Showing papers on "Big Rip published in 1990"
TL;DR: In this article, the authors explore the possibility that a new universe can be created by producing a small bubble of false vacuum, which would then evolve to a larger bubble of the same mass.
246 citations
TL;DR: In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far as discussed by the authors.
Abstract: Inflationary cosmological theories predict, and some more general aesthetic criteria suggest, that the large-scale spatial curvature of the universe k should be accurately zero (i.e., flat), a condition which is satisfied when the universe's present mean density and the value of the cosmological constant Lambda have certain pairs of values. Available data on the frequency of multiple image-lensing of high-redshift quasars by galaxies suggest that the cosmological constant cannot make a dominant contribution to producing a flat universe. In particular, if the mean density of the universe is as small as the baryon density inferred from standard cosmic nucleosynthesis calculations or as determined from typical dynamical studies of galaxies and galaxy clusters, then a value of Lambda large enough to produce a k = 0 universe would result in a substantially higher frequency of multiple-image lensing of quasars than has been observed so far. Shortcomings of the available lens data and uncertainties concerning galaxy properties allow some possibility of escaping this conclusion, but systematic searches for a gravitational lenses and continuing investigations of galaxy mass distributions should soon provide decisive information. It is also noted that nonzero-curvature cosmological models can account for the observed frequency of galaxy-quasar lens systems and for a variety of other constraints.
190 citations
TL;DR: The analysis of the quantum Robertson-Walker universe indicates that if the superspace is extended to such a classically forbidden region, the holomorphic representation picks up some restricted class of solutions in general, which leads to a new ansatz on the boundary condition of the Universe.
Abstract: The quantum behavior of the vacuum Bianchi type-IX universe with the cosmological constant is investigated in terms of the Ashtekar variables. An exact solution to the quantum Hamiltonian constraint in the holomorphic representation is given. This solution reduces to the Hartle-Hawking wave function in the spatially isotropic sector and extends in the triad representation to the classically forbidden region where the determinant of the spatial metric becomes negative. The analysis of the quantum Robertson-Walker universe indicates that if the superspace is extended to such a classically forbidden region, the holomorphic representation picks up some restricted class of solutions in general. This observation leads to a new ansatz on the boundary condition of the Universe. In particular, the behavior of the Lorentzian and Euclidean WKB orbits corresponding to the solution suggests a new picture on the semiclassical behavior of the quantum Universe: that the Universe is created from an ensemble of Euclidean mother spacetimes. Further it is pointed out that the solution is a restriction to the spatially homogeneous sector of an almost exact solution to all the quantum constraints in the holomorphic representation for generic vacuum spacetime with the cosmological constant. The latter generic solution has a WKB structure for which the phase is proportional to the Chern-Simons functional.
176 citations
TL;DR: In this paper, a static model of the universe was derived by means of the Endo-Fukui modified Brans-Dicke theory, where density and pressure are constant, but the gravitational constant and cosmological term vary with time.
Abstract: We derive a static model of the universe, where density and pressure are constant, but the gravitational “constant” and the cosmological term vary with time, by means of the Endo-Fukui modified Brans-Dicke theory
75 citations
TL;DR: In this paper, the Bianchi type I cosmological models with a bulk viscosity were analyzed and the characteristics of evolution were clarified for the models with arbitrary value of n. Although the exact solutions are obtainable only when the 2n is an integer, the authors showed that the anisotropic solutions that evolve to positive Hubble functions in the later stage will begin with Kasner-type curvature singularity and zero energy density at finite past for the n≥1 models, and with finite Hubble functions and finite negative energydensity at infinite past for n<1 models
Abstract: An analysis is presented of the Bianchi type I cosmological models with a bulk viscosity when the universe is filled with the stiff fluid p=e while the viscosity is a power function of the energy density, such as η=α‖e‖n. Although the exact solutions are obtainable only when the 2n is an integer, the characteristics of evolution can be clarified for the models with arbitrary value of n. It is shown that, except for the n=0 model that has solutions with infinite energy density at initial state, the anisotropic solutions that evolve to positive Hubble functions in the later stage will begin with Kasner‐type curvature singularity and zero energy density at finite past for the n≥1 models, and with finite Hubble functions and finite negative energy density at infinite past for the n<1 models. In the course of evolution, matters are created and the anisotropies of the universe are smoothed out. At the final stage, cosmologies are driven to infinite expansion state, de Sitter space‐time, or Friedman universe asy...
