometric phase to the geometric one. It is suggested that in our universe there may exist ''pregeometric holes'' where the space-time metric absolutely vanishes and/or ''space-time discontinuities'' where the metric discretely changes. (author)
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. Copyright © 2014 Elsevier Inc. All rights reserved.
Big bang nucleosynthesis constraints on bulk neutrinos
International Nuclear Information System (INIS)
Goh, H.S.; Mohapatra, R.N.
2002-01-01
We examine the constraints imposed by the requirement of successful nucleosynthesis on models with one large extra hidden space dimension and a single bulk neutrino residing in this dimension. We solve the Boltzmann kinetic equation for the thermal distribution of the Kaluza-Klein modes and evaluate their contribution to the energy density at the big bang nucleosynthesis epoch to constrain the size of the extra dimension R -1 ≡μ and the parameter sin 2 2θ which characterizes the mixing between the active and bulk neutrinos
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.
Big bang nucleosynthesis and the cosmic neutrino background
International Nuclear Information System (INIS)
Cao Yun; Xing Zhizhong
2013-01-01
We present a brief overview of the neutrino decoupling and big bang nucleosynthesis in the early universe. The big bang relic neutrinos formed one of the backgrounds of the universe. A few possible ways to directly detect the cosmic neutrino background are briefly introduced, and particular attention is paid to the relic neutrino capture on b-decaying nuclei. (authors)
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…
Beyond concordance cosmology with magnification of gravitational-wave standard sirens.
Camera, Stefano; Nishizawa, Atsushi
2013-04-12
We show how future gravitational-wave detectors would be able to discriminate between the concordance Λ cold dark matter cosmological model and up-to-date competing alternatives, e.g., dynamical dark energy (DE) models or modified gravity (MG) theories. Our method consists of using the weak-lensing magnification effect that affects a standard-siren signal because of its traveling through the Universe's large scale structure. As a demonstration, we present constraints on DE and MG from proposed gravitational-wave detectors, namely Einstein Telescope and DECI-Hertz Interferometer Gravitational-Wave Observatory and Big-Bang Observer.
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.
Quantum nature of the big bang: An analytical and numerical investigation
International Nuclear Information System (INIS)
Ashtekar, Abhay; Pawlowski, Tomasz; Singh, Parampreet
2006-01-01
Analytical and numerical methods are developed to analyze the quantum nature of the big bang in the setting of loop quantum cosmology. They enable one to explore the effects of quantum geometry both on the gravitational and matter sectors and significantly extend the known results on the resolution of the big bang singularity. Specifically, the following results are established for the homogeneous isotropic model with a massless scalar field: (i) the scalar field is shown to serve as an internal clock, thereby providing a detailed realization of the 'emergent time' idea; (ii) the physical Hilbert space, Dirac observables, and semiclassical states are constructed rigorously; (iii) the Hamiltonian constraint is solved numerically to show that the big bang is replaced by a big bounce. Thanks to the nonperturbative, background independent methods, unlike in other approaches the quantum evolution is deterministic across the deep Planck regime. Our constructions also provide a conceptual framework and technical tools which can be used in more general models. In this sense, they provide foundations for analyzing physical issues associated with the Planck regime of loop quantum cosmology as a whole
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...
Black Holes, the Big Bang and the Habitable Universe: Are They Really Compatible?
Hujeirat, Ahmad A.
Astronomical observations have confirmed the existence of BHs and the occurrence of the Big Bang event to beyond any reasonable doubt. While quantum field theory and general theory of relativity predict the mass-spectrum of BHs to be unlimited, both theories agree that their creation is irreversible. In this article I argue that the recently-proposed SuSu-objects (: objects that are made of incompressible superconducting gluon-qurak superfluids), may not only entail the required properties to be excellent BH-candidates, but also encoding a hidden connection to dark matter and dark energy in cosmology. If such connection indeed exists, then the inevitable consequence would be that our universe is infinite and subject to repeated Big Bang events of the second kind, which makes the habitability of the universe certain and our cosmic relevance insignificant and meaningless.
Introduction to particle cosmology the standard model of cosmology and its open problems
Bambi, Cosimo
2016-01-01
This book introduces the basic concepts of particle cosmology and covers all the main aspects of the Big Bang Model (expansion of the Universe, Big Bang Nucleosynthesis, Cosmic Microwave Background, large scale structures) and the search for new physics (inflation, baryogenesis, dark matter, dark energy). It also includes the majority of recent discoveries, such as the precise determination of cosmological parameters using experiments like WMAP and Planck, the discovery of the Higgs boson at LHC, the non-discovery to date of supersymmetric particles, and the search for the imprint of gravitational waves on the CMB polarization by Planck and BICEP. This textbook is based on the authors’ courses on Cosmology, and aims at introducing Particle Cosmology to senior undergraduate and graduate students. It has been especially written to be accessible even for those students who do not have a strong background in General Relativity and quantum field theory. The content of this book is organized in an easy-to-use ...
Dark/visible parallel universes and Big Bang nucleosynthesis
International Nuclear Information System (INIS)
Bertulani, C. A.; Frederico, T.; Fuqua, J.; Hussein, M. S.; Oliveira, O.; Paula, W. de
2012-01-01
We develop a model for visible matter-dark matter interaction based on the exchange of a massive gray boson called herein the Mulato. Our model hinges on the assumption that all known particles in the visible matter have their counterparts in the dark matter. We postulate six families of particles five of which are dark. This leads to the unavoidable postulation of six parallel worlds, the visible one and five invisible worlds. A close study of big bang nucleosynthesis (BBN), baryon asymmetries, cosmic microwave background (CMB) bounds, galaxy dynamics, together with the Standard Model assumptions, help us to set a limit on the mass and width of the new gauge boson. Modification of the statistics underlying the kinetic energy distribution of particles during the BBN is also discussed. The changes in reaction rates during the BBN due to a departure from the Debye-Hueckel electron screening model is also investigated.
The Cosmic Bellows: The Big Bang and the Second Law
Directory of Open Access Journals (Sweden)
Stanley Salthe
2006-01-01
Full Text Available We present here a cosmological myth, alternative (but complementary to "the Universe Story" and "the Epic of Evolution", highlighting the roles of entropy and dissipative structures in the universe inaugurated by the Big Bang. Our myth offers answers these questions: Where are we? What are we? Why are we here? What are we to do? It also offers answers to a set of "why" questions: Why is there anything at all? and Why are there so many kinds of systems? - the answers coming from cosmology and physics (thermodynamics; Why do systems not last once they exist? - the answer coming from a materialist interpretation of information theory; and, Why are systems just the way they are and not otherwise? - the answer coming from evolutionary biology. We take into account the four kinds of causation designated by Aristotle as efficient, final, and material formal, with the Second Law of thermodynamics in the role of final cause. Conceptual problems concerning reductionism, "teleology", and the choice/chance distinction are dealt with in the framework of specification hierarchy, and the moral implications of our story explored in the conclusion.
The Cosmic Bellows: The Big Bang and the Second Law
Directory of Open Access Journals (Sweden)
Stanley Salthe
2005-01-01
Full Text Available We present here a cosmological myth, alternative (but complementary to "the Universe Story" and "the Epic of Evolution", highlighting the roles of entropy and dissipative structures in the universe inaugurated by the Big Bang. Our myth offers answers these questions: Where are we? What are we? Why are we here? What are we to do? It also offers answers to a set of "why" questions: Why is there anything at all? and Why are there so many kinds of systems? - the answers coming from cosmology and physics (thermodynamics; Why do systems not last once they exist? - the answer coming from a materialist interpretation of information theory; and, Why are systems just the way they are and not otherwise? - the answer coming from evolutionary biology. We take into account the four kinds of causation designated by Aristotle as efficient, final, and material formal, with the Second Law of thermodynamics in the role of final cause. Conceptual problems concerning reductionism, "teleology", and the choice/chance distinction are dealt with in the framework of specification hierarchy, and the moral implications of our story explored in the conclusion.
Big Bang Tumor Growth and Clonal Evolution.
Sun, Ruping; Hu, Zheng; Curtis, Christina
2017-07-14
The advent and application of next-generation sequencing (NGS) technologies to tumor genomes has reinvigorated efforts to understand clonal evolution. Although tumor progression has traditionally been viewed as a gradual stepwise process, recent studies suggest that evolutionary rates in tumors can be variable with periods of punctuated mutational bursts and relative stasis. For example, Big Bang dynamics have been reported, wherein after transformation, growth occurs in the absence of stringent selection, consistent with effectively neutral evolution. Although first noted in colorectal tumors, effective neutrality may be relatively common. Additionally, punctuated evolution resulting from mutational bursts and cataclysmic genomic alterations have been described. In this review, we contrast these findings with the conventional gradualist view of clonal evolution and describe potential clinical and therapeutic implications of different evolutionary modes and tempos. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.
Antimatter questions the big-bang theory
International Nuclear Information System (INIS)
Daninos, F.
2005-01-01
A few moments after the big-bang matter an antimatter existed in the same quantities. Today the universe seems to be exclusively composed of matter. Nature prefers matter to antimatter but scientists do not know why. Experimental results from Babar and Belle experiments have confirmed the existence of CP violation in quark systems. This article draws the story of the quest for symmetry violation since the discovery of P violation in cobalt decay in the end of the fifties. Our understanding of CP violation is by far insufficient for explaining the matter-antimatter imbalance and may be we will have to admit that CP violation might concern other systems like neutrinos or super-symmetric particles. (A.C.)
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)
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...
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)
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)
Scientists seek to explain how Big Bang let us live
Hawke, N
2000-01-01
Scientists at CERN have opened an antimatter factory, the Antiproton Decelerator. They hope to discover why, in the Big Bang, the amount of matter and antimatter produced was not equal, so allowing the universe to exist at all (1 page).
Prospects for NATO Enlargement: Examining the "Big Bang" Approach
National Research Council Canada - National Science Library
Moyer, Andrew
2000-01-01
...) aspire to membership. Led by the Baltic states, these nine countries have signed the May 2000 Vilnius Declaration, advocating the admission of all nine aspirants simultaneously, a so called "big bang" approach to the next...
L'antimatière questionne toujours le Big Bang
Daninos, Franck
2005-01-01
A few moments after the Big Bang, matter and antimatter were created in the same quantities. But, the actual Universe is made only from matter. Will the problem of disappearance of the antimatter be solved? (4 pages)
International Nuclear Information System (INIS)
Zeldovich, Y.B.
1983-01-01
This paper fives a general review of modern cosmology. The following subjects are discussed: hot big bang and periodization of the evolution; Hubble expansion; the structure of the universe (pancake theory); baryon asymmetry; inflatory universe. (Auth.)
Ekpyrotic and cyclic cosmology
International Nuclear Information System (INIS)
Lehners, Jean-Luc
2008-01-01
Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes - and thus the big bang is not the beginning of time. Before the big bang, there is an ekpyrotic phase with equation of state w=P/(ρ) >>1 (where P is the average pressure and ρ the average energy density) during which the universe slowly contracts. This phase resolves the standard cosmological puzzles and generates a nearly scale-invariant spectrum of cosmological perturbations containing a significant non-Gaussian component. At the same time it produces small-amplitude gravitational waves with a blue spectrum. The dark energy dominating the present-day cosmological evolution is reinterpreted as a small attractive force between our brane and a parallel one. This force eventually induces a new ekpyrotic phase and a new brane collision, leading to the idea of a cyclic universe. This review discusses the detailed properties of these models, their embedding in M-theory and their viability, with an emphasis on open issues and observational signatures
R-parity violation and the cosmological gravitino problem
International Nuclear Information System (INIS)
Moreau, G.; Chemtob, M.
2002-01-01
Based on the R-parity violation option of the minimal supersymmetric standard model, we examine the scenario where the massive gravitino, a relic from the hot big-bang, is the lightest supersymmetric particle and can decay through one or several of the trilinear R-parity violating interactions. We calculate the rates of the gravitino decay via the various three-body decay channels with final states involving three quarks and/or leptons. By taking into account the present constraints on the trilinear R-parity violating coupling constants and assuming the gravitino and scalar superpartner masses do not exceed ∼80 TeV, it turns out that the gravitinos could easily have decayed before the present epoch but not earlier than the big-bang nucleosynthesis one. Therefore, the considered scenario would upset the standard big-bang nucleosynthesis scenario and we conclude that it does not seem to constitute a natural solution for the cosmological gravitino problem
A first order phase transition from inflationary to big bang universe
International Nuclear Information System (INIS)
Horwitz, G.
1986-01-01
The microcanonical entropy is calculated for a system of massive, conformally coupled, scalar bosons using a conformal gravitational theory. The resulting entropy is seen to indicate a first order phase transition from an inflationary expansion stage (where the amplitude of the scalar boson follows that of the scale function of the universe and the mass of the solar boson is the source of the cosmological constant) to a big bang stage (where neither of these conditions hold). Such a first order phase transition involves an entropy increase of some thirty orders of magnitude. In the author's theory, the invariant temperature (proper temperature times scale function) is not zero, nor is it the Hawking temperature, but it is tens of magnitudes smaller than the corresponding temperature of the big bang stage. A specific model for these bosons that provides the phase transition and serves as the source of the cosmological constant is also examined briefly, where the bosons are identified as spontaneously generated primordial black holes as in the cosmological model of Brout, Englert and Casher. In that case, the decay of the black holes provides a decaying cosmological constant and an explicit mechanism for heating up the universe
Big Bang synthesis of nuclear dark matter
International Nuclear Information System (INIS)
Hardy, Edward; Lasenby, Robert; March-Russell, John; West, Stephen M.
2015-01-01
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. ≳10 8 , 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 ≫10 8 , 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.
Inhomogeneous neutrino degeneracy and big bang nucleosynthesis
International Nuclear Information System (INIS)
Whitmire, Scott E.; Scherrer, Robert J.
2000-01-01
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 ν e 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
The Big Bang on the laboratory bench
International Nuclear Information System (INIS)
Roy, Ch.; Daninos, F.; Baruch, J.O.
2006-01-01
For a few fractions of a second after the Big-Bang, the temperature of the universe reached several thousands milliards degrees and till now quarks and gluons have been thought to be dissociated in a kind of primordial plasma but recent experimental results from the RHIC (relativistic heavy ions collider in Brookhaven) show that the quark and gluon plasma flows like a fluid and that the interaction between quarks generates that flow. Another feature of the quark and gluon plasma is an ability to behave like an almost perfect gas: it shows very low viscosity and reaches thermal equilibrium very quickly. Alice, a huge particle detection system that will equip the future LHC (large hadron collider in CERN), will shed light on an energy range that has been scarcely touched by RHIC. Confirmation of RHIC results is expected but the discovery of totally new phenomena like the creation of mini black holes or the existence of extra spatial dimensions remains possible. Another issue concerns nucleosynthesis and the problem that nuclear models predict a ratio of helium 7 in stars 3 times as high as what is really found in the oldest stars of our galaxy. (A.C.)
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.
Five-dimensional null-cone structure of big bang singularity
Energy Technology Data Exchange (ETDEWEB)
Lauro, S.; Schucking, E.L.
1985-04-01
The Friedmann model PHI of positive space curvature, vanishing pressure and cosmological constant when isometrically imbedded as a hypersurface in five-dimensional Minkowski space MV is globally rigid: if F(PHI) and F'(PHI) are isometric embeddings in MV there is a motion of MV such that F'= F. The big bang singularity is the vertex of a null half-cone in MV. Global rigidity leads to an invariant characterization of the singularity. The structure of matter at the singularity is governed by the de Sitter group.
Five-dimensional null-cone structure of big bang singularity
International Nuclear Information System (INIS)
Lauro, S.; Schucking, E.L.
1985-01-01
The Friedmann model PHI of positive space curvature, vanishing pressure and cosmological constant when isometrically imbedded as a hypersurface in five-dimensional Minkowski space M 5 is globally rigid: if F(PHI) and F'(PHI) are isometric embeddings in M 5 there is a motion π of M 5 such that F'=π 0 F. The big bang singularity is the vertex of a null half-cone in M 5 . Global rigidity leads to an invariant characterization of the singularity. The structure of matter at the singularity is governed by the de Sitter group. (author)
Gravitationally induced adiabatic particle production: from big bang to de Sitter
International Nuclear Information System (INIS)
Haro, Jaume de; Pan, Supriya
2016-01-01
In the background of a flat homogeneous and isotropic space–time, we consider a scenario of the Universe driven by the gravitationally induced ‘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. (paper)
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...
Regularization of the big bang singularity with random perturbations
Belbruno, Edward; Xue, BingKan
2018-03-01
We show how to regularize the big bang singularity in the presence of random perturbations modeled by Brownian motion using stochastic methods. We prove that the physical variables in a contracting universe dominated by a scalar field can be continuously and uniquely extended through the big bang as a function of time to an expanding universe only for a discrete set of values of the equation of state satisfying special co-prime number conditions. This result significantly generalizes a previous result (Xue and Belbruno 2014 Class. Quantum Grav. 31 165002) that did not model random perturbations. This result implies that the extension from a contracting to an expanding universe for the discrete set of co-prime equation of state is robust, which is a surprising result. Implications for a purely expanding universe are discussed, such as a non-smooth, randomly varying scale factor near the big bang.
What if the big bang didn't happen?
International Nuclear Information System (INIS)
Narlikar, J.
