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We analyse the possibility that our Universe could be described by the model recently proposed by Melia & Shevchuk (2012), where the Hubble scale R_h=c/H is at all times equal to the distance ct that light has travelled since the Big Bang.…

宇宙学与河外天体物理 · 物理学 2012-08-28 Maciej Bilicki , Marina Seikel

In inflationary cosmology all particle states decay as a consequence of the lack of kinematic thresholds. The decay of an initial single particle state yields an \emph{entangled quantum state of the product particles}. We generalize and…

宇宙学与河外天体物理 · 物理学 2014-04-15 Louis Lello , Daniel Boyanovsky , Richard Holman

In the action formalism variations of metric tensors usually are limited by the Hubble horizon. Contrary, variations of quantum fields should be extended up to the event horizon, which is the real boundary of the spacetime. As the result…

综合物理 · 物理学 2018-11-29 Merab Gogberashvili

The present work deals with universe bounded by the cosmological event horizon as a thermodynamical system which is irreversible in nature.Using non-equilibrium thermodynamical approach the entropy variation on the event horizon has been…

综合物理 · 物理学 2014-06-30 Subenoy Chakraborty , Atreyee Biswas

The holographic entropy bound is discussed in cosmology. Inspired by the work of Fischler and Susskind [hep-th/9806039], we aim to define a special class of spherical systems in cosmology, within which the entropy of matter remains…

广义相对论与量子宇宙学 · 物理学 2025-10-15 Hao Yu , Zi-Chao Lin , Jin Li

The universal validity of the second law of thermodynamics is widely attributed to a finely tuned initial condition of the universe. This creates a problem: why is the universe atypical? We suggest that the problem is an artefact created by…

广义相对论与量子宇宙学 · 物理学 2015-07-27 Julian Barbour , Tim Koslowski , Flavio Mercati

At present, there is practically no doubt that general relativity is closely related to gravity. Moreover, after the work of Jacobson, Padmanabhan and others, it became clear that a thermodynamic interpretation of Einstein's relativistic…

广义相对论与量子宇宙学 · 物理学 2024-03-19 Yu. L. Bolotin , V. V. Yanovsky

Decoupling of heavy modes in effective low energy theory is one of the most fundamental concepts in physics. It tells us that modes must have a negligible effect on the physics of gravitational backgrounds with curvature radius larger than…

高能物理 - 理论 · 物理学 2020-05-12 Gia Dvali , Alex Kehagias , Antonio Riotto

The probability of there being sufficient inflation to solve the fine-tuning associated with the horizon and flatness problems has recently been shown to be exponentially small, within the context of classical general relativity. Here this…

广义相对论与量子宇宙学 · 物理学 2007-08-27 William Nelson

The present discussion contribution is some remarks concerning and review of the proposal by one of us (C. Balazs) to explain the cosmological constant by a/the principle of entropy. Used without further comment this principle of entropy…

宇宙学与河外天体物理 · 物理学 2013-06-26 H. B. Nielsen , C. Balazs

In a recent paper Yu and Eberly [Phys. Rev. Lett. {\bf 93}, 140404 (2004)] have shown that two initially entangled and afterwards not interacting qubits can become completely disentangled in a finite time. We study transient entanglement…

量子物理 · 物理学 2009-11-13 Z. Ficek , R. Tanas

We investigate entropic force cosmological models with the possibility of matter creation and energy exchange between the bulk and the horizon of a homogeneous and an isotropic flat Universe. We consider three different kinds of entropy,…

广义相对论与量子宇宙学 · 物理学 2021-07-27 Hussain Gohar , Vincenzo Salzano

Quantum gravity in a finite region of spacetime is conjectured to be dual to a conformal field theory deformed by the irrelevant operator $T \overline{T}$. We test this conjecture with entanglement entropy, which is sensitive to ultraviolet…

高能物理 - 理论 · 物理学 2018-10-03 William Donnelly , Vasudev Shyam

We examine the evolution of the Friedmann Universe within our recent model of space-time identified with an elastic continuous medium whose deformations are described by a vector field constrained to obey a generalized four-dimensional…

广义相对论与量子宇宙学 · 物理学 2015-12-22 Fayçal Hammad

Cosmological perturbations with wavelengths smaller than Hubble radius can be handled in the context of Newtonian theory with very high accuracy. The application of this Newtonian approximation, however, is restricted to nonrelativistic…

广义相对论与量子宇宙学 · 物理学 2007-05-23 Ali Nayeri , T. Padmanabhan

We investigate the relaxation and decay of a particle during inflation by implementing the dynamical renormalization group. This investigation allows us to give a meaningful definition for the decay rate in an expanding universe. As a…

天体物理学 · 物理学 2009-11-10 D. Boyanovsky , H. J. de Vega

We consider a variant of the brane-world model in which the universe is the direct product of a Friedmann, Robertson-Walker (FRW) space and a compact hyperbolic manifold of dimension $d\geq2$. Cosmology in this space is particularly…

高能物理 - 理论 · 物理学 2009-10-31 Glenn D. Starkman , Dejan Stojkovic , Mark Trodden

In a recent paper \cite{Artymowski:2020zwy} we suggested the possibility that the present acceleration of the Universe is due to thermodynamical behavior of unparticles. The model is free of scalar fields, modified gravity, a Cosmological…

宇宙学与河外天体物理 · 物理学 2022-10-19 Michał Artymowski , Ido Ben-Dayan , Utkarsh Kumar

Recently a covariant entropy conjecture has been proposed for dynamical horizons. We apply this conjecture to concordance cosmological models, namely, those cosmological models filled with perfect fluids, in the presence of a positive…

高能物理 - 理论 · 物理学 2008-11-26 Song He , Hongbao Zhang

In a recent model Choudhury proposed that a collapsing matter generates an adiabatic pressure which can be used to explain the acceleration of the physical universe under certain approximation. In this work we superimpose the core pressure…

广义相对论与量子宇宙学 · 物理学 2008-05-26 A. M. Haruar Rashid , A. L. Choudhury