Showing papers on "Big Rip published in 1986"
TL;DR: An empty Kantowski-Sachs universe model with a cosmological constant was found in this article, and the universe emerges from a pancake singularity at t = 0.
Abstract: An empty Kantowski-Sachs universe model with a cosmological constant is found. It emerges from a pancake singularity at t = 0. If the cosmological constant is of the same magnitude as that induced by a GUT vacuum phase transition, this universe enters an exponentially expanding era at the GUT time t/sub G/ = 1,0x10/sup -35/ sec. The universe then isotropizes rapidly, and the shear diminishes by a factor of 10/sup -56/ if this inflationary era lasts for t/sub 1/ = 1,3x10/sup -33/ sec, as is the case in Guth's inflationary universe model.
44 citations
TL;DR: In this paper, conditions on the universe are derived that must hold if such processing and storage is to be possible, and it is shown that it is possible only if the universe is closed and only if its future c-boundary consists of a single point.
Abstract: A true universal Turing machine can be constructed only if it is possible to actually process and store an infinite number of bits between now and the end of the universe. Conditions on the universe are derived that must hold if such processing and storage is to be possible. In particular, it is shown that it is possible only if the universe is closed and only if its futurec-boundary consists of a single point.
28 citations
TL;DR: The possible thermal histories of the universe during the epoch z = 10-1000 are studied in this article, where expressions for fractional ionization and electron temperature are given in the case of homogeneous heating as a function of the parameters of arbitrary ionizing sources.
Abstract: The possible thermal histories of the universe during the epoch z = 10-1000 are studied. Expressions for the fractional ionization and electron temperature are given in the case of homogeneous heating as a function of the parameters of arbitrary ionizing sources. It is shown that present and future limits on spectral distortions to the microwave background radiation do not provide very restrictive constraints on possible thermal histories of the universe. If H(0) = 50 km/s Mpc, the universe could have been completely ionized throughout its history with no observable spectral effects even if Omega = 1 and the universe is entirely made of baryons. Heating by cosmic rays and very massive stars is briefly discussed.
27 citations
TL;DR: In this article, the authors investigated cosmological solutions in Kaluza-Klein models with and without an anti-symmetric tensor field and showed that the universe can evolve into a four-dimensional world with compactified extra dimensions in later time.
25 citations
01 Sep 1986
TL;DR: In this paper, a Hamiltonian approach for describing tunneling processes with allowance for expansion of the universe is developed, and the results of this method are compared with the results obtained by means of the Euclidean approach.
Abstract: The theory of the decay of the false vacuum in de Sitter space and in an inflationary universe, and also the theory of the creation of the universe ''from nothing'' are discussed. The reasons why tunneling in an inflationary universe differs from tunneling in de Sitter space and cannot be completely homogeneous are explained. It is shown that in a number of important cases the Euclidean approach must be significantly modified or is even completely invalid for the description of tunneling in an expanding universe and for the description of quantum creation of the universe. A Hamiltonian approach for describing tunneling processes with allowance for expansion of the universe is developed. The results of this method are compared with the results obtained by means of the Euclidean approach.
18 citations
TL;DR: In this article, a simple evolution equation is derived for the ratio of gravitational correlation energy to kinetic energy in the expanding universe, which gives the observed asymptotic value of 0.7 and also predicts the behavior of the ratio at earlier times.
Abstract: A simple evolution equation is derived for b(t), the ratio of gravitational correlation energy to kinetic energy in the expanding universe, which gives the observed asymptotic value of 0.7 and also predicts the behavior of the ratio at earlier times. The equation is obtained by combining the cosmic energy equation with the BBGKY clustering hierarchy. The relationship of the solutions of b(t) to the thermodynamic description of gravitational clustering in the expanding universe is briefly discussed. 13 references.
18 citations
TL;DR: In this article, it is shown that, when the dimensionality of the kinetic energy term is increased in Einstein's field equations for the Friedmann-Robertson-Walker metric, stable bound states of the universe are only found forn=2, 3 and 4.
Abstract: It is shown that, when the dimensionality of the kinetic-energy term is increased in Einstein’s field equations for the Friedmann-Robertson-Walker metric inn dimensions, in the absence of a pressure term, stable bound states of the Universe are only found forn=2, 3 and 4. With the further assumption that space is closed, together with a suitable application of Mach’s principle, the casesn=2, 4 can be excluded, so that one has a cosmological approach to deriving the three-dimensionality of space. A speculative way to resolve the «short age» problem of a Ω>1 Universe is also described.
18 citations
16 citations
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TL;DR: In this paper, the second law of thermodynamics in the frame of general relativity is reconsidered in the case of an istotropic homogeneous universe, and there appears a direct link between the cosmological state of the universe, as expressed in terms of conformal coordinates, and quantities such as energy density, pressure, and entropy associated with the description of nature.