1991-01-01
Although it has wide support amongst cosmologists, the big bang theory of the origin of the Universe is brought into question in this article because of several recent observations. The large red shift observed in quasars does not fit with Hubble's Law which is so successful for galaxies. Some quasars appear to be linked to companion galaxies by filaments and, again, anomalous red shifts have been observed. The cosmic microwave background, or relic radiation, seems to be too uniform to fit with the big bang model. Lastly, the dark matter, necessary to explain the coalescing of galaxies and clusters, has yet to be established experimentally. A new alternative to the big bang model is offered based on recent work on cosmic grains. (UK)
What if the big bang didn't happen
Energy Technology Data Exchange (ETDEWEB)
Narlikar, J. (Inter-University Centre for Astronomy and Astrophysics, Pune (India))
1991-03-02
Although it has wide support amongst cosmologists, the big bang theory of the origin of the Universe is brought into question in this article because of several recent observations. The large red shift observed in quasars does not fit with Hubble's Law which is so successful for galaxies. Some quasars appear to be linked to companion galaxies by filaments and, again, anomalous red shifts have been observed. The cosmic microwave background, or relic radiation, seems to be too uniform to fit with the big bang model. Lastly, the dark matter, necessary to explain the coalescing of galaxies and clusters, has yet to be established experimentally. A new alternative to the big bang model is offered based on recent work on cosmic grains. (UK).
Influence of Parallel Dark Matter Sectors on Big Bang Nucleosynthesis
Challa, Venkata Sai Sreeharsha
Big Bang Nucleosynthesis (BBN) is a phenomenological theory that describes the synthesis of light nuclei after a few seconds of the cosmic time in the primordial universe. The twelve nuclear reactions in the first few seconds of the cosmic history are constrained by factors such as baryon to photon ratio, number of neutrino families, and present day element abundances. The belief that the expansion of the universe must be slowed down by gravity, was defeated by the recent observation of an accelerated expansion of the universe. Friedmann equations, which describe the cosmic dynamics, need to be revised considering also the existence of dark matter, another recent astronomical observation. The effects of multiple parallel universes of dark matter (dark sectors) on the accelerated expansion of the universe are studied. Collectively, these additional effects will lead to a new cosmological model. We had developed a numerical code on BBN to address the effects of such dark sectors on the abundances of all the light elements. We have studied the effect of degrees of freedom of dark-matter in the early universe on primordial abundances of light elements. The predicted abundances of light elements are compared with observed constraints to obtain bounds on the number of dark sectors, NDM. Comparison of the obtained results with the observations during the BBN epoch shows that the number of dark matter sectors are only loosely constrained, and the dark matter sectors are colder than the ordinary matter sectors. Also, we verified that the existence of parallel dark matter sectors with colder temperatures does not affect the constraints set by observations on the number of neutrino families, Nnu .
Energy Technology Data Exchange (ETDEWEB)
Marochnik, L.S.
1981-01-01
The equations for the correlation functions (derived from the Einstein equations) that describe a statistically chaotic universe are solved in this paper as well as in Paper II. From these solutions the corresponding changes in the standard big bang scenario are determined, and the degree of disorder (that is, constaints on the fluctuation spectrum) which an initially wholly chaotic universe could have retained by the epoch t/sub es/ of light-element nucleosynthesis is established. The time boundaries of the hadron and lepton eras as well as the epochs when electron neutrinos and neutrons become frozen out in weak interactions shift by a factor of up to 1.4 compared with the standard model; the corresponding temperature will drop to 0.88 times the standard value if the rms level of fluctuations averaged over the spectrum during these eras is of order unity. If the fluctuations concentrated in the short-wavelength part of the spectrum have an energy density epsilon<1.5epsilon-bar, then nucleosynthesis in the chaotic cosmology would yield a helium abundance consistent with that observed. If at epoch t/sub es/ the spectral energy density peaks in the long-wave region (lambda/sub max/>>ct/sub es/), the degree of disorder during the nucleosynthesis era would be limited to ..nu..< or =1.76 (here ..nu..approx...integral..Vertical Barc/sub k/Vertical Bar/sup 2/d/sup 3/k; c/sub k/ represents the Fourier amplitude of the metric fluctuations). In particular, Ozernoi's protogalactic vortex perturbations with a wide spectrum (..delta.. = ..delta..k/k> or approx. =4 x 10/sup 3/..cap omega../sup -1/, ..cap omega.. = rho/rho/sub crit/) are compatible with the observed He abundance.
The exact parity symmetric model and big bang nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Foot, R.; Volkas, R.R.
1996-12-01
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{sup -10} eV{sup 2} {<=} |{delta}m{sup 2}| {<=} 10{sup -3} eV{sup 2} 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 |{delta}m{sup 2}| {approx} 10{sup -2} eV{sup 2} 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).
The exact parity symmetric model and big bang nucleosynthesis
International Nuclear Information System (INIS)
Foot, R.; Volkas, R.R.
1996-12-01
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 eV 2 ≤ |δm 2 | ≤ 10 -3 eV 2 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 |δm 2 | ∼ 10 -2 eV 2 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)
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.
A cosmogonical analogy between the Big Bang and a supernova
International Nuclear Information System (INIS)
Brown, W.K.
1981-01-01
The Big Bang may be discussed most easily in analogy with an expanding spherical shell. An expanding spherical shell, in turn, is quite similar to an ejected supernova shell. In both the Big Bang and the supernova, fragmentation is postulated to occur, where each fragment of the universe becomes a galaxy, and each fragment of supernova shell becomes a solar system. By supporting the presence of shearing flow at the time of fragmentation, a model has been constructed to examine the results in both cases. It has been shown that the model produces a good description of reality on both the galactic and solar system scales. (Auth.)
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
Big Bang-Like Phenomenon in Multidimensional Data
Jiřina, M. (Marcel)
2014-01-01
Notion of the Big Bang in Data was introduced, when it was observed that the quantity of data grows very fast and the speed of this growth rises with time. This is parallel to the Big Bang of the Universe which expands and the speed of the expansion is the larger the farther the object is, and the expansion is isotropic. We observed another expansion in data embedded in metric space. We found that when distances in data space are polynomially expanded with a proper exponent, the space around ...
Perfect fluid of p-branes, 2D dilaton gravity and the big-bang
Energy Technology Data Exchange (ETDEWEB)
Borlaf, J. E-mail: jborlaf@redestb.es
2001-01-15
This paper starts by building the energy-momentum tensor of a perfect fluid of p-branes coupled to (p+4)-dimensional general relativity. Having three homogeneous and isotropic macroscopical spatial dimensions, the system gravity/fluid can be reduced to an effective theory over the branes. For the string fluid (p=1) the effective theory is nothing but the 2D dilaton gravity where the potential for the scalar field, which is the scale factor of the macroscopical space, is fixed by the state equation and the three-dimensional geometry. This theory can be solved allowing us to compare some relevant aspects in our homogeneous and isotropic string cosmologies with those of the Robertson-Walker ones. In particular, unlike the point-particle models, the existence of an initial singularity is strongly sensitive to the state equation, and it is remarkable that this model picks out the radiation state equation as the canonical case where the big-bang is kinematically forbidden. Moreover, we cannot reduce the Robertson-Walker cosmologies to the limit when the string size approaches to zero, because the existence of an upper bound on the string size is not compatible with the big-bang. Some examples are presented.
Perfect fluid of p-branes, 2D dilaton gravity and the big-bang
International Nuclear Information System (INIS)
Borlaf, J.
2001-01-01
This paper starts by building the energy-momentum tensor of a perfect fluid of p-branes coupled to (p+4)-dimensional general relativity. Having three homogeneous and isotropic macroscopical spatial dimensions, the system gravity/fluid can be reduced to an effective theory over the branes. For the string fluid (p=1) the effective theory is nothing but the 2D dilaton gravity where the potential for the scalar field, which is the scale factor of the macroscopical space, is fixed by the state equation and the three-dimensional geometry. This theory can be solved allowing us to compare some relevant aspects in our homogeneous and isotropic string cosmologies with those of the Robertson-Walker ones. In particular, unlike the point-particle models, the existence of an initial singularity is strongly sensitive to the state equation, and it is remarkable that this model picks out the radiation state equation as the canonical case where the big-bang is kinematically forbidden. Moreover, we cannot reduce the Robertson-Walker cosmologies to the limit when the string size approaches to zero, because the existence of an upper bound on the string size is not compatible with the big-bang. Some examples are presented
Repulsive and attractive timelike singularities in vacuum cosmologies
International Nuclear Information System (INIS)
Miller, B.D.
1979-01-01
Spherically symmetric cosmologies whose big bang is partially spacelike and partially timelike are constrained to occur only in the presence of certain types of matter, and in such cosmologies the timelike part of the big bang is a negative-mass singularity. In this paper examples are given of cylindrically symmetric cosmologies whose big bang is partially spacelike and partially timelike. These cosmologies are vacuum. In some of them, the timelike part of the big bang is clearly a (generalized) negative-mass singularity, while in others it is a (generalized) positive-mass singularity
On the cosmological gravitational waves and cosmological distances
Belinski, V. A.; Vereshchagin, G. V.
2018-03-01
We show that solitonic cosmological gravitational waves propagated through the Friedmann universe and generated by the inhomogeneities of the gravitational field near the Big Bang can be responsible for increase of cosmological distances.
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."
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)
EMR implementation: big bang or a phased approach?
Owens, Kathleen
2008-01-01
There are two major strategies to implementing an EMR: the big-bang approach and the phased, or incremental, approach. Each strategy has pros and cons that must be considered. This article discusses these approaches and the risks and benefits of each as well as some training strategies that can be used with either approach.
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…
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)
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
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…
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...
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. ...
"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)
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…
Big bang in a universe with infinite extension
Energy Technology Data Exchange (ETDEWEB)
Groen, Oeyvind [Oslo College, Department of Engineering, PO Box 4, St Olavs Pl, 0130 Oslo (Norway); Institute of Physics, University of Oslo, PO Box 1048 Blindern, 0316 Oslo (Norway)
2006-05-01
How can a universe coming from a point-like big bang event have infinite spatial extension? It is shown that the relativity of simultaneity is essential in answering this question. Space is finite as defined by the simultaneity of one observer, but it may be infinite as defined by the simultaneity of all the clocks participating in the Hubble flow.
Big bang in a universe with infinite extension
International Nuclear Information System (INIS)
Groen, Oeyvind
2006-01-01
How can a universe coming from a point-like big bang event have infinite spatial extension? It is shown that the relativity of simultaneity is essential in answering this question. Space is finite as defined by the simultaneity of one observer, but it may be infinite as defined by the simultaneity of all the clocks participating in the Hubble flow
Relic abundance of WIMPs in non-standard cosmological scenarios
Energy Technology Data Exchange (ETDEWEB)
Yimingniyazi, W.
2007-08-06
In this thesis we study the relic density n{sub {chi}} of non--relativistic long--lived or stable particles {chi} in various non--standard cosmological scenarios. First, we discuss the relic density in the non--standard cosmological scenario in which the temperature is too low for the particles {chi} to achieve full chemical equilibrium. We also investigated the case where {chi} particles are non--thermally produced from the decay of heavier particles in addition to the usual thermal production. In low temperature scenario, we calculate the relic abundance starting from arbitrary initial temperatures T{sub 0} of the radiation--dominated epoch and derive approximate solutions for the temperature dependence of the relic density which can accurately reproduces numerical results when full thermal equilibrium is not achieved. If full equilibrium is reached, our ansatz no longer reproduces the correct temperature dependence of the {chi} number density. However, we can contrive a semi-analytic formula which gives the correct final relic density, to an accuracy of about 3% or better, for all cross sections and initial temperatures. We also derive the lower bound on the initial temperature T{sub 0}, assuming that the relic particle accounts for the dark matter energy density in the universe. The observed cold dark matter abundance constrains the initial temperature T{sub 0} {>=}m{sub {chi}}/23, where m{sub {chi}} is the mass of {chi}. Second, we discuss the {chi} density in the scenario where the the Hubble parameter is modified. Even in this case, an approximate formula similar to the standard one is found to be capable of predicting the final relic abundance correctly. Choosing the {chi} annihilation cross section such that the observed cold dark matter abundance is reproduced in standard cosmology, we constrain possible modifications of the expansion rate at T {proportional_to}m{sub {chi}}/20, well before Big Bang Nucleosynthesis. (orig.)
Big bang nucleosynthesis with a stiff fluid
International Nuclear Information System (INIS)
Dutta, Sourish; Scherrer, Robert J.
2010-01-01
Models that lead to a cosmological stiff fluid component, with a density ρ S that scales as a -6 , where a is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking ρ S10 and ρ R10 to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at T=10 MeV, we find that the change in the primordial helium abundance is well-fit by ΔY p =0.00024(ρ S10 /ρ R10 ). The changes in the helium-4 abundance produced by additional radiation or by a stiff fluid are identical when these two components have equal density at a 'pivot temperature', T * , where we find T * =0.55 MeV. Current estimates of the primordial 4 He abundance give the constraint on a stiff fluid energy density of ρ S10 /ρ R10 <30.
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.
A big bang in a little room the quest to create new universes
Merali, Zeeya
2017-01-01
What if you could become God, with the ability to build a whole new universe? As startling as it sounds, modern physics suggests that within the next two decades, scientists may be able to perform this seemingly divine feat-to concoct an entirely new baby universe, complete with its own physical laws, star systems, galaxies, and even intelligent life. A Big Bang in a Little Room takes the reader on a journey through the history of cosmology and unravels-particle by particle, theory by theory, and experiment by experiment-the ideas behind this provocative claim made by some of the most respected physicists alive today. Beyond simply explaining the science, A Big Bang in a Little Room also tells the story of the people who have been laboring for more than thirty years to make this seemingly impossible dream a reality. What has driven them to continue on what would seem, at first glance, to be a quixotic quest? This mind-boggling book reveals that we can nurse other worlds in the tiny confines of a lab, raising...
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...
Quantum Gravity and Cosmology: an intimate interplay
Sakellariadou, Mairi
2017-08-01
I will briefly discuss three cosmological models built upon three distinct quantum gravity proposals. I will first highlight the cosmological rôle of a vector field in the framework of a string/brane cosmological model. I will then present the resolution of the big bang singularity and the occurrence of an early era of accelerated expansion of a geometric origin, in the framework of group field theory condensate cosmology. I will then summarise results from an extended gravitational model based on non-commutative spectral geometry, a model that offers a purely geometric explanation for the standard model of particle physics.
International Nuclear Information System (INIS)
Cattoen, Celine; Visser, Matt
2005-01-01
Until recently, the physically relevant singularities occurring in FRW cosmologies had traditionally been thought to be limited to the 'big bang', and possibly a 'big crunch'. However, over the last few years, the zoo of cosmological singularities considered in the literature has become considerably more extensive, with 'big rips' and 'sudden singularities' added to the mix, as well as renewed interest in nonsingular cosmological events such as 'bounces' and 'turnarounds'. In this paper we present an extensive catalogue of such cosmological milestones, both at the kinematical and dynamical level. First, using generalized power series, purely kinematical definitions of these cosmological events are provided in terms of the behaviour of the scale factor a(t). The notion of a 'scale-factor singularity' is defined, and its relation to curvature singularities (polynomial and differential) is explored. Second, dynamical information is extracted by using the Friedmann equations (without assuming even the existence of any equation of state) to place constraints on whether or not the classical energy conditions are satisfied at the cosmological milestones. We use these considerations to derive necessary and sufficient conditions for the existence of cosmological milestones such as bangs, bounces, crunches, rips, sudden singularities and extremality events. Since the classification is extremely general and, modulo certain technical assumptions, is complete, the corresponding results are to a high degree model independent: in particular, we provide a characterization of the class of bangs, crunches and sudden singularities for which the dominant energy condition is satisfied
Hadronic decay of late-decaying particles and big-bang nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Kawasaki, Masahiro [Research Center for the Early Universe, Graduate School of Science, University of Tokyo, Tokyo 113-0033 (Japan)]. E-mail: masahiro_kawasaki@mac.com; Kohri, Kazunori [Department of Earth and Space Science, Osaka University, Osaka 560-0043 (Japan); Moroi, Takeo [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)
2005-10-06
We study the big-bang nucleosynthesis (BBN) scenario with late-decaying exotic particles with lifetime longer than {approx}1 s. With a late-decaying particle in the early universe, predictions of the standard BBN scenario can be significantly altered. Therefore, we derive constraints on its primordial abundance. We pay particular attention to hadronic decay modes of such particles. We see that the non-thermal production process of D, {sup 3}He and {sup 6}Li provides a stringent upper bound on the primordial abundance of late-decaying particles with hadronic branching ratio.
Directory of Open Access Journals (Sweden)
Jakub Mielczarek
2017-01-01
Full Text Available This article addresses the issue of possible gravitational phase transitions in the early universe. We suggest that a second-order phase transition observed in the Causal Dynamical Triangulations approach to quantum gravity may have a cosmological relevance. The phase transition interpolates between a nongeometric crumpled phase of gravity and an extended phase with classical properties. Transition of this kind has been postulated earlier in the context of geometrogenesis in the Quantum Graphity approach to quantum gravity. We show that critical behavior may also be associated with a signature change in Loop Quantum Cosmology, which occurs as a result of quantum deformation of the hypersurface deformation algebra. In the considered cases, classical space-time originates at the critical point associated with a second-order phase transition. Relation between the gravitational phase transitions and the corresponding change of symmetry is underlined.
Critical geometry of a thermal big bang
Afshordi, Niayesh; Magueijo, João
2016-11-01
We explore the space of scalar-tensor theories containing two nonconformal metrics, and find a discontinuity pointing to a "critical" cosmological solution. Due to the different maximal speeds of propagation for matter and gravity, the cosmological fluctuations start off inside the horizon even without inflation, and will more naturally have a thermal origin (since there is never vacuum domination). The critical model makes an unambiguous, nontuned prediction for the spectral index of the scalar fluctuations: nS=0.96478 (64 ) . Considering also that no gravitational waves are produced, we have unveiled the most predictive model on offer. The model has a simple geometrical interpretation as a probe 3-brane embedded in an E AdS2×E3 geometry.
