An oscillatory big-bang singularity

1986 ◽  
Vol 64 (2) ◽  
pp. 200-203 ◽  
Author(s):  
J. Wainwright
Keyword(s):  
Cosmological Solution ◽  
Big Bang ◽  
Clock Time ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Cosmological Solutions ◽  
Exact Cosmological Solution ◽  
Self Similar ◽  
The Big Bang ◽  
Big Bang Singularity

The big-bang singularities in the exact cosmological solutions of the Einstein field equations that have been studied up to now are power asymptotes in the sense that all scalar polynomials in the curvature tensor diverge monotonically as a power of clock time along the fundamental world lines, as the singularity is approached. One can thus regard the solutions as being asymptotically self-similar near the singularity. In this paper, we illustrate a more complicated type of singularity by giving an example of an exact cosmological solution in which the big-bang singularity is of an oscillatory nature, so that the solution is not asymptotically self-similar.

scholarly journals On the stability of Einstein universe in f(R, T, Rμν Tμν) gravity

2018 ◽  
Vol 33 (36) ◽  
pp. 1850216 ◽  
Author(s):  
M. Sharif ◽  
Arfa Waseem
Keyword(s):  
State Parameter ◽  
Big Bang ◽  
Graphical Analysis ◽  
Momentum Tensor ◽  
Field Equations ◽  
Einstein Universe ◽  
Existence And Stability ◽  
The Stability ◽  
The Big Bang ◽  
Big Bang Singularity

This paper investigates the existence and stability of Einstein universe in the context of f(R, T, Q) gravity, where Q = R[Formula: see text] T[Formula: see text]. Considering linear homogeneous perturbations around scale factor and energy density, we formulate static as well as perturbed field equations. We parametrize the stability regions corresponding to conserved as well as non-conserved energy–momentum tensor using linear equation of state parameter for particular models of this gravity. The graphical analysis concludes that for a suitable choice of parameters, stable regions of the Einstein universe are obtained which indicates that the big bang singularity can be avoided successfully by the emergent mechanism in non-minimal matter-curvature coupled gravity.

PLANE SYMMETRIC VISCOUS-FLUID COSMOLOGICAL MODELS WITH HEAT FLUX

1994 ◽  
Vol 03 (03) ◽  
pp. 639-645
Author(s):  
L.K. PATEL ◽  
LAKSHMI S. DESAI
Keyword(s):  
Heat Flux ◽  
Viscous Fluid ◽  
Vacuum Solution ◽  
Big Bang ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Plane Symmetric ◽  
Inhomogeneous Plane ◽  
Physical Features ◽  
Big Bang Singularity

A class of nonstatic inhomogeneous plane-symmetric solutions of Einstein field equations is obtained. The source for these solutions is a viscous fluid with heat flow. The fluid flow is irrotational and it has nonzero expansion, shear and acceleration. All these solutions have a big-bang singularity. The matter-free limit of the solutions is the well-known Kasner vacuum solution. Some physical features of the solutions are briefly discussed.

scholarly journals Invariant Bianchi type I models in f(R,T) gravity

2018 ◽  
Vol 15 (02) ◽  
pp. 1850026 ◽  
Author(s):  
Anil Kumar Yadav ◽  
Ahmad T. Ali
Keyword(s):  
Bianchi Type ◽  
Big Bang ◽  
Type I ◽  
Analysis Method ◽  
Field Equations ◽  
Bianchi Type I ◽  
Nonsingular Solution ◽  
The Big Bang ◽  
Big Bang Singularity ◽  
Special Case

In this paper, we search the existence of invariant solutions of Bianchi type I space-time in the context of [Formula: see text] gravity with special case [Formula: see text]. The exact solution of the Einstein’s field equations are derived by using Lie point symmetry analysis method that yield two models of invariant universe for symmetries [Formula: see text] and [Formula: see text]. The model with symmetries [Formula: see text] begins with big bang singularity while the model with symmetries [Formula: see text] does not favor the big bang singularity. Under this specification, we find out at set of singular and nonsingular solution of Bianchi type I model which present several other physically valid features within the framework of [Formula: see text] gravity.

scholarly journals Deformation of the Wheeler–DeWitt equation

2014 ◽  
Vol 29 (20) ◽  
pp. 1450106 ◽  
Author(s):  
Mir Faizal
Keyword(s):  
Commutation Relation ◽  
Canonical Commutation Relation ◽  
Big Bang ◽  
Minimum Length ◽  
Second Quantization ◽  
Canonical Commutation Relations ◽  
Commutation Relations ◽  
The Big Bang ◽  
Big Bang Singularity ◽  
Modified Theory

In this paper, we will analyze the consequences of deforming the canonical commutation relations consistent with the existence of a minimum length and a maximum momentum. We first generalize the deformation of first quantized canonical commutation relation to second quantized canonical commutation relation. Thus, we arrive at a modified version of second quantization. A modified Wheeler–DeWitt equation will be constructed by using this deformed second quantized canonical commutation relation. Finally, we demonstrate that in this modified theory the big bang singularity gets naturally avoided.

scholarly journals Quantum Gravity Phenomenology from the Thermodynamics of Spacetime

Universe ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 50
Author(s):  
Ana Alonso-Serrano ◽  
Marek Liška
Keyword(s):  
Quantum Gravity ◽  
Big Bang ◽  
Einstein Equations ◽  
Logarithmic Term ◽  
Quantum Gravity Phenomenology ◽  
Gravity Effects ◽  
Energy Quantum ◽  
The Big Bang ◽  
Big Bang Singularity ◽  
Modified Dynamics

This work is based on the formalism developed in the study of the thermodynamics of spacetime used to derive Einstein equations from the proportionality of entropy within an area. When low-energy quantum gravity effects are considered, an extra logarithmic term in the area is added to the entropy expression. Here, we present the derivation of the quantum modified gravitational dynamics from this modified entropy expression and discuss its main features. Furthermore, we outline the application of the modified dynamics to cosmology, suggesting the replacement of the Big Bang singularity with a regular bounce.

