Zero-curvature FRW models and Bianchi I space-time as solutions of the same equation

1987 ◽  
Vol 26 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Joseph Hajj-Boutros ◽  
Jamil Sfeila
Keyword(s):  
Space Time ◽  
Bianchi I ◽  
Zero Curvature ◽  
Frw Models

Theory of the Stationary Self-Consistent Universe

2021 ◽  
Author(s):  
Alexander Shamailovich Avshalumov
Keyword(s):  
Quantum Physics ◽  
Space Time ◽  
Theoretical Physics ◽  
Time Model ◽  
Zero Curvature ◽  
Modern Cosmology ◽  
Simultaneous Existence ◽  
Three Space ◽  
Space Time Model ◽  
The Universe

Since the creation of GR and subsequent works in cosmology, the question of the curvature of space in the Universe is considered one of the most important and debated to this day. This is evident, because the curvature of space depends whether the Universe expands, contracts or is static. These discussions allowed the author to propose a paradoxical idea: simultaneous existence in the Universe of three interconnected space-times (positive, negative and zero curvature) and on this basis, to develop a theory in which each space-time plays its own role and develops in a strict accordance with its sign of curvature. The three space-time model of the structure of the Universe, proposed by the author, allows to solve many fundamental problems of modern cosmology and theoretical physics and creates the basis for building a unified physical theory (including one that unites GR and quantum physics).

Bianchi-I cosmology within f(T): Reconstruction method and dynamical study

2020 ◽  
Vol 18 (01) ◽  
pp. 2150012
Author(s):  
C. Ainamon ◽  
M. G. Ganiou ◽  
H. F. Abadji ◽  
M. J. S. Houndjo
Keyword(s):  
Space Time ◽  
Anisotropic Fluid ◽  
Anisotropic Universe ◽  
Reconstruction Method ◽  
Dynamical Study ◽  
Bianchi I ◽  
Dynamical Behaviors ◽  
Modified Gravity Theories ◽  
Universe Evolution ◽  
Autonomous Dynamical System

This paper is fundamentally devoted to the cosmological reconstruction and dynamic studying in homogeneous BIANCHI-I space-time under the [Formula: see text] background. Its content is supported by the fact that in the General Relativity description of the standard cosmological paradigm, the evolution from an anisotropic universe into an Friedmann–Lemaitre–Robertson–Walker (FLRW) one can be achieved by a period of inflationary expansion. Nowadays, modified gravity theories like [Formula: see text] are widely accepted to provide a real description of some universe evolution phases like inflation era, matter-dominated era, etc. So, we aim to examine here what [Formula: see text] gravity model can accommodate with an anisotropic universe, an expanding universe and even the transition between both evolutions. To reach this goal, we use a reconstruction method based on dynamic equations in Bianchi-I space-time by assuming a particular form for the metric anisotropy and by specifying some time functions describing average scale factor. Most of the obtained models are consistent with certain known results in the literature but other add new results in this work. In the second part of this work, the dynamical behaviors of the Bianchi-I space-time are addressed through the reconstruction of an autonomous dynamical system. For an aleatory choice of anisotropic fluid, the numerical analysis of the system shows that the metric anisotropy decreases with expansion. Then, an attractor point is reached and becomes unstable by the end of inflation. Such interesting properties found in this work on Bianchi-I space-time are often interpreted as graceful exit from inflation which doesn’t occur in ordinary FLRW space-time.

scholarly journals Quantum entanglement of fermions–antifermions pair creation modes in noncommutative Bianchi I space–time

2015 ◽  
Vol 30 (24) ◽  
pp. 1550141 ◽  
Author(s):  
M. F. Ghiti ◽  
N. Mebarki ◽  
H. Aissaoui
Keyword(s):  
Quantum Entanglement ◽  
Entanglement Entropy ◽  
Space Time ◽  
Pair Creation ◽  
Theory Approach ◽  
Quantum Field ◽  
Von Neumann ◽  
Curved Space ◽  
Bianchi I ◽  
Bogoliubov Transformations

The noncommutative Bianchi I curved space–time vierbeins and spin connections are derived. Moreover, the corresponding noncommutative Dirac equation as well as its solutions are presented. As an application within the quantum field theory approach using Bogoliubov transformations, the von Neumann fermion–antifermion pair creation quantum entanglement entropy is studied. It is shown that its behavior is strongly dependent on the value of the noncommutativity [Formula: see text] parameter, [Formula: see text]-modes frequencies and the structure of the curved space–time. Various discussions of the obtained features are presented.

Generalized Null Bertrand Curves In Minkowski Space-Time

2014 ◽  
Vol 60 (2) ◽  
pp. 489-502 ◽  
Author(s):  
Ferdag Kahraman Aksoyak ◽  
Ismail Gok ◽  
Kazim Ilarslan
Keyword(s):  
Minkowski Space ◽  
Space Time ◽  
Nonzero Constant ◽  
Bertrand Curve ◽  
Zero Curvature ◽  
Null Curve ◽  
Minkowski Space Time ◽  
Similar Idea ◽  
New Type

Abstract Çöken and ÇIFTCI proved that a null Cartan curve in Minkowski space-time E41 is a null Bertrand curve if and only if k2 is nonzero constant and k3 is zero. That is, the null curve with non-zero curvature k2 is not a Bertrand curve in Minkowski space-time E41. So, in this paper we defined a new type of Bertrand curve in Minkowski space-time E41 for a null curve with non-zero curvature k3 by using the similar idea of generalized Bertrand curve given by Matsuda and Yorozu and we called it a null (1, 3)-Bertrand curve. Also, we proved that if a null curve with non-zero curvatures in Minkowski space-time E41 is a null (1, 3)-Bertrand curve then it is a null helix. We give an example of such curves.

A FIRST STUDY OF GENERIC CUBIC TERMS IN GRAVITATION THEORIES

1993 ◽  
Vol 02 (03) ◽  
pp. 257-278
Author(s):  
H. CAPRASSE ◽  
J. DEMARET ◽  
P. HOUBA
Keyword(s):  
Exact Solutions ◽  
Computer Algebra ◽  
Space Time ◽  
Cosmological Models ◽  
Gravitation Theory ◽  
Algebraic Equations ◽  
Field Equations ◽  
Time Dimension ◽  
Bianchi I ◽  
The Way

The generic cubic contributions to the Lagrangian of gravitation theory are considered. Field equations are determined and put in their simplest form. In the framework of Bianchi I cosmological models with a metric which is power-like in time, algebraic equations are obtained and their exact solutions are derived exploiting computer algebra techniques. These solutions are fully discussed. The analysis is, presently, essentially restricted to a space-time dimension equal to four but results obtained here open the way to an analysis in any dimension.

scholarly journals Non-minimal matter-geometry coupling in Bianchi I space-time

2018 ◽  
Vol 10 ◽  
pp. 738-742 ◽  
Author(s):  
Lokesh Kumar Sharma ◽  
Anil Kumar Yadav ◽  
P.K. Sahoo ◽  
Benoy Kumar Singh
Keyword(s):  
Space Time ◽  
Bianchi I

scholarly journals Lorentz symmetry in QFT on quantum Bianchi I space-time

2012 ◽  
Vol 86 (6) ◽  
Author(s):  
Andrea Dapor ◽  
Jerzy Lewandowski ◽  
Yaser Tavakoli
Keyword(s):  
Lorentz Symmetry ◽  
Space Time ◽  
Bianchi I
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