Showing papers on "Big Rip published in 1980"

Dynamics of the universe and spontaneous symmetry breaking

Abstract: It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.

Production of phonons in an isotropic universe

Abstract: A quantum theory of irrotational perturbations of an ideal fluid in a spatially flat isotropic homogeneous cosmological model is constructed Two gauge-invariant canonically conjugate scalars are obtained that describe the evolution of the two physical degrees of freedom of irrotational perturbations of the matter in an expanding universe; they are analogs of the velocity potential and the density perturbation in a stationary nongravitating medium (EM Lifshitz and L P Pitaevskii, Statistical Physics, Part 2, 1978, section24) A Lagrangian and an equation of motion of second order are obtained Canonical quantization is performed, and the concept of phonons (sound quanta in a nonstationary universe) is introduced Conformal noninvariance of sound waves in an isotropic universe is proved It is shown that the mechanism of spontaneous production of phonons in the process of the cosmological expansion is the cause of the formation of the initial spectrum of adiabatic perturbations of the matter density in an isotropic Friedmann universe In the subsequent evolution in the stage after hydrogen recombination in an expanding universe the long-wavelength density fluctuations may lead to the formation of galaxies and clusters of galaxies Estimates are made of the spectrum of the primordial density fluctuations It it shown thatmore » they are in agreement with the requirements imposed on the initial spectrum by the adiabatic theory of the origin of galaxies« less

Weak interactions in the early Universe: is the Universe open?

Abstract: Big-bang nucleosynthesis per se cannot decide if the universe is open or not. Present gauge theories of elementary particles favour, on several grounds, low values (much less than unity) of the universal lepton numbers. These values, in the context of nucleosynthesis compatibility, still suggest an open Universe (13

Effects of phase transitions on the evolution of the early universe

Abstract: In spontaneously broken gauge theories, the gauge symmetry is restored at high temperatures, ie, in the early universe As the universe cools, it undergoes a phase transition from the symmetric to asymmetric phase We examine two interesting cosmological effects of such phase transitions in detail First, the latent heat released in the SU(2) x U(1)-->U(1) phase transition will decrease the previously generated baryon number to entropy ratio This decrease is calculated as a function of the Higgs meson mass, and the range of Higgs masses for which this decrease is significant (and perhaps unacceptably large) is found Second, the observation that the present universe has a low vacuum energy density (cosmological constant) implies that, prior to symmetry breakdown, the universe had a very large vacuum energy density, and this large energy density may have had an effect on the expansion of the universe We show that, in any phase transition, there exists a range of parameters for which the vacuum energy dominates the radiation energy for a short time, causing an exponential cosmic expansion; the corresponding range of Higgs masses in SU(2) x U(1) is found A suggestion that the large vacuum energy could reverse the collapse of a collapsingmore » universe is investigated, and it is shown that such a ''bounce'' will not occur within the framework of perturbative gauge theories, unless the vacuum energy always dominates the radiation density before the bounce, a condition not satisfied by our present universe« less

The Inhomogeneity and Entropy of the Universe: Some Puzzles

Abstract: Three basic questions about the physics of the early universe are briefly discussed: the origin of the entropy, the amplitude of initial fluctuations, and the overall homogeneity of the universe.

Pair creation in cosmology when electromagnetic fields are present

Abstract: The amount of particle pairs created in a 3-flat Robertson-Walker Universe with an expansion law for the early Universe is calculated exactly when a homogeneous electromagnetic field is present. Under some restrictions a time-dependent particle creation rate is found. Finally it is shown that the low-frequency part of the cosmological 2.7K background radiation can be identified with the stationary electromagnetic field discussed before. According to this a large amount of particles of the order of the number of particles in the Universe should be created out of the vacuum in the immediate neighbourhood of the 'big bang'.

The physics-astronomy frontier

Abstract: Spacetime diagrams and the structure of matter are considered, and aspects of electrical interaction are investigated. Attention is given to radiation, quantum mechanics, spectrum lines, black bodies, stellar spectra, the H-R diagram, radio astronomy, millimeter-wave astronomy, interstellar grains and infrared astronomy, and X-ray astronomy. The strong and weak interactions are examined, taking into account atoms, nuclei, the evolution of stars, and the measurement of astronomical distances. A description of gravitational interaction is also presented. The laws of motion and gravitation are considered along with black holes, the significance of cosmology, Hubble's law, the expanding universe, the symmetries of the universe, Olbers' paradox, the big-bang universe, Mach's principle, the meaning of the expansion of the system of galaxies, the redshift-magnitude relation of Hubble and Humason, the early universe, and the geometry of special relativity.

