Showing papers on "Particle horizon published in 1983"
TL;DR: In this paper, the authors 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, and found that 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.
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.
258 citations
TL;DR: In this paper, the main contribution to axion energy density fluctuations at horizon crossing are those impressed on the axions by the geometry, i.e. by the original adiabatic variations in the radiation field.
127 citations
Journal Article•
TL;DR: In this paper, it is shown that inflation is a natural result of chaotic initial conditions in the early universe and that these initial conditions are found in a wide class of elementary particle theories.
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
63 citations
TL;DR: In this paper, the authors predict the structure expected in the cosmic microwave background over large angular scales in realistic anisotropic and inhomogeneous universes, showing that there exist two possibilities, a quadrupole or a hotspot pattern with and without dipole contributions.
Abstract: We predict the structure expected in the cosmic microwave background over large angular scales in realistic anisotropic and inhomogeneous universes. In a homogeneous anisotropic universe we find that there exist two possibilities, a quadrupole or a hotspot pattern with and without dipole contributions. A hotspot allows a direct observational test of an open universe. We show how infinite wavelength inhomogeneous perturbations of the Friedman universe can be represented as ensembles of different homogeneous universes.
42 citations
Book•
01 Jan 1983
TL;DR: In this article, the evolution of galaxies can be represented by a Hubble Tuning Fork, displaying elliptical, spiral, and barred spiral galaxies, and examples of galactic mergers were also viewed.
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.
41 citations
TL;DR: In this paper, the authors examined whether the density fluctuations required to explain galaxies and their clustering could have arisen spontaneously in an initially Friedmann universe as a result of statistical effects associated with the universe developing nonlinear lumps.
Abstract: We examine whether the density fluctuations required to explain galaxies and their clustering could have arisen spontaneously in an initially Friedmann universe as a result of statistical effects associated with the universe developing nonlinear lumps. Such graininess could be produced whenever the universe underwent a phase transition, and the associated fluctuations would arise either from an intrinsic randomness in the grain formation process or from the grains developing small-scale motions. In both cases the fluctuations would have the same distinctive form at their inception, and we show how they would evolve thereafter. In the conventional hot big-bang model we find that the grain effect produces fluctuations which scale as M/sup -1/2/ at decoupling. This form is consistent with observations of the galaxy correlation function. However, the fluctuations would be large enough in amplitude to generate galaxies and clusters directly only if the grains were much larger than the usual Friedmann particle horizon at formation. Such grains might arise if the very early universe underwent a period of exponential expansion associated with the supercooled symmetric evolutionary phase predicted by some Grand Unified theories. In a less conventional ''tepid'' or ''cold'' big-bang model, the grain effect might produce galaxies directly even withmore » grains smaller than the horizon. However, in this case the fluctuations would scale as M/sup -7/6/ at decoupling, which may be too steep to explain the galaxy correlation function. Even if the grain-induced fluctuations cannot produce galaxies directly, they may still be able to produce objects smaller than galaxies. Since astrophysical processes associated with these objects could themselves produce large-scale density fluctuations, it may be possible to generate galaxies and the observed correlation function from the grain effect indirectly.« less
22 citations
TL;DR: In this paper, the authors investigated the relativistic effect 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 relativism equation.
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.
22 citations
TL;DR: Using the grand unified theories, the authors of as discussed by the authors extrapolate cosmic events into a future that is up to 10/sup 100/times the current age of the universe. But the authors do not specify whether the universe is closed or open.
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)
22 citations
TL;DR: Asymptotically free models of grand unification predict the existence of metastable superheavy fermions, determining the evolution of the very early universe as discussed by the authors, and they provide stringent restrictions both on the parameters of grand unified models and on possible scenarios of the early universe.
22 citations
TL;DR: In this article, it was shown that the cosmic background radiation (CBR) is not uniquely or scientifically relatively economically indicative of a "big bang" and that essentially any temporally homogeneous theory in the Einstein universe is consistent with the existence of a CBR conforming to the Planck law.