37 citations
TL;DR: A review of the outstanding questions of cosmology in the plasma universe can be found in this article, where the same basic laws of plasma physics hold everywhere; mapping of electric fields and currents is necessary to understand cosmic plasma; space is filled with a network of currents leading to the cellular and filamentary structure of matter; double layers, critical velocity, and pinch effects are of decisive importance in how cosmic evolves.
Abstract: Acceptance of the plasma universe model is now leading to drastically new views of the structure of the universe. The basic aspects of cosmological importance are: (a) the same basic laws of plasma physics hold everywhere; (b) mapping of electric fields and currents is necessary to understand cosmic plasma; (c) space is filled with a network of currents leading to the cellular and filamentary structure of matter; and (d) double layers, critical velocity, and pinch effects are of decisive importance in how cosmic evolves. A review is presented of a number of the outstanding questions of cosmology in the plasma universe. >
36 citations
TL;DR: A review of the evidence for large-scale motions of galaxies out to a distance of approximately 5000 km s-1 is given in this article, where the authors present a review of evidence for the large scale motion of galaxies.
Abstract: The expansion of the Universe can be retarded in localised regions within the Universe both by the presence of gravity and by non-gravitational motions generated in the post-recombination Universe. The motions of galaxies thus generated are called 'peculiar motions', and the amplitudes, size scales and coherence of these peculiar motions are among the most direct records of the structure of the Universe. As such, measurements of these properties of the present-day Universe provide some of the severest tests of cosmological theories. The author presents a review of the evidence for large-scale motions of galaxies out to a distance of approximately 5000 km s-1.
31 citations
19 citations
TL;DR: In this paper, the authors studied the problem of nonsingular cosmological models based on a theory of gravitation in flat space-times and gave the solution of the model analytically.
Abstract: The study of nonsingular cosmological models [4] based on a theory of gravitation in flat space-times [1] is continued. For a radiation free universe the solution of the model is given analytically. Under the assumption that entropy cannot decrease the cosmological constant must be zero. At the beginning of the universe all energy is in the form of gravitation. The universe contracts. Matter and radiation are created out of gravitational energy and entropy is produced. The contraction stops and then the universe expands without limit. The creation of matter continues producing entropy but today the production of matter and entropy is negligible. The density parameter Ω0 ≈ 1, i.e. there must be “missing mass” in the universe. The “flatness” and the “homogeneity” problem are solved.
14 citations
TL;DR: This paper showed that the universe could have begun from a state of zero energy and maximum entropy, and then naturally evolved into what we see today without violating any known principles of physics, and that the fundamental particles and the force laws they obey then come about through a series of random symmetry-breaking phase transitions during the period of exponential expansion in the first fraction of a second after the Universe appears as a quantum fluctuation.
Abstract: It is commonly believed that the origin of the Universe must have involved the violation of natural laws, particularly energy conservation and the second law of thermodynamics. This need not have been the case, the present author shows that the Universe could have begun from a state of zero energy and maximum entropy, and then naturally evolved into what we see today without violating any known principles of physics. The fundamental particles and the force laws they obey then come about through a series of random symmetry-breaking phase transitions during the period of exponential expansion in the first fraction of a second after the Universe appears as a quantum fluctuation.
10 citations
TL;DR: In this article, the effects of shear on the occurrence of inflation were studied on the basis of a simple model for a spatially closed universe which enters an inflationary era, assuming that the universe enters a vacuumdominated phase in an abrupt transition that occurs everywhere at the same time, and the space-time geometries, before and after the phase transition, are matched to each other via the Lichnerowicz junction conditions.
