Entropy generation in cosmological particle creation

A very simplified model of the Universe is considered in order to propose an alternative approach to the irreversible evolution of the Universe at very early times. The entropy generation at the quantum stage can be thought of as a consequence of an instability of the system. Then particle creation arises from this instability.     

Analogue of cosmological particle creation in an ion trap

We study phonons in a dynamical chain of ions confined by a trap with a time-dependent (axial) potential strength and demonstrate that they behave in the same way as quantum fields in an expanding or contracting Universe. Based on this analogy, we present a scheme for the detection of the analogue of cosmological particle creation which should be feasible with present day technology. In order to test the quantum nature of the particle creation mechanism and to distinguish it from classical effects such as heating, we propose to measure the two-phonon amplitude via the 2nd red sideband transition and to compare it with the one-phonon amplitude (1st red sideband).     

Intrinsic measures of field entropy in cosmological particle creation

Using the properties of quantum parametric oscillators, two quantities are identified which increase monotonically in time in the process of parametric amplification. The use of these quantities as possible measures of entropy generation in vacuum cosmological particle creation is suggested. These quantities which are of complementary nature are both related to the number of particles spontaneously created.     

Particle creation in a f(R) theory with cosmological constraints

The novel idea that spatial expansion of our universe can be regarded as the consequence of the emergence of space was proposed by Padmanabhan. By using of the basic law governing the emergence, which Padmanabhan called holographic equipartition, he also arrives at the Friedmann equation in a flat universe. When generalized to other gravity theories, the holographic equipartition need to be generalized with an expression of $f(\Delta N,N_{sur})$ . In this paper, we give general expressions of $f(\Delta N,N_{sur})$ for generalized holographic equipartition which can be used to derive the Friedmann equations of the Friedmann–Robertson–Walker universe with any spatial curvature in higher ( $\hbox {n}+1$ )-dimensional Einstein gravity, Gauss–Bonnet gravity and more general Lovelock gravity. The results support the viability of the perspective of holographic equipartition.     

Construction of an elementary particle theory in cosmological spaces

Using the system of enclosure, a four-dimensional curved (conformai) space is inserted in a six-dimensional plane space, where it occupies some surface. Based upon the symmetry of the surface indicated, the equation of the scalar field on the surface is written. Thereupon, using the enclosure formula, the equation obtained is transcribed into the original four-dimensional space. It is shown that the well-known scalar field equation obtained by other authors is a particular case of the equation obtained in this study.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 10, pp. 79–83, October, 1971.The authors express their gratitude to Professor D. Ivanenko for his discussion of the question.     

Spatially homogeneous and anisotropic cosmological solution in Brans-Dicke theory

An exact solution of the vacuum Brans-Dicke (BD) field equations has been obtained for the metric tensor of a spatially homogeneous and anisotropic Bianchi type-I cosmological model. The Kasner metric is shown to be a special case. Some physical properties of the model have been discussed.     

Exact solution for particle trajectories in modified quantum mechanics

Considering a simple quantum master equation for a free particle we prove that after a given period of relaxation the solutions can be interpreted exactly in terms of uniform localized wave packets whose centers imitate classical trajectories.     

Exact solution and scaling theory of superradiance

The general scaling theory of transient phenomena near the instability point, which has been proposed by one of the present authors (M.S.), is applied to investigate the fluctuation and relaxation of superradiance near the complete inversion (or instability point). An exact solution for a simple model of superradiance has been obtained to study the relaxation and fluctuation of it near the complete inversion and to confirm the validity of the scaling theory. It is found that this asymptotic evaluation method yields very good results for a large system size Ω. The Ω-expansion method by van Kampen and by Kubo et al. is also discussed in this model in order to clarify the connection of it with the scaling theory.     

Exact solutions in cosmological inflationary models

The exact solutions of the Einstein equations that correspond to a given evolution of the scale factor in the inflationary stage in the development of the universe are considered within the framework of the theory of a self-acting scalar field that interacts minimally with a gravitational field. The form of the potential that ensures a given rate of expansion and the solution for the scalar field are calculated for each type of inflation considered. Some general laws of the relation between the form of potential and the scale factor evolution are analyzed. Moscow State University Branch in Ul'yanovsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 83–88, August, 1996.     

Particle creation in a cosmological anisotropic universe

We analyze the phenomenon of particle creation in a cosmological anisotropic universe. We compute, via the Bogoliubov transformations, the density number of scalar and spin-1/2 particles created. We obtain that they are respectively described by Bose-Einstein and Fermi-Dirac distributions.     

Nonsingular cosmological model with matter creation and entropy production

The study of nonsingular cosmological models [4] based on a theory of gravitation in flat space-times [1] is continued. For a radiation free universe the solution of the model is given analytically. Under the assumption that entropy cannot decrease the cosmological constant must be zero. At the beginning of the universe all energy is in the form of gravitation. The universe contracts. Matter and radiation are created out of gravitational energy and entropy is produced. The contraction stops and then the universe expands without limit. The creation of matter continues producing entropy but today the production of matter and entropy is negligible. The density parameter ₀ 1, i.e. there must be missing mass in the universe. The flatness and the homogeneity problem are solved.     

Exact bianchi type I solutions with a cosmological constant

We present exact solutions of Einstein's field equations with a cosmological constant. The space-time considered here is a Bianchi type I and includes an electromagnetic field.     

Exact inhomogeneous models of cosmological inflation

Exact spherically symmetric solutions of the Einstein equations with quasi-vacuum source p = −ε are found in the form of spatially inhomogeneous Tolman metrics describing the inflationary stage of the evolution of the universe. Ul’yanov State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 3–7, February, 1998.     

Higher-dimensional Florides-like solution with cosmological constant

N-dimensional generalization of Florides' interior solution with cosmological constant and Kotller's exterior solution are presented here. The case of uniform density configuration is also considered. One can get back the solutions in four-dimensional space-time by puttingN=4 in the solutions presented here.     

A new particle solution in aesthetic field theory

In present theories a particle is commonly associated with a singularity of the field. A more realistic picture would describe the particle by an intense but singularity-free field. We have found a new solution to the aesthetic field equations for which the field associated with the particle has a very large magnitude. The particle appears to be bounded despite the large numbers appearing in the solution. We prove that this present solution is not equivalent to theO(3)-invariant solution discussed in Muraskin (1973b). Since our present solution appears well-behaved, the suggestion is that we do not confine ourselves toO(3)-invariant data in future work. Owing to the large magnitude fields, we were unable to study trajectories of the particle in any detail. There is nothing wrong, in itself, with large numbers. The present solution, which we have now studied, is the first instance in our work on aesthetic field theory in which large numbers appear without the suggestion of unboundedness.     

Neutralization of the cosmological constant by membrane creation

The quantum creation of closed membranes by totally antisymmetric tensor and gravitational fields is considered in arbitrary space-time dimension. The creation event is described by instanton tunneling. As membranes are produced, the energy density associated with the antisymmetric tensor fielld decreases, reducing the effective value of the cosmological constant. For a wide range of parameters and initial conditions, this process will naturally stop as soon as the cosmological constant is near zero, even if the energy remaining in the antisymmetric tensor field is large. Among the instantons obtained, some are interpreted as representing a topology change, in which an open space spontaneously compactifies; however, the quantum probability for these processes vanishes.