Showing papers on "Big Rip published in 2000"
306 citations
TL;DR: In this paper, a model of the universe is considered as a thin shell expanding in 5D space-time, and the width of the shell is described by the difference of outer and inner cosmological constants.
Abstract: The model of the Universe is considered as a thin shell expanding in 5-dimensional space-time. The width of the shell is described by the difference of outer and inner cosmological constants. In our approach dark matter is not necessary to explain the observed expansion rate of the Universe.
187 citations
TL;DR: In this paper, the authors examined the implications for the future under these assumptions, and found that they are striking: if the universe is cosmological constant-dominated, our ability to probe the evolution of large-scale structure will decrease with time; presently observable distant sources will disappear on a timescale comparable to the period of stellar burning, while the integrated conscious lifetime of any civilization will be finite, although it can be astronomically long.
Abstract: Current evidence suggests that the cosmological constant is not zero, or that we live in an open universe. We examine the implications for the future under these assumptions, and find that they are striking. If the universe is cosmological constant-dominated, our ability to probe the evolution of large-scale structure will decrease with time; presently observable distant sources will disappear on a timescale comparable to the period of stellar burning. Moreover, while the universe might expand forever, the integrated conscious lifetime of any civilization will be finite, although it can be astronomically long. We argue that this latter result is far more general. In the absence of possible exotic and uncertain strong gravitational effects, the total information recoverable by any civilization over the entire history of our universe is finite. Assuming that consciousness has a physical computational basis, and therefore is ultimately governed by quantum mechanics, life cannot be eternal.
115 citations
TL;DR: In this paper, the evolution of U(1) symmetric scalar field at the inflation epoch with a pseudo Nambu-Goldstone tilt revealing after the end of exponential expansion of the Universe is discussed.
Abstract: We discuss the evolution of U(1) symmetric scalar field at the inflation epoch with a pseudo Nambu-Goldstone tilt revealing after the end of exponential expansion of the Universe. The U(1) symmetry is supposed to be associated with baryon charge. It is shown that quantum fluctuations lead in natural way to baryon dominated Universe with antibaryon excess regions. The range of parameters is calculated at which the fraction of Universe occupied by antimatter and the size of antimatter regions satisfy the observational constraints, survive to the modern time and lead to effects, accessible to experimental search for antimatter.
70 citations
TL;DR: In this paper, it was shown that the observed spell of vacuum domination is only a transient phenomenon and that the vacuum energy's anti-gravitational properties are reversed, and a matter-dominated decelerating cosmic expansion resumes.
Abstract: Recent astronomical observations of distant supernovae light-curves suggest that the expansion of the universe has recently begun to accelerate. Acceleration is created by an anti-gravitational repulsive stress, like that produced by a positive cosmological constant, or universal vacuum energy. It creates a rather bleak eschatological picture. An ever-expanding universe's future appears to be increasingly dominated by its constant vacuum energy. A universe doomed to accelerate forever will produce a state of growing uniformity and cosmic loneliness. Structures participating in the cosmological expansion will ultimately leave each others' horizons and information-processing must eventually die out. Here, we examine whether this picture is the only interpretation of the observations. We find that in many well-motivated scenarios the observed spell of vacuum domination is only a transient phenomenon. Soon after acceleration starts, the vacuum energy's anti-gravitational properties are reversed, and a matter-dominated decelerating cosmic expansion resumes. Thus, contrary to general expectations, once an accelerating universe does not mean always an accelerating universe.
63 citations
01 Jan 2000
58 citations
Posted Content•
TL;DR: In this article, it was shown that the restoration of the full Standard Model symmetry leads to the result that time, light, along with it's velocity c and the theory of relativity, all lose any physical meaning.
