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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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TL;DR: In this article, the authors used holography for the ab-initio determination of the non-equilibrium behavior of matter in a Friedmann-Lemaitre-Robertson-Walker universe.
Abstract: We use holography for the ab-initio determination of the non-equilibrium behavior of matter in a Friedmann-Lemaitre-Robertson-Walker Universe. We focus on matter without scale invariance and develop an expansion for the corresponding entropy production in terms of the derivatives of the cosmological scale factor. We show that the resulting series is asymptotic and we discuss its resurgent properties. Finally, we compute the resummed entropy production rate in de Sitter Universe at late times and show that the leading order approximation given by bulk viscosity effects can strongly overestimate/underestimate the rate depending on the microscopic parameters.
21 citations
TL;DR: In this article, the authors show that universal thermodynamics with an event horizon is favored by dark energy from the point of view of an equilibrium thermodynamical prescription, i.e., thermodynamics of a universe bounded by an apparent or event horizon.
Abstract: Recent observational evidence supports an accelerating expansion of the Universe during the present epoch. It is commonly incorporated into standard cosmology by the introduction of exotic matter (which violates the strong energy condition) known as dark energy (DE). As an event horizon exists for an accelerating universe, there has been much work on universal thermodynamics, i.e., thermodynamics of a universe bounded by an apparent or event horizon. Recently, thermodynamical equilibrium has been examined for both types of horizons. In the present work we show that universal thermodynamics with an event horizon is favored by DE from the point of view of an equilibrium thermodynamical prescription.
21 citations
TL;DR: In this paper, the authors study the physical meaning of the wave function of the universe and show that the quantity ρ(a) =| ψ(a)| 2 for the universe is inversely proportional to the Hubble parameter.
21 citations
TL;DR: In this paper, a new model of the Archimedean-type interaction between dark matter and dark energy is presented, based on the results of numerical and qualitative analysis, and the universe expansion is shown to be perpetually accelerated, periodic or quasiperiodic with a finite number of deceleration/acceleration epochs.
Abstract: In this (second) part of the work we present the results of numerical and qualitative analysis, based on a new model of the Archimedean-type interaction between dark matter and dark energy. The Archimedean-type force is linear in the four-gradient of the dark energy pressure and plays a role of self-regulator of the energy redistribution in a cosmic dark fluid. Because of the Archimedean-type interaction the cosmological evolution is shown to have a multistage character. Depending on the choice of the values of the model-guiding parameters, the Universe expansion is shown to be perpetually accelerated, periodic or quasiperiodic with a finite number of deceleration/acceleration epochs. We distinguished the models, which can be definitely characterized by the inflation in the early Universe, by the late-time accelerated expansion and nonsingular behavior in intermediate epochs, and classified them with respect to a number of transition points. Transition points appear, when the acceleration parameter changes the sign, providing the natural partition of the Universe's history into epochs of accelerated and decelerated expansion. The strategy and results of numerical calculations are advocated by the qualitative analysis of the instantaneous phase portraits of the dynamic system associated with the key equation for the dark energy pressure evolution.
21 citations
TL;DR: In this article, it was shown that the required initial conditions should not have been obtained the maximal entropy, like a random state, and the intrinsic periodicity successfully explains why entropy is not maximal but it fails, phenomenologically, in leading to a constant entropy.
Abstract: The universe is certainly not yet in a total thermodynamical equilibrium. Thus some law of special initial conditions is needed. A universe or a system imposed to behave periodically will then require "initial conditions." Those initial conditions will not look like the type we already have, which have been suffered the heat death. In other words, the required initial conditions should not have been obtained the maximal entropy — like a random state. The intrinsic periodicity successfully explains why entropy is not maximal but it fails, phenomenologically, in leading to a constant entropy.
21 citations