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In this work, we will explore the effects of F(R) theories in the classical scheme using the anisotropic Bianchi Type I cosmological model with standard matter employing a barotropic fluid with equation of state $P=\gamma \rho$. In this…

General Relativity and Quantum Cosmology · Physics 2026-04-15 J. Socorro , Juan Luis Pérez , Luis Rey Díaz-Barrón , Abraham Espinoza García , Sinuhé Pérez Payán

The future asymptotic behaviour of a non-titled Bianchi Type IV viscous fluid model is analyzed. In particular, we consider the case of a viscous fluid without heat conduction, and constant expansion-normalized bulk and shear viscosity…

General Relativity and Quantum Cosmology · Physics 2014-02-26 Ikjyot Singh Kohli , Michael C. Haslam

We analyze the dynamics of a class of cosmological solutions of the Einstein-Vlasov equations. These equations describe an ensemble of collisionless particles (which represent galaxies or clusters of galaxies) that interact gravitatively…

General Relativity and Quantum Cosmology · Physics 2010-11-18 Simone Calogero , J. Mark Heinzle

The Einstein vacuum equations in five dimensions with negative cosmological constant are studied in biaxial Bianchi IX symmetry. We show that if initial data of Eguchi-Hanson type, modelled after the four-dimensional Riemannian…

General Relativity and Quantum Cosmology · Physics 2018-04-18 Dominic Dold

In this letter we discuss the connection between so-called homoclinic chaos and the violation of energy conditions in locally rotationally symmetric Bianchi type IX models, where the matter is assumed to be non-tilted dust and a positive…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. Mark Heinzle , N. Rohr , C. Uggla

It is believed that soon after the Planck time, Einstein's general relativity theory should be corrected to an effective quadratic theory. Numerical solutions for the anisotropic generalization of the Friedmann "open" model $H^ 3$ for this…

General Relativity and Quantum Cosmology · Physics 2012-04-11 Juliano A. de Deus , Daniel Müller

Due to the numerical complexities of studying evolution in an anisotropic quantum spacetime, in comparison to the isotropic models, the physics of loop quantized anisotropic models has remained largely unexplored. In particular, robustness…

General Relativity and Quantum Cosmology · Physics 2017-04-14 Peter Diener , Anton Joe , Miguel Megevand , Parampreet Singh

Methods of dynamical systems analysis are used to show rigorously that the presence of a magnetic field orthogonal to the two commuting Killing vector fields in any spatially homogeneous Bianchi type VI_0 vacuum solution to Einstein's…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Marsha Weaver

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

Using appropriate harmonics, we study the future asymptotic behavior of massless scalar fields on a class of cosmological vacuum spacetimes. The spatial manifold is assumed to be a circle bundle over a higher genus surface with a locally…

General Relativity and Quantum Cosmology · Physics 2014-11-17 Masayuki Tanimoto

We hereby address the cosmological singularity problem in a general gravitational theory invariant under Weyl conformal transformations. In particular, we focus on the Bianchi IX spacetime and we show that both the initial (big bang) and…

General Relativity and Quantum Cosmology · Physics 2026-01-21 Jiale Gu , Leonardo Modesto , Cosimo Bambi

We analyze some relevant features of the primordial Universe as viewed in the Jordan frame formulation of the f(R)-gravity, especially when the potential term of the non-minimally coupled scalar field is negligible. We start formulating the…

General Relativity and Quantum Cosmology · Physics 2023-04-13 Nicola Bamonti , Andrea Costantini , Giovanni Montani

We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., $p = \zeta \ve$, with…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha

We analyze the quantum Bianchi I model in the setting of the nonstandard loop quantum cosmology. Elementary observables are used to quantize the volume operator. The spectrum of the volume operator is bounded from below and discrete. The…

General Relativity and Quantum Cosmology · Physics 2011-04-04 Przemyslaw Malkiewicz , Wlodzimierz Piechocki , Piotr Dzierzak

We analyze the Bianchi IX Universe in the Polymer Quantum Mechanics framework by facing both semiclassical and purely quantum effects near the cosmological singularity. We adopt Misner variables to describe the model dynamics, applying the…

General Relativity and Quantum Cosmology · Physics 2019-12-03 Eleonora Giovannetti , Giovanni Montani

In this paper we study the Einstein-Boltzmann system for Israel particles with a positive cosmological constant. We consider spatially homogeneous solutions of Bianchi types except IX and obtain future global existence and asymptotic…

General Relativity and Quantum Cosmology · Physics 2017-12-27 Ho Lee , Ernesto Nungesser

The comprehensive formulation for loop quantum cosmology in the spatially flat, isotropic model was recently constructed. In this paper, the methods are extended to the anisotropic Bianchi I cosmology. Both the precursor and the improved…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Dah-Wei Chiou

We consider the dynamics towards the initial singularity of Bianchi type IX vacuum and orthogonal perfect fluid models with a linear equation of state. The `Bianchi type IX attractor theorem' states that the past asymptotic behavior of…

General Relativity and Quantum Cosmology · Physics 2009-03-27 J. Mark Heinzle , Claes Uggla

The dynamics of the general Bianchi IX spacetime, near the gravitational singularity, underlies the Belinskii, Khalatnikov and Lifshitz scenario. Asymptotically, near the singularity, the oscillations of the directional scale factors…

General Relativity and Quantum Cosmology · Physics 2017-05-12 Andrzej Góźdź , Włodzimierz Piechocki , Grzegorz Plewa

We study the dynamics of the vacuum Bianchi IX model with timelike singularity and compare it with the dynamics of the Bianchi IX model with cosmological singularity. We show that differences in the signs of some terms in the set of…

General Relativity and Quantum Cosmology · Physics 2017-06-27 S. L. Parnovsky , W. Piechocki