Abstract: It has been proven recently that the Standard Model of particle physics has electric charge quantization built into it. It has also been shown by the author that there was no electric charge in the early universe. Further it is shown here that the restoration of the full Standard Model symmetry (as in the Early Universe) leads to the result that `time', `light', along with it's velocity c and the theory of relativity, all lose any physical meaning. The physical Universe as we know it, with its space-time structure, disappears in this phase transition. Hence it is hypothesized here that the Universe came into existence when the Standard Model symmetry $SU(3)_C \otimes SU(2)_L \otimes U(1)_Y$ was spontaneously broken to $SU(3)_C \otimes U(1)_{em}$. This does not require any spurious extensions of the Standard Model and in a simple and consistent manner explains the origin of the Universe within the framework of the Standard Model itself.
57 citations
TL;DR: For a wide range of possible cosmological models, the results in this article indicate that the universe appears to have a kinematic age less than about 14±2 billion years.
53 citations
TL;DR: The quintessence cosmological model is proposed in this article, which is a time-dependent, spatially inhomogeneous, negative pressure energy component which drives the cosmic expansion.
Abstract: There is a missing energy problem in cosmology: the total energy density of the Universe, based on a wide range of observations, is much greater than the energy density contributed by all baryons, neutrinos, photons, and dark matter. Deepening this mystery are the recent observations of type la supernovae which suggest that the expansion rate of the Universe is accelerating. One possible resolution is the existence of a cosmological constant which fills this energy gap. However, a logical alternative is “quintessence,” a time-dependent, spatially inhomogeneous, negative pressure energy component which drives the cosmic expansion. This lecture will serve as an introduction to the quintessence cosmological scenario.
44 citations
TL;DR: It is shown that the supernovae results, which imply that there is evidence for an accelerating universe, may be closely related to the recent discovery of redshift dependence in the fine-structure constant alpha.
Abstract: We show that the supernovae results, which imply that there is evidence for an accelerating universe, may be closely related to the recent discovery of redshift dependence in the fine-structure constant alpha. The link is a class of varying speed-of-light (VSL) theories that contain cosmological solutions that are similar to quintessence. During the radiation-dominated epoch, the cosmological constant Lambda is prevented from dominating the universe by the usual VSL mechanism. In the matter-dominated epoch, the varying-c effects switch off, allowing Lambda to eventually surface and lead to an accelerating universe. By the time this happens, the residual variations in c imply a changing alpha at a rate that is in agreement with observations.
TL;DR: In this paper, the authors investigated a new scenario for the universe's evolution, where the present Friedmann universe originates from a primordial G\"odel universe by a phase transition during which the cosmological constant vanishes.
Abstract: Based on the mathematical similarity between the Friedmann open metric and G\"odel's metric in the case of nearby distances, we investigate a new scenario for the universe's evolution, where the present Friedmann universe originates from a primordial G\"odel universe by a phase transition during which the cosmological constant vanishes. Using Hubble's constant and the present matter density as input, we show that the radius and density of the primordial G\"odel universe are close, in order of magnitude, to the present values, and that the time of expansion coincides with the age of the universe in the standard Friedmann model. In addition, the conservation of angular momentum provides, in this context, a possible origin for the rotation of galaxies, leading to a relation between the masses and spins corroborated by observational data.
TL;DR: In this paper, the authors measured the mass density, energy density, and cosmological-constant energy density of 42 Type Ia supernovae from the Cal?n/Tololo Supernova Survey at redshifts below 0.1.
Abstract: The fate of the Universe, infinite expansion or a ldquo;big crunchrdquo;, can be determined by measuring the redshifts and brightness of very distant supernovae. These provide a record of changes in the expansion rate of the Universe over the past several billion years. The mass density, ?M, and cosmological-constant energy density ??, are measured from a data-set consisting of 42 high-redshift Type Ia supernovae discovered by the Supernova Cosmology Project. The magnitude-redshift data for these supernovae, at redshifts between 0.18 and 0.83, are fit jointly with a set of supernovae from the Cal?n/Tololo Supernova Survey, at redshifts below 0.1, to yield values for the cosmological parameters. We find ?Mflat = 0.28+0.09-0.08 (1? statistical)+0.05-0.04 (identified systematics). The data are strongly inconsistent with a ? = 0 flat cosmology, the simplest inflationary universe model. An open, ? = 0 cosmology also does not fit the data well: the data indicate that the cosmological constant is non-zero and positive, with a confidence of P(?>0) = 99%, including the identified systematic uncertainties. Thus, the Universe is found to be accelerating, i.e., q0 = ?M/2 - ?? < 0. The best-fit age of the universe relative to the Hubble time is t0flat = 14.9+1.4-1.1 (0.63/h) Gyr for a flat cosmology.
