Showing papers on "Big Rip published in 1983"

Introduction to Cosmology

Abstract: Foreword by Professor Sir Fred Hoyle 1. The large-scale structure of the universe 2. General relativity 3. From relativity to cosmology 4. The Friedman models 5. Relics of the Big Bang 6. The very early universe 7. The formation of structures in the universe 8. Alternative cosmologies 9. Local observations of cosmological significance 10. Observations of distant parts of the universe 11. A critical overview.

The structure and evolution of the universe

Abstract: Though the kinematics of the evolving universe became known decades ago, research into the physics of processes occurring in the expanding universe received a reliable observational and theoretical basis only in more recent years. These achievements have led in turn to the emergence of new problems, on which an unusually active assault has begun. This second volume of "Relativistic Astrophysics "provides a remarkably complete picture of the present state of cosmology. It is a synthesis of the theoretical foundations of contemporary cosmology, which are derived from work in relativity, plasma theory, thermodynamics, hydrodynamics, and particle physics. It presents the theoretical work that explains, describes, and predicts the nature of the universe, the physical process that occur in it, the formation of galaxies, the synthesis of the light elements, and the cosmological singularity and the theory of gravitation. This book, long and eagerly awaited, is essential for everyone whose work is related to cosmology and astrophysics.

Clustering in a neutrino-dominated universe

Abstract: We have simulated the nonlinear growth of structure in a universe dominated by massive neutrinos using initial conditions derived from detailed linear calculations of earlier evolution. Codes based on a direct N-body integrator and on a fast Fourier transform Poisson solver produce very similar results. The coherencce length of the neutrino distribution at early times is directly related to the mass of the neutrino and thence to the present density of the universe. We find this length to be too large to be consistent with the observed clustering scale of galaxies if other cosmological parameters are to remain within their accepted ranges. The conventional neutrino-dominated picture appears to be ruled out.

Chaotic inflating universe

Abstract: It is shown that inflation is a natural result of chaotic initial conditions in the early universe These initial conditions are found in a wide class of elementary particle theories

Arbitrary-spin theory in the Einstein universe

Abstract: Some arbitrary-spin results are resuscitated, in particular the vacuum energies for massless fields on the Einstein universe T x S/sup 3/.

Evolution of the Universe

Abstract: Observations of specific objects and phenomena in space provide basic fundamental information on the evolution of the universe. Some stars, such as the Sun, will evolve into planetary nebulae, while a larger star will explode as a supernova. Examining planetary nebulae will show the final stage in the evolution of Sun-like stars. The Ring Nebula and the Dumbbell Nebula were observed, and composite constructions of each planetary nebula were created after observation with red, green, and blue filters. It was discovered that the nebulae consisted of hydrogen, double ionized oxygen, neon, and helium. Observations of globular clusters show the evolutionary states of many stars at once. M13 and M56 were the two globular clusters observed. Hertzsprung-Russell diagrams were created for each cluster, portraying the relationship between magnitude and temperature of various stars in a cluster. Due to limited resolution, the diagrams do not show conclusive results, but they do indicate the point where stars leave the main hydrogen-burning stage of evolution. The evolution of galaxies can be represented by a Hubble Tuning Fork, displaying elliptical, spiral, and barred spiral galaxies. Several galaxies were observed and the spiral branch of the Hubble Tuning Fork was created. Examples of galactic mergers were also viewed. The study of each of these phenomena will help shape our perception of the evolution of the universe.

Pancakes and the formation of galaxies in a neutrino-dominated universe

Abstract: A detailed, numerical hydrodynamical calculation is presented of the growth of a combined neutrino-baryon pancake in a postrecombination Friedmann universe dominated by massive neutrinos. The purpose of this calculation is to test the hypothesis that galaxies can form within the adiabatic, or so-called pancake, scenario, if the universe is neutrino-dominated. First, we present the results of a detailed, numerical, three-dimensional collisionless particle simulation which demonstrates that one-dimensional, plane-symmetric pancakes are a generic form for the structure which develops from a general, three-dimensional perturbation spectrum with a short-wavelength cutoff. The evolution of an individual pancake is then calculated by numerically solving the hydrodynamical conservation equations for the baryonic fluid, together with the Poisson equation for the combined neutrino-baryon gravitational potential and the Vlasov equation for the collisionless neutrinos, all in a homogeneous, isotropically expanding universe described by the Robertson-Walker metric. The effects of ionization, recombination, and radiative cooling are explicitly included.