Case for an open universe

Abstract: The determination of the geometrical structure of the universe through the magnitude-vs-redshift relation in standard cosmology has not been very successful, mainly because of the intrinsic insensitivity of the m-vs-z relation to a deceleration parameter, which determines the spatial curvature and therefore the geometry. By relaxing the assumption usually made, i.e., the identity of gravitational and atomic clocks, sufficient sensitivity is achieved. Existing observational evidence then leads one to conclude that the universe is open.

Isotropy of the universe and equation of state of vacuum

Abstract: We analyse the isotropization of homogeneous cosmological models including phenomenologically the contribution of vacuum polarization to the energy content of the Universe. The combined effect of dissipative processes at early epochs and of vacuum at relatively late epochs guarantees the isotropy of the Universe at large times for arbitrary initial anisotropies, provided the Universe expands forever and the vacuum has positive energy density and negative stresses with a sufficiently hard equation of state. Isotropy at the present epoch is secured by a negative deceleration parameter consistent with observation.

Astrophysical implications of the neutrino rest mass. I. The universe

Abstract: Recent measurements of the spectrum of tritium decay electrons in the USSR suggest that electronic neutrinos may have a rest energy m/sub ..nu../c/sup 2/approx. =30 eV. Primordial neutrinos would then make a major contribution to the mean density of matter in the universe, enough for the universe to be closed. If future reactor and accelerator experiments should reveal that muonic and tau neutrinos have a mass of the same order, then one would infer an age of less than 10/sup 10/ yr for the Friedmann universe, contrary to the age observed for the oldest stars in the Galaxy. The contradiction can be removed by introducing the cosmological constant ..lambda... Conversely, measuring the rest mass of all neutrino species as well as the age of the universe would afford a unique opportunity to evaluate ..lambda...

The Evolution of Matter in the Universe

Abstract: It is now generally believed that our Universe originated some 1010 yr ago in a singular event which is referred to as the ‘Big Bang’.

High-energy gravity and the very early universe

Abstract: It is suggested that gravity may not be asymptotically free at short distances because of the interaction of the graviton with matter. If gravity indeed becomes strong at high energies, a revolutionary change of our present theory on the early universe would seem to be necessary. During the first extremely small fraction of a second in the big-bang universe, gravity would have been so strong that it might not have been described by Einstein's theory of general relativity. The possibility of abnormally strong gravity at high energies or short distances is discussed in some detail. A possible explanation is proposed for the nonvanishing mean baryon number density of the universe. It is also pointed out that the universe may well escape from the catastrophic singularity of Penrose and Hawking.

Time's arrow in an oscillating universe

Abstract: In view of the time-symmetric nature of the laws of physics, time asymmetry in the universe must arise from “initial” conditions A fully time-symmetric oscillating model is presented which exists in a highly compressed, highly ordered state att=0 and evolves forward, in the thermodynamic sense, as ∣t ∣ increases This model offers the possibility of accounting for several fundamental and puzzling aspects of our universe, including matter-antimatter asymmetry, the large entropy per baryon, primordial density enhancements sufficient to form galaxies, and large-scale homogeneity

The Beam and Stay of the Taub Universe

Abstract: The single mode of gravitational radiation that activates the otherwise empty Taub model universe has the longest possible wavelength that will fit into that universe and an amplitude just sufficient to curve the geometry up into closure, via its “effective” content of mass energy, both kinetic and potential. A parameter m' of time asymmetry in the Taub family of models allows one to adjust the ratio kinetic/potential at the phase of time asymmetry. A sufficiently extreme value of this parameter, m' = 10 12 , gives a universe that will live as long as a typical Friedmann “dust-dominated” model (“stay”) = 60 × 19 9 years, but will have a volume-at-maximum expansion smaller by a factor of 4.8 × 10 10 , or a (“beam”) = [(π/2) (volume at maximum)] 1/3 that is smaller than that of the Friedmann model by a factor of 3.64 × 10 3 . If with a universe so small it is nevertheless possible to secure a stretch of time quite adequate for the development of life, it is not clear what is the point of a larger universe. Neither is it clear how the anthropic principle of Dicke and Carter is to come to terms with this “missed chance for economy.”

The Density of the Universe

Abstract: Having collected all the available information on the distribution of galaxies in space and on intergalactic material, we are able to attack the problem of the density of the universe. This density is one of the four fundamental parameters observable within a gigaparsec and contributing to cosmology. The other three are the distance scale, the Hubble constant which we have already studied, and the age of the universe which is the subject of the next chapter.

Models of the universe compatible with present observations

Abstract: It is shown that cosmic radiation almost follows a Planck distribution, because just as matter is formed, its density of energy is negligible in comparison with that of radiation, and that the present age of the Universe does not depend on the particular manner in which the matter is formed.