TL;DR: In this paper, the dynamics of first-order phase transition in the early Universe when it was $10-50 \mu s$ old with quarks and gluons condensing into hadrons were studied.
Abstract: We study the dynamics of first-order phase transition in the early Universe when it was $10-50 \mu s$ old with quarks and gluons condensing into hadrons. We look at how the Universe evolved through the phase transition in small as well as large super cooling scenario, specifically exploring the formation of quark nuggets and their possible survival. The nucleation of the hadron phase introduces new distance scales in the Universe, which we estimate along with the hadron fraction, temperature, nucleation time etc. It is of interest to explore whether there is a relic signature of this transition in the form of quark nuggets which might be identified with the recently observed dark objects in our galactic halo and account for the Dark Matter in the Universe at present.
TL;DR: In this article, the authors proposed cosmological theories and theories of fundamental physics must ultimately not only account for the structure and evolution of the universe, the physics of fundamental interactions but also lead to an understanding of why this particular universe follows the physics that it does.
Abstract: Cosmological theories and theories of fundamental physics must ultimately not only account for the structure and evolution of the universe, the physics of fundamental interactions but also lead to an understanding of why this particular universe follows the physics that it does. Such theories must lead to an understanding of the values of the fundamental constants themselves. Moreover, the understanding of universe has to utilize experimental data from the present to deduce the state of the universe in distant regions of the past and also account for certain peculiarities or coincidences observed.
TL;DR: In this paper, the authors investigated the evolution of different measures of ''Gravitational Entropy'' in Bianchi type I and Lema-itre-Tolman universe models and introduced a new quantity behaving in accordance with the second law of thermodynamics.
Abstract: We investigate the evolution of different measures of ``Gravitational Entropy'' in Bianchi type I and Lema\^itre-Tolman universe models
A new quantity behaving in accordance with the second law of thermodynamics is introduced We then go on and investigate whether a quantum calculation of initial conditions for the universe based upon the Wheeler-DeWitt equation supports Penrose's Weyl Curvature Conjecture, according to which the Ricci part of the curvature dominates over the Weyl part at the initial singularity of the universe The theory is applied to the Bianchi type I universe models with dust and a cosmological constant and to the Lema\^itre-Tolman universe models We investigate two different versions of the conjecture First we investigate a local version which fails to support the conjecture Thereafter we construct a non-local entity which shows more promising behaviour concerning the conjecture
Book•
14 Feb 2000
TL;DR: A Universe Custom Made for Us? A Cosmological Aesthetic Principle? Index. as discussed by the authors The Case of the Missing Matter The case of the missing matter is a classic example.
Abstract: Prologue. Beauty and the Beast. Expansion. The Case of the Missing Matter. Flat Is Beautiful. When Inflation Is Good. Creation. The Meaning of Life. A Universe Custom Made for Us? A Cosmological Aesthetic Principle? Index.
TL;DR: In this article, it was shown that many small universe models provide a good fit to the COBE-DMR data, provided that space is hyperbolic, which is not the case in our model.
Abstract: The cosmic microwave background radiation allows us to measure both the geometry and topology of the universe. It has been argued that the COBE-DMR data already rule out models that are multiply connected on scales smaller than the particle horizon. To the contrary, we find that many small universe models provide a good fit to the COBE-DMR data, provided that space is hyperbolic.
Journal Article•
TL;DR: A brief review of basic concepts of cosmic topology and of the rapidly growing gamut of diverse and complementary observational strategies for measuring the topology of the universe is provided in this article.
