Showing papers on "Big Rip published in 1987"
TL;DR: A cosmological model with an additional term Λ(x)gμν in the energy-momentum tensor is introduced in this article, and the model displays a flow of energy from curvature to matter such that the entropy of matter is not conserved.
299 citations
TL;DR: In this paper, a review of recent results concerning the global structure of the inflationary universe, which have been obtained within stochastic approach to inflation, is given, and it is shown in particular that the evolution of the universe in the chaotic inflation scenario has no end and may have no beginning.
Abstract: In this article we give a review of recent results concerning the global structure of the inflationary universe, which have been obtained within stochastic approach to inflation. It is shown in particular that the evolution of the universe in the chaotic inflation scenario has no end and may have no beginning. In this scenario the major part of the physical volume of the universe always remains in the inflationary phase. During inflation the universe becomes divided into many exponentially large domains, inside which all possible metastable vacuum states and all possible types of compactification compatible with inflation are realized.
220 citations
01 Jan 1987
TL;DR: In this article, it was shown that galaxies are surrounded by massive halos and that there is a lot more matter in a cluster than we can observe, and there must be sufficient of it in the form of some intergalactic medium to prevent the member galaxies from escaping.
Abstract: The clusters of galaxies have a diameter greater than 1 Mpc. The member galaxies have velocities of the order of 1000 km/sec and require a billion years to cross them. In some cases the galaxies require even more time to cross the cluster once, a good fraction of the age of the Universe. Even so, the velocities of galaxies inside a cluster are much greater than the velocities of stars inside a galaxy. For example, the Sun moves with a velocity of 220 km/sec about the galactic centre, while the galaxies in the Coma cluster move with velocities of 2000 km/sec. This could mean that some groups and clusters of galaxies may be unstable, having insufficient mass to hold the member galaxies together. It is more likely, however, that there is a lot more matter in a cluster than we can observe. It must be in the form of some intergalactic medium, and there must be sufficient of it to prevent the member galaxies from escaping. We have two indications that this is true: (1) The velocity curves of galaxies show that galaxies are surrounded by massive halos. (2) We frequently observe matter between the galaxies.
144 citations
Journal Article•
131 citations
TL;DR: In this paper, it is shown that the large-scale quantum fluctuations of the scalar field generated in the chaotic inflation scenario lead to an infinite process of self-reproduction of inflationary mini-universes.
Abstract: It is shown that the large-scale quantum fluctuations of the scalar field generated in the chaotic inflation scenario lead to an infinite process of self-reproduction of inflationary mini-universes. A model of an eternally existing chaotic inflationary universe is suggested. It is pointed out that whereas the universe locally is very homogeneous as a result of inflation, which occurs at the classical level, the global structure of the universe is determined by quantum effects and is highly non-trivial. The universe consists of exponentially large number of different mini-universes, inside which all possible (metastable) vacuum states and all possible types of compactification are realized. The picture differs crucially from the standard picture of a one-domain universe in a "true" vacuum state. Our results may serve as a justification of the anthropic principle in the inflationary cosmology. These results may have important implications for the elementary particle theory as well. Namely, since all possible types of mini-universes, in which inflation may occur, should exist in our universe, there is no need to insist (as it is usually done) that in realistic theories the vacuum state of our type should be the only possible one or the best one.
91 citations
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01 Jan 1987
TL;DR: In this paper, the early universe originates from the cosmic background radiation of the universe, and the first detected signature of dark matter from the Halo of our galaxy was detected. But the early galaxies were not observed until the early 1970s.
Abstract: The Quantum Origin of the Universe.- Cosmology and Particle Physics.- Supersymmetry and the Early Universe.- Relativistic Cosmology.- Yet Another Scenario for Galaxy Formation.- Non-Gaussian Fluctuations.- N-body Methods and the Formation of Large-Scale Structure.- Numerical Relativity and Cosmology.- Distortions and Anisotropies of the Cosmic Background Radiation.- The Early Universe - An Observer's View.- Can the Solar Neutrino Problem be the First Detected Signature of Dark Matter from the Halo of Our Galaxy?.- Detecting Cold Dark Matter Candidates.- The Early Universe: Historical and Philosophical Perspectives.