Expansion of a Thin Shell around a Void in Expanding Universe. II

Abstract: Motion of a compressed shell in the dust universe model is investigated in a fully relativistic manner under the approximation of infinitesimally thin shell: All voids smaller than the horizon size expand similarly, but the voids larger than the horizon do not expand appreciably until the horizon encompasses their sizes. In the open universe model, the enlargement of the void stops actually after some period. In the flat universe, the void expands forever faster than the background and its radius R behaves asymptotically as R/ ace 1°130, where a is the scale factor of the background universe. In the closed universe, the void expands much faster and tends to the light velocity at the final stage. In our previous papers,0-5) we consider the enlargement of a less-dense region in an expanding dust universe with the motivation to explain the large voids in galaxy distribu­ tions. The less-dense region, in the non-linear stage of perturbation, expands much faster than the background expansion of the universe, and then the medium surrounding a void is compressed to a thin dense shell behind the shock front by a snow-plow mechanism. As to the shock compression, we can consider two extreme situations, i.e., "adiabatic" and "isothermal". The expansion law of a spherical compressed shell in the flat universe was discussed in Refs. 4) and 5) under the Newtonian approximation. In the "adiabatic" case the shell radius R expands as to. 8 and in the "isothermal" case it expands as to 797, while the background universe expands as t2/3. The expansion laws for both cases are nearly the same. In this paper, we will treat the "isothermal" case only and use the fully relativistic equation derived in Ref. 5). In the present paper, we investigate the relativistic effect such as the behaviour of a super-horizon void, whose size is larger than the horizon at the initial time, and the expansion behaviour in various types of the background universe, numerically integrating the fully relativistic equation. In § 2, we present the basic equation derived in Ref. 5), and, in § 3, we show the results obtained by the numerical integration for the expansion law of the compressed shell. In § 4, we give the discussion including some future problems.

The Future of the Universe

Abstract: Using the grand unified theories, the authors extrapolate cosmic events into a future that is up to 10/sup 100/ times the current age of the universe. The framework for the calculations about the remote future is the big-bang model. From the standpoint of cosmology the importance of the extrapolations is that the grand unified theories have consequences that can be tested in terrestial laboratories, and so the predictions they make under extreme conditions can be confirmed. Since it is not know if the universe is closed or open, the authors give a future for each type universe. The main events for an open universe are: (1) stars will run out of fuel; (2) stars will lose their planets; (3) galactic evaporation; (4) proton decay; (5) decay of black holes. For a closed universe the expansion phase follows the same events as that of the open universe. It is possible that if the universe is closed, it could be cyclic. (SC)

Void in the Closed Universe

Abstract: Motivated by the observation of a large void in the distribution of galaxies, the dynamics of a less-dense domain of matter, which we call a void, in the expanding universe was investigated by one of the present authors.l) There, in order to see a non-linear effect of the perturbation qualitatively, he analysed the density perturbation in the flat universe in the spherically symmetric case. In this paper we generalize this analysis to the perturbation in the closed universe. Since we found that the dynamics of a void in the closed model contains various theoretically interesting problems, we will analyse a simple spherically symmetric model in some detail without any particular intention to apply to the observed voids. To simulate the evolution of a star or a black hole in the expanding universe, a spherically symmetric over-dense perturbation in the cosmological background metric has been studied since the work done by Einstein and Straus in 1945. 2 ).3) The model of our problem in this paper is similar to this Einstein-Straus model. In contrast with the over-dense perturbation in that model, the less-dense pertur­ bation in our model may cause a more drastic change for the global structure of the universe; the perturbed region expands much faster than the unperturbed region. For example, the perturbed region with a density less than the critical density expands forever but the closed universe itself shrinks to zero volume within a finite time. In § 2, the basic relations for our problem are given. We present an example of spherically symmetric density perturbation which is compatible with the globally closed topology in § 3. In § 4, we consider a void of small size and the enlargement factor of the void is calculated in a form convenient for an astro­ physical discussion. In § 5, the global space-time structure is analysed and a schematic Penrose diagram is given. In § 6, a possible application of our result

How big is the universe today

Abstract: If one defines the size of the present universe in terms of a hypersurface of simultaneity generated by the spatial geodesies orthogonal to our world line today, then it is finite in all expanding Big Bang Friedmann models.