Abstract: The Hilbert-Einstein equations are insufficient to describe the geometry of the Universe, as they only constrain a local geometrical property: curvature. A global knowledge of the geometry of space, if possible, would require measurement of the topology of the Universe. Since the subject was discussed in 1900 by Schwarzschild, observational attempts to measure global topology have been rare for most of this century, but have accelerated in the 1990's due to the rapidly increasing amount of observations of non-negligible fractions of the observational sphere. A brief review of basic concepts of cosmic topology and of the rapidly growing gamut of diverse and complementary observational strategies for measuring the topology of the Universe is provided here.
TL;DR: The Fifth Essence as discussed by the authors is a classic book about the dark matter problem in the universe and its relationship with the cosmological constant, which has been studied extensively in recent years.
Abstract: Will the universe continue to expand forever, reverse its expansion and begin to contract, or reach a delicately poised state where it simply persists forever? The answer depends on the amount and properties of matter in the universe, and that has given rise to one of the great paradoxes of modern cosmology: there is too little visible matter to account for the behavior we can see. Over ninety percent of the universe consists of missing mass or dark matter - what Lawrence Krauss, in his classic book, termed the fifth essence. In this new edition of The Fifth Essence, retitled Quintessence after the now widely accepted term for dark matter, Krauss shows how the dark matter problem is now connected with two of the hottest areas in recent cosmology: the fate of the universe and the cosmological constant. With a new introduction, epilogue, and chapter updates, Krauss updates his classic for 1999 and shares one of the most stunning discoveries of recent years: an anti-gravity force that explains recent observations of a permanently expanding universe.
TL;DR: In this paper, the authors discuss a mechanism for generating baryon density perturbations and study the evolution of the charge density distribution in the framework of the low temperature baryogenesis scenario.
Abstract: We discuss a mechanism for generating baryon density perturbations and study the evolution of the baryon charge density distribution in the framework of the low temperature baryogenesis scenario. This mechanism may be important for the large scale structure formation of the Universe and particularly, may be essential for understanding the existence of a characteristic scale of 130ft" Mpc in the distribution of the visible matter. The detailed analysis showed that both the observed very large scale of the visible matter distribution in the Universe and the observed baryon asymmetry value could naturally appear as a result of the evolution of a complex scalar field condensate, formed at the inflationary stage. Moreover, according to our model, at present the visible part of the Universe may consist of baryonic and antibaryonic sheila, sufficiently separated, so that annihilation radiation is not observed. This is an interesting possibility as far as the observational data of antiparticles in cosmic rays do not rule out the possibility of antimatter superclusters in the Universe.
Posted Content•
TL;DR: One of the greatest achievements of twentieth century physics is the discovery of a very close link between the microcosm and the macrocosm This follows from the two basic principles of quantum mechanics and relativity, the uncertainty principle and the mass energy equivalence, along with the standard big bang model of cosmology as discussed by the authors.
Abstract: One of the greatest achievements of twentieth century physics is the discovery of a very close link between the microcosm and the macrocosm This follows from the two basic principles of quantum mechanics and relativity, the uncertainty principle and the mass energy equivalence, along with the standard big bang model of cosmology As we probe deeper into the microcosm we encounter states of higher mass and energy, which were associated with the early history of the universe Thus discovery of the atomic nucleus followed by the nuclear particles, quarks & gluons and finally the $W$ & $Z$ bosons have recreated in the laboratory the forms of matter that abounded in the very early universe This has helped us to trace back the history of the universe to within a few picoseconds of its creation Finally the discovery of the Higgs and supersymmetric particles will help to solve the mystry of the invisible matter, which abound throughout the universe today, as relics of that early history
TL;DR: In this paper, the authors generalize the spherical collapse model for the formation of dark matter halos to apply in a universe with arbitrary positive cosmological constant and calculate the critical condition for collapse of an overdense region and give exact values of the characteristic densities and redshifts of its evolution.