74 citations
TL;DR: The notions of phase transition and causality, combined with the standard cosmological model, lead to the appearance of topological defects in the early Universe, and the whole Universe takes on a winding number.
Abstract: The notions of phase transition and causality, combined with the standard cosmological model, lead to the appearance of topological defects in the early Universe. The most familiar types of defects are solitons, strings, and domain walls. Another type---textures---can exist when the spatial universe is compact. When these appear the whole Universe takes on a winding number, and the consequences are quite amusing.
51 citations
TL;DR: In this paper, it is shown that the existence of such a limit leads necessarily to modify the standard model in a way which avoids the initial singularity and introduces an inflationary expansion of the power-law type.
Abstract: It is stressed that the very early Universe provides an example of a physical system in which the phenomenological consequences of a natural limit for the accelerations cannot be neglected. It is shown that the existence of such limit leads necessarily to modify the standard model in a way which avoids the initial singularity and introduces an inflationary expansion of the power-law type. The possibility is also suggested to relate the maximal acceleration hypothesis to a decaying vacuum scenario, in which the cosmological constant is proportional to the radiation density, and is then a decreasing function of the cosmic time.
35 citations
TL;DR: In this paper, general limits on the cosmological constant (or equivalently the vacuum energy density) were derived for an inflationary universe under the general assumption of global hyperbolicity and without the use of any special properties like spherical symmetry or homogeneity of the underlying spacetime.
32 citations
01 May 1987
TL;DR: In this paper, the authors discuss what criteria a cosmological theory must satisfy in order to be acceptable in the plasma universe and discuss the criteria that must be satisfied in the visual light universe.
Abstract: Space observations have opened the spectral regions of X-rays and γ-rays, which are produced by plasma processes. The Plasma Universe derived from observations in these regions is drastically different from the now generally accepted ‘Visual Light Universe’ based on visual light observations alone. Historically this transition can be compared only to the transition from the the geocentric to the heliocentric cosmology.The purpose of this paper is to discuss what criteria a cosmological theory must satisfy in order to be acceptable in the Plasma Universe.
21 citations
TL;DR: In this article, the wave function of the universe is interpreted as giving the probability for the universe to appear from nothing, which is not a correct interpretation since the normalization presupposes a universe, not nothing.
Abstract: Hawking and Hartle interpreted their wave function of the universe as giving the probability for the universe to appear from nothing. However, this is not a correct interpretation, since the normalization presupposes a universe, not nothing. Transition probabilities require a measure on the initial state and a physical result requires a physical initial state.
TL;DR: In this article, a new solution of Einstein's field equations is found, which describes a dust-filled Kantowski-Sachs universe with a positive cosmological constant, where the mass density of the dust is positive.
TL;DR: The Hartle-Hawking wave function of a homogeneous-isotropic rotating universe has been found in this article and it is shown that the universe with large global rotation is unlikely.
01 Jan 1987
TL;DR: Hartle as discussed by the authors reviewed and outlined the basic physical nature of these two mechanisms, leaving out the details, and referred the reader to more comprehensive reviews and to the primary literature throughout these lectures.
Abstract: The observed universe is homogeneous and isotropic on the largest observable scales. The best evidence for this comes from observations of the cosmic background radiation (CBR). On smaller scales, a striking amount of structure can be seen — galaxies, clusters of galaxies, and the “large scale structure” in the form of possible filaments, bubbles, sheets or voids. The best proximate explanation for this structure is small amplitude perturbations in the early universe, which grew by gravitational instability into the observed large scale structure during the expansion of the universe. At some time in the future when we have a complete theory of the universe and its initial conditions — see James Hartle’s lectures in this volume1 for some promising ideas toward such a theory — both the overall homogeneity and the structure should be a calculable consequence of the theory. Until then, people have made partial progress toward understanding the genesis of structure on a homogeneous background, based on the laws of fundamental physics as currently known. At this time we have at least two possible fundamental mechanisms for generation of the conjectural initial perturbations, namely quantum fluctuations, or thermodynamic fluctuations of a particular sort. My purpose in these lectures is to review and outline the basic physical nature of these two mechanisms, leaving out the details. Both mechanisms are well reviewed in the literature, and the reader will be referred both to more comprehensive reviews and to the primary literature throughout these lectures.