Abstract: The formulation of the second law of thermodynamics in the frame of general relativity is reconsidered in the case of an istotropic homogeneous universe. We show that there appears then a direct link between the cosmological state of the universe, as expressed in terms of conformal coordinates, and quantities such as energy density, pressure, and entropy associated with the description of nature. In the early universe there appears a kind of phase transition due to transfer of gravitational energy to matter associated with the cosmological expansion if the universe starts with a non-Euclidian (space) state. As a result, we may envisage the possibility of a “cold big-bang model,” in which the universe would start at zero temperature and entropy. The temperature goes then through a maximum before entering the present area of cooling related to adiabatic expansion.
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01 Jan 1986
TL;DR: In this paper, the goal is to find a unified theory of the universe for the first time in the history of the world, including the early universe and the singularity of star death.
Abstract: The Goal.- Warped Space-Time.- Early Unified Field Theories.- Star Death.- The Ultimate Abyss: The Black Hole.- The Early Universe.- Cosmological Controversy.- The Final Fate of the Universe.- The World of Particles and Fields.- A Unified Theory of the Universe.- Epilogue.
TL;DR: In this article, the Robertson-Walker geometry in an empty five-dimensional universe is derived and the effective four-dimensional evolution is analyzed, and the radius of the compact fifth dimension is regarded as a non-static quantity.
TL;DR: In this article, the chaotic inflationary model of the early universe is studied within the framework of an anisotropic Kantowski-Sachs cosmology, and it is shown that the chaotic model naturally leads to an inflationary phase which also helps in the isotropization of the universe.
Abstract: The chaotic inflationary model of the early universe, proposed by Linde is studied within the framework of an anisotropic Kantowski-Sachs cosmology. It is shown that the chaotic model naturally leads to an inflationary phase which also helps in the isotropization of the universe.
TL;DR: It is shown that the lifetime of the X-italic particle in cosmological models dominated by unstable weakly interacting particles with lifetime on the order of the age of the Universe is close to those required.
Abstract: We consider cosmological models in which the mass of the Universe is dominated by unstable weakly interacting particles (X-italic) with lifetime on the order of the age of the Universe. In our picture the mass of galaxies and clusters is dominated by undecayed X-italic particles while the Universe is closed in the large by their relativistic decay products. Quantitative results are given based on Turner's equations for evolution in the presence of dominant unstable particles. Several possibilities for the X-italic particle are considered. Lifetimes are calculated within these scenarios and shown to be close to those required.
TL;DR: In this article, it is shown that if our universe is described by the cosmological, classical, Einstein equations based on a manifold M 4 × G where G is the product of any number of Ricci flat manifolds (as is expected to occur in superstring theories), then our universe must, today, be radiation dominated.
01 Jan 1986
TL;DR: In this article, the main features of inflationary universe models are reviewed, and a modified model, called chaotic inflation, is discussed, in which the fine-tuning problem is less severe.
Abstract: I briefly review the main features of inflationary universe models. Inflation provides a mechanism which produces energy density fluctuations on cosmological scales. In the original models it was not possible to obtain the correct magnitude of these fluctuations without fine tuning the particle physics models. I discuss a modified model, “chaotic inflation”, in which the fine tuning problem is less severe. I also mention other approaches to early universe cosmology.
TL;DR: In this paper, initial conditions in a higher-dimensional cosmology that can achieve our present universe are investigated, and it is shown that most of the created universes can reach our present universes.
TL;DR: In this paper, it is shown that the relationship between the matter density, Hubble's constant and the deceleration parameter is different from that predicted by classical general relativity, and this difference is on the verge of being observable.
TL;DR: In this article, the evolution of density perturbations in a two-component universe composed of neutrinos and dissipative gas on a spherically-symmetric model has been studied.
Abstract: The recent discovery of the large ‘honeycomb’ structure of the Universe has triggered many models of the Universe dominated by dark matter. The neutrino-dominated universe is a favorable model for explaining the size of the large-scale structure and the dark matter of the larger scale than the galactic one. Our calculations on the evolution of density perturbations in a two-component universe composed of neutrinos and dissipative gas on a spherically-symmetric model have shown that the galactic scale does correlate the scale of a void of galaxies: if a neutrino has the mass of some tens eV, galaxies of the typical size form surrounding a typical void.
TL;DR: In this paper, it was shown that Hartly-Hawking's wave function of the ground state of the universe is equal to zero when its arguments (i.e. the universe and matter fields in it) satisfy some topological conditions.
TL;DR: In this paper, the evolution of the universe in the framework of the relativistic theory of gravitation is considered and it is proved that under this assumption there exists only a flat infinite universe.
Abstract: The evolution of the Universe in the framework of the relativistic theory of gravitation is considered. It is assumed that in Minkowski coordinates the matter is at rest in the gravitational field which it produces and is distributed homogeneously and isotropically. It is proved that under this assumption there exists only a flat infinite Universe.
09 Dec 1986
TL;DR: In this article, a solution of the Einstein field equation in a Bianchi-V type universe with incoherent radiation is presented, and it is shown that, with the lapse of time, the model approaches the state of isotropic expansion.