Primordial alchemy: a test of the standard model
International Nuclear Information System (INIS)
Steigman, G.
1987-01-01
Big Bang Nucleosynthesis provides the only probe of the early evolution of the Universe constrained by observational data. The standard, hot, big bang model predicts the synthesis of the light elements (D, 3 He, 4 He, 7 Li) in astrophysically interesting abundances during the first few minutes in the evolution of the Universe. A quantitative comparison of the predicted abundances with those observed astronomically confirms the consistency of the standard model and yields valuable constraints on the parameters of cosmology and elementary particle physics. The current status of the comparison between theory and observation will be reviewed and the opportunities for future advances outlined
Primordial lithium and the standard model(s)
International Nuclear Information System (INIS)
Deliyannis, C.P.; Demarque, P.; Kawaler, S.D.; Krauss, L.M.; Romanelli, P.
1989-01-01
We present the results of new theoretical work on surface 7 Li and 6 Li evolution in the oldest halo stars along with a new and refined analysis of the predicted primordial lithium abundance resulting from big-bang nucleosynthesis. This allows us to determine the constraints which can be imposed upon cosmology by a consideration of primordial lithium using both standard big-bang and standard stellar-evolution models. Such considerations lead to a constraint on the baryon density today of 0.0044 2 <0.025 (where the Hubble constant is 100h Km sec/sup -1/ Mpc /sup -1/), and impose limitations on alternative nucleosynthesis scenarios
Dirac fields in loop quantum gravity and big bang nucleosynthesis
International Nuclear Information System (INIS)
Bojowald, Martin; Das, Rupam; Scherrer, Robert J.
2008-01-01
Big bang nucleosynthesis requires a fine balance between equations of state for photons and relativistic fermions. Several corrections to equation of state parameters arise from classical and quantum physics, which are derived here from a canonical perspective. In particular, loop quantum gravity allows one to compute quantum gravity corrections for Maxwell and Dirac fields. Although the classical actions are very different, quantum corrections to the equation of state are remarkably similar. To lowest order, these corrections take the form of an overall expansion-dependent multiplicative factor in the total density. We use these results, along with the predictions of big bang nucleosynthesis, to place bounds on these corrections and especially the patch size of discrete quantum gravity states.
Introduction to Big Bang nucleosynthesis: open and closed models, anisotropies
International Nuclear Information System (INIS)
Taylor, R.J.
1982-01-01
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)
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.
Electron screening and its effects on big-bang nucleosynthesis
International Nuclear Information System (INIS)
Wang Biao; Bertulani, C. A.; Balantekin, A. B.
2011-01-01
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 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
Era of superheavy-particle dominance and big bang nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Polnarev, A.G.; Khlopov, M.Y.
1982-01-01
The observed primordial He/sup 4/ abundance imposes astrophysical constraints on the possible departures from radiation dominance in the big bang universe during the neutron hardening era (at epoch t roughly-equal1 sec). Limits are obtained which, along with the data on the spectrum of the cosmic background radiation, practically rule out any stages of superheavy stable-particle dominance in the era 1< or approx. =t<10/sup 10/ sec, thereby setting restrictions on current elementary-particle theories.
International Nuclear Information System (INIS)
Schramm, D.N.
1989-12-01
Nuclear physics has provided one of the 2 critical observational tests of all Big Bang cosmology, namely Big Bang Nucleosynthesis. Furthermore, this same nuclear physics input enables a prediction to be made about one of the most fundamental physics questions of all, the number of elementary particle families. This paper reviews the standard Big Bang Nucleosynthesis arguments. The primordial He abundance is inferred from He--C and He--N and He--O correlations. The strengthened Li constraint as well as 2 D plus 3 He are used to limit the baryon density. This limit is the key argument behind the need for non-baryonic dark matter. The allowed number of neutrino families, N ν , is delineated using the new neutron lifetime value of τ n = 890 ± 4s (τ 1/2 = 10.3 min). The formal statistical result is N ν = 2.6 ± 0.3 (1σ) providing a reasonable fit (1.3σ) to 3 families but making a fourth light (m ν approx-lt 10 MeV) neutrino family exceedingly unlikely (approx-gt 4.7σ) (barring significant systematic errors either in D + 3 He, and Li and/or 4 He and/or τ n ). It is also shown that uncertainties induced by postulating a first-order quark-hadron phase transition do not seriously affect the conclusions. 21 refs., 3 figs
The Big Bang, Genesis, and Knocking on Heaven's Door
Gentry, Robert
2012-03-01
Michael Shermer recently upped the ante in the big bang-Genesis controversy by citing Lisa Randall's provocative claim (Science 334, 762 (2011)) that ``it is inconceivable that God could continue to intervene without introducing a material trace of his actions.'' So does Randall's and Shermer's agreement that no such evidence exists disprove God's existence? Not in my view because my 1970s Science, Nature and ARNS publications, and my article in the 1982 AAAS Western Division's Symposium Proceedings, Evolution Confronts Creation, all contain validation of God's existence via discovery of His Fingerprints of Creation and falsification of the big bang and geological evolution. These results came to wide public/scientific attention in my testimony at the 1981 Arkansas creation/evolution trial. There ACLU witness G Brent Dalrymple from the USGS -- and 2005 Medal of Science recipient from President Bush -- admitted I had discovered a tiny mystery (primordial polonium radiohalos) in granite rocks that indicated their almost instant creation. As a follow-up in 1992 and 1995 he sent out SOS letters to the entire AGU membership that the polonium halo evidence for fiat creation still existed and that someone needed to urgently find a naturalistic explanation for them. Is the physics community guilty of a Watergate-type cover-up of this discovery of God's existence and falsification of the big bang? For the answer see www.halos.tv.
Testing the Friedmann equation: The expansion of the universe during big-bang nucleosynthesis
International Nuclear Information System (INIS)
Carroll, Sean M.; Kaplinghat, Manoj
2002-01-01
In conventional general relativity, the expansion rate H of a Robertson-Walker universe is related to the energy density by the Friedmann equation. Aside from the present day, the only epoch at which we can constrain the expansion history in a model-independent way is during big-bang nucleosynthesis (BBN). We consider a simple two-parameter characterization of the behavior of H during BBN and derive constraints on this parameter space, finding that the allowed region of parameter space is essentially one dimensional. We also study the effects of a large neutrino asymmetry within this framework. Our results provide a simple way to compare an alternative cosmology to the observational requirement of matching the primordial abundances of the light elements
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.
Further holographic investigations of big bang singularities
Energy Technology Data Exchange (ETDEWEB)
Engelhardt, Netta [Department of Physics, UCSB,Santa Barbara, CA 93106 (United States); Hertog, Thomas [Institute for Theoretical Physics, KU Leuven,3001 Leuven (Belgium); Horowitz, Gary T. [Department of Physics, UCSB,Santa Barbara, CA 93106 (United States)
2015-07-09
We further explore the quantum dynamics near past cosmological singularities in anisotropic Kasner-AdS solutions using gauge/gravity duality. The dual description of the bulk evolution involves N=4 super Yang-Mills on the contracting branch of an anisotropic de Sitter space and is well defined. We compute two-point correlators of Yang-Mills operators of large dimensions using spacelike geodesics anchored on the boundary. The correlator between two points separated in a direction with negative Kasner exponent p always exhibits a pole at horizon scales, in any dimension, which we interpret as a dual signature of the classical bulk singularity. This indicates that the geodesic approximation selects a non-normalizable Yang-Mills state.
Further holographic investigations of big bang singularities
Engelhardt, Netta; Hertog, Thomas; Horowitz, Gary T.
2015-07-01
We further explore the quantum dynamics near past cosmological singularities in anisotropic Kasner-AdS solutions using gauge/gravity duality. The dual description of the bulk evolution involves super Yang-Mills on the contracting branch of an anisotropic de Sitter space and is well defined. We compute two-point correlators of Yang-Mills operators of large dimensions using spacelike geodesics anchored on the boundary. The correlator between two points separated in a direction with negative Kasner exponent p always exhibits a pole at horizon scales, in any dimension, which we interpret as a dual signature of the classical bulk singularity. This indicates that the geodesic approximation selects a non-normalizable Yang-Mills state.
International Nuclear Information System (INIS)
Jittoh, Toshifumi; Koike, Masafumi; Sato, Joe; Yamanaka, Masato; Kohri, Kazunori; Shimomura, Takashi
2008-01-01
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 7 Li 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 7 Li by these values of parameters. The lifetime of staus in this scenario is predicted to be O(100-1000) sec.
International Nuclear Information System (INIS)
Lee, David M
2010-01-01
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.
Classical and quantum cosmology
Calcagni, Gianluca
2017-01-01
This comprehensive textbook is devoted to classical and quantum cosmology, with particular emphasis on modern approaches to quantum gravity and string theory and on their observational imprint. It covers major challenges in theoretical physics such as the big bang and the cosmological constant problem. An extensive review of standard cosmology, the cosmic microwave background, inflation and dark energy sets the scene for the phenomenological application of all the main quantum-gravity and string-theory models of cosmology. Born of the author's teaching experience and commitment to bridging the gap between cosmologists and theoreticians working beyond the established laws of particle physics and general relativity, this is a unique text where quantum-gravity approaches and string theory are treated on an equal footing. As well as introducing cosmology to undergraduate and graduate students with its pedagogical presentation and the help of 45 solved exercises, this book, which includes an ambitious bibliography...
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
Big Bang et au-delà les nouveaux horizons de l'Univers
Barrau, Aurélien
2015-01-01
Notre Univers a-t-il un début ? Est-il unique ? La science moderne a révolutionné notre compréhension de l’Univers. Bien que l’étude du cosmos soit sans doute aussi ancienne que la pensée, notre image du réel est en ce moment même en train de se redessiner. Il est maintenant possible de connaître certains aspects des processus qui eurent lieu moins d’un milliardième de milliardième de milliardième de seconde après le Big Bang. À la lumière des dernières découvertes du satellite Planck, Aurélien Barrau décrit en termes simples le cosmos qui se dessine sous nos yeux. Trous noirs, modèle standard de la physique des particules, gravité… les piliers et les énigmes du Big Bang sont abordés les uns après les autres, à la manière d’une balade aux origines de l’Univers. « Parce que la science est avant tout une aventure humaine, j’ai esquissé, ici et là, en contrepoint des explications physiques fournies dans la langue la plus simple et la plus accessible possible, mon expér...
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
Astrophysical cosmology - a conventional view, its successes and problems
International Nuclear Information System (INIS)
Longair, M.S.
1988-01-01
It is my task to survey the successes and problems of what has become the standard model of our Universe - the canonical Hot Big Bang. This is the framework within which essentially all astrophysical cosmological studies are undertaken. There has been an enormous explosion of activity over the last few years, both as a result of new observations and because of new theoretical insights. Some of the experiments, results and explanations of the research are reviewed. (author)
Quark mass variation constraints from Big Bang nucleosynthesis
International Nuclear Information System (INIS)
Bedaque, Paulo F.; Luu, Thomas; Platter, Lucas
2011-01-01
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 4 He abundances put a bound of -1% q /m q q /m q .
Constraining axion dark matter with Big Bang Nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Blum, Kfir; D' Agnolo, Raffaele Tito [Institute for Advanced Study, Princeton, NJ 08540 (United States); Lisanti, Mariangela; Safdi, Benjamin R. [Department of Physics, Princeton University, Princeton, NJ 08544 (United States)
2014-10-07
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 {sup 4}He 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.
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.
Constraining axion dark matter with Big Bang Nucleosynthesis
International Nuclear Information System (INIS)
Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.
2014-01-01
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 4 He 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
Constraining axion dark matter with Big Bang Nucleosynthesis
Blum, Kfir; D'Agnolo, Raffaele Tito; Lisanti, Mariangela; Safdi, Benjamin R.
2014-10-01
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.
Making a Big Bang on the small screen
Thomas, Nick
2010-01-01
While the quality of some TV sitcoms can leave viewers feeling cheated out of 30 minutes of their lives, audiences and critics are raving about the science-themed US comedy The Big Bang Theory. First shown on the CBS network in 2007, the series focuses on two brilliant postdoc physicists, Leonard and Sheldon, who are totally absorbed by science. Adhering to the stereotype, they also share a fanatical interest in science fiction, video-gaming and comic books, but unfortunately lack the social skills required to connect with their 20-something nonacademic contemporaries.
García-Bellido, J
2000-01-01
These notes are intended as an introductory course for experimental particle physicists interested in the recent developments in astrophysics and cosmology. I will describe the standard Big Bang theory of the evolution of the universe, with its successes and shortcomings, which will lead to inflationary cosmology as the paradigm for the origin of the global structure of the universe as well as the origin of the spectrum of density perturbations responsible for structure in our local patch. I will present a review of the very rich phenomenology that we have in cosmology today, as well as evidence for the observational revolution that this field is going through, which will provide us, in the next few years, with an accurate determination of the parameters of our standard cosmological model.
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)
Re-evaluation of the immunological Big Bang.
Flajnik, Martin F
2014-11-03
Classically the immunological 'Big Bang' of adaptive immunity was believed to have resulted from the insertion of a transposon into an immunoglobulin superfamily gene member, initiating antigen receptor gene rearrangement via the RAG recombinase in an ancestor of jawed vertebrates. However, the discovery of a second, convergent adaptive immune system in jawless fish, focused on the so-called variable lymphocyte receptors (VLRs), was arguably the most exciting finding of the past decade in immunology and has drastically changed the view of immune origins. The recent report of a new lymphocyte lineage in lampreys, defined by the antigen receptor VLRC, suggests that there were three lymphocyte lineages in the common ancestor of jawless and jawed vertebrates that co-opted different antigen receptor supertypes. The transcriptional control of these lineages during development is predicted to be remarkably similar in both the jawless (agnathan) and jawed (gnathostome) vertebrates, suggesting that an early 'division of labor' among lymphocytes was a driving force in the emergence of adaptive immunity. The recent cartilaginous fish genome project suggests that most effector cytokines and chemokines were also present in these fish, and further studies of the lamprey and hagfish genomes will determine just how explosive the Big Bang actually was. Copyright © 2014 Elsevier Ltd. All rights reserved.
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 ...
Modeling of virtual particles of the Big Bang
Corral-Bustamante, L. R.; Rodriguez-Corral, A. R.; Amador-Parra, T.; Martinez-Loera, E.; Irigoyen-Chavez, G.
2012-01-01
In this work, a mathematical model in four dimensions proposed to predict the behavior of the transport phenomena of mass (energy) in the space-time continuum through a metric tensor in the Planck scale is presented. The Ricci tensor was determined with the aim of measuring the turbulent flow of a mass with a large gravitational field similar to that which is believed to have existed in the Big Bang. Computing the curvature of space-time through tensor analysis, we predict a vacuum solution of the Einstein field equations through numerical integration with approximate solutions. A quantum vacuum is filled with virtual particles of enormous superficial gravity of black holes and wormholes as predicted by other authors. By generating the geodesic equations, we obtain the relativistic equation, which is the carrier of information pertaining to the behavior of the entropy of matter. The results of the measurements of the evolution of the mass during its collapse and evaporation allow us to argue the evidence of virtual particles including all the values (and beyond) of the experimental search by other authors for gauges and Higgs bosons. We conclude that the matter behaves as virtual particles, which appear and disappear in Planck time at speeds greater than that of light, representing those that probably existed during the Big Bang.
On the Geocentric Nature of the Big Bang Theory
Wang, Ling Jun
2008-04-01
An expanding universe with all heavenly bodies moving isotropically away from the earth seems to suggest a geocentric theory which is evidently false. To defend the Big Bang Theory (BBT) from falling into a geocentric theory, it is argued that if the universe is expanding linearly from the singularity, the heavenly bodies would appear to be leaving away from each other with isotropic velocity distribution with respect to any observer. In this presentation we will prove rigorously with both classical and relativistic analysis that even strict linearity of Hubble's law would not save the Big Bang from falling into a geocentric theory. The key of the analysis rests on the two crucial necessary conditions for the raisin-pudding model: 1) The velocities and the positions of the earth and the galaxies must be measured simultaneously; 2) The velocity transformation between the reference frame of the earth and that of the singularity must be linear. The first condition can not be satisfied due to the speed limit of light; and the second condition can not be satisfied due to non linear velocity transformation of relativity. The whole problem is originated from the Doppler shift explanation of the red shift. Wang's Dispersive Extinction Theory (DET), however, interprets the red shift as being caused by the dispersive extinction of the star light by the space medium, and therefore does not lead to a geocentric universe. This lends a strong support to DET over BBT.
Cosmic inflation and big bang interpreted as explosions
Rebhan, E.
2012-12-01
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 explosionlike 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 extension expand and thus constitute an exemption from the rule that small objects up to the size of the solar system or even galaxies do not participate in the expansion of the universe. It is also discussed how the two interpretations can be reconciled with each other.