TL;DR: In this article, exact solutions for radiation-filled cosmological differential equations of Brans-Dicke theory with the assumption that the radius of curvatureQ of the universe varies directly as thenth power of time were obtained.
Abstract: Considering a Robertson-Walker line element, exact solutions are obtained for radiation-filled cosmological differential equations of Brans-Dicke theory with the assumption that the radius of curvatureQ of the universe varies directly as thenth power of time. The solution is found to be valid for closed space only and the coupling constantw of the scalar tensor theory is necessarily negative. The radius of curvature of increases linearly with respect to the age of the universe, while the gravitational constantk varies directly as the square of the radius of the universe. The solution obtained is in contradiction to Dirac's hypothesis, in which the gravitational constant should decrease with time in an expanding universe.
TL;DR: In this paper, it was shown that the universe departed from the thermal equilibrium in the past by an interplay among dynamic instability, matter differentiation and weakening of some interactions, and that this was the outcome of an interaction between dynamic instability and matter differentiation.
Abstract: The relic microwave radiation indicates that the universe was in the state of thermal equilibrium (heat death) in the past. The question arises how could it happen that the universe departed from the thermal equilibrium? According to the models presented here this was the outcome of an interplay among dynamic instability, matter differentiation and weakening of some interactions.
TL;DR: In this paper, the Stanyukovich formula S ∼ N3/2 is derived for the rotation of the observable universe, which is based on the existence of Eddington-Dirac large numbers.
Abstract: We study the problem of a possible rotation of the observable Universe (Metagalaxy) from the point of view of the general-relativistic theory of gravitation. We employ the concept of a hierarchical structure of reality, based on the existence of Eddington-Dirac “large numbers.” From the Einstein equations in their Landau-Raichaudhuri form we derive expressions for the angular momentum and angular velocity ω of the rotation of the Metagalaxy. These expressions give an ω coinciding in order of magnitude with the observed one. Using the formulas obtained, and using the hierarchy relation (“large number” relation), we obtain the Stanyukovich formula S ∼ N3/2 which relates the number of nucleons in the Metagalaxy N and its angular momentum S. We show that the angular velocity may decrease in inverse proportionality to the scale factor, which may explain its small value at this time. We show that the source of rotation in cosmology can be space-time torsion, induced by the spin of fermionic matter.
TL;DR: In this paper, it was shown that, in order for plane accumulations of matter with a density much greater than the mean density of the matter in the Universe to exist in the universe at the present time, perturbations of the density are necessary at the time of recombination.
Abstract: The general solution of Einstein's equations with the energy-momentum tensor of an ideal dust in the plane-symmetric case is used to obtain the generalization of the solutions for scalar perturbations in a spatial-plane Friedman universe. It is shown that, in order for plane accumulations of matter with a density much greater than the mean density of the matter in the Universe to exist in the Universe at the present time, perturbations of the density are necessary at the time of recombination, (δɛ/ɛ)p ∿ 10−4.
TL;DR: In this paper, the issue of whether the present observational evidence that the mean mass density of the universe is less than the critical density (i.e., μ < 1) implies an infinite future expansion of the observable universe is discussed.
