Particle horizon

About: Particle horizon is a research topic. Over the lifetime, 2096 publications have been published within this topic receiving 69137 citations.

Evolution of a Spherical Universe in a Short Range Collapse/Generation Interval

Abstract: We study the final/initial behavior of a dust Universe with spatial spherical symmetry. This study is done in proximity of the collapse/generation times by an expansion in fractional Puiseux series. Even if the evolution of the universe has different behaviours depending on the initial data (in particular on the initial spatial curvature), we show that, in proximity of generation or collapse time, the Universe expands or collapses with the same behavior.

Nonsingular cosmological model with background field in flat space-time theory of gravitation

Abstract: A previously studied theory of gravitation in flat space-time is applied to homogeneous, isotropic cosmological models. In addition to radiation a two-component fluid model consisting of dust and of a background field is studied. This universe starts from a nonsingular state and expands for ever. The energy of radiation, of dust and of the background are emerged from the gravitational energy. Entropy is produced. The age of the universe is infinite measured in units of absolute time whereas the proper-time of the universe is finite. The sum of the density parameters of dust, of radiation and of the background field is about one. There is no flatness and no monopole problem.

Matter production in the early universe

Abstract: The coupled Dirac-Einstein equations with a negative cosmological constant for an open FRW universe are studied in detail. The corresponding solutions admit bounces (⇝ minimal radius) of the universe such that the matter energy in any comoving 3-volume is either increased or decreased during the bounce according to whether the bounce pressure of the spinor field is appropriately negative or not. If matter is generated (annihilated) during a bounce, the universe subsequently becomes larger (smaller) than before the bounce. Therefore matter can be generated only during the growth of the universe, but it is annihilated again during the subsequent shrinking phase, which together with the growing phase forms a cosmic supercycle.

The chaotic universe, friedmannian on the average: I

Abstract: The chaotic Universe is considered, which is homogeneous and isotropic on the sealesL ≫L whereL is the scale of averaging. From the Einstein equations, the equations for the correlation functions have been obtained which describe the statistically chaotic model with the fluctuations of arbitrary amplitudeh. In the approximation of δ-correlated fluctuations andh≪1, the infinite set of coupled equations for the correlators closes and gives a self-consistent description of the inverse influence of the vortical and potential perturbations and gravitational waves with random initial phases on the Friedmann expansion of the Universe. For the state equationp=ne, the cosmological solutions have been foud.. They depend on the position of the maximum in the spectrum of the metric perturbations (λmax >ct or λmax 0.26 it goes below it. The effect of the finites ast → 0 long-wave fluctuations leads to an averaged quasi-isotropic solution. The contribution of the quantum and short-wave classical fluctuation to the expansion law is also considered. Their effect is equivalent to the contribution from an additional ultrarelativistic gas at corresponding energy density and pressure. In Paper II, the constraints on the degree of the chaos (the spectrum characteristics) of the Universe by the time of nucleosynthesis are obtained, which involve the observed helium abundance.