Abstract: We generalize the spherical collapse model for the formation of dark matter halos to apply in a universe with arbitrary positive cosmological constant. We calculate the critical condition for collapse of an overdense region and give exact values of the characteristic densities and redshifts of its evolution.
TL;DR: In this paper, the curvature of the universe has been shown to be flat and the angle subtended by the characteristic scale on the Cosmic Microwave sky provides a direct test.
Abstract: The Universe could be spatially flat, positively curved or negatively curved. Each option has been popular at various times, partly affected by an understanding that models tend to evolve away from flatness. The curvature of the Universe is amenable to measurement, through tests such as the determination of the angles of sufficiently large triangles. The angle subtended by the characteristic scale on the Cosmic Microwave sky provides a direct test, which has now been realised through a combination of exquisite results from a number of CMB experiments.
After a long and detailed investigation, with many false clues, it seems that the mystery of the curvature of the Universe is now solved. It's an open and shut case: the Universe is flat.
TL;DR: In this paper, a simple perturbation description unique for all signs of curvature, and based on the gauge-invariant formalisms, is proposed to demonstrate that density perturbations propagate in the flat radiation-dominated universe in exactly the same way as electromagnetic or gravitational waves propagated in the epoch of the matter domination.
Abstract: A simple perturbation description unique for all signs of curvature, and based on the gauge-invariant formalisms is proposed to demonstrate that:
(1) The density perturbations propagate in the flat radiation-dominated universe in exactly the same way as electromagnetic or gravitational waves propagate in the epoch of the matter domination.
(2) In the open universe, sounds are dispersed by curvature. The space curvature defines the minimal frequency $\omega_{\rm c}$ below which the propagation of perturbations is forbidden.
Gaussian acoustic fields are considered and the curvature imprint in the perturbations spectrum is discussed.
TL;DR: In this article, a form of quintessence with an attractor-like solution is proposed, which leads to the same conditions today for a very wide range of initial conditions.
Abstract: Recent evidence suggests that the total matter density of the universe is significantly less than the critical density. The shortfall may be explained by curvature (an open universe), vacuum energy density (a cosmological constant), or quintessence (a time-evolving, spatially inhomogeneous component with negative pressure). In all three cases, a key problem is to explain the initial conditions required to have the energy density nearly coincident with the matter density today. A possible solution is "tracker fields," a form of quintessence with an attractor-like solution which leads to the same conditions today for a very wide range of initial conditions. Tracker field make quintessence a more viable candidate for the missing energy component and produce more distinctive predictions.
TL;DR: In this paper, the authors make the following claims: (1) the theory of CMB anisotropies is understood; (2) using this understanding, they are able to extract from future observations extremely accurate measurements of about ten cosmological parameters; (3) taken at face value, present data determines one of these parameters, the curvature of the universe; and (4) the present data is good enough that the measurements should be believed.
Abstract: Anisotropies in the Cosmic Microwave Background (CMB) carry an enormous amount of information about the early universe. The anisotropy spectrum depends sensitively on close to a dozen cosmological parameters, some of which have never been measured before. Experiments over the next decade will help us extract these parameters, teaching us not only about the early universe, but also about physics at unprecedented energies. One of the dangers now is that scientist are tempted to ignore the present data and rely too much on the future. This would be a shame, for hundreds of individuals have put in a great amount of time building state-of-the-art instruments, making painstaking observations at remote places on and off the globe. It seems unfair to ignore all the data that has been taken to date simply because there will be more and better data in the future. The author then makes the following claims: (1) the theory of CMB anisotropies is understood; (2) using this understanding, he is able to extract from future observations extremely accurate measurements of about ten cosmological parameters; (3) taken at face value, present data determines one of these parameters, the curvature of the universe; and (4) the present data ismore » good enough that the measurements should be believed. The first of these claims are well-known. The last claim is more controversial, but the author presents evidence for it.« less
TL;DR: In this paper, the authors consider cosmological models in which a homogeneous isotropic universe is embedded as a 3+1 dimensional surface into a 4+ 1 dimensional manifold.