Abstract: The issue of whether the present observational evidence that the mean mass density of the universe is less than the critical density (i.e., μ<1) implies an infinite future expansion of the universe is discussed. Although in conventional cosmological scenarios μ<1 necessarily leads to a universe that will grow infinitely old, this conclusion can be avoided in ways which are reasonably natural. One of these is to assume the existence of a small negative cosmological constant. Another way is to postulate the existence of unstable fields with a long time scale for the onset of the instability. An example is a scalar field with a negative squared mass and ¦m¦≲10−32eV. Other examples include fields for which the instability is generated by quantum corrections in curved space-time. All of these are capable of halting the expansion of an open universe and forcing it to recollapse into a “big crunch.”
TL;DR: In this paper, a model for continuously following a model of a universe that in its evolution makes a transition from one type of universe to another is presented, where the epoch when the universe changes from being radiation-dominated to being matter-dominated is related to the epoch of radiation decoupling from matter.
Abstract: A method is given for continuously following a model of a universe that in its evolution makes a transition from one type of universe to another. As an illustration, a universe is considered that initially is radiation-dominated and then makes a transition to a final matter-dominated Einstein-de Sitter universe. The epoch when the universe changes from being radiation-dominated to being matter-dominated is found and is related to the epoch when radiation decouples from matter.
TL;DR: In this paper, it was shown how the vacuum energy may dominate the energy density of the very early universe even when the Higg's field in the Coleman-Weinberg potential is confined near the origin at extremely high temperature and the inflationary scenario may start.
Abstract: Here it is shown how the vacuum energy may dominate the energy density of the very early universe even when the Higg's field in the Coleman-Weinberg potential is confined near the origin at extremely high temperature and the inflationary scenario may start. Also it is shown that supersymmetry breaking may be responsible for this phenomenon. Thus it provides another support for the hypothesis of primordial inflation proposed by Ellis et al. [4],
01 Jan 1987
TL;DR: Cosmology is unique among sciences because it deals with the whole physical universe, while other sciences deal with only part of it, or with certain aspects of physical reality as discussed by the authors, which makes it unique among all sciences.
Abstract: Cosmology is unique among sciences because it deals with the whole physical Universe, while other sciences deal with only part of it, or with certain aspects of physical reality.
TL;DR: In this article, the conceptual basis of assigning a beginning and an age to the universe is discussed, especially with regard to big bang scenarios, and it is shown how to assign the beginning and the age of the universe to the Big Bang.
Abstract: The conceptual basis of assigning a beginning and an age to the universe is discussed, especially with regard to big bang scenarios.
TL;DR: In this article, the authors argue that the density of the universe is not the minimum required to prevent indefinite expansion, but the evidence is not all on their side, and they point out that the existence of infinite numbers of stars is not a sign of infinite expansion.
Abstract: Astronomers hanker after the notion that the density of the Universe is the minimum required to prevent indefinite expansion, but the evidence is not all on their side.
TL;DR: In this paper, the exterior field of the Robertson-Walker metric in the Lyttleton-Bondi universe with cosmological constant was considered and it was shown that the exterior solution of this universe is simply the empty space-time of general relativity.
Abstract: The exterior field of the Robertson-Walker metric in the Lyttleton-Bondi universe with cosmological constant is considered. It is shown that in the presence of cosmological constant, the exterior solution of this Universe is simply the empty space-time of general relativity.
TL;DR: In this article, the cosmological constant A and the density parameter f.1 depend on the decay time and the cosmic ages are found to be of the order of or larger than 0.6/Ho in the fitted models.
Abstract: Decaying-particle universe models with nonzero cosmological constant A are considered in connection with the recent observational [Galaxy number count N-redshift zl relation and it is shown that the best-fitted values of A and the density parameter f.1 depend on the decay time td: For Hotd =0.05, we get .G,=0.494 and Ac2/(3Ho2) = -0.046. If the model is required to be fiat, the fitted values are f.1=0.689 and Ac2/(3Ho2)=0.311 for Hotd=0.05. The cosmic ages are found to be of the order of or larger than 0.6/Ho in the fitted models. Moreover the nonlinear growth of the density perturbations is considered and the evolution of the baryon density is examined in several fitted models.