The Biological Big Bang model for the major transitions in evolution
Directory of Open Access Journals (Sweden)
Koonin Eugene V
2007-08-01
of evolution incorporates the previously developed concepts of the emergence of protein folds by recombination of small structural units and origin of viruses and cells from a pre-cellular compartmentalized pool of recombining genetic elements. The model is extended to encompass other major transitions. It is proposed that bacterial and archaeal phyla emerged independently from two distinct populations of primordial cells that, originally, possessed leaky membranes, which made the cells prone to rampant gene exchange; and that the eukaryotic supergroups emerged through distinct, secondary endosymbiotic events (as opposed to the primary, mitochondrial endosymbiosis. This biphasic model of evolution is substantially analogous to the scenario of the origin of universes in the eternal inflation version of modern cosmology. Under this model, universes like ours emerge in the infinite multiverse when the eternal process of exponential expansion, known as inflation, ceases in a particular region as a result of false vacuum decay, a first order phase transition process. The result is the nucleation of a new universe, which is traditionally denoted Big Bang, although this scenario is radically different from the Big Bang of the traditional model of an expanding universe. Hence I denote the phase transitions at the end of each inflationary epoch in the history of life Biological Big Bangs (BBB. Conclusion A Biological Big Bang (BBB model is proposed for the major transitions in life's evolution. According to this model, each transition is a BBB such that new classes of biological entities emerge at the end of a rapid phase of evolution (inflation that is characterized by extensive exchange of genetic information which takes distinct forms for different BBBs. The major types of new forms emerge independently, via a sampling process, from the pool of recombining entities of the preceding generation. This process is envisaged as being qualitatively different from tree
The Biological Big Bang model for the major transitions in evolution.
Koonin, Eugene V
2007-08-20
concepts of the emergence of protein folds by recombination of small structural units and origin of viruses and cells from a pre-cellular compartmentalized pool of recombining genetic elements. The model is extended to encompass other major transitions. It is proposed that bacterial and archaeal phyla emerged independently from two distinct populations of primordial cells that, originally, possessed leaky membranes, which made the cells prone to rampant gene exchange; and that the eukaryotic supergroups emerged through distinct, secondary endosymbiotic events (as opposed to the primary, mitochondrial endosymbiosis). This biphasic model of evolution is substantially analogous to the scenario of the origin of universes in the eternal inflation version of modern cosmology. Under this model, universes like ours emerge in the infinite multiverse when the eternal process of exponential expansion, known as inflation, ceases in a particular region as a result of false vacuum decay, a first order phase transition process. The result is the nucleation of a new universe, which is traditionally denoted Big Bang, although this scenario is radically different from the Big Bang of the traditional model of an expanding universe. Hence I denote the phase transitions at the end of each inflationary epoch in the history of life Biological Big Bangs (BBB). A Biological Big Bang (BBB) model is proposed for the major transitions in life's evolution. According to this model, each transition is a BBB such that new classes of biological entities emerge at the end of a rapid phase of evolution (inflation) that is characterized by extensive exchange of genetic information which takes distinct forms for different BBBs. The major types of new forms emerge independently, via a sampling process, from the pool of recombining entities of the preceding generation. This process is envisaged as being qualitatively different from tree-pattern cladogenesis.
Greyber, Howard D.
2010-01-01
My Strong Magnetic Field model (SMF) for the Origin of Magnetic Fields at Combination Time analyzes this first-order transition in the Big Bang Model, (Astro-ph0509223), an age of about 400,000 years. SMF exploits facts about the rapid Spinodal Decomposition instability and other facts from plasma physics, that determine the morphology and dynamics of our universe. This leads to a unique Supercluster topology with all the mass, visible and invisible, on the shell of an ellipsoid surrounding an extremely high vacuum void. SMF assumes, in accord with Einstein's theory of general relativity's Lambda term (1918), that there exists a finite "cosmological" constant of energy (ees), representing the negative pressure/repulsive gravitational force associated with every unit volume of empty space. However, over billions of years, the force of attractive gravity from all the matter, visible and invisible, on the Supercluster shell, dramatically reduced the density of particles in the Supercluster's central high vacuum region. Thus, eventually, the ees repulsive gravity force overcame any attractive gravity in the Supercluster's huge central region and an accelerating expansion of the Supercluster began. The region where the ees repulsive gravity force dominates is perhaps what the WMAP satellite authors have termed "Dark Energy". Our Big Bang universe probably has similar Superclusters with voids everywhere in the universe, as astronomers have suggested, thus producing the observed quite smooth transition to an accelerating expansion of our entire Big Bang universe. This matches what two independent, international groups of astronomers both separately observed and concluded in 1998.
The great adventure of the LHC - From big bang to the Higgs boson
International Nuclear Information System (INIS)
Denegri, D.; Guyot, C.; Hoecker, A.; ); Roos, L.; Rubbia, C.
2014-03-01
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
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.
D-branes in a big bang/big crunch universe: Nappi-Witten gauged WZW model
Energy Technology Data Exchange (ETDEWEB)
Hikida, Yasuaki [School of Physics and BK-21 Physics Division, Seoul National University, Seoul 151-747 (Korea, Republic of); Nayak, Rashmi R. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' ' , Rome 00133 (Italy); Panigrahi, Kamal L. [Dipartimento di Fisica and INFN, Sezione di Roma 2, ' Tor Vergata' , Rome 00133 (Italy)
2005-05-01
We study D-branes in the Nappi-Witten model, which is a gauged WZW model based on (SL(2,R) x SU(2))/(U(1) x U(1)). The model describes a four dimensional space-time consisting of cosmological regions with big bang/big crunch singularities and static regions with closed time-like curves. The aim of this paper is to investigate by D-brane probes whether there are pathologies associated with the cosmological singularities and the closed time-like curves. We first classify D-branes in a group theoretical way, and then examine DBI actions for effective theories on the D-branes. In particular, we show that D-brane metric from the DBI action does not include singularities, and wave functions on the D-branes are well behaved even in the presence of closed time-like curves.
np→dγ for big-bang nucleosynthesis
International Nuclear Information System (INIS)
Chen, Jiunn-Wei; Savage, Martin J.
1999-01-01
The cross section for np→dγ is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to N 3 LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to next-to-leading order, and the four-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E∼1 MeV is estimated to be (less-or-similar sign)4%. (c) 1999 The American Physical Society
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.
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.
The Big Bang as the Ultimate Traffic Jam
Jejjala, Vishnu; Kavic, Michael; Minic, Djordje; Tze, Chia-Hsiung
We present a novel solution to the nature and formation of the initial state of the Universe. It derives from the physics of a generally covariant extension of matrix theory. We focus on the dynamical state space of this background-independent quantum theory of gravity and matter — an infinite-dimensional, complex, nonlinear Grassmannian. When this space is endowed with a Fubini-Study-like metric, the associated geodesic distance between any two of its points is zero. This striking mathematical result translates into a physical description of a hot, zero-entropy Big Bang. The latter is then seen as a far-from-equilibrium, large-fluctuation-driven, metastable ordered transition — a "freezing by heating" jamming transition. Moreover, the subsequent unjamming transition could provide a mechanism for inflation while rejamming may model a Big Crunch, the final state of gravitational collapse.
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.
DLCQ and plane wave matrix Big Bang models
International Nuclear Information System (INIS)
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 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.
Quark mass variation constraints from Big Bang nucleosynthesis
Energy Technology Data Exchange (ETDEWEB)
Bedaque, P; Luu, T; Platter, L
2010-12-13
We study the impact on the primordial abundances of light elements created of a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way we use lattice QCD data and an hierarchy of effective field theories. We find that the measured {sup 4}He abundances put a bound of {delta}-1% {approx}< m{sub q}/m{sub 1} {approx}< 0.7%. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio {eta}. Including the bounds on the variation of {eta} coming from WMAP results and some additional assumptions narrows the range of allowed values of {delta}m{sub q}/m{sub q} somewhat.
Ether-theoretic model of the universe without the ''big bang''
International Nuclear Information System (INIS)
Podlaha, M.F.
1983-01-01
Authors rejecting singularities in the general theory of relativity still did not find a possibility of avoiding the ''time singularity'' known as the ''big bang''. Of course, mathematics and physics are two different things, and the existence of the ''time singularity'' as the mathematical solutions of the relativistic equations does not yet mean that the ''big bang'' actually happened. The author designs an alternative explanation of the galactic red shift and proposes a model of a universe in which no ''big bang'' exists. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Shi, X. [Department of Physics, Queen`s University, Kingston, Ontario, K7L 3N6 (CANADA)
1996-08-01
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 {approximately}1 eV {nu}{sub {ital e}}, 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} {ital 1996 The American Physical Society.}
International Nuclear Information System (INIS)
Shi, X.
1996-01-01
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 ν e , 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
Big-bang nucleosynthesis through bound-state effects with a long-lived slepton in the NMSSM
Kohri, Kazunori; Koike, Masafumi; Konishi, Yasufumi; Ohta, Shingo; Sato, Joe; Shimomura, Takashi; Sugai, Kenichi; Yamanaka, Masato
2014-08-01
We show that the Li problems can be solved in the next-to-minimal supersymmetric standard model where the slepton as the next-to-lightest supersymmetric (SUSY) particle is very long lived. Such a long-lived slepton induces exotic nuclear reactions in big-bang nucleosynthesis, and destroys and produces the Li7 and Li6 nuclei via bound state formation. We study cases where the lightest SUSY particle is singlino-like neutralino and bino-like neutralino to present allowed regions in the parameter space, which is consistent with the observations on the dark matter and the Higgs mass.
Why No Dark Energy, No Big Bang, But A Likely Fractal Universe?
Mitra, Abhas
Recently, it has been shown that the "Big Bang Model" (BBM) actually corresponds to zero pressure and zero temperature (Mitra, Astr. Sp. Sc., 333, 351, 2011). Thus BBM cannot explain the observed universe having radiation and pressure. Consequently, the very idea of a "Dark Energy" resulting from the attempt of explaining the observed universe by BBM gets invalidated. Also, the fact that the BBM badly violates the principle of energy conservation independently suggests that it is physically unacceptable (Mitra, Gen. Rel. Grav. 42, 443 2010). To confirm this, we consider the transformation of vacuum de-Sitter metric from comoving coordinates to original Schwarzschild coordinates. Since the proper space-time volume must remain invariant for all such coordinate transformations, it is found cosmological constant Λ = 0; implying no dark energy. It is pointed out that, recent observations have (actually) shown that observed universe has a fractal structure upto largest observed scale with D˜2.2. Thus the universe is likely to be infinite hierarchial fractal rather than any smooth distribution of matter presumed by BBM. It is pointed out that the observed microwave background radiation may be explained as superposition of gravitationally red-shifted quiescent thermal radiation from the photosphere of the so-called black hole candidates.
A probable stellar solution to the cosmological lithium discrepancy.
Korn, A J; Grundahl, F; Richard, O; Barklem, P S; Mashonkina, L; Collet, R; Piskunov, N; Gustafsson, B
2006-08-10
The measurement of the cosmic microwave background has strongly constrained the cosmological parameters of the Universe. When the measured density of baryons (ordinary matter) is combined with standard Big Bang nucleosynthesis calculations, the amounts of hydrogen, helium and lithium produced shortly after the Big Bang can be predicted with unprecedented precision. The predicted primordial lithium abundance is a factor of two to three higher than the value measured in the atmospheres of old stars. With estimated errors of 10 to 25%, this cosmological lithium discrepancy seriously challenges our understanding of stellar physics, Big Bang nucleosynthesis or both. Certain modifications to nucleosynthesis have been proposed, but found experimentally not to be viable. Diffusion theory, however, predicts atmospheric abundances of stars to vary with time, which offers a possible explanation of the discrepancy. Here we report spectroscopic observations of stars in the metal-poor globular cluster NGC 6397 that reveal trends of atmospheric abundance with evolutionary stage for various elements. These element-specific trends are reproduced by stellar-evolution models with diffusion and turbulent mixing. We thus conclude that diffusion is predominantly responsible for the low apparent stellar lithium abundance in the atmospheres of old stars by transporting the lithium deep into the star.
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
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...
Study of the 2H(p,γ)3He reaction in the Big Bang Nucleosynthesis energy range at LUNA
Mossa, Viviana
2018-01-01
Deuterium is the first nucleus produced in the Universe, whose accumulation marks the beginning of the so called Big Bang Nucleosynthesis (BBN). Its primordial abundance is very sensitive to some cosmological parameters like the baryon density and the number of the neutrino families. Presently the main obstacle to an accurate theoretical deuterium abundance evaluation is due to the poor knowledge of the 2H(p,γ)3He cross section at BBN energies. The aim of the present work is to describe the experimental approach proposed by the LUNA collaboration, whose goal is to measure, with unprecedented precision, the total and the differential cross section of the reaction in the 30 < Ec.m. [keV] < 300 energy range.
Hepatic encephalopathy: Ever closer to its big bang.
Souto, Pablo A; Marcotegui, Ariel R; Orbea, Lisandro; Skerl, Juan; Perazzo, Juan Carlos
2016-11-14
Hepatic encephalopathy (HE) is a neuropsychiatric disorder that commonly complicates the course of patients with liver disease. Despite the fact that the syndrome was probably first recognized hundreds of years ago, the exact pathogenesis still remains unclear. Minimal hepatic encephalopathy (MHE) is the earliest form of HE and is estimated to affect more that 75% of patients with liver cirrhosis. It is characterized by cognitive impairment predominantly attention, reactiveness and integrative function with very subtle clinical manifestations. The development of MHE is associated with worsen in driving skills, daily activities and the increase of overall mortality. Skeletal muscle has the ability to shift from ammonia producer to ammonia detoxifying organ. Due to its large size, becomes the main ammonia detoxifying organ in case of chronic liver failure and muscular glutamine-synthase becomes important due to the failing liver and brain metabolic activity. Gut is the major glutamine consumer and ammonia producer organ in the body. Hepatocellular dysfunction due to liver disease, results in an impaired clearance of ammonium and in its inter-organ trafficking. Intestinal bacteria, can also represent an extra source of ammonia production and in cirrhosis, small intestinal bacterial overgrowth and symbiosis can be observed. In the study of HE, to get close to MHE is to get closer to its big bang; and from here, to travel less transited roads such as skeletal muscle and intestine, is to go even closer. The aim of this editorial is to expose this road for further and deeper work.
Can history improve big bang health reform? Commentary.
Marchildon, Gregory P
2018-01-26
At present, the professional skills of the historian are rarely relied upon when health policies are being formulated. There are numerous reasons for this, one of which is the natural desire of decision-makers to break with the past when enacting big bang policy change. This article identifies the strengths professional historians bring to bear on policy development using the establishment and subsequent reform of universal health coverage as an example. Historians provide pertinent and historically informed context; isolate the forces that have historically allowed for major reform; and separate the truly novel reforms from those attempted or implemented in the past. In addition, the historian's use of primary sources allows potentially new and highly salient facts to guide the framing of the policy problem and its solution. This paper argues that historians are critical for constructing a viable narrative of the establishment and evolution of universal health coverage policies. The lack of this narrative makes it difficult to achieve an accurate assessment of systemic gaps in coverage and access, and the design or redesign of universal health coverage that can successfully close these gaps.
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.
The big bang? An eventful year in workers' compensation.
Guidotti, Tee L
2006-01-01
Workers' compensation in the past two years has been dominated by events in California, which have been so fundamental as to merit the term big bang. Passage of Senate Bill 899 has led to a comprehensive program of reform in access to medical care, access to rehabilitation services, temporary and permanent disability, evidence-based management, dispute resolution, and system innovation. Two noteworthy developments thus arose: a new requirement for apportionment by cause in causation analysis, and the adoption of evidence-based criteria for impairment assessment, treatment guidelines, and, soon, utilization review. Elsewhere in the United States, changes were modest, but extensive legislative activity in Texas suggests that Texas will be next to make major changes. In Canada, the Workers' Compensation Board of British Columbia has adopted an ambitious strategic initiative, and there is a Canadawide movement to establish presumption for certain diseases in firefighters. Suggestions for future directions include an increased emphasis on prevention, integration of programs, worker participation, enhancing the expertise of health care professionals, evidence-based management, process evaluation, and opportunities for innovation.
Stilometrie en karakterisering in The Big Bang Theory
Directory of Open Access Journals (Sweden)
Maryka van Zyl
2016-11-01
Full Text Available Dialoog is ’n belangrike aspek van televisuele karakterkonstruering. Skrywers maak talige keuses namens die karakters en hierdie keuses kan daartoe aanleiding gee dat kykers ’n karakter met ’n spesifieke stereotipe subkultuur of sosiale groep vereenselwig. Hierdie studie ondersoek die talige konstruering van die karakter Sheldon Cooper in die CBS-sitkom The Big Bang Theory. ’n Trosanaliseboom van die spraak van elk van die vyf hoofkarakters in die eerste sewe seisoene (gegenereer deur die R-skrip Stylo 0.6.0 dui daarop dat die karakter Sheldon Cooper van die ander hoofkarakters (Leonard, Penny, Howard en Rajesh verskil ten opsigte van taalstyl. Hierdie verskille word verder ondersoek deur gebruik te maak van die korpusanalise program (WordSmith 6.0. om sleutelwoorde en leksikale bondels te identifiseer en om die gebruik van aktiewe en passiewe werkwoordkonstruksies te vergelyk. Sheldon se keuse van wetenskaplike of meer formele woorde en sy relatiewe voorkeur vir die passiefkonstruksie tipeer sy taalstyl as verduidelikend eerder as tipies van omgangstaal.
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...
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.
The big bang and inflation united by an analytic solution
International Nuclear Information System (INIS)
Bars, Itzhak; Chen, Shih-Hung
2011-01-01
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.
Particle physics and cosmology
International Nuclear Information System (INIS)
Ellis, J.; Nanopoulos, D.
1983-01-01
The authors describe the connection between cosmology and particle physics in an introductory way. In this connection the big bang theory and unified gauge models of strong, electromagnetic, and weak interactions are considered. Furthermore cosmological nucleosynthesis is discussed in this framework, and the problem of cosmic neutrinos is considered with special regards to its rest mass. (HSI).