Abstract: The effects of shear on the occurrence of inflation are studied on the basis of a simple model for a spatially closed universe which enters an inflationary era. It is assumed that the universe enters a vacuum‐dominated phase in an abrupt transition that occurs everywhere at the same time. The space‐time geometries, before and after the phase transition, are matched to each other via the Lichnerowicz junction conditions. The Einstein field equations are solved exactly for a viscous universe of the Kantowski–Sachs type. It is found that the inclusion of (positive) shear retards the occurrence of the vacuum phase transition. The magnitude of this effect depends on the mass of the universe at the time of the phase transition. For a universe with a mass of about 10 kg (which is a value usually associated with the mass of the region from which our universe originated), it is found that the inclusion of shear does not really have a large effect on the time at which the vacuum phase transition occurs. The generality of the results is also discussed.
TL;DR: In this paper, a model of a spatially finite universe with constant negative curvature and no boundary is presented, and the observational consequences of such a model are examined and it is shown that microwave isotropy and large scale structure with a characteristic lenghth of 100 −200 h −1 0 Mpc can be predicted.
TL;DR: In this article, the conditions for the existence of a universe dominated by a scalar field in its early stages were analyzed in a homogeneous, Isotropic and spatially flat universe model.
Abstract: Analyzing the Klein-Gordon equation in a homogeneous, Isotropic and spatially flat universe model, we find the conditions for the existence of a universe dominated by a scalar field in its early stages.
TL;DR: In this article, the authors review the modern theory of the origin of the universe as astronomers and physicists are coming to understand it during the last decades of the twentieth century, and they make an unexpected discovery that the story of cosmogenesis cannot be completely told unless we understand the fundamental nature of matter, space, and time.
Abstract: . In what follows, I review the modern theory of the origin of the universe as astronomers and physicists are coming to understand it during the last decades of the twentieth century. An unexpected discovery of this study is that the story of “cosmogenesis” cannot be completely told unless we understand the fundamental nature of matter, space, and time. In the context of modern cosmology space has become not only the bedrock (so to speak) of our physical existence, it may yield a fuller understanding of the universe itself.
TL;DR: In this article, the authors investigated the dynamics of the quantum universe under self-measurement in the framework of the path-integral approach to quantum theory of continuous measurements and the corresponding amplitude (propagator) was evaluated explicitly for a simple superspace model.
Abstract: The dynamics of the quantum universe under self-measurement is investigated in the framework of the path-integral approach to quantum theory of continuous measurements. The corresponding amplitude (propagator) is evaluated explicitly for a simple superspace model. It is shown that the picture of time evolution of the quantum universe naturally emerges as a result of its self-measurement. The Wheeler-DeWitt dynamics holds for small times when the effect of measurement can be neglected and time dependence disappears.
TL;DR: Recently, the cold dark matter model has been challenged from two sides: first, ever more sensitive probes of the so-called cosmic microwave background, a cool bath of microwaves that is thought to be the faint afterglow of the big bang, have yet to reveal any regional variations in intensity as discussed by the authors.
Abstract: In June more than 30 prominent cosmologist, astronomers and physicists gathered for six days at an isolated resort in northern Sweden. Their topic: the origin of the universe. While most agreed the big bang theory is still sound, new data are challenging a more detailed scenario: the cold dark matter model. Recent observations are squeezing this model from two sides. First, ever more sensitive probes of the so-called cosmic microwave background, a cool bath of microwaves that is thought to be the faint afterglow of the big bang, have yet to reveal any regional variations in intensity. That has forced modelers to assume the early universe was exceptionally smooth, or homogeneous, with matter spread uniformly through space. At the same time, maps of the universe have revealed ever larger thickets of galaxies surrounded by larger voids. If the universe was so smooth early on, how did it come to be so clumpy This article addresses how cosmologist at this meeting addressed the big questions.
TL;DR: A recent observational advance has been the mapping of the expansion pattern of the universe in the neighbourhood of the Milky Way as discussed by the authors, revealing significant departures from uniform Hubble expansion, which is thought to be associated with the growth of superclusters.
