Showing papers on "Cosmology published in 1974"
01 Jan 1974
52 citations
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34 citations
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23 citations
01 Jan 1974
17 citations
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01 Jan 1974
TL;DR: In this article, Field and Rees discuss the contemporary structure and dynamics of the universe, including the superclustering of galaxies and their formation in Friedmannian Universes.
Abstract: I / The Contemporary Structure and Dynamics of the Universe.- Observational Foundations for Assumptions in Cosmology.- Intergalactic Gas.- Confrontation of Lemaitre Models and the Cosmological Constant with Observations.- The Hubble Constant and the Deceleration Parameter.- Evidence for Non-Velocity Redshifts.- General Discussion and Short Contributions.- II / The Structure of the Universe.- Superclustering of Galaxies.- The Counts of Radio Sources.- Radio Source Counts at Centimetre Wavelengths.- Observational Foundations of Inhomogeneous Universe.- Field Galaxies and Cluster Galaxies: Abundances of Morphological Types and Corresponding Luminosity Functions.- III / Relic Radiation.- Energy Density of the Relic Radiation.- Large Scale Anisotropy of the Cosmic Microwave Background.- Fine Scale Anisotropy of the Cosmic Microwave Background Radiation.- The Thermal History of the Universe and the Spectrum of Relic Radiation.- The Spectrum of Density Perturbations in an Expanding Universe.- Cosmological Synthesis of the Elements.- IV / The Origin of Structure in the Expanding Universe.- The Formation of Galaxies in Friedmannian Universes.- Whirl Theory of the Origin of Galaxies and Clusters of Galaxies.- Generation of Sound from Primordial Cosmic Turbulence.- General Discussion and Short Contributions.- V / The Structure of Singularities.- General Solutions of the Equations of General Relativity near Singularities.- Singularities in Cosmology.- Isotropization of Homogeneous Cosmological Models.- The Anisotropy of the Universe at Large Times.- General Discussion and Short Contribution.- Large Number Coincidences and the Anthropic Principle in Cosmology.- Low Frequency Gravitational Waves in Cosmology.- VI / Matter-Antimatter Universes and Physical Processes Near the Singularity.- Quantum Descriptions of Singularities Leading to Pair Creation.- Creation of Particles in Cosmology.- Baryon Symmetric Big Bang Cosmology.- The Low Density Symmetric Cosmology.- Confrontation of Antimatter Cosmologies with Observational Data.- Short Contribution.- Concluding Remarks by M. J. Rees.- Vote of Thanks to Organisers by G. B. Field.- Index of Authors.- Index of Subjects.
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TL;DR: In this paper, a connection between the effective path length of the matter which nuclei encounter in the Galaxy and the parameters of the diffusion model with an inhomogeneous distribution of an interstellar gas is established.
Abstract: The homogeneous and flat diffusion models of the propagation of cosmic rays through the Galaxy are considered. It is shown that, with the usual choice of galactic parameters, in particular, those pertaining to its gas distribution, and subject to the restriction of not too heavy nuclei (nuclei no heavier than iron), both models are equivalent from the point of view of the description of the element composition of cosmic rays. This conclusion is justifiable both for galactic and metagalactic theories of the occurrence of cosmic rays. A connection is established between the effective path length of the matter which nuclei encounter in the Galaxy and the parameters of the diffusion model with an inhomogeneous distribution of an interstellar gas. Initial results allow the interpretation of a relationship of cosmic ray element composition to their energies. Restrictions which must be placed on such a relationship are shown from the different data on cosmic rays at the Earth.
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01 Jan 1974TL;DR: The authors showed that the Friedmann cosmological models are a good approximation today for the expanding universe and this is valid for at least some period of time in the past too, but how did the universe expand and what was the matter distribution close to the starting point, near the cosmologically singularity?
Abstract: Observations primarily of the microwave background radiation show that the Universe expands isotropically with a high degree of accuracy at the present time and that the matter distribution is homogeneous on a large scale. Thus, the Friedmann cosmological models are a good approximation today for the expanding Universe. This is valid for at least some period of time in the past too. But how did the Universe expand and what was the matter distribution close to the starting point, near the cosmological singularity?
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TL;DR: In this article, an analysis of the implications of assuming an extragalactic origin for cosmic rays above 1017 eV is made and the effect of the black-body radiation on the propagation of extragalanactic protons is examined in some detail.
Abstract: An analysis is made of the implications of assuming an extragalactic origin for cosmic rays above 1017 eV. The effect of the black- body radiation on the propagation of extragalactic protons is examined in some detail and the expected spectral shape is derived for alternative assumptions about the origin and confinement of the particles. The possibility of distinguishing between the various models using contemporary extensive air shower arrays is considered.
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TL;DR: In this article, it was shown that singularity-free big bang models are possible under the modified field equations of general relativity, but the case is made out that matter creation takes place in several mini-bangs at different epochs rather than in one big bang.
Abstract: The ideas originally proposed to discuss continuous creation of matter are reconsidered in the context of the big bang cosmological models. It is shown that singularity-free big bang models are possible under the modified field equations of general relativity. However, the case is made out that matter creation takes place in several mini-bangs at different epochs rather than in one big bang. The implications of this idea for high energy astrophysics and for gravitational radiation are discussed.
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TL;DR: In this article, an upper limit on the rest masses of the neutrinos was proposed, based on the temperature of the electromagnetic background radiation, which is more restrictive than the laboratory values.
Abstract: The age of the Universe and the Hubble deceleration of galaxies depends upon the average mass density. The temperature of the electromagnetic background radiation determines also the neutrino particle density. These empirical informations put an upper limit on the rest masses of the neutrinos, which are more restrictive than the laboratory values.