Cosmological simulations of the first galaxies
Latif, M. A.
The study of the cosmos has mesmerized humans since many centuries. Our present knowledge of the Universe is based on the standard Big Bang theory. The detection of the cosmic microwave background (CMB) is one of the strongest evidences of the Big Bang model. The isotropy of the CMB shows that the
International Nuclear Information System (INIS)
Stabell, R.
1979-01-01
Einstein applied his gravitation theory to a universe model with positively curved space in 1917. In order to maintain a static universe he introduced the cosmological constant, which in the light of later nonstatic universe models, he described as his life's greatest mistake. The best known such model is the Einstein-de Sitter model, which is here discussed in some detail. The 'big bang' theory is also discussed leading to the cosmic background radiation. The early phase of the 'big bang' cosmology, the first ten seconds, and the first minutes are discussed, leading to the transparent stage. (JIW)
Cosmological models without singularities
International Nuclear Information System (INIS)
Petry, W.
1981-01-01
A previously studied theory of gravitation in flat space-time is applied to homogeneous and isotropic cosmological models. There exist two different classes of models without singularities: (i) ever-expanding models, (ii) oscillating models. The first class contains models with hot big bang. For these models there exist at the beginning of the universe-in contrast to Einstein's theory-very high but finite densities of matter and radiation with a big bang of very short duration. After short time these models pass into the homogeneous and isotropic models of Einstein's theory with spatial curvature equal to zero and cosmological constant ALPHA >= O. (author)
Gentry, Robert
2010-02-01
Until now science's greatest debacle occurred when Copernicus exposed Ptolemaic cosmologists' 1300 hundred year-long fraud that it must be true because observations fit theory so well, while they ignored the untested state of its central assumption of Earth centered planetary motion. With much hubris modern physicists are confident this could never happen again, that the integrity of physics journals editors suffices to guarantee that a challenge to the reigning cosmological theory -- big bang cosmology -- would immediately be brought to the center of scientific attention for analysis and discussion. In fact a decade ago it was reported [MPLA 2619 (1997); arXiv:gr-gc/9806061] that, like Ptolemaic cosmology before it, big bang's central assumption that GR expansion effects cause in-flight expansion had never been tested and, further, that experimental testing of it using GR operation of the GPS showed it to be false. This result proves it is impossible for the 2.73 K CBR to be fireball relic radiation. These results were expanded in CERN reports EXT-2003-021;022, but have been uniformly rejected by physics journals, one of which accepted a paper similar to CERN EXT-2003-022, only to reject it a few days later with the admission not to publish it because of fearing reaction of the worldwide physics community. For update on my PRL submission see http://www.alphacosmos.net. )
Drosophila Big bang regulates the apical cytocortex and wing growth through junctional tension.
Tsoumpekos, Giorgos; Nemetschke, Linda; Knust, Elisabeth
2018-03-05
Growth of epithelial tissues is regulated by a plethora of components, including signaling and scaffolding proteins, but also by junctional tension, mediated by the actomyosin cytoskeleton. However, how these players are spatially organized and functionally coordinated is not well understood. Here, we identify the Drosophila melanogaster scaffolding protein Big bang as a novel regulator of growth in epithelial cells of the wing disc by ensuring proper junctional tension. Loss of big bang results in the reduction of the regulatory light chain of nonmuscle myosin, Spaghetti squash. This is associated with an increased apical cell surface, decreased junctional tension, and smaller wings. Strikingly, these phenotypic traits of big bang mutant discs can be rescued by expressing constitutively active Spaghetti squash. Big bang colocalizes with Spaghetti squash in the apical cytocortex and is found in the same protein complex. These results suggest that in epithelial cells of developing wings, the scaffolding protein Big bang controls apical cytocortex organization, which is important for regulating cell shape and tissue growth. © 2018 Tsoumpekos et al.
L'universo prima del Big Bang cosmologia e teoria delle stringhe
Gasperini, Maurizio
2002-01-01
Termini come "universo in espansione", "big bang", "singolarità iniziale" sono ormai entrati a far parte del linguaggio comune. L'idea che l'universo che oggi osserviamo abbia avuto origine da una grossa esplosione (big bang) è ormai ampiamente diffusa e accettata nella moderna cultura popolare, a tutti i libelli. Ma cosa c'era prima del big bang? E ha senso porsi questo interrogativo in un contesto scientifico? I recenti progressi della fisica teoria, e in particolare della cosiddetta teoria delle stringhe, suggeriscono una risposta a questa domanda, fornendo degli strumenti matematici capaci, in linea di principio, di ricostruire la storia dell'universo spingendosi anche oltre l'istante del big bang. Ne emerge un possibile scenario cosmologico nel quale l'universo, anzichè essere "appena nato" al momento del big bang, era piuttosto nel punto di mezzo della sua evoluzione, di durata probabilmente infinita. In questo libro si cerca di illustrare tale scenario usando un linguaggio non troppo tecnico, rivolt...
Temple, Blake; Smoller, Joel
2009-08-25
We derive a system of three coupled equations that implicitly defines a continuous one-parameter family of expanding wave solutions of the Einstein equations, such that the Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology is embedded as a single point in this family. By approximating solutions near the center to leading order in the Hubble length, the family reduces to an explicit one-parameter family of expanding spacetimes, given in closed form, that represents a perturbation of the Standard Model. By introducing a comoving coordinate system, we calculate the correction to the Hubble constant as well as the exact leading order quadratic correction to the redshift vs. luminosity relation for an observer at the center. The correction to redshift vs. luminosity entails an adjustable free parameter that introduces an anomalous acceleration. We conclude (by continuity) that corrections to the redshift vs. luminosity relation observed after the radiation phase of the Big Bang can be accounted for, at the leading order quadratic level, by adjustment of this free parameter. The next order correction is then a prediction. Since nonlinearities alone could actuate dissipation and decay in the conservation laws associated with the highly nonlinear radiation phase and since noninteracting expanding waves represent possible time-asymptotic wave patterns that could result, we propose to further investigate the possibility that these corrections to the Standard Model might be the source of the anomalous acceleration of the galaxies, an explanation not requiring the cosmological constant or dark energy.
Cosmology and the weak interaction
International Nuclear Information System (INIS)
Schramm, D.N.
1989-12-01
The weak interaction plays a critical role in modern Big Bang cosmology. This review will emphasize two of its most publicized cosmological connections: Big Bang nucleosynthesis and Dark Matter. The first of these is connected to the cosmological prediction of Neutrino Flavours, N ν ∼ 3 which is now being confirmed at SLC and LEP. The second is interrelated to the whole problem of galaxy and structure formation in the universe. This review will demonstrate the role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure. 87 refs., 3 figs., 5 tabs
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.
Some cosmological constraints on gauge theories
International Nuclear Information System (INIS)
Schramm, D.N.
1983-01-01
In these lectures, a review is made of various constraints cosmology may place on gauge theories. Particular emphasis is placed on those constraints obtainable from Big Bang Nucleosynthesis, with only brief mention made of Big Bang Baryosynthesis. There is also a considerable discussion of astrophysical constraints on masses and lifetimes of neutrinos with specific mention of the 'missing mass (light)' problem of galactic dynamics. (orig./HSI)
Using Big Bang Nucleosynthesis to extend CMB probes of neutrino physics
Energy Technology Data Exchange (ETDEWEB)
Shimon, M.; Miller, N.J.; Fuller, G.M.; Keating, B.G. [Center for Astrophysics and Space Sciences, University of California, San Diego, La Jolla, CA, 92093 (United States); Kishimoto, C.T. [Department of Physics and Astronomy, University of California, Los Angeles, CA, 90095 (United States); Smith, C.J., E-mail: meirs@mamacass.ucsd.edu, E-mail: nmiller@physics.ucsd.edu, E-mail: ckishimo@physics.ucsd.edu, E-mail: christel.smith@asu.edu, E-mail: gfuller@ucsd.edu, E-mail: bkeating@ucsd.edu [Department of Physics, Arizona State University, Tempe, AZ, 85287 (United States)
2010-05-01
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 M{sub ν} > 0.29 eV could be ruled out at 2σ or better. Likewise neutrino degeneracy parameters ξ{sub ν{sub e}} > 0.11 and |ξ{sub ν{sub μ{sub /{sub τ}}}}| > 0.49 could be detected or ruled out at 2σ confidence, or better. For POLARBEAR we find that the corresponding detectable values are M{sub ν} > 0.75 eV, ξ{sub ν{sub e}} > 0.62, and |ξ{sub ν{sub μ{sub /{sub τ}}}}| > 1.1, while for EPIC we obtain M{sub ν} > 0.20 eV, ξ{sub ν{sub e}} > 0.045, and |ξ{sub ν{sub μ{sub /{sub 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.
Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis
Saviano, Ninetta; Pisanti, Ofelia; Mangano, Gianpiero; Mirizzi, Alessandro
2014-12-01
Short-baseline neutrino anomalies suggest the existence of low-mass [m ˜O (1 ) eV ] sterile neutrinos νs. These would be efficiently produced in the early universe by oscillations with active neutrino species, leading to a thermal population of the sterile states seemingly incompatible with cosmological observations. In order to relieve this tension it has been recently speculated that new "secret" interactions among sterile neutrinos, mediated by a massive gauge boson X (with MX≪MW), can inhibit or suppress the sterile neutrino thermalization, due to the production of a large matter potential term. We note however, that they also generate strong collisional terms in the sterile neutrino sector that induce an efficient sterile neutrino production after a resonance in matter is encountered, increasing their contribution to the number of relativistic particle species Neff. Moreover, for values of the parameters of the νs-νs interaction for which the resonance takes place at temperature T ≲few MeV , significant distortions are produced in the electron (anti)neutrino spectra, altering the abundance of light element in big bang nucleosynthesis (BBN). Using the present determination of 4He and deuterium primordial abundances we determine the BBN constraints on the model parameters. We find that 2H/H density ratio exclude much of the parameter space if one assumes a baryon density at the best fit value of Planck experiment, ΩBh2=0.02207 , while bounds become weaker for a higher ΩBh2=0.02261 , the 95% C.L. upper bound of Planck. Due to the large error on its experimental determination, the helium mass fraction Yp gives no significant bounds.
Topics in inflationary cosmologies
International Nuclear Information System (INIS)
Mahajan, S.
1986-04-01
Several aspects of inflationary cosmologies are discussed. An introduction to the standard hot big bang cosmological model is reviewed, and some of the problems associated with it are presented. A short review of the proposals for solving the cosmological conundrums of the big bang model is presented. Old and the new inflationary scenarios are discussed and shown to be unacceptable. Some alternative scenarios especially those using supersymmetry are reviewed briefly. A study is given of inflationary models where the same set of fields that breaks supersymmetry is also responsible for inflation. In these models, the scale of supersymmetry breaking is related to the slope of the potential near the origin and can thus be kept low. It is found that a supersymmetry breaking scale of the order of the weak breaking scale. The cosmology obtained from the simplest of such models is discussed in detail and it is shown that there are no particular problems except a low reheating temperature and a violation of the thermal constraint. A possible solution to the thermal constraint problem is given by introducing a second field, and the role played by this second field in the scenario is discussed. An alternative mechanism for the generation of baryon number within the framework of supergravity inflationary models is studied using the gravitational couplings of the heavy fields with the hidden sector (the sector which breaks supersymmetry). This mechanism is applied to two specific models - one with and one without supersymmetry breaking. The baryon to entropy ratio is found to be dependent on parameters which are model dependent. Finally, the effect of direct coupling between the two sectors on results is related, 88 refs., 6 figs
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.)
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.
Time, space, stars and man the story of the Big Bang
Woolfson, Michael M
2009-01-01
Most well-read, but non-scientific, people will have heard of the term "Big Bang" as a description of the origin of the Universe. They will recognize that DNA identifies individuals and will know that the origin of life is one of the great unsolved scientific mysteries. This book brings together all of that material. Starting with the creation of space and time - known as the Big Bang - the book traces causally related steps through the formation of matter, of stars and planets, the Earth itself, the evolution of the Earth's surface and atmosphere, and then through to the beginnings of life an
Catena, R; Pato, M; Pieri, L; Masiero, A
2010-01-01
Alternative cosmologies, based on extensions of General Relativity, predict modified thermal histories in the Early Universe in the pre Big Bang Nucleosynthesis (BBN) era, epoch which is not directly constrained by cosmological observations. When the expansion rate is enhanced with respect to the standard case, thermal relics typically decouple with larger relic abundances. The correct value of the relic abundance is therefore obtained for larger annihilation cross sections, as compared to standard cosmology. A direct consequence is that indirect detection rates are enhanced. Extending previous analyses of ours, we derive updated astrophysical bounds on the dark matter annihilation cross sections and use them to constrain alternative cosmologies in the pre-BBN era. We also determine the characteristics of these alternative cosmologies in order to provide the correct value of relic abundance for a thermal relic for the (large) annihilation cross section required to explain the PAMELA results on the positron fr...
Silk, Joseph
2008-11-01
The field of cosmology has been transformed since the glorious decades of the 1920's and 1930's when theory and observation converged to develop the current model of the expanding universe. It was a triumph of the theory of general relativity and astronomy. The first revolution came when the nuclear physicists entered the fray. This marked the debut of the hot big bang, in which the light elements were synthesized in the first three minutes. It was soon realised that elements like carbon and iron were synthesized in exploding stars. However helium, as well as deuterium and lithium, remain as George Gamow envisaged, the detritus of the big bang. The climax arrived with one of the most remarkable discoveries of the twentieth century, the cosmic microwave background radiation, in 1964. The fossil glow turned out to have the spectrum of an ideal black body. One could not imagine a stronger confirmation of the hot and dense origin of the universe. This discovery set the scene for the next major advance. It was now the turn of the particle physicists, who realized that the energies attained near the beginning of the universe, and unachievable in any conceivable terrestrial accelerator, provided a unique testing ground for theories of grand unification of the fundamental forces. This led Alan Guth and Andrei Linde in 1980 to propose the theory of inflation, which solved outstanding puzzles of the big bang. One could now understand why the universe is so large and homogeneous, and the origin of the seed fluctuations that gave rise to large-scale structure. A key prediction was that the universe should have Euclidean geometry, now verified to a precision of a few percent. Modern cosmology is firmly embedded in particle physics. It merits a text written by a particle physicist who can however appreciate the contributions of astronomy that provide the foundation and infrastructure for the theory of the expanding universe. There are now several such texts available. The most
Particle physics and cosmology beyond the Standard Model: inflation, dark matter and flavour
International Nuclear Information System (INIS)
Heurtier, L.
2015-01-01
This thesis has been focusing on beyond the Standard Model aspects of particle physics and their implication in cosmology. We have gone through this work along the timeline of the Universe History focusing on three major topics that are the inflationary period, the dark matter relic density production and detection, and finally the question of flavor changing constraints on low energy supersymmetric theories. In the first part of this thesis, after reviewing the theoretical and phenomenological aspects of both the Big Bang theory and the theory of Inflation we will study in detail how describing Inflation in a high energy supersymmetric theory. The second part of this thesis is dedicated to dark matter. We have studied phenomenological aspects of simple models, extending the present Standard Model with simple abelian symmetries, by assuming that the constituent of dark matter would be able to exchange information with the visible sector by the help of a mediator particle. We have studied in particular possible interactions of heavy or light dark matter with respectively the strong and the electroweak sectors of the Standard Model. Our models are strongly constrained of course by experiments. The third part of this work will be dedicated to a different aspect of beyond Standard Model theories, that is the treatment of the flavour changing processes of particle physics. The Minimal Supersymmetric Standard Model (MSSM), as one of these possible enlargement of the Standard Model, introduces new processes of flavour changing that are highly constrained by experiment. We present some works in which we consider the possibility of adding so called Dirac Gauginos to the MSSM to render flavour changing weaker in the theory, and propose different flavour patterns theories
Inflation after COBE: Lectures on inflationary cosmology
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. (Chicago Univ., IL (United States). Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL (United States))
1992-01-01
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the initial data'' for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
Inflation after COBE: Lectures on inflationary cosmology
International Nuclear Information System (INIS)
Turner, M.S.
1992-01-01
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ''initial data'' for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models
Inflation after COBE: Lectures on inflationary cosmology
Energy Technology Data Exchange (ETDEWEB)
Turner, M.S. [Chicago Univ., IL (United States). Enrico Fermi Inst.]|[Fermi National Accelerator Lab., Batavia, IL (United States)
1992-12-31
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ``initial data`` for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
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…
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.
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.
Communicating the Nature of Science through "The Big Bang Theory": Evidence from a Focus Group Study
Li, Rashel; Orthia, Lindy A.
2016-01-01
In this paper, we discuss a little-studied means of communicating about or teaching the nature of science (NOS)--through fiction television. We report some results of focus group research which suggest that the American sitcom "The Big Bang Theory" (2007-present), whose main characters are mostly working scientists, has influenced…
Compilation and R-matrix analysis of Big Bang nuclear reaction rates
International Nuclear Information System (INIS)
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. 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
Big-Bang reaction rates within the R-matrix model
Energy Technology Data Exchange (ETDEWEB)
Descouvemont, P. [Physique Nucleaire Theorique et Physique Mathematique, CP229, Universite Libre de Bruxelles, B-1050 Brussels (Belgium); Adahchour, A. [Physique Nucleaire Theorique et Physique Mathematique, CP229, Universite Libre de Bruxelles, B-1050 Brussels (Belgium); Angulo, C. [Centre de Recherches du Cyclotron, Universite catholique de Louvain, Chemin du cyclotron 2, B-1348 Louvain-la-Neuve (Belgium); Coc, A. [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS/IN2P3/UPS, Bat. 104, F-91405 Orsay Campus (France); Vangioni-Flam, E. [Institut d' Astrophysique de Paris, CNRS, 98 bis Bd. Arago, F-75014 Paris (France)
2005-07-25
We use the R-matrix theory to fit S-factor data on nuclear reactions involved in Big Bang nucleosynthesis. We derive the reaction rates with associated uncertainties, which are evaluated on statistical grounds. We provide S factors and reaction rates in tabular and graphical formats (available at http://pntpm3.ulb.ac.be/bigbang)
The evolution of modern cosmology as seen through a personal walk across six decades
Narlikar, Jayant V.