Cosmological constant and absence of particle creation

Abstract: If one requires as an equilibrium condition that the creation rate for gravitons or minimally coupled massless scalar particles vanishes in the radiation-dominated early universe, then the expansion of the universe must be isotropic and the cosmological constant must be zero A similar equilibrium condition involving massive particles is also discussed

A Bianchi type I tilted universe

Abstract: The Bianchi type I cosmological models have been extensively studied in the past especially as examples of the homogeneous shearing universe. This paper presents a tilted universe solution admitting this group of motion where the velocity field is shear-free but there is an energy flux term.

Cosmology with very large gauge models

Abstract: Several theoretical principles suggest the existence of large numbers of very massive particles. Such particles have negligible effect in the present universe, but may have been important in the very early universe. It is shown that under some circumstances their presence could completely change the equation of state and expansion rate of the very early universe, and could have important effects on baryon-number generation. Possible cosmological constraints on the complexity of grand unified gauge models are discussed.

The Inflationary Universe

Abstract: In the past few years certain flaws in the standard big-bang theory of cosmology have led to the development of a new model of the very early history of the universe. The model, known as the inflationary universe, agrees precisely with the generally accepted description of the observed universe for all times after the first 10-30 second. For this first fraction of a second, however, the story is dramatically different. According to the inflationary model, the universe had a brief period of extraordinarily rapid inflation, or expansion, during which its diameter increased by a factor perhaps 1050 times larger than had been thought. In the course of this stupendous growth spurt all the matter and energy in the universe could have been created from virtually nothing. The inflationary process also has important implications for the present universe. If the new model is correct, the observed universe is only a very small fraction of the entire universe.

Second-order phase transitions, inflationary universe, and formation of galaxies

Abstract: At the critical point of a second-order phase transition, statistical fluctuations are correlated and enhanced in amplitude. We explore this phenomenon in the early universe as a possible mechanism for the formation of galaxies. In an inflationary universe, such dynamical effects on galactic scales are consistent with the constraints imposed by the horizon. Spontaneous breakdown of lepton number provides a model where these ideas are realized. The two-point correlation function for density fluctuations is calculated and agrees with the observed correlation for galaxies. An estimate of the density contrast is shown to be of the required magnitude.

Nuclear constraints on the age of the universe.

Abstract: In this paper a review is made of how one can use nuclear physics to put rather stringent limits on the age of the universe and thus the cosmic distance scale As the other papers in this session have demonstrated there is some disagreement on the distance scale and thus the limits on the age of the universe (if the cosmological constant lambda = 0) However, the disagreement is only over the last factor of 2, the basic timescale seems to really be remarkably well agreed upon The universe is billions of years old - not thousands, not quintillions but bilions of years That our universe has a finite age is philosophically intriguing That we can estimate that age to a fair degree of accuracy is truly impressive No single measurement of the time since the Big Bang gives a specific, unambiguous age Fortunately, we have at our disposal several methods that together fix the age with surprising precision In particular, as the other papers show, there are three totally independent techniques for estimating an age and a fourth technique which involves finding consistency of the other three in the framework of the standard Big Bang cosmological model The threemore » independent methods are: cosmological dynamics, the age of the oldest stars, and radioactive dating This paper concentrates on the third of the three methods, as well as go into the consistency technique« less

Physics of the Bi-Partition of the Universe

Abstract: Using already tested physics of matter-antimatter interaction, an attempt is made of a check of the bi-partition model of the Universe of Fliche, Souriau and Triay (1982b). No inconsistency is found.

Particle Physics and the New Cosmology

Abstract: During the past year, astounding progress has been made in the development of a radically new theory of the evolution of the early Universe. The new theory derives from the possibility that the Universe underwent a symmetry breaking phase transition in its early history that was strongly first order. During such a transition, the Universe can supercool into a metastable phase with a large vacuum energy density which results in a period of exponential expansion. It has recently been shown that in special types of first order transitions the Universe can escape from the metastable phase to a stable phase. Without a vacuum energy density contribution to the total energy density, the Universe returns to the expansion rate found in the hot big bang model. The existence of an epoch of exponential growth leads to a natural explanation of the cosmological homogeneity, isotropy, flatness, monopole and domain wall problems that plague the standard hot big bang model. The new cosmology has also been shown to lead to a (nearly) scale invariant spectrum of density perturbations in the early Universe, just the spectrum many cosmologists believe is necessary to explain the evolution of galaxies and clusters in our Universe.