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TL;DR: The formation and spontaneous decay of supernovae prior to the formation of the solar system is discussed in this article, where the age of the universe as derived from nucleocosmochronology is compared to the ages derived from expansion and globular clusters.
Abstract: The formation and spontaneous decay of /sup 232/Th, /sup 235/U, /238/U, and /sup 244/Pu is reviewed. The rate supernovae prior to the formation of the solar system is discussed. The age of the Universe as derived from nucleocosmochronology is compared to the ages derived from expansion and globular clusters. (DM)
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01 Jan 1974TL;DR: In this article, it is shown that the absence of noticeable deviations from the Planckian spectrum enables us to set limits to the energy release in the early universe (102 < z < 108).
Abstract: Many of the cosmological models currently under discussion and theories of the origin of galaxies which involve antimatter, strong turbulence and so on result in significant energy release during the evolution of the Universe. It is evident that significant energy production should lead to distortions of the spectrum of the relic radiation. The absence of noticeable deviations from the Planckian spectrum enables us to set limits to the energy release in the early Universe (102 < z < 108). But in order to have a clear picture of possible distortions, let us first review the idealized situation.
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TL;DR: In this article, the very early universe must have been extremely homogeneous, even on scales far exceeding the particle horizon, and the assumption that statistical departures from equilibrium started to grow after this epoch leads to a prediction of the density fluctuations at recombination.
Abstract: The very early universe must have been extremely homogeneous, even on scales far exceeding the particle horizon. Within the framework of the standard Friedmann cosmology, homogenization can only be achieved by quantum effects which violate classical causality. This could happen when the particle horizon was smaller than the Compton wavelength of the pion. The assumption that statistical departures from equilibrium started to grow after this epoch leads to a prediction of the density fluctuations at recombination. The amplitude ν of the fluctuations should have a maximum of about 0.007 on scales of 81017M. For smaller scales, ν ∝M
+1/6, and for larger scales, ν ∝M
−1/2. This suggests that superclusters condense out at a red shift of about 11, and clusters and then galaxies form shortly after by fragmentation.
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01 Jan 1974TL;DR: In this article, observational material testing the cosmological principle separately for geometry and substratum, is discussed without referring to any given model of the Universe, as long as the theoretical assumptions on which these models are based are true.
Abstract: Testing cosmological models is worthwhile as long as the theoretical assumptions, on which these models are based, are true In this report observational material testing the Cosmological Principle separately for geometry and substratum, is discussed without referring to any given model of the Universe
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TL;DR: In this paper, the main results of the work of Stecker and Puget concerning the behaviour of the most important quantities of the matter-antimatter annihilation theory are used, in order to describe the properties of the energy source for the turbulence down to recombination time, and extended to take a somewhat more detailed account of theirz and mean matter density dependences.
Abstract: In a previous work by two of us, the main difficulties of the theory of galaxy formation from universal primordial cosmic turbulence were focussed; it was mainly found that the decay of the turbulence was so strong during the plasma era that turbulence should have been almost completely washed out before recombination, unless, and only for low-density universes, unlikely large turbulent velocities were postulated at the largest scale of the turbulence at the end of the radiation era. It was suggested that a possibility to turn around such a difficulty should consist in finding en adequate physical energy source feeding the turbulence during at least the whole plasma phase. The present work is intended to test whether matter-antimatter annihilation theory at the origin of the universe, as it is developed by Omnes and his collaborators, may be considered to yield the required energy source of the turbulence. To this aim, the main results of the work of Stecker and Puget concerning the behaviour of the most important quantities of the matter- antimatter annihilation theory are used, in order to describe the properties of the energy source for the turbulence down to recombination time, and extended to take a somewhat more detailed account of theirz and mean matter density dependences. The energy feeding source thus obtained is then introduced into the general framework of the galaxy formation theory from cosmic turbulence taking account of energy dissipation as developed in our previous works. The results obtained concerning the comparison of the main parameters of galaxies derived from the theory with the experimental data are much more satisfactory than in the previous approach, and show that, inside the errors of the present day values, sufficiently good fits are possible in a range of mean universe densities between 0.4 to 1 times the critical density.
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01 Jan 1974TL;DR: In this article, a particular example of the impact of quantum mechanics on cosmological theory is presented, where the creation of particles may influence the cos-mological equations through the energy-stress tensor of these particles.
Abstract: The creation of particles is a process which can only be described by quantum field theory. The old classical theories dealing with indestructible particles are incompatible with particle creation. It was the discovery of the corpuscular nature of light (Einstein, 1905) and the prediction of antiparticles (Dirac, 1929) which demonstrated that particle creation was possible. The creation of particles may influence the cos-mological equations through the energy-stress tensor of these particles. For physical cosmology the particles themselves are important. Therefore this report deals with a particular example of the impact of quantum mechanics on cosmological theory.
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01 Jan 1974TL;DR: The spectrum of density inhomogeneities that survive decoupling of matter and radiation at z~1000 and provide the primordial fluctuations that can eventually generate galaxies is discussed in this article.
Abstract: Perhaps the most challenging problem confronting a cosmologist is to reconcile the observed large-scale structure of the Universe with the Friedmann-Lemaitre cosmological models that have gained such widespread acceptance in recent years (cf however the alternative viewpoint, as exemplified in this Symposium by Arp and others) In this review, I shall look anew at the spectrum of density inhomogeneities that survive decoupling of matter and radiation at z~1000 and provide the primordial fluctuations that can eventually generate galaxies A closely related matter, that of the associated fluctuations in the background radiation, is discussed elsewhere in this volume by Doroshkevich, Sunyaev and Zel’dovich