scholarly journals Energy of the universe in Bianchi-type I models in Møller’s tetrad theory of gravity

2008 ◽  
Vol 314 (1-3) ◽  
pp. 245-245
Author(s):  
Oktay Aydoğdu ◽  
Mustafa Salti
Keyword(s):  
Bianchi Type ◽  
Type I ◽  
Bianchi Type I ◽  
Theory Of Gravity ◽  
The Universe ◽  
Tetrad Theory

scholarly journals Time-Dependent Toroidal Compactification Proposals and the Bianchi Type I Model: Classical and Quantum Solutions

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
L. Toledo Sesma ◽  
J. Socorro ◽  
O. Loaiza
Keyword(s):  
Bianchi Type ◽  
Time Dependent ◽  
Type I ◽  
Dilaton Field ◽  
Dimensional Model ◽  
Dimensional Theory ◽  
Standard Quantum ◽  
Bianchi Type I ◽  
Real Scalar ◽  
The Universe

We construct an effective four-dimensional model by compactifying a ten-dimensional theory of gravity coupled with a real scalar dilaton field on a time-dependent torus. This approach is applied to anisotropic cosmological Bianchi type I model for which we study the classical coupling of the anisotropic scale factors with the two real scalar moduli produced by the compactification process. Under this approach, we present an isotropization mechanism for the Bianchi I cosmological model through the analysis of the ratio between the anisotropic parameters and the volume of the Universe which in general keeps constant or runs into zero for late times. We also find that the presence of extra dimensions in this model can accelerate the isotropization process depending on the momenta moduli values. Finally, we present some solutions to the corresponding Wheeler-DeWitt (WDW) equation in the context of standard quantum cosmology.

The Mimetic Matter in LRS Bianchi Type-I Model

2021 ◽  
Author(s):  
Ertan Gudekli ◽  
E. Demir
Keyword(s):  
Bianchi Type ◽  
State Parameter ◽  
Relativity Theory ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Rotationally Symmetric ◽  
Bianchi Type I Universe ◽  
Expansion Of The Universe ◽  
The Universe

This paper deals with the Locally rotationally symmetric (LRS) Bianchi type-I universe model in Mimetic Gravity Theory assuming it an extended form of General Relativity Theory. It was proclaimed as a conformal transformation of the Einstein-Hilbert action from Einstein frame to Jordon frame. At the outset, we have proposed a potential function on account of clarifying the expansion of our universe by considering the general solutions of the field equations that originate from the action of the theory including the Lagrange multipliers. Lastly, after having been achieved the general equation of the state parameter ω, we discussed whether the result corresponds to some fluids illuminating the expansion of the Universe or not.

Bianchi type I Universe: An extension of ΛCDM model

2021 ◽  
pp. 2150069
Author(s):  
Rajendra Prasad ◽  
Lalit Kumar Gupta ◽  
A. Beesham ◽  
G. K. Goswami ◽  
Anil Kumar Yadav
Keyword(s):  
Bianchi Type ◽  
Hubble Constant ◽  
Model Parameters ◽  
Constant Density ◽  
Data Sets ◽  
Type I ◽  
Data Set ◽  
Bianchi Type I ◽  
Age Of The Universe ◽  
The Universe

In this paper, we investigate a Bianchi type I exact Universe by taking into account the cosmological constant as the source of energy at the present epoch. We have performed a [Formula: see text] test to obtain the best fit values of the model parameters of the Universe in the derived model. We have used two types of data sets, viz., (i) 31 values of the Hubble parameter and (ii) the 1048 Pantheon data set of various supernovae distance moduli and apparent magnitudes. From both the data sets, we have estimated the current values of the Hubble constant, density parameters [Formula: see text] and [Formula: see text]. The dynamics of the deceleration parameter shows that the Universe was in a decelerating phase for redshift [Formula: see text]. At a transition redshift [Formula: see text], the present Universe entered an accelerating phase of expansion. The current age of the Universe is obtained as [Formula: see text] Gyrs. This is in good agreement with the value of [Formula: see text] calculated from the Plank collaboration results and WMAP observations.

scholarly journals Bianchi Type I Cosmological Models with Expansion Driven by Particle Creation

2018 ◽  
Author(s):  
Kalyani Desikan
Keyword(s):  
Bianchi Type ◽  
Energy Momentum Tensor ◽  
Particle Creation ◽  
Momentum Tensor ◽  
Conservation Equation ◽  
Type I ◽  
Field Equations ◽  
Bianchi Type I ◽  
Energy Conservation Equation ◽  
The Universe

A study of Bianchi Type I cosmological model is undertaken in the framework of creation of particles. To accommodate the creation of new particles, the universe is regarded as an Open thermodynamical system. The energy conservation equation is modified with the incorporation of a creation pressure in the energy momentum tensor. Exact solutions of the field equations are obtained (i) for a particular choice of the particle creation function and (ii) by considering the deceleration parameter to be constant. In the first model the behavior of the solution at late times is investigated. The physical aspects of the model have also been discussed. In the case of the second model we have restricted our analysis to the power law behaviour for the average scale factor. This leads to a particular form for the particle creation function. The behavior of the solution is investigated and the physical aspects of the model have also been discussed for the matter dominated era.

scholarly journals BIANCHI TYPE I UNIVERSES WITH CAUSAL BULK VISCOUS COSMOLOGICAL FLUID

2002 ◽  
Vol 11 (03) ◽  
pp. 447-462 ◽  
Author(s):  
M. K. MAK ◽  
T. HARKO
Keyword(s):  
Bianchi Type ◽  
Viscosity Coefficient ◽  
State Equation ◽  
Type I ◽  
Bianchi Type I ◽  
Boltzmann Gas ◽  
Bulk Viscous ◽  
Barotropic Equation ◽  
Bulk Viscosity Coefficient ◽  
The Universe

We consider the dynamics of a causal bulk viscous cosmological fluid filled flat constantly decelerating Bianchi type I spacetime. The matter component of the Universe is assumed to satisfy a linear barotropic equation of state and the state equation of the small temperature Boltzmann gas. The resulting cosmological models satisfy the condition of smallness of the viscous stress. The time evolution of the relaxation time, temperature, bulk viscosity coefficient and comoving entropy of the dissipative cosmological fluid is also obtained.

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