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Particle horizon

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


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Journal Article
TL;DR: In this article, a non-relativistic Lagrangian model for the evolution of the fractal dimension of the universe has been proposed, and it has been shown that the model is homogeneous at the time of the last scattering, but evolves into a self-similar universe with a remarkably constant fractal dimensions.
Abstract: We write a non-relativistic Lagrangian for a hierar- chical universe. The equations of motion are solved numerically and the evolution of the fractal dimension is obtained for differ- ent initial conditions. We show that our model is homogeneous at the time of the last scattering, but evolves into a self-similar universe with a remarkably constant fractal dimension. We also show that the Hubble law is implied by this model and make an estimate for the age of the universe.

7 citations

Posted Content
TL;DR: In this paper, the properties of the quantum universe on extremely small spacetime scales are studied in the semi-classical approach to the well-defined quantum model, in which matter is represented by the radiation and additional matter source of quantum nature.
Abstract: The properties of the quantum universe on extremely small spacetime scales are studied in the semi-classical approach to the well-defined quantum model. It is shown that near the initial cosmological singularity point quantum gravity effects ~ h exhibit themselves in the form of additional matter source with the negative pressure and the equation of state as for ultrastiff matter. The analytical solution of the equations of theory of gravity, in which matter is represented by the radiation and additional matter source of quantum nature, is found. It is shown that in the stage of the evolution of the universe, when quantum corrections ~ h dominate over the radiation, the geometry of the universe is described by the metric which is conformal to a metric of a unit four-sphere in a five-dimensional Euclidean flat space. In the radiation dominated era the metric is found to be conformal to a unit hyperboloid embedded in a five-dimensional Lorentz-signatured flat space. The origin of the universe can be interpreted as a quantum transition of the system from the region in a phase space with a trajectory in imaginary time into the region, where the equations of motion have the solution in real time. Near the boundary between two regions the universe undergoes almost an exponential expansion which passes smoothly into the expansion under the action of radiation dominating over matter. As a result of such a quantum transition the geometry of the universe changes. This agrees with the hypothesis about the possible change of geometry after the nucleation of expanding universe from `nothing'.

7 citations

Posted Content
01 Jul 2019-viXra
TL;DR: In this article, an exact cosmological constant is theoretically and numerically derived and described as the squared ratio of Planck length and the particle horizon radius, which is tested for convergence for an overall flat curvature using the Friedmann equations.
Abstract: A new methodology is introduced suggesting that an exact cosmological constant is theoretically and numerically derived and described as the squared ratio of Planck length and the particle horizon radius. Additionally, equations relating the sterile neutrino mass, Planck mass and mass of the universe are established. Furthermore, the mass of the universe can be derived as encoded information located on the cosmic horizon. Finally, a relationship of the Hubble radius and comoving radius is reviewed. This hypothesis is tested for convergence for an overall flat curvature using the Friedmann equations.

7 citations

Journal ArticleDOI
TL;DR: In this article, a unified description of early universe is given in which an inflationary phase is followed by radiation-dominated phase, and various physical aspects of the models are also discussed.
Abstract: Einstein's field equations with variable gravitational and cosmological "constants" are considered in the presence of perfect fluid for a spatially homogeneous and isotropic universe. Exact solutions of the field equations are obtained by using the "gamma-law" equation of state p=(γ-1)ρ, where the adiabatic parameter γ, varies with cosmic time. The functional form of γ, which is assumed to be the function of scale factor R as proposed by Carvalho, is used to describe the early evolution of universe. A unified description of early universe is given in which an inflationary phase is followed by radiation-dominated phase. The various physical aspects of the models are also discussed.

7 citations

Journal ArticleDOI
TL;DR: The trace of the stress energy tensor of the cosmological fluid, proportional to the Ricci scalar curvature in general relativity, is determined on cosmic scales for times ranging from the inflationary epoch to the present day in the expanding Universe.
Abstract: The trace of the stress-energy tensor of the cosmological fluid, proportional to the Ricci scalar curvature in general relativity, is determined on cosmic scales for times ranging from the inflationary epoch to the present day in the expanding Universe. The post-inflationary epoch and the thermal history of the relativistic fluid, in particular the QCD transition from asymptotic freedom to confinement and the electroweak phase transition, leave significant imprints on the scalar curvature. These imprints can be of either sign and are orders of magnitude larger than the values that would be obtained by naively extrapolating the pressureless matter of the present epoch back into the radiation-dominated epoch.

7 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202320
202247
20216
202010
201910
201814