Abstract: It is shown that the cosmic background radiation is not at all uniquely or scientifically relatively economically indicative of a ''big bang.'' Specifically, essentially any temporally homogeneous theory in the Einstein universe is consistent with the existence of a cosmic background radiation (CBR) conforming to the Planck law; in particular, the chronometric cosmology is such. It is noted that the Einstein universe appears particularly natural as a habitat for photons by virtue of the absence of infrared divergences and of the absolute convergence of the trace for associated Gibbs-state density matrices. These features are connected with the closed character of space in the Einstein universe, and facilitate the use of the latter in modeling local phenomena, in place of Minkowski space with periodic boundary conditions or the like, with minimal loss of covariance or effect on the wave functions. In particular, the Einstein universe may be used in the analysis of the perturbation of a Planck-law spectrum due to a local nonvanishing isotropic angular momentum of the CBR, of whatever origin. The estimated distortion of the spectrum due to such a kinematically admissible effect is in very good agreement with that observed by Woody and Richards, which is opposite inmore » direction to those earlier predicted by big-bang theories. The theoretical analysis involves a preliminary treatment of equilibria of linear quantum fields with supplementary quasilinear constraints.« less
19 citations
TL;DR: In this article, a compact hyperbolic three-manifold is substituted for the infinite space H/sup 3/, as space section of Friedmann's cosmological model of negative curvature.
Abstract: A compact hyperbolic three-manifold is substituted for the infinite space H/sup 3/, as space section of Friedmann's cosmological model of negative curvature. Some consequences are briefly analyzed. In particular it is shown that an apparent observational isotropy persists when the particle horizon intersects an anisotropic region of space.
TL;DR: In this paper, the authors define the size of the present universe in terms of a hypersurface of simultaneity generated by the spatial geodesies orthogonal to our world line.
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.
TL;DR: In this article, the decay of a metastable state in the early universe was investigated and it was found that the decay is not possible under certain conditions which involve the parameters of a field theory and the sign of the curvature of a cosmological model.
TL;DR: In this paper, a model of a perpetually oscillating universe is considered, in which the universe transforms from the Friedmann to the De Sitter phase with one and the same Λ ∼ 1 l 2 P 1, irrespective of the value of the total bare mass of the entire Friedmann universe.
TL;DR: In this paper, it is shown that it is extremely unlikely that the universe evolved to the present state from quantum states with singularity and particle horizon, and the Robertson-Walker model of flat spatial sections is the most likely state for the universe to evolve out of a quantum fluctuation.
TL;DR: In this paper, the creation rate for gravitons or minimally coupled massless scalar particles vanishes in the radiation-dominated early universe, and the expansion of the universe must be isotropic and the cosmological constant must be zero.
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
20 Dec 1983-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this article, the authors derived upper limits to variability over look-back times comparable with the Hubble time and distances exceeding that of the particle horizon in the Einstein-de Sitter universe.
Abstract: Given that the redshifts of quasars are due to the universal expansion, the details of their spectra can be used to check the constancy of certain dimensionless ratios of physics over look-back times comparable with the Hubble time and distances exceeding that of the particle horizon in the Einstein-de Sitter universe. With c, gp, ge, mp, me denoting the fine structure constant, and the gyromagnetic ratios and masses of protons and electrons respectively, the following upper limits to variability over such times and distances have been derived in this way:
TL;DR: The production of closed loops of string in an expanding universe, and how these might later seed the process of galaxy formation is discussed in this article, where the motion of string is damped on scales larger than the horizon, and is free beneath the horizon.
TL;DR: In this article, a tilted universe solution admits a group of motion where the velocity field is shear-free but there is an energy flux term, which is a variant of the Bianchi type I cosmological model.
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.
TL;DR: In this article, the existence of large numbers of very massive particles in the very early universe has been investigated, and it has been shown that their presence could completely change the equation of state and expansion rate of the early universe, and could have important effects on baryon-number generation.
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.
TL;DR: In this article, the authors explore the 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.
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.