Abstract: A recent observational advance has been the mapping of the expansion pattern of the universe in the neighbourhood of the Milky Way. These studies reveal significant departures from uniform Hubble expansion, which is thought to be associated with the growth of superclusters. Part 1 of this review concerned currently popular hypotheses for how structure in our universe might have originated and how it is thought to be evolving today. In this second part I shall describe the observations and show how these can be used to test the theoretical ideas.
TL;DR: In this article, the optical depths of a radiation-dominated universe were derived for photoionization, Compton scattering, photon-matter pair production, photon photon scattering, and photon-photon pair production in interactions with the cosmic thermal background and baryonic matter.
Abstract: If the universe were radiation-dominated at redshifts greater than about 100-1000, eg, due to the presence of a small fraction of light particles in the dark matter, it would be optically thin in soft gamma-rays up to redshifts of 10,000 This is larger by an order of magnitude than for the matter-dominated universe X-rays and gamma-rays produced by cosmological high-energy processes are thus potentially observable up to z of about 10,000 Analytical formulas are derived for the optical depths of radiation-dominated universe due to photoionization, Compton scattering, photon-matter pair production, photon-photon scattering, and photon-photon pair production, in interactions with the cosmic thermal background and baryonic matter 29 refs
TL;DR: In this paper, the exterior field of the Bianchi type-II metric in the Lyttleton-Bondi universe is considered and an exact cosmological model is presented.
Abstract: The exterior field of the Bianchi type-II metric in the Lyttleton-Bondi universe is considered and an exact cosmological model is presented The behaviour of the model is also discussed
TL;DR: In this article, a study of matter-radiation universes under certain supplementary conditions specified in the introduction shows that the only model of this class compatible with observations is a parabolic universe which at the present time is almost the same as an Einstein-de Sitter model.
Abstract: A study of matter-radiation universes under certain supplementary conditions specified in the introduction shows us that the only model of this class compatible with observations is a parabolic universe which at the present time is almost the same as an Einstein-de Sitter model. The numerical values obtained for Hubble's constant, the age of the universe and the matter density at the present time are quite acceptable. We can also obtain some limits for the mass of neutrinos. The advantage of this parabolic model is that it gives the same results as thet
2/3 model at the present time and what is more could be used in studying problems of the formation of galaxies, after the recombination epoch, where matter and radiation have comparable importance.
TL;DR: The Hartle-Hawking no-boundary proposal for the wave function of the universe suggests, via a minisuperspace calculation, that the Universe may have had an infinite period of inflation as mentioned in this paper.
Abstract: The Hartle-Hawking no-boundary proposal (1983) for the wavefunction of the Universe suggests, via a minisuperspace calculation, that the Universe may have had an infinite period of inflation If the classical spacetime is said to have an edge or singularity where the semiclassical approximation breaks down, that would be at an infinite amount of comoving time in the past, though at only a finite proper time for geodesics with non-zero momentum, so the spacetime would still be singular even if infinitely old
TL;DR: In this article, the relation between the peculiar velocity and the density parameter in a one-dimensional inhomogeneous universe was derived for the case in which the density distribution is described by the Zeldovich solution.
Abstract: We derive the relation between the peculiar velocity and the density parameter in a one· dimensional inhomogeneous universe for the case in which the density distribution is described by the Zeldovich solution. We find that the simple relation obtained in the linear perturbation theory holds without any correction in spite of a fully non·linear nature of the problem. We also find that the inclusion of the cosmological constant in the present context does not change the above result.
TL;DR: Our knowledge of the universe can be compared with our ancestor's emerging awareness of the planet Earth in the 15th century as mentioned in this paper, when a rudimentary understanding of the galaxy building-blocks of the visible universe was established.
01 Jan 1990
TL;DR: In this paper, it is shown that the existence of horizons of knowledge in any cosmological view of the universe is then tantamount to inherent observational limits imposed by acts of observation and theory itself.