2018-02-01
This highly personal account of evolution of cosmology spans a period of approximately six decades 1959-2017. It begins when in 1959 the author, as an undergraduate at Cambridge, was attracted to the subject by the thought provoking lectures by Fred Hoyle as well as by his popular books The Nature of Universe and The Frontiers of Astronomy. The result was that after a successful performance at the Mathematical Tripos (Part III) examination, he enrolled as a research student of Hoyle. In this article the author describes the interesting works in cosmology that kept him busy both in Cambridge and in India. The issues pertinent to cosmological research in the 1960s and 1970s included the Mach's principle, the Wheeler-Feynman theory relating the local electromagnetic arrow of time to the cosmological one, the observational tests of specific expanding universe models, and issues like singularity in quantum cosmology. However, post-1965, the nature of cosmological research changed dramatically with the discovery of the cosmic microwave background radiation (CMBR). Given the assumption that the CMBR is a relic of big bang there has been a host of papers on the early universe, going as close to the big bang as the very early universe would permit: around just 10-36 s. The author argues that despite the popularity of the standard hot big bang cosmology (SBBC) it rests on rather shaky foundations. On the theoretical side there is no well established physical framework to support the SBBC; nor is there independent observational support for its assumptions like the nonbaryonic dark matter, inflation and dark energy. While technological progress has made it possible to explore the universe in greater detail with open mind, today's cosmologists seem caught in a range of speculations in support of the big bang dogma. Thus, in modern times cosmology appears to have lost the Camelot spirit encouraging adventurous studies of the unknown. A spirit of openness is advocated to restore
Gonzalez-Mestres, Luis
2014-04-01
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 the standard
Barbagallo, M.; Colonna, N.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bacak, M.; Balibrea, J.; Barros, S.; Bečvář, F.; Beinrucker, C.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brugger, M.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Castelluccio, D. M.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Furman, V.; Göbel, K.; García, A. R.; Gawlik, A.; Glodariu, T.; Gonçalves, I. F.; González, E.; Goverdovski, A.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Harada, H.; Heftrich, T.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Katabuchi, T.; Kavrigin, P.; Ketlerov, V.; Khryachkov, V.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lerendegui-Marco, J.; Meo, S. Lo; Lonsdale, S. J.; Losito, R.; Macina, D.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Matteucci, F.; Maugeri, E. A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Montesano, S.; Musumarra, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, J. I.; Praena, J.; Quesada, J. M.; Rajeev, K.; Rauscher, T.; Reifarth, R.; Riego-Perez, A.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Sabaté-Gilarte, M.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Sedyshev, P.; Smith, A. G.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Warren, S.; Weigand, M.; Weiss, C.; Wolf, C.; Woods, P. J.; Wright, T.; Žugec, P.
2017-09-01
The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial 7Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called "Spite plateau" in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of 7Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the 7Be(n,α) and 7Be(n,p) reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of 7Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.
Directory of Open Access Journals (Sweden)
Barbagallo M.
2017-01-01
Full Text Available The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial 7Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called “Spite plateau” in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of 7Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the 7Be(n,α and 7Be(n,p reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of 7Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.
Energy Technology Data Exchange (ETDEWEB)
Ehlers, J.; Rindler, W.
1989-05-15
We classify all non-static Friedmann-Lemaitre universes containing dust and radiation (or, as limiting cases, vacuum), and exhibit their histories as orbits in a three-dimensional (phase-) space ''S'', which faithfully reflects the topology of the set of states. As coordinates in ''S'' we take the dimensionless parameters /Omega/, /omega/ and /lambda/ representing, respectively, the energy density of the dust, the radiation and the vacuum (corresponding to the cosmological constant). Three open subspaces of ''S'' contain, respectively, the orbits representing oscillating, inflectional and bouncing universes; their boundaries and edges contain the orbits of all the other universes. We show that present-day redshift and density data exclude all models not having a big bang, without using assumptions about the origin of the microwave background radiation and without a priori assumptions about the value of the cosmological constant. (Author).
International Nuclear Information System (INIS)
Ehlers, J.; Rindler, W.
1989-01-01
We classify all non-static Friedmann-Lemaitre universes containing dust and radiation (or, as limiting cases, vacuum), and exhibit their histories as orbits in a three-dimensional (phase-) space ''S'', which faithfully reflects the topology of the set of states. As coordinates in ''S'' we take the dimensionless parameters Ω, ω and λ representing, respectively, the energy density of the dust, the radiation and the vacuum (corresponding to the cosmological constant). Three open subspaces of ''S'' contain, respectively, the orbits representing oscillating, inflectional and bouncing universes; their boundaries and edges contain the orbits of all the other universes. We show that present-day redshift and density data exclude all models not having a big bang, without using assumptions about the origin of the microwave background radiation and without a priori assumptions about the value of the cosmological constant. (Author)
Non-minimally coupled varying constants quantum cosmologies
International Nuclear Information System (INIS)
Balcerzak, Adam
2015-01-01
We consider gravity theory with varying speed of light and varying gravitational constant. Both constants are represented by non-minimally coupled scalar fields. We examine the cosmological evolution in the near curvature singularity regime. We find that at the curvature singularity the speed of light goes to infinity while the gravitational constant vanishes. This corresponds to the Newton's Mechanics limit represented by one of the vertex of the Bronshtein-Zelmanov-Okun cube [1,2]. The cosmological evolution includes both the pre-big-bang and post-big-bang phases separated by the curvature singularity. We also investigate the quantum counterpart of the considered theory and find the probability of transition of the universe from the collapsing pre-big-bang phase to the expanding post-big-bang phase
Primordial nucleosynthesis: A cosmological point of view
International Nuclear Information System (INIS)
Mathews, G. J.; Kajino, T.; Yamazaki, D.; Kusakabe, M.; Cheoun, M.-K.
2014-01-01
Primordial nucleosynthesis remains as one of the pillars of modern cosmology. It is the test-ing ground upon which all cosmological models must ultimately rest. It is our only probe of the universe during the first few minutes of cosmic expansion and in particular during the important radiation-dominated epoch. These lectures review the basic equations of space-time, cosmology, and big bang nucleosynthesis. We will then review the current state of observational constraints on primordial abundances along with the key nuclear reactions and their uncertainties. We summarize which nuclear measure-ments are most crucial during the big bang. We also review various cosmological models and their constraints. In particular, we summarize the constraints that big bang nucleosynthesis places upon the possible time variation of fundamental constants, along with constraints on the nature and origin of dark matter and dark energy, long-lived supersymmetric particles, gravity waves, and the primordial magnetic field
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.
Turning big bang into big bounce. I. Classical dynamics
Dzierżak, Piotr; Małkiewicz, Przemysław; Piechocki, Włodzimierz
2009-11-01
The big bounce (BB) transition within a flat Friedmann-Robertson-Walker model is analyzed in the setting of loop geometry underlying the loop cosmology. We solve the constraint of the theory at the classical level to identify physical phase space and find the Lie algebra of the Dirac observables. We express energy density of matter and geometrical functions in terms of the observables. It is the modification of classical theory by the loop geometry that is responsible for BB. The classical energy scale specific to BB depends on a parameter that should be fixed either by cosmological data or determined theoretically at quantum level, otherwise the energy scale stays unknown.
Implication of the Proton-Deuteron Radiative Capture for Big Bang Nucleosynthesis.
Marcucci, L E; Mangano, G; Kievsky, A; Viviani, M
2016-03-11
The astrophysical S factor for the radiative capture d(p,γ)^{3}He in the energy range of interest for big bang nucleosynthesis (BBN) is calculated using an ab initio approach. The nuclear Hamiltonian retains both two- and three-nucleon interactions-the Argonne v_{18} and the Urbana IX, respectively. Both one- and many-body contributions to the nuclear current operator are included. The former retain for the first time, besides the 1/m leading order contribution (m is the nucleon mass), also the next-to-leading order term, proportional to 1/m^{3}. The many-body currents are constructed in order to satisfy the current conservation relation with the adopted Hamiltonian model. The hyperspherical harmonics technique is applied to solve the A=3 bound and scattering states. Particular attention is paid in this second case in order to obtain, in the energy range of BBN, an uncertainty on the astrophysical S factor of the order or below ∼1%. Then, in this energy range, the S factor is found to be ∼10% larger than the currently adopted values. Part of this increase (1%-3%) is due to the 1/m^{3} one-body operator, while the remaining is due to the new more accurate scattering wave functions. We have studied the implication of this new determination for the d(p,γ)^{3}He S factor on the deuterium primordial abundance. We find that the predicted theoretical value for ^{2}H/H is in excellent agreement with its experimental determination, using the most recent determination of the baryon density of the Planck experiment, and with a standard number of relativistic degrees of freedom N_{eff}=3.046 during primordial nucleosynthesis. This calls for a more accurate measurement of the astrophysical S factor in order to confirm the present predictions.
'Big Bang' tomography as a new route to atomic-resolution electron tomography.
Van Dyck, Dirk; Jinschek, Joerg R; Chen, Fu-Rong
2012-06-13
Until now it has not been possible to image at atomic resolution using classical electron tomographic methods, except when the target is a perfectly crystalline nano-object imaged along a few zone axes. The main reasons are that mechanical tilting in an electron microscope with sub-ångström precision over a very large angular range is difficult, that many real-life objects such as dielectric layers in microelectronic devices impose geometrical constraints and that many radiation-sensitive objects such as proteins limit the total electron dose. Hence, there is a need for a new tomographic scheme that is able to deduce three-dimensional information from only one or a few projections. Here we present an electron tomographic method that can be used to determine, from only one viewing direction and with sub-ångström precision, both the position of individual atoms in the plane of observation and their vertical position. The concept is based on the fact that an experimentally reconstructed exit wave consists of the superposition of the spherical waves that have been scattered by the individual atoms of the object. Furthermore, the phase of a Fourier component of a spherical wave increases with the distance of propagation at a known 'phase speed'. If we assume that an atom is a point-like object, the relationship between the phase and the phase speed of each Fourier component is linear, and the distance between the atom and the plane of observation can therefore be determined by linear fitting. This picture has similarities with Big Bang cosmology, in which the Universe expands from a point-like origin such that the distance of any galaxy from the origin is linearly proportional to the speed at which it moves away from the origin (Hubble expansion). The proof of concept of the method has been demonstrated experimentally for graphene with a two-layer structure and it will work optimally for similar layered materials, such as boron nitride and molybdenum disulphide.
Energy Technology Data Exchange (ETDEWEB)
Barbour, J B [Department of Physics and Astronomy, University of Rochester (United States)
2007-02-07
to a far better review article or book on modern cosmology. The doubters' case is threadbare at best, as Alain Blanchard put it rather more politely in his panel contribution. The Burbidges and Halton Arp reiterate the difficulties that these eminent scientists have long had in reconciling certain observations with the standard model. Most workers in the field are aware of their views and find they lack substance, especially Arp's worries about some close coincidences between the observed positions of low-redshift galaxies and high-redshift quasars. Virtually everyone believes that they have no statistical significance. Arp's belief that some quasars have non-cosmological redshifts and are being spewed out of nearby exploding galactic centres raises eyebrows. For me the most worthwhile of the 'rebel' papers is Narlikar's. Its first half is a thought-provoking survey of the many modifications through which the big-bang model has passed. He calls them additions of epicycles and in some cases I think he has a point. But his rival theory seems very far fetched and makes my point about Hamlet's ghost. The steady-state theory just will not die: in 1994, Hoyle, G. Burbidge, and Narlikar published the quasi-steady-state theory (The Astrophysical Journal 410 437) in which the universe expands, not perfectly steadily but 'in mini-creation events at regular intervals and in response the universe oscillates on a short-term period of about 50 Gyr while it also has a steady (exponential) long-term expansion at a characteristic time scale of about 1000 Gyr.' I won't go into details, but this looks like a whopping epicycle on the steady-state model{exclamation_point} Wickramasinghe's paper is on iron whiskers, which have now taken over from standard dust as the agents that must transform starlight into the microwave background. In my view the two best papers in the volume are those of the panellists Alain Blanchard (in favour of
International Nuclear Information System (INIS)
Barbour, J B
2007-01-01
cosmology. The doubters' case is threadbare at best, as Alain Blanchard put it rather more politely in his panel contribution. The Burbidges and Halton Arp reiterate the difficulties that these eminent scientists have long had in reconciling certain observations with the standard model. Most workers in the field are aware of their views and find they lack substance, especially Arp's worries about some close coincidences between the observed positions of low-redshift galaxies and high-redshift quasars. Virtually everyone believes that they have no statistical significance. Arp's belief that some quasars have non-cosmological redshifts and are being spewed out of nearby exploding galactic centres raises eyebrows. For me the most worthwhile of the 'rebel' papers is Narlikar's. Its first half is a thought-provoking survey of the many modifications through which the big-bang model has passed. He calls them additions of epicycles and in some cases I think he has a point. But his rival theory seems very far fetched and makes my point about Hamlet's ghost. The steady-state theory just will not die: in 1994, Hoyle, G. Burbidge, and Narlikar published the quasi-steady-state theory (The Astrophysical Journal 410 437) in which the universe expands, not perfectly steadily but 'in mini-creation events at regular intervals and in response the universe oscillates on a short-term period of about 50 Gyr while it also has a steady (exponential) long-term expansion at a characteristic time scale of about 1000 Gyr.' I won't go into details, but this looks like a whopping epicycle on the steady-state model! Wickramasinghe's paper is on iron whiskers, which have now taken over from standard dust as the agents that must transform starlight into the microwave background. In my view the two best papers in the volume are those of the panellists Alain Blanchard (in favour of the standard model though he has difficulties with X-ray clusters) and the observer Michael Disney, who expresses radical doubts
International Nuclear Information System (INIS)
Bertolami, O.; Santos, N. M. C.
2009-01-01
We use big bang nucleosynthesis bounds on the variation of the gravitational coupling to derive constraints on the strength of the deviation from the gravitational inverse-square law due to tensor and vector unparticle exchange.
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
Barbagallo, M; Aberle, O; Andrzejewski, J; Audouin, L; Bécares, V; Bacak, M; Balibrea, J; Barros, S; Bečvář, F; Beinrucker, C; Berthoumieux, E; Billowes, J; Bosnar, D; Brugger, M; Caamaño, M; Calviño, F; Calviani, M; Cano-Ott, D; Cardella, R; Casanovas, A; Castelluccio, D M; Cerutti, F; Chen, Y H; Chiaveri, E; Cortés, G; Cortés-Giraldo, M A; Cosentino, L; Damone, L A; Diakaki, M; Domingo-Pardo, C; Dressler, R; Dupont, E; Durán, I; Fernández-Domínguez, B; Ferrari, A; Ferreira, P; Finocchiaro, P; Furman, V; Göbel, K; García, A R; Gawlik, A; Glodariu, T; Gonçalves, I F; González, E; Goverdovski, A; Griesmayer, E; Guerrero, C; Gunsing, F; Harada, H; Heftrich, T; Heinitz, S; Heyse, J; Jenkins, D G; Jericha, E; Käppeler, F; Kadi, Y; Katabuchi, T; Kavrigin, P; Ketlerov, V; Khryachkov, V; Kimura, A; Kivel, N; Kokkoris, M; Krtička, M; Leal-Cidoncha, E; Lederer, C; Leeb, H; Lerendegui-Marco, J; Lo Meo, S; Lonsdale, S J; Losito, R; Macina, D; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mastromarco, M; Matteucci, F; Maugeri, E A; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Montesano, S; Musumarra, A; Nolte, R; Oprea, A; Patronis, N; Pavlik, A; Perkowski, J; Porras, J I; Praena, J; Quesada, J M; Rajeev, K; Rauscher, T; Reifarth, R; Riego-Perez, A; Rout, P C; Rubbia, C; Ryan, J A; Sabaté-Gilarte, M; Saxena, A; Schillebeeckx, P; Schmidt, S; Schumann, D; Sedyshev, P; Smith, A G; Stamatopoulos, A; Tagliente, G; Tain, J L; Tarifeño-Saldivia, A; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Vlachoudis, V; Vlastou, R; Wallner, A; Warren, S; Weigand, M; Weiss, C; Wolf, C; Woods, P J; Wright, T; Žugec, P
2017-01-01
The Cosmological Lithium Problem refers to the large discrepancy between the abundance of primordial $^7$Li predicted by the standard theory of Big Bang Nucleosynthesis and the value inferred from the so-called “Spite plateau” in halo stars. A possible explanation for this longstanding puzzle in Nuclear Astrophysics is related to the incorrect estimation of the destruction rate of $^7$Be, which is responsible for the production of 95% of primordial Lithium. While charged-particle induced reactions have mostly been ruled out, data on the $^7 \\text{Be(n,} \\alpha)$ and $^7 \\text{Be(n,p)}$ reactions are scarce or completely missing, so that a large uncertainty still affects the abundance of $^7$Li predicted by the standard theory of Big Bang Nucleosynthesis. Both reactions have been measured at the n_TOF facility at CERN, providing for the first time data in a wide neutron energy range.
