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In this paper, we analyze the anisotropy of the scale factor in the Kantowski-Sachs spacetime. We show that the anisotropy will not increase when the expansion rate is greater than certain values while it will increase when the expansion…

High Energy Physics - Theory · Physics 2007-05-23 Jian-gang Hao , Xin-zhou Li

Recent released Planck data and other astronomical observations show that the universe may be anisotropic on large scales. Inspired by this, anisotropic cosmological models have been proposed. We note that the Finsler-Randers spacetime…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-25 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

In this work, we investigate the cosmological dynamics of an anisotropic Universe within the framework of $f(R,T)$ gravity by incorporating pressureless dark matter and the dark energy models. The analysis is carried out in a Bianchi type-I…

General Relativity and Quantum Cosmology · Physics 2026-05-13 S. H. Shekh , N. Myrzakulov , Anirudh Pradhan , M. Zeyauddin

The theory of cosmological perturbations is extended to spacetimes displaying isotropic expansion but anisotropic curvature. The perturbed Einstein equation and Boltzmann equations for massless and massive particles are derived in a general…

General Relativity and Quantum Cosmology · Physics 2014-05-08 T. G. Zlosnik

The chaotical dynamics is studied in different Friedmann-Robertson- Walker cosmological models with scalar (inflaton) field and hydrodynamical matter. The topological entropy is calculated for some particular cases. Suggested scheme can be…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. Yu. Kamenshchik , I. M. Khalatnikov S. V. Savchenko , A. V. Toporensky

Possible connections between quantum entanglement and cosmological eras are considered. In particular, assuming that two epochs are each other entangled, by measuring the entanglement degree, it is possible to recover dynamical properties…

General Relativity and Quantum Cosmology · Physics 2015-06-19 S. Capozziello , O. Luongo

In this manuscript, we investigate the patterns satisfied by the cosmological anisotropy under the hypothesis of the observers being co-moving with a perfect fluid whose induced space sections are homogeneous with vanishing scalar…

General Relativity and Quantum Cosmology · Physics 2021-03-31 Leandro G. Gomes

We construct general anisotropic cosmological scenarios governed by an $f(R)=R^n$ gravitational sector. Focusing then on some specific geometries, and modelling the matter content as a perfect fluid, we perform a phase-space analysis. We…

General Relativity and Quantum Cosmology · Physics 2014-03-11 Genly Leon

Recently, an anisotropic cosmological model was proposed. An arbitrary 1-form, which picks out a privileged axis in the universe, was added to the Friedmann-Robertson-Walker line element. The distance-redshift relation was modified such…

Cosmology and Nongalactic Astrophysics · Physics 2014-05-14 Zhe Chang , Xin Li , Hai-Nan Lin , Sai Wang

Anisotropies in the distance-redshift relation of cosmological sources are expected due to large-scale inhomogeneities in the local Universe. When the observed sources are tracing a large-scale matter flow in a general spacetime geometry,…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-05 Julian Adamek , Chris Clarkson , Ruth Durrer , Asta Heinesen , Martin Kunz , Hayley J. Macpherson

arXiv:1205.2953 defines an entropy for a gaussian scalar field $\phi$ in an arbitrary region of either a causal set or a continuous spacetime, given only the correlator $\langle\phi(x)\phi(y)\rangle$ within the region. As a first…

High Energy Physics - Theory · Physics 2020-12-25 Mehdi Saravani , Rafael D. Sorkin , Yasaman K. Yazdi

We evaluate reflected entropy in certain anisotropic boundary theories dual to nonrelativistic geometries using holography. It is proposed that this quantity is proportional to the minimal area of the entanglement wedge cross section. Using…

High Energy Physics - Theory · Physics 2025-01-23 Mohammad Javad Vasli , M. Reza Mohammadi Mozaffar , Komeil Babaei Velni , Mohammad Sahraei

We investigate the behavior of the entanglement entropy of a confining gauge theory near cosmological singularities using gauge/gravity duality. As expected, the coefficients of the UV divergent terms are given by simple geometric…

High Energy Physics - Theory · Physics 2017-07-26 Netta Engelhardt , Gary T. Horowitz

It seems generic to have vacua with lower dimensionality than ours. We consider the possibility that the observable universe originated in a transition from one of these vacua. Such a universe has anisotropic spatial curvature. This may be…

High Energy Physics - Theory · Physics 2010-09-29 Peter W. Graham , Roni Harnik , Surjeet Rajendran

In special relativity, testing for spatial anisotropy usually means testing for anisotropic propagation of light. This paper explores a different possibility, in which light is still assumed to propagate isotropically in all frames with an…

Classical Physics · Physics 2011-11-21 Alon Drory

We investigate entanglement production by inhomogeneous perturbations over a homogeneous and isotropic cosmic background, demonstrating that the interplay between quantum and geometric effects can have relevant consequences on entanglement…

General Relativity and Quantum Cosmology · Physics 2022-10-17 Alessio Belfiglio , Orlando Luongo , Stefano Mancini

We challenge the widely held belief that the cosmological principle is an obvious consequence of the observed isotropy of the cosmic microwave background radiation, combined with the Copernican principle. We perform a detailed analysis of a…

Astrophysics · Physics 2009-10-31 R. K. Barrett , C. A. Clarkson

The role of anisotropic components on the dark energy and the dynamics of the universe is investigated. An anisotropic dark energy fluid with different pressures along different spatial directions is assumed to incorporate the effect of…

General Physics · Physics 2018-04-16 B. Mishra , S. K. Tripathy , Pratik P Ray

We study the entanglement between two modes of Dirac field in an expanding spacetime characterized by the Robertson-Walker metric. This spacetime model turns out to be asymptotically (in the remote past and far future regions) Minkowskian.…

General Relativity and Quantum Cosmology · Physics 2014-01-21 Shahpoor Moradi , Roberto Pierini , Stefano Mancini

In this study, we establish a connection between timelike and spacelike entanglement entropy. We show that timelike entanglement entropy is closely related to spacelike entanglement entropy and its temporal derivative. For a broad class of…

High Energy Physics - Theory · Physics 2026-01-01 Wu-zhong Guo , Song He , Yu-Xuan Zhang