The New Inflationary Nothing Universe - Grand Unified Theory

Abstract: Cosmology started out as a branch of astronomy. Lately it seems to be becoming a branch of particle physics, or at least a meeting and commingling place of astronomy and particle physics. If a dinnertable conversation at the recent Eleventh Texas Symposium on Relativistic Astrophysics (held in Austin) is any indicator, some of the traditional astronomer cosmologists resent the invasion of the particle physicists. But as Alan H. Guth of Massachusetts Institute of Technology pointed out in a talk at the same meeting, particle physicists have nowhere else to go. The theorists of particle physics have made much progress toward a theory that would unify most of that science, but in so doing they have left the realm of practical experiment behind. To test the several candidates proposed to be the Grand Unified Theory (GUT), physicists have to study phenomena that occur at fantastically high energies. There is no hope of producing such energies in a laboratory. As Guth remarks, it would take "a linear accelerator one light-year long-unlikely to be funded during the Reagan administration." The only place to find such energies is in the early stages of the history of the universe, and so numbers of particle physicists are landing in cosmology. They hit the ground running. The application of what Guth calls the simplest of the GUT theories, the one based on the mathematical symmetry group SU(5) and proposed by Howard Georgi and Sheldon Glashow, produces radical changes in cosmology. The standard astronomically derived big-bang theory has the universe expanding smoothly, causally and adiabatically from the moment of origin to the present time. (Adiabatic cooling is a drop in temperature due to expansion alone without loss of heat from the system.) GUT cosmology rejects this, proposing that the universe in its very early stages went through one or more phase transitions (like a freeze or onset of boiling), and that these transitions interrupted causality and adiabatics. Another "dramatic difference from earlier cosmology," in Guth's words, is that GUT cosmology seems to be a theory of creation truly ex nihilo, and the universe seems to remain perpetually nothing as long as it exists. That is, all of the quantities that are the subjects of conservation laws and so important to a physical analysis of the system (such as electric charge, angular momentum, "color" charge, etc.) seem to be so arranged that negative and positive amounts of them are equal and so always add up to zero, a situation "you can't distinguish from nothing," Guth says. (Guth also says that he has been trying to persuade his colleagues to start abbreviating "theory" with Th instead of just T. If they do, it would be tempting to call this the world according to GUTh.) GUT cosmology has three main consequences. It predicts first that there was one or more phase transitions at a time when the temperature of the universe was 10's billion electron-volts (101' GeV). In Guth's use of units 1 GeV is about the equivalent of 10's kelvins, so in kelvins that temperature comes out to 1027 compared to the universal mean temperature of about 3 kelvins at present. The second prediction is that magnetic monopoles exist (SN: 11/27/82, p.348; 12/ 4/82, p. 362) and that their mass is about 1016 GeV. In Guth's units this equals about a hundred-millionth of a gram. The third consequence is that the law of conservation of baryons no longer holds. Baryons are a class of particles whose lightest member is the proton. They include the neutron and several dozen heavier, radioactively unstable varieties. The baryon conservation law, the proposition that the net number of baryons and antibaryons never changes (which means that baryons change into other baryons when they do change), was a pillar that held up the roof of the older particle physics and the older cosmology. Application of the new particle physics to cosmology deals in particular with three serious problems, the horizon problem, the flatness problem and the magnetic monopole problem. Under the assumptions of the standard big-bang theory -that is, the old cosmology -the universe in its earliest moments expands too fast to maintain causal relations. The speed of light is too slow for messages to catch up, and different parts of the universe get out of communication with each other. However, at the present time we observe a high degree of isotropy in the universe: things are very much the same in all directions. That tells us that all parts of the universe were in communication with each other throughout the expansion or at least through as much of it as serves to de~~~~~~~~~~~~~~ Q

R2 Gravity and the Structure of the Universe

Abstract: The “standard” hot big bang model accounts for the expansion of the Universe, the existence of the microwave background radiation, and the mass fraction of the light elements up to 4He. It does not account for the high degree of isotropy and homogeneity of the Universe in the large, nor of the existence of structure (galaxies, clusters) on smaller scales. Other problems, such as the lepton to baryon ratio, the preponderance of matter over antimatter, and the “coincidences” of dimensionless ratios of several fundamental physical and cosmological “constants” also lie outside of the “standard” model at present.

Compatibility of a closed singular universe with present observational data

Abstract: The influence of the constant term A on the cosmological equations is investigated. It is shown that a closed singular universe is possible even with the presently known matter and radiation densities, provided that the universe age is restricted to a suitable range.