Constraints on pre-big-bang parameter space from CMBR anisotropies
International Nuclear Information System (INIS)
Bozza, V.; Gasperini, M.; Giovannini, M.; Veneziano, G.
2003-01-01
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 initial displacement of the axion from the minimum of its potential and the rate of evolution of the compactification volume during pre-big-bang inflation. The combination of theoretical and experimental constraints favors a slightly blue spectrum of scalar perturbations, and/or a value of the string scale in the vicinity of the SUSY GUT scale
Low-energy photodisintegration of the deuteron and Big-Bang nucleosynthesis
International Nuclear Information System (INIS)
Tornow, W.; Czakon, N.G.; Howell, C.R.; Hutcheson, A.; Kelley, J.H.; Litvinenko, V.N.; Mikhailov, S.F.; 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 potential model and effective field theory calculations. Therefore, the uncertainty in the baryon density Ω B h 2 obtained from Big-Bang Nucleosynthesis can be reduced at least by 20%
Constraints on pre-big bang parameter space from CMBR anisotropies
Bozza, Valerio; Giovannini, Massimo; Veneziano, Gabriele
2003-01-01
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 initial displacement of the axion from the minimum of its potential and the rate of evolution of the compactification volume during pre-big bang inflation. The combination of theoretical and experimental constraints favours a slightly blue spectrum of scalar perturbations, and/or a value of the string scale in the vicinity of the SUSY-GUT scale.
Sufficient conditions for a period incrementing big bang bifurcation in one-dimensional maps
International Nuclear Information System (INIS)
Avrutin, V; Granados, A; Schanz, M
2011-01-01
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
Sufficient conditions for a period incrementing big bang bifurcation in one-dimensional maps
Avrutin, V.; Granados, A.; Schanz, M.
2011-09-01
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.
The Big Bang of tissue growth: Apical cell constriction turns into tissue expansion.
Janody, Florence
2018-03-05
How tissue growth is regulated during development and cancer is a fundamental question in biology. In this issue, Tsoumpekos et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201705104) and Forest et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201705107) identify Big bang (Bbg) as an important growth regulator of the Drosophila melanogaster wing imaginal disc. © 2018 Janody.
Calixarenes and cations: a time-lapse photography of the big-bang.
Casnati, Alessandro
2013-08-07
The outstanding cation complexation properties emerging from the pioneering studies on calixarene ligands during a five-year period in the early 1980s triggered a big-bang burst of publications on such macrocycles that is still lasting at a distance of more than 30 years. A time-lapse photography of this timeframe is proposed which allows the readers to pinpoint the contributions of the different research groups.
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.
Cross-section of 8Li(α,n)11B: Inhomogeneous Big Bang nucleosynthesis
International Nuclear Information System (INIS)
Cherubini, S.; Rolfs, C.; Strieder, F.; Figuera, P.; Agodi, C.; Alba, R.; Calabretta, L.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; La Cognata, M.; Lamia, L.; Pappalardo, L.; Pizzone, R.G.; Musumarra, A.; Pellegriti, M.G.; Rinollo, A.; Romano, S.; Spitaleri, C.; Tudisco, S.; Tumino, A.
2004-01-01
The cross-section of 8 Li(α,n) 11 B has been measured at E cm =1.25 MeV to be σ(E) =500 mb using novel techniques, i.e. a 8 Li radioactive ion beam produced at the tandem in Catania in combination with a 4 He gas cell and a 4π neutron detector. The value is in fair agreement with previous work strengthening the model of inhomogeneous Big Bang nucleosynthesis. (orig.)
Cross-section of 8Li(α ,n)11B: Inhomogeneous Big Bang nucleosynthesis
Cherubini, S.; Figuera, P.; Musumarra, A.; Agodi, C.; Alba, R.; Calabretta, L.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; La Cognata, M.; Lamia, L.; Pappalardo, L.; Pellegriti, M. G.; Pizzone, R. G.; Rinollo, A.; Rolfs, C.; Romano, S.; Spitaleri, C.; Strieder, F.; Tudisco, S.; Tumino, A.
. The cross-section of 8Li(α ,n)11B has been measured at E cm = 1.25 MeV to be σ (E) = 500 mb using novel techniques, i.e. a 8Li radioactive ion beam produced at the tandem in Catania in combination with a 4He gas cell and a 4π neutron detector. The value is in fair agreement with previous work strengthening the model of inhomogeneous Big Bang nucleosynthesis.
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.
LANGUAGE FORM AND FUNCTION OF CARETAKERS FOUND IN NANNY MCPHEE AND THE BIG BANG MOVIE
Directory of Open Access Journals (Sweden)
Aditya Putri Kusuma Andani
2016-02-01
Full Text Available This study deals with the form and the function of caretaker speech which is found in caretaker’s utterance in Nanny McPhee and The Big Bang Movie. The objectives of this study are (1 to describe the type of language form of the caretaker and (2 to describe the type of language function of the caretaker found in Nanny McPhee and The Big Bang Movie. The type of this research is descriptive qualitative research. The data of this research are the utterance from the caretaker found in manuscript of Nanny McPhee and The Big Bang Movie. The data collection technique is documentation. The technique of analyzing data are descriptive qualitative. The writer uses the theories from Frank (1972 to analyze the type of language form, and M.A.K. Halliday (1977 to analyze the type of language function. The result of this study shows that (1 there are four types of word: noun, verb, adjective, and adverb; three types of phrase: noun phrase, verb phrase, and adverb phrase; and two types of sentence categorized into two. The first category is based on type, namely: declarative, imperative, interrogative, and exclamatory sentence; the second one by number of full predication, namely: simple, compound, complex, and compound-complex sentence. (2 The writer found 6 types of language function, they are: regulatory function, instrumental function, representational function, personal function, interactional function, and imaginative function.
The New Big Bang Theory according to Dimensional Continuous Space-Time Theory
Martini, Luiz Cesar
2014-04-01
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.
The new Big Bang Theory according to dimensional continuous space-time theory
International Nuclear Information System (INIS)
Martini, Luiz Cesar
2014-01-01
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.
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...
Turning big bang into big bounce: II. Quantum dynamics
Energy Technology Data Exchange (ETDEWEB)
Malkiewicz, Przemyslaw; Piechocki, Wlodzimierz, E-mail: pmalk@fuw.edu.p, E-mail: piech@fuw.edu.p [Theoretical Physics Department, Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland)
2010-11-21
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.
Stable emergent Universe - a creation without Big-Bang
Guendelman, E.; Herrera, R.; Labrana, P.; Nissimov, E.; Pacheva, S.
2015-11-01
Based on an earlier introduced new class of generalized gravity-matter models defined in terms of two independent non-Riemannian volume forms (alternative generally covariant integration measure densities) on the space-time manifold, we derive an effective ``Einstein-frame'' theory featuring the following remarkable properties: (i) We obtain effective potential for the cosmological scalar field possessing two infinitely large flat regions which allows for a unified description of both early Universe inflation as well as of present dark energy epoch; (ii) for a specific parameter range the model possesses a non-singular stable ``emergent Universe'' solution which describes an initial phase of evolution that precedes the inflationary phase.
International Nuclear Information System (INIS)
Copeland, E.J.
2003-01-01
In these lectures we review recent advances in string cosmology. Starting with the Dilaton-Moduli Cosmology (known also as the Pre Big Bang), we go on to include the effects of axion fields and address the thorny issue of the Graceful Exit in String Cosmology. This is followed by a review of density perturbations arising in string cosmology and we finish with a brief introduction to the impact moving of five branes on the Dilaton-Moduli cosmological solutions
Directory of Open Access Journals (Sweden)
Daywitt W. C.
2009-04-01
Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.
Before time began the Big Bang and the emerging universe
Satz, Helmut
2017-01-01
What is the origin of the universe? What was there before the universe appeared? We are currently witnessing a second Copernican revolution: neither our Earth and Sun, nor our galaxy, nor even our universe, are the end of all things. Beyond our world, in an endless multiverse, are innumerable other universes, coming and going, like ours or different. Fourteen billion years ago, one of the many bubbles constantly appearing and vanishing in the multiverse exploded to form our universe. The energy liberated in the explosion provided the basis for all the matter our universe now contains. But how could this hot, primordial plasma eventually produce the complex structure of our present world? Does not order eventually always lead to disorder, to an increase of entropy? Modern cosmology is beginning to find out how it all came about and where it all might lead. Before Time Began tells that story.
Testing the Big Bang: Light elements, neutrinos, dark matter and large-scale structure
Schramm, David N.
1991-01-01
Several experimental and observational tests of the standard cosmological model are examined. In particular, a detailed discussion is presented regarding: (1) nucleosynthesis, the light element abundances, and neutrino counting; (2) the dark matter problems; and (3) the formation of galaxies and large-scale structure. Comments are made on the possible implications of the recent solar neutrino experimental results for cosmology. An appendix briefly discusses the 17 keV thing and the cosmological and astrophysical constraints on it.
How Cosmology Became a Science.
Brush, Stephen G.
1992-01-01
Describes the origin of the science of cosmology and the competing theories to explain the beginning of the universe. The big bang theory for the creation of the universe is contrasted with the steady state theory. The author details discoveries that led to the demise of the steady state theory. (PR)
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.
The Graceful Exit in String Cosmology
Cartier, C.; Madden, R.
2000-01-01
We re-examine the graceful exit problem in the pre-big bang scenario of string cosmology, by considering the most general time-dependent classical correction to the Lagrangian with up to four derivatives. By including possible forms for quantum loop corrections we examine the allowed region of parameter space for the coupling constants which enable our solutions to link smoothly the two asymptotic low-energy branches of the pre-big bang scenario, and observe that these solutions can satisfy recently proposed entropic bounds on viable singularity free cosmologies.
The cosmological slingshot scenario: a stringy early times universe
Energy Technology Data Exchange (ETDEWEB)
Germani, Cristiano [D.A.M.T.P., Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Grandi, Nicolas [SISSA, via Beirut 4, 34014 Trieste (Italy); Kehagias, Alex [Physics Division, National Technical University of Athens, 15780 Zografou Campus, Athens (Greece)], E-mail: Germani@sissa.it, E-mail: grandi@fisica.unlp.edu.ar, E-mail: kehagias@central.ntua.gr
2008-07-07
A cosmological model for the early time universe is proposed. In this model, the universe is a wandering brane moving in a warped throat of a Calabi-Yau space. A nonzero angular momentum induces a turning point in the brane trajectory, and leads to a bouncing cosmology as experienced by an observer living on the brane. The universe undergoes a decelerated contraction followed by an accelerating expansion and no big-bang singularity. Although the number of e-folds of accelerated motion is low (less than 2), standard cosmological problems are not present in our model; thanks to the absence of an initial singularity and the violation of energy conditions of mirage matter at high energies. Density perturbations are also calculated in our model and we find a slightly red spectral index with negligible tensorial perturbations in compatibility with WMAP data.
Combining experimental and cosmological constraints on heavy neutrinos
Directory of Open Access Journals (Sweden)
Marco Drewes
2017-08-01
Full Text Available We study experimental and cosmological constraints on the extension of the Standard Model by three right handed neutrinos with masses between those of the pion and W boson. We combine for the first time direct, indirect and cosmological constraints in this mass range. This includes experimental constraints from neutrino oscillation data, neutrinoless double β decay, electroweak precision data, lepton universality, searches for rare lepton decays, tests of CKM unitarity and past direct searches at colliders or fixed target experiments. On the cosmological side, big bang nucleosynthesis has the most pronounced impact. Our results can be used to evaluate the discovery potential of searches for heavy neutrinos at LHCb, BELLE II, SHiP, ATLAS, CMS or a future lepton collider.
Helium synthesis, neutrino flavors, and cosmological implications
International Nuclear Information System (INIS)
Stecker, F.W.
1980-01-01
The problem of the production of helium in the big bang is reexamined in the light of several recent astrophysical observations. These data, and theoretical particle-physics considerations, lead to some important inconsistencies in the standard big-bang model and suggest that a more complicated picture is needed. Thus, recent constraints on the number of neutrino flavors, as well as constraints on the mean density (openness) of the universe, need not be valid
Holographic description of AdS cosmologies
International Nuclear Information System (INIS)
Hertog, Thomas; Horowitz, Gary T.
2005-01-01
To gain insight in the quantum nature of the big bang, we study the dual field theory description of asymptotically anti-de Sitter solutions of supergravity that have cosmological singularities. The dual theories do not appear to have a stable ground state. One regularization of the theory causes the cosmological singularities in the bulk to turn into giant black holes with scalar hair. We interpret these hairy black holes in the dual field theory and use them to compute a finite temperature effective potential. In our study of the field theory evolution, we find no evidence for a 'bounce' from a big crunch to a big bang. Instead, it appears that the big bang is a rare fluctuation from a generic equilibrium quantum gravity state
Scale factor duality for conformal cyclic cosmologies
International Nuclear Information System (INIS)
Silva, University Camara da; Lima, A.L. Alves; Sotkov, G.M.
2016-01-01
The scale factor duality is a symmetry of dilaton gravity which is known to lead to pre-big-bang cosmologies. A conformal time version of the scale factor duality (SFD) was recently implemented as a UV/IR symmetry between decelerated and accelerated phases of the post-big-bang evolution within Einstein gravity coupled to a scalar field. The problem investigated in the present paper concerns the employment of the conformal time SFD methods to the construction of pre-big-bang and cyclic extensions of these models. We demonstrate that each big-bang model gives rise to two qualitatively different pre-big-bang evolutions: a contraction/expansion SFD model and Penrose’s Conformal Cyclic Cosmology (CCC). A few examples of SFD symmetric cyclic universes involving certain gauged Kähler sigma models minimally coupled to Einstein gravity are studied. We also describe the specific SFD features of the thermodynamics and the conditions for validity of the generalized second law in the case of Gauss-Bonnet (GB) extension of these selected CCC models.
International Nuclear Information System (INIS)
Desert, F.-Xavier
2004-01-01
After an introduction comprising some definitions, an historical overview, and a discussion of the paradoxical Universe, this course proposes a presentation of fundamental notions and theories, i.e. the restrained relativity and the universal gravitation. The next part addresses the general relativity with the following notions: space-time metrics and principle of generalised covariance, basics of tensor analysis, geodesics, energy-pulse tensor, curvature, Einstein equations, Newtonian limit, Schwarzschild metrics, gravitational waves, gravitational redshift. The next part addresses the standard cosmology with the Friedmann-Robertson-Walker metrics and the Friedmann-Lemaitre equations of the evolution of the Universe. The Universe expansion is then addressed: distances and horizons, Hubble law, determination of the Hubble constant. The next chapter deals with the constituents of the Universe: light matter, baryonic dark matter, black matter, supernovae, Universe acceleration and black energy. Then comes the nuclear evolution of the Universe: thermodynamics of the primordial Universe, the matter-antimatter asymmetry, from quarks to atoms, cosmic abundance, neutron cosmological background, matter-radiation equality, cosmo-chronology or the age of the Universe. The next chapter addresses the cosmological background at 3 K: sky electromagnetic spectrum, measurement of CMB anisotropies, interpretation of anisotropies, growth of perturbations. The last chapter addresses the quantum field theory and inflation: paradoxes of the standard Big Bang, the simple inflation, noticeable consequences
Cosmological implications of light element abundances: theory.
Schramm, D N
1993-06-01
Primordial nucleosynthesis provides (with the microwave background radiation) one of the two quantitative experimental tests of the hot Big Bang cosmological model (versus alternative explanations for the observed Hubble expansion). The standard homogeneous-isotropic calculation fits the light element abundances ranging from 1H at 76% and 4He at 24% by mass through 2H and 3He at parts in 105 down to 7Li at parts in 1010. It is also noted how the recent Large Electron Positron Collider (and Stanford Linear Collider) results on the number of neutrinos (Nnu) are a positive laboratory test of this standard Big Bang scenario. The possible alternate scenario of quark-hadron-induced inhomogeneities is also discussed. It is shown that when this alternative scenario is made to fit the observed abundances accurately, the resulting conclusions on the baryonic density relative to the critical density (Omegab) remain approximately the same as in the standard homogeneous case, thus adding to the robustness of the standard model and the conclusion that Omegab approximately 0.06. This latter point is the driving force behind the need for nonbaryonic dark matter (assuming total density Omegatotal = 1) and the need for dark baryonic matter, since the density of visible matter Omegavisible < Omegab. The recent Population II B and Be observations are also discussed and shown to be a consequence of cosmic ray spallation processes rather than primordial nucleosynthesis. The light elements and Nnu successfully probe the cosmological model at times as early as 1 sec and a temperature (T) of approximately 10(10) K (approximately 1 MeV). Thus, they provided the first quantitative arguments that led to the connections of cosmology to nuclear and particle physics.
Researchers Develop Method to Identify Sparticles in Big Bang Conditions
2008-01-01
Three Northeastern University researchers have proposed a new approach for the highly anticipated discovery of supersymmetric particles, often called sparticles. The methodology, which was published in the December 21 issue of the Physical Review Letters, is based on identifying the hierarchical mass patterns of sparticles, which are assumed to exist in a new class of particle physics theories beyond the Standard Model.
Pashitskii, E. A.; Pentegov, V. I.
