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It is shown that only in the space-times admitting a 1+3-foliation by flat Cauchy hypesurfaces (i.e., in the Bianchi I type space-times the isotropic version of which the spatially flat Friedmann-Robertson-Walker space-times are) the…

General Relativity and Quantum Cosmology · Physics 2007-05-23 E. A. Tagirov

According to standard cosmology, the universe is homogeneous and isotropic at large scales. However, some anisotropies can be observed at the local scale in the universe through various ways. Here we have studied the Bianchi type I model…

General Relativity and Quantum Cosmology · Physics 2022-09-12 Pranjal Sarmah , Umananda Dev Goswami

We present a study of the vacuum transition probabilities taking into account quantum corrections. We first introduce a general method that expands previous works employing the Lorentzian formalism of the Wheeler-De Witt equation by…

General Relativity and Quantum Cosmology · Physics 2025-01-03 H. García-Compeán , J. Hernández-Aguilar , D. Mata-Pacheco , C. Ramírez

A specific loop quantum cosmology model, mLQC-I, motivated by Thiemann's regularization of the Hamiltonian constraint, leads to the resolution of the big bang singularity and bounce in the isotropic setting, in which either the pre-bounce…

General Relativity and Quantum Cosmology · Physics 2026-03-24 Meysam Motaharfar , Parampreet Singh

We analyze the semiclassical and quantum polymer dynamics of the isotropic Universe in terms of both the standard Ashtekar-Barbero-Immirzi connection and its conjugate momentum and also of the new generalized coordinate conjugate to the…

General Relativity and Quantum Cosmology · Physics 2022-06-01 Eleonora Giovannetti , Gabriele Barca , Federico Mandini , Giovanni Montani

Some new exact solutions of Einstein's field equations have come forth within the scope of a spatially homogeneous and anisotropic Bianchi type-III space-time filled with barotropic fluid and dark energy by considering a variable…

Cosmology and Nongalactic Astrophysics · Physics 2014-03-20 Hassan Amirhashchi , Anirudh Pradhan , Rekha Jaiswal

The behavior near the initial singular state of the anisotropy parameter of the arbitrary type, homogeneous and anisotropic Bianchi models is considered in the framework of the brane world cosmological models. The matter content on the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 T. Harko , M. K. Mak

We have studied the locally rotationally symmetric (LRS) Bianchi type-I cosmological model in $f(R,T)$ gravity ($R$ is the Ricci scalar and $T$ is the trace of the stress energy tensor) with Bulk viscous fluid as matter content. The model…

General Relativity and Quantum Cosmology · Physics 2018-03-29 Parbati Sahoo , Raghavender Reddy

This paper deals with a spatially homogeneous and totally anisotropic Bianchi type-V cosmological model within the framework of self interacting Brans Dicke theory of gravity in the background of anisotropic dark energy (DE) with variable…

General Relativity and Quantum Cosmology · Physics 2018-02-14 J. K. Singh , Sarita Rani

We analyze the big bounce transition of the quantum FRW model in the setting of the nonstandard loop quantum cosmology (LQC). Elementary observables are used to quantize compound observables. The spectrum of the energy density operator is…

General Relativity and Quantum Cosmology · Physics 2015-05-20 Wlodzimierz Piechocki

We use a dynamical systems approach based on the method of orthonormal frames to study the dynamics of a two-fluid, non-tilted Bianchi Type I cosmological model. In our model, one of the fluids is a fluid with bulk viscosity, while the…

General Relativity and Quantum Cosmology · Physics 2015-10-22 Ikjyot Singh Kohli , Michael C. Haslam

Using the ADM formalism in the minisuperspace, we obtain the commutative and noncommutative exact classical solutions and exact wave function to the Wheeler-DeWitt equation with an arbitrary factor ordering, for the anisotropic Bianchi type…

General Relativity and Quantum Cosmology · Physics 2015-05-14 J. Socorro , Luis O. Pimentel , C. Ortiz , M. Aguero

In this article we perform the Wheeler-DeWitt quantization for Bianchi type $I$ anisotropic cosmological model in the presence of a scalar field minimally coupled to the Einstein-Hilbert gravity theory. We also consider the cosmological…

General Relativity and Quantum Cosmology · Physics 2019-08-14 Saumya Ghosh , Sunandan Gangopadhyay , Prasanta K. Panigrahi

In the framework of loop quantum cosmology anomaly free quantizations of the Hamiltonian constraint for Bianchi class A, locally rotationally symmetric and isotropic models are given. Basic ideas of the construction in (non-symmetric) loop…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Martin Bojowald

In some interesting work of James Lidsey, the dynamics of Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmology with positive curvature and a perfect fluid matter source is shown to be modeled in terms of a time-dependent, harmonically…

Mathematical Physics · Physics 2014-11-21 Jennie D'Ambroise , Floyd L. Williams

In this paper, aniostropic dark energy cosmological models have been constructed in a Bianchi-V space-time with the energy momentum tensor consisting of two non-interacting fluids namely bulk viscous fluid and dark energy fluid. Two…

General Relativity and Quantum Cosmology · Physics 2018-02-01 B. Mishra , Pratik P. Ray , S. K. J. Pacif

The present study deals with spatially homogeneous and anisotropic Bianchi-I cosmological model representing massive strings. The energy-momentum tensor, as formulated by Letelier (Phys. Rev. D 28: 2414, 1983) has been used to construct…

General Physics · Physics 2014-03-11 Chanchal Chawla , R. K. Mishra , Anirudh Pradhan

We derived equations of motion corresponding to Bianchi-I cosmological models in the Lovelock gravity. Equations derived in the general case, without any specific ansatz for any number of spatial dimensions and any order of the Lovelock…

General Relativity and Quantum Cosmology · Physics 2010-01-22 S. A. Pavluchenko

Following up on hints of anisotropy in the cosmic microwave background radiation (CMB) data, we investigate locally rotational symmetric (LRS) Bianchi type I spacetimes with non-minimally coupled scalar fields. To single out potentially…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Y. Kucukakca , U. Camci , İ. Semiz

The dynamics of cosmological models with isotropic matter sources (perfect fluids) is extensively studied in the literature; in comparison, the dynamics of cosmological models with anisotropic matter sources is not. In this paper we…

General Relativity and Quantum Cosmology · Physics 2011-02-16 Simone Calogero , J. Mark Heinzle