Abstract: Unlike the usual situation with theoretical physics which is testable in the laboratory, in cosmological theories of the universe one faces the following problems: The observer is part of the system, the universe, and this system cannot be altered to test physical theory. Even though one can in principle consider any part of the observable universe as separate from the acts of observation, the very hypothesis of big bang implies that in the distant past, space-time regions containing current observers were part of the same system. One, therefore, faces a situation where the observer has to be considered as inherently a part of the entire system. The existence of horizons of knowledge in any cosmological view of the universe is then tantamount to inherent observational limits imposed by acts of observation and theory itself. For example, in the big bang cosmology the universe becomes opaque to radiation early on, and the images of extended distant galaxies merge for redshifts, z, of the order of a few. Moreover, in order to measure the distance of a remote galaxy to test any cosmological theory, one has to disperse its light to form a spectrum which would cause confusion with other background galaxies. Since the early universe should be described in quantum terms, it follows that the same problems regarding quantum reality and the role of the observer apply to the universe as a whole. One of the most fundamental properties of quantum theory, non-locality, may then apply equally well to the universe. Some of the problems facing big bang cosmology, like the horizon and flatness problems, may not then be preconditions on theoretical models but may instead be the manifestations of the quantum nature of the universe.
TL;DR: In the course of the past decade, Andrei Linde has almost single-handedly crafted the inflationary universe scenario as discussed by the authors, which represents a quantum leap in our understanding of the formation and evolution of the universe.
Abstract: In the course of the past decade, Andrei Linde has almost single-handedly crafted the inflationary Universe scenario. The inflationary Universe has now become nearly as much part of the standard cosmological model as the theory of the expanding Universe itself. It represents a quantum leap in our understanding of the formation and evolution of the Universe. A whole range of questions about the structure of the Universe now admit causal and quantitative answers.
Book•
16 Mar 1990
Abstract: Ninety percent or more of the matter in the universe is unseen. Nobody knows what it is. The universe expands, but nobody knows how long the expansion has been going on. Will it expand forever, or collapse in a Big Crunch, perhaps a Big Bang in reverse? From Aristotle to Newton, Einstein and Quantum Mechanics, Introducing The Universe recounts the revolutions in physics and astronomy which underlie the present-day scientific picture of the universe. It describes the scale of things, from atoms to galactic superclusters, and sketches the cosmological theories, based on Einstein's theory of general relativity, used to describe the universe's expansion. It discusses the significance of the cosmic background satellite observations, and explains why current theories have nothing reliable to say about whether the universe had a beginning.
TL;DR: In this paper, the authors show that the understanding of the problem of time asymmetry can be reached from the hypothesis of typicalness of the universe, and they come to the following consequences: 1) the cosmological arrow of time, in general, should not coincide with the thermodynamic one, while the universe turns from the expanding phase to the contracting one.
Abstract: We show that the understanding of the problem of time asymmetry can be reached proceeding from the hypothesis of typicalness of the Universe. We come to the following consequences: 1) the cosmological arrow of time, in general, should not coincide with the thermodynamic one; 2) the thermodynamic arrow should not change its direction, while the Universe turns from the expanding phase to the contracting one; 3) CPT-invariance has to be violated. The last prediction, in principle, allows experimental verification.
TL;DR: A recent observational advance has been the mapping of the expansion pattern of the universe in the neighbourhood of the Milky Way as mentioned in this paper, revealing significant departures from uniform Hubble expansion, thought to be associated with the growth of superclusters.
Abstract: A recent observational advance has been the mapping of the expansion pattern of the universe in the neighbourhood of the Milky Way. These studies reveal significant departures from uniform Hubble expansion, thought to be associated with the growth of superclusters. In part 1 of this review I discuss currently popular hypotheses concerning how structure in our universe might have originated and its current evolution. In part 2 I shall describe the observations and show how these can be used to test the theoretical ideas.
TL;DR: In this article, a massive U (1) vector field A μ in a charged Robertson-Walker universe for k =+1, 0, and −1 can solve the initial singularity problem even at the level of classical gravity because the energy density becomes negative as the scale factor of the metric approaches zero.