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 the expanding cold Universe, filled with nonlinear scalar field φ and neutral matter with equation of state p = vɛ (where p and ɛ are pressure and energy density of matter). We consider a Lagrangian for scalar field in curved space-time with nonlinearity φ, which along with the quadratic term -ΣR|φ|2 (where Σ is interaction constant and R is scalar curvature) contains a term ΣR(φ +φ+) linear in φ. Due to this term the condition for the extrema of the potential energy of the scalar field is given by a cubic equation. Provided v > 1/3 the scalar curvature R = [κ(3v-1)ɛ - 4Γ (where κ and Γ are Einstein's gravitational and cosmological constants) decreases along with decreasing " in the process of the Universe's expansion, and at some critical value Rc < 0 a first-order phase transition occurs, driven by an "external field" parameter proportional to R. Given certain conditions the critical radius of the early Universe at the point of the first-order phase transition may reach arbitrary large values, so this scenario of unrestricted "inflation" of the Universe may be called "hyperinflation". Beyond the point of phase transition the system is rolling down into the potential minimum releasing the potential energy of scalar field with subsequent powerful heating of the Universe playing the role of "Big Bang".
Energy Technology Data Exchange (ETDEWEB)
Biswas, Tirthabir [Department of Physics, St. Cloud State University, St. Cloud, MN 56301 U.S.A (United States); Koivisto, Tomi [Institute for Theoretical Physics and Spinoza Institute, Postbus 80.195, 3508 TD Utrecht (Netherlands); Mazumdar, Anupam, E-mail: tbiswas@loyno.edu, E-mail: T.S.Koivisto@uu.nl, E-mail: a.mazumdar@lancaster.ac.uk [Physics Department, Lancaster University, Lancaster, LA1 4YB (United Kingdom)
2010-11-01
One of the greatest problems of standard cosmology is the Big Bang singularity. Previously it has been shown that non-local ghostfree higher-derivative modifications of Einstein gravity in the ultra-violet regime can admit non-singular bouncing solutions. In this paper we study in more details the dynamical properties of the equations of motion for these theories of gravity in presence of positive and negative cosmological constants and radiation. We find stable inflationary attractor solutions in the presence of a positive cosmological constant which renders inflation geodesically complete, while in the presence of a negative cosmological constant a cyclic universe emerges. We also provide an algorithm for tracking the super-Hubble perturbations during the bounce and show that the bouncing solutions are free from any perturbative instability.
An origin of the universe: a model alternative to Big Bang
Mercik, Andrzej; Mercik, Szymon
2006-01-01
We propose a new approach to the model of an origin of the universe built by Oscar Klein and Hannes Alfv\\'{e}n. Some modifications of assumptions underlying the model result in a possible scenario of the universe creation consistent with observations. We explain the large scale structre of the universe and we estimate the Hubble constant value as well as the number of galaxies in the universe. The model does not require many assumptions made in the model based on the Big Bang idea.
Quantum Big Bang without fine-tuning in a toy-model
International Nuclear Information System (INIS)
Znojil, Miloslav
2012-01-01
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 = t c . 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 = t c .
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.
Big Bang to Little Bang ---- Study of Quark-Gluon Plasma
Indian Academy of Sciences (India)
Tapan K. Nayak
2013-07-05
Jul 5, 2013 ... BIG BANG. Time = 13.7 billion years, Temp = 3 K. Time = 10-43 s, Temp = 1019 GeV. Time = 10-35 s, Temp = 1015 GeV. Time = 10-11 s, Temp = 103 GeV. Time = 10-6 s, Temp = 1 GeV. Time = 1sec, Temp = 1 MeV. Time = 3minutes. Time = 400,000 years. Temp = 1 eV (11604 K). T. Time. Temp. The Plank ...
Constraining antimatter domains in the early universe with big bang nucleosynthesis.
Kurki-Suonio, H; Sihvola, E
2000-04-24
We consider the effect of a small-scale matter-antimatter domain structure on big bang nucleosynthesis and place upper limits on the amount of antimatter in the early universe. For small domains, which annihilate before nucleosynthesis, this limit comes from underproduction of 4He. For larger domains, the limit comes from 3He overproduction. Since most of the 3He from &pmacr; 4He annihilation are themselves annihilated, the main source of primordial 3He is the photodisintegration of 4He by the electromagnetic cascades initiated by the annihilation.
Quantum origin of pre-big-bang collapse from induced matter theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Bellini, Mauricio, E-mail: mbellini@conicet.gov.ar [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, C.P. 7600, Mar del Plata (Argentina); Instituto de Investigaciones Fisicas de Mar del Plata (IFIMAR), Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina)
2012-03-23
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 of the effective 4D scalar field {phi}{sup Macron }.
Quantum Big Bang without fine-tuning in a toy-model
Znojil, Miloslav
2012-02-01
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.
Quantum origin of pre-big-bang collapse from induced matter theory of gravity
Bellini, Mauricio
2012-03-01
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 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
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.
Big Bang Nucleosynthesis in Visible and Hidden-Mirror Sectors
Directory of Open Access Journals (Sweden)
Paolo Ciarcelluti
2014-01-01
dark matter. The production of ordinary nuclides shows differences from the standard model for a ratio of the temperatures between mirror and ordinary sectors x=T′/T≳0.3, and they present an interesting decrease of the abundance of Li7. For the mirror nuclides, instead, one observes an enhanced production of He4, which becomes the dominant element for x≲0.5, and much larger abundances of heavier elements.
Big bang machine searching for the Higgs boson particle
2015-01-01
On July 4, 2012, scientists at the giant atom smashing facility at CERN announced the discovery of a subatomic particle that seems like a tantalizingly close match to the elusive Higgs Boson, thought to be responsible for giving all the stuff in the universe its mass. Since it was first proposed nearly fifty years ago, the Higgs has been the holy grail of particle physicists: in finding it they validate the “standard model” that underlies all of modern physics and open the door to new discoveries when CERN’s giant collider switches on at higher power in 2015.
Directory of Open Access Journals (Sweden)
Sarah Aretz
2016-12-01
However, it is not yet clear in science education if students’ conceptions about the Big Bang vary by nationality, and therefore, if it is possible to apply the same teaching modules to students from different countries, who may have diverse social and cultural backgrounds and different curricula. These conceptions with which students enter the classroom were investigated in our study. We implemented an open-ended questionnaire survey in Germany, with questions based on recent U.S. studies. The results clearly showed, with high interrater reliabilities, widespread misconceptions like the Big Bang being an explosion of preexisting matter into empty space or the universe having a centre. Furthermore, a comparison of results from researchers in the USA, Sweden and Germany allowed us to identify differences in students’ conceptions between the countries. Our findings appear to indicate that German students have slightly better pre-instructional conceptions about the Big Bang theory.
Big-bang nucleosynthesis with high-energy photon injection
Energy Technology Data Exchange (ETDEWEB)
Holtmann, Erich Nielsen [Univ. of California, Berkeley, CA (United States)
1999-05-01
The author discusses the photodissociation of light elements due to the radiative decay of a massive particle, and he has shown how to constrain the model parameters from the observed light-element abundances. He adopted two quasar absorption system (QAS) D/H values, as well as solar system data for D/H and ^{3}He/H. For each of these, he used two ^{4}He values. He presents his results in terms of the confidence level at which each theoretical parameter set (i.e., the set of properties of a radiatively decaying particle) is excluded by the observed abundances. His algorithm for computing the confidence level is consistent and general enough to apply not only to the scenarios investigated in this work, but also to many other non-standard theories of BBN.
On initial conditions for the hot big bang
International Nuclear Information System (INIS)
Bezrukov, F.; Gorbunov, D.; Shaposhnikov, M.
2009-01-01
We analyse the process of reheating the Universe in the electroweak theory where the Higgs field plays a role of the inflaton. We estimate the maximal temperature of the Universe and fix the initial conditions for radiation-dominated phase of the Universe expansion in the framework of the Standard Model (SM) and of the νMSM—the minimal extension of the SM by three right-handed singlet fermions. We show that the inflationary epoch is followed by a matter dominated stage related to the Higgs field oscillations. We investigate the energy transfer from Higgs-inflaton to the SM particles and show that the radiation dominated phase of the Universe expansion starts at temperature T r ≅ (3−15) × 10 13 GeV, where the upper bound depends on the Higgs boson mass. We estimate the production rate of singlet fermions at preheating and find that their concentrations at T r are negligibly small. This suggests that the sterile neutrino Dark Matter (DM) production and baryogenesis in the νMSM with Higgs-driven inflation are low energy phenomena, having nothing to do with inflation. We study then a modification of the νMSM, adding to its Lagrangian higher dimensional operators suppressed by the Planck scale. The role of these operators in Higgs-driven inflation is clarified. We find that these operators do not contribute to the production of Warm Dark Matter (WDM) and to baryogenesis. We also demonstrate that the sterile neutrino with mass exceeding 100 keV (a Cold Dark Matter (CDM) candidate) can be created during the reheating stage of the Universe in necessary amounts. We argue that the mass of DM sterile neutrino should not exceed few MeV in order not to overclose the Universe
Energy Technology Data Exchange (ETDEWEB)
Dai, Wei-Ming; Cai, Rong-Gen [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Physical Sciences, Beijing (China); Guo, Zong-Kuan [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China); University of Chinese Academy of Sciences, School of Astronomy and Space Science, Beijing (China); Zhang, Yuan-Zhong [Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, P.O. Box 2735, Beijing (China)
2017-06-15
We investigate constraints on Lorentz invariance violation in the neutrino sector from a joint analysis of big bang nucleosynthesis and the cosmic microwave background. The effect of Lorentz invariance violation during the epoch of big bang nucleosynthesis changes the predicted helium-4 abundance, which influences the power spectrum of the cosmic microwave background at the recombination epoch. In combination with the latest measurement of the primordial helium-4 abundance, the Planck 2015 data of the cosmic microwave background anisotropies give a strong constraint on the deformation parameter since adding the primordial helium measurement breaks the degeneracy between the deformation parameter and the physical dark matter density. (orig.)
International Nuclear Information System (INIS)
Feng, Jonathan L.
2005-01-01
Cosmology now provides unambiguous, quantitative evidence for new particle physics. I discuss the implications of cosmology for supersymmetry and vice versa. Topics include: motivations for supersymmetry; supersymmetry breaking; dark energy; freeze out and WIMPs; neutralino dark matter; cosmologically preferred regions of minimal supergravity; direct and indirect detection of neutralinos; the DAMA and HEAT signals; inflation and reheating; gravitino dark matter; Big Bang nucleosynthesis; and the cosmic microwave background. I conclude with speculations about the prospects for a microscopic description of the dark universe, stressing the necessity of diverse experiments on both sides of the particle physics/cosmology interface
Instanton transition in thermal and moduli deformed de Sitter cosmology
International Nuclear Information System (INIS)
Kounnas, Costas; Partouche, Herve
2008-01-01
We consider the de Sitter cosmology deformed by the presence of a thermal bath of radiation and/or time-dependent moduli fields. Depending on the parameters, either a first or second-order phase transition can occur. In the first case, an instanton allows a double analytic continuation. It induces a probability to enter the inflationary evolution by tunnel effect from another cosmological solution. The latter starts with a big bang and, in the case the transition does not occur, ends with a big crunch. A temperature duality exchanges the two cosmological branches. In the limit where the pure de Sitter universe is recovered, the tunnel effect reduces to a 'creation from nothing', due to the vanishing of the big bang branch. However, the latter may be viable in some range of the deformation parameter. In the second case, there is a smooth evolution from a big bang to the inflationary phase
Deep mixing of 3He: reconciling Big Bang and stellar nucleosynthesis.
Eggleton, Peter P; Dearborn, David S P; Lattanzio, John C
2006-12-08
Low-mass stars, approximately 1 to 2 solar masses, near the Main Sequence are efficient at producing the helium isotope 3He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3He with the predictions of both stellar and Big Bang nucleosynthesis. Here we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus, we are able to remove the threat that 3He production in low-mass stars poses to the Big Bang nucleosynthesis of 3He.
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.
Galaxies 800 million years after the Big Bang seen with the Atacama Large Millimetre Array
Smit, Renske
2018-01-01
The identification of galaxies in the first billion years after the Big Bang presents a challenge for even the largest optical telescopes. When the Atacama Large Millimetre Array (ALMA) started science operations in 2011 it presented a tantalising opportunity to identify and characterise these first sources of light in a new window of the electromagnetic spectrum. I will present new sources successfully identified at z=6.8 using ALMA; the first spectroscopic confirmations of typical star-forming galaxies during the Epoch or Reionization using a sub-millimetre telescope. Moreover, these observations reveal the gas kinematics of such distant sources for the first time. The velocity gradient in these galaxies indicate that these galaxies likely have similar dynamical properties as the turbulent, yet rotation-dominated disks that have been observed for Hα emitting galaxies 2 billion years later at cosmic noon. This novel approach for confirming galaxies during Reionization paves the way for larger studies of distant galaxies with spectroscopic redshifts. Particularly important, this opens up opportunities for the measurement of high angular-resolution dynamics in galaxies less than one billion years after the Big Bang.
Constraints on lifetime and mass of heavy lepton neutrinos imposed by big bang nucleosynthesis
International Nuclear Information System (INIS)
Miyama, Shoken; Sato, Katsuhiko
1978-01-01
If there exist massive neutral leptons (heavy neutrinos), they would have been produced in thermal equilibrium in the early stages of the universe. The effects of their presence and decay on the big bang nucleosynthesis are investigated in detail and abundances of the products 4 He, 2 H and 7 Li are compared with the observed cosmic abundances. We have determined a region in the lifetime-mass diagram of the heavy neutrino which should be ruled out in order for the big bang nucleosynthesis not to conflict with observed abundances of the elements. In addition, if a lower limit of the lifetime obtained from the Weinberg-Salam type theory, tau>=6 x 10 7 (1 MeV/m sub(νh)) 5 sec, is assumed, where m sub(νh) is the mass of the heavy neutrino, the mass range of 70 eV< m sub(νh)<10 MeV is ruled out. The other constraints on the mass and the lifetime obtained from astrophysical considerations are also discussed and summarized. (author)
Classical propagation of strings across a big crunch/big bang singularity
International Nuclear Information System (INIS)
Niz, Gustavo; Turok, Neil
2007-01-01
One of the simplest time-dependent solutions of M theory consists of nine-dimensional Euclidean space times 1+1-dimensional compactified Milne space-time. With a further modding out by 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 [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
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 ...
Deep Mixing of 3He: Reconciling Big Bang and Stellar Nucleosynthesis
International Nuclear Information System (INIS)
Eggleton, P P; Dearborn, D P; Lattanzio, J
2006-01-01
Low-mass stars, ∼ 1-2 solar masses, near the Main Sequence are efficient at producing 3 He, which they mix into the convective envelope on the giant branch and should distribute into the Galaxy by way of envelope loss. This process is so efficient that it is difficult to reconcile the low observed cosmic abundance of 3 He with the predictions of both stellar and Big Bang nucleosynthesis. In this paper we find, by modeling a red giant with a fully three-dimensional hydrodynamic code and a full nucleosynthetic network, that mixing arises in the supposedly stable and radiative zone between the hydrogen-burning shell and the base of the convective envelope. This mixing is due to Rayleigh-Taylor instability within a zone just above the hydrogen-burning shell, where a nuclear reaction lowers the mean molecular weight slightly. Thus we are able to remove the threat that 3 He production in low-mass stars poses to the Big Bang nucleosynthesis of 3 He
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...
Testing the big bang: Light elements, neutrinos, dark matter and large-scale structure
Energy Technology Data Exchange (ETDEWEB)
Schramm, D.N. (Chicago Univ., IL (United States) Fermi National Accelerator Lab., Batavia, IL (United States))
1991-06-01
In this series of lectures, several experimental and observational tests of the standard cosmological model are examined. In particular, detailed discussion is presented regarding nucleosynthesis, the light element abundances and neutrino counting; the dark matter problems; and the formation of galaxies and large-scale structure. Comments will also be made on the possible implications of the recent solar neutrino experimental results for cosmology. An appendix briefly discusses the 17 keV thing'' and the cosmological and astrophysical constraints on it. 126 refs., 8 figs., 2 tabs.
Anisotropic cosmological models with bulk viscosity and particle ...
Indian Academy of Sciences (India)
equations in two types of cosmologies, one with power-law expansion and the other with expo- nential expansion. Cosmological model with power-law expansion has a Big-Bang singularity at time t = 0, whereas the model with exponential expansion has no finite singularity. We study bulk viscosity and particle creation in ...
Neutrinos in astrophysics and cosmology
Energy Technology Data Exchange (ETDEWEB)
Balantekin, A. B. [Physics Department, University of Wisconsin, Madison WI 53706 (United States)
2016-06-21
Neutrinos play a crucial role in many aspects of astrophysics and cosmology. Since they control the electron fraction, or equivalently neutron-to-proton ratio, neutrino properties impact yields of r-process nucleosynthesis. Similarly the weak decoupling temperature in the Big Bang Nucleosynthesis epoch is exponentially dependent on the neutron-to-proton ratio. In these conference proceedings, I briefly summarize some of the recent work exploring the role of neutrinos in astrophysics and cosmology.
Jittoh, Toshifumi; Kohri, Kazunori; Koike, Masafumi; Sato, Joe; Shimomura, Takashi; Yamanaka, Masato
2010-12-01
We calculate the relic density of stau at the big-bang nucleosynthesis era in the coannihilation scenario of the minimal supersymmetric standard model. In this scenario, stau can be long lived and have significance in the remediation of light elements abundances. The freeze-out of stau is corroborated by solving the Boltzmann equation numerically, and the parameter dependence of the relic density is investigated. The possibility of solving the Li7 problem is examined by taking account into the long-lived stau. By adopting an observational value of Li7 in [J. Meléndez and I. Ramírez, Astrophys. J. 615, L33 (2004).ASJOAB0004-637X10.1086/425962], we get minimal supersymmetric standard model parameter space in which abundances of both dark matter and all of the light elements are reproduced in accordance with observations. We also address the influence of intergenerational mixing on our calculation.