COSMOLOGICAL SOLUTIONS AND THEIR EFFECTIVE PROPERTIES OF MATTER IN KALUZA-KLEIN THEORY

1994 ◽  
Vol 03 (03) ◽  
pp. 627-637 ◽  
Author(s):  
HONGYA LIU ◽  
PAUL S. WESSON
Keyword(s):  
Globular Clusters ◽  
Effective Properties ◽  
Plane Waves ◽  
Big Bang ◽  
Field Equations ◽  
Fifth Dimension ◽  
Cosmological Solutions ◽  
Klein Theory ◽  
The Universe ◽  
Kaluza Klein

We derive a “wave-like” class of exact cosmological solutions of the apparently empty 5D Kaluza-Klein field equations. Here by “wave-like” we mean that the solutions look like plane waves propagating in the fifth dimension. In the interpretation that the fifth dimension in Kaluza-Klein theory may induce matter in four dimensions, we then calculate the effective energy density ρ and pressure p, and study in detail the case for which the equation of state is p=γρ (where γ is an arbitrary constant). We show that for both the matter-dominated (γ=0) and radiation-dominated (γ=1/3) eras of the universe, the 4D spacetime defined by hypersurfaces of the 5D metrics are just the same as those of the standard Friedmann-Robertson-Walker models of general relativity. However, in our models the big bang is like a shock wave propagating along the fifth dimension, and different observers can measure different ages for the universe. This property may be tested using the spread in ages of astrophysical objects such as globular clusters.

scholarly journals Gauss–Bonnet gravity in D = 4 without Gauss–Bonnet coupling to matter: Cosmological implications

2019 ◽  
Vol 34 (07n08) ◽  
pp. 1950051
Author(s):  
Eduardo Guendelman ◽  
Emil Nissimov ◽  
Svetlana Pacheva
Keyword(s):  
Functional Dependence ◽  
Equations Of Motion ◽  
Scalar Potential ◽  
Big Bang ◽  
Gravity Models ◽  
Back Reaction ◽  
Field Equations ◽  
Dark Energy Density ◽  
Bonnet Gravity ◽  
The Big Bang

We propose a new model of D = 4 Gauss–Bonnet gravity. To avoid the usual property of the integral over the standard D = 4 Gauss–Bonnet scalar becoming a total derivative term, we employ the formalism of metric-independent non-Riemannian spacetime volume elements which makes the D = 4 Gauss–Bonnet action term nontrivial without the need to couple it to matter fields unlike the case of ordinary D = 4 Gauss–Bonnet gravity models. The non-Riemannian volume element dynamically triggers the Gauss–Bonnet scalar to be an arbitrary integration constant M on-shell, which in turn has several interesting cosmological implications. (i) It yields specific solutions for the Hubble parameter and the Friedmann scale factor as functions of time, which are completely independent of the matter dynamics, i.e. there is no back reaction by matter on the cosmological metric. (ii) For M[Formula: see text]0, it predicts a “coasting”-like evolution immediately after the Big Bang, and it yields a late universe with dynamically produced dark energy density given through M. (iii) For the special value M = 0, we obtain exactly a linear “coasting” cosmology. (iv) For M[Formula: see text]0, we have in addition to the Big Bang also a Big Crunch with “coasting”-like evolution around both. (v) It allows for an explicit analytic solution of the pertinent Friedmann and [Formula: see text] scalar field equations of motion, while dynamically fixing uniquely the functional dependence on [Formula: see text] of the scalar potential.

scholarly journals HIGHER DIMENSIONAL SZEKERES' SPACE–TIME IN BRANS–DICKE SCALAR TENSOR THEORY

2004 ◽  
Vol 13 (06) ◽  
pp. 1073-1083
Author(s):  
ASIT BANERJEE ◽  
UJJAL DEBNATH ◽  
SUBENOY CHAKRABORTY
Keyword(s):  
Turning Point ◽  
Coupling Parameter ◽  
Big Bang ◽  
Space Time ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Tensor Theory ◽  
Higher Dimensional ◽  
Theory Of Gravitation ◽  
The Big Bang

The generalized Szekeres family of solution for quasi-spherical space–time of higher dimensions are obtained in the scalar tensor theory of gravitation. Brans–Dicke field equations expressed in Dicke's revised units are exhaustively solved for all the subfamilies of the said family. A particular group of solutions may also be interpreted as due to the presence of the so-called C-field of Hoyle and Narlikar and for a chosen sign of the coupling parameter. The models show either expansion from a big bang type of singularity or a collapse with the turning point at a lower bound. There is one particular case which starts from the big bang, reaches a maximum and collapses with the in course of time to a crunch.

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