TL;DR: It is shown in this paper that if the universe originated through quantum conformal fluctuations from the empty Minkowski space, then it is most likely to be spatially flat, and it is shown that the universe originates from the same configuration as ours.
TL;DR: In this paper, it was shown that it is extremely unlikely that the universe originated from a singularity and small particle horizon, under the framework of quantum conformal fluctuations, and therefore it is not possible to know the origin of the universe.
TL;DR: In the early moments of time, when the expansion was far more rapid, producing in this brief instant a radial increase 25 orders of magnitude greater than that which would otherwise have occurred, it could account for some features of our observable universe hitherto unexplained by the standard theory of the Big Bang as mentioned in this paper.
Abstract: Ever since the Big Bang, the universe has been growing at a rate proportional to a fractional power of time—or has it been? Could there have been an instant, in the earliest moments of time, when the expansion was far more rapid, producing in this brief instant a radial increase 25 orders of magnitude greater than that which would otherwise have occurred? If such an inflationary period did occur, it could account for some features of our observable universe hitherto unexplained by the standard theory of the Big Bang. These features include the remarkable homogeneity of the universe, its sparse population of magnetic monopoles (if there are any at all) and the pinpoint balance it maintains between an infinitely expanding and an eventually collapsing condition. In short, inflation may be far better news for cosmology than it is for the economy.
01 Dec 1983
TL;DR: The first scale of extragalactic distances between 1925-35 by demonstrating a direct proportion between the distances of galaxies and their recession velocities was used to define the expansion rate of the universe, which could be traced back to the Big Bang as discussed by the authors.
Abstract: The progress in techniques for measuring distances in the universe is traced to present capabilities and reference objects and length scales. Hubble established the first scale of extragalactic distances between 1925-35 by demonstrating a direct proportion between the distances of galaxies and their recession velocities. The Hubble parameter defined the expansion rate of the universe, which could be traced back to the Big Bang. Corrections have been made to the Hubble parameter since that time, increasing the estimate of the age of the universe to 15-20 billion years. Reconsideration of the distance scales has indicated that the scale is linear, i.e., the relative distance determinations maintain proportions independent of systematic error in the fundamental scale, the distances to the nearest galaxies. This factor permits a scale model of the universe to be constructed with an error factor of 10 percent.
01 Mar 1983
TL;DR: In this paper, the distance of the neutrino horizon as a function of a relativistic parameter was derived at the epochs of emission and observation of a particle with nonzero rest mass in the Friedmann model.
Abstract: Analysis of the propagation of a particle with nonzero rest mass in a Friedmann model universe yields the distance of the neutrino horizon as a function of the neutrino relativistic parameter ..gamma.. at the epochs of emission and observation.
TL;DR: The cosmological principle that the universe is homogeneous and isotropic on the largest observable scale has been confirmed to a high degree of accuracy; spatial inhomogeneities in the temperature of the background radiation are less than 1 part in 104.
Abstract: From the beginning of this century, study of the origin and evolution of the Universe has been informed by the Cosmological Principle: The Universe is homogeneous and isotropic. On the largest observable scale, that of the blackbody cosmic background radiation, this statement has been confirmed to a high degree of accuracy; spatial inhomogeneities in the temperature of the background radiation are less than 1 part in 104. On the human scale, the Principle is patently absurd. A question of considerable current interest is to ascertain on what scale the postulate breaks down. Observers have recently been working hard on mapping structure on scales of 106 to 3×108 light years, and theorists have been exploiting the increasingly important connections between particle physics and cosmology in an attempt to understand how these structures come to be.
TL;DR: In this article, 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 and how to fix the age with surprising precision.
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
TL;DR: In this paper, a collection of galaxies evolves under the influence of time-dependent forces, and hence a timedependent hamiltonian, which guarantees that, even if the universe were always spatially homogeneous and were completely free of correlations at some initial time, it would eventually develop large-amplitude correlations.
01 Jan 1983
TL;DR: In this paper, it has been shown that in special types of first order transitions the universe can escape from the metastable phase to a stable phase, and 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.
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.