scholarly journals Variation of Vacuum Energy if Scale Factor Becomes Infinitely Small, with Fixed Entropy Due to a Non Pathological Big Bang Singularity Accessible to Modified Einstein Equations

2012 ◽  
Vol 03 (09) ◽  
pp. 1336-1341
Author(s):  
Andrew Beckwith
Keyword(s):  
Vacuum Energy ◽  
Big Bang ◽  
Scale Factor ◽  
Einstein Equations ◽  
Big Bang Singularity

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.

scholarly journals BORN–INFELD COSMOLOGIES

2000 ◽  
Vol 15 (27) ◽  
pp. 4341-4353 ◽  
Author(s):  
RICARDO GARCÍA-SALCEDO ◽  
NORA BRETÓN
Keyword(s):  
Electromagnetic Field ◽  
Early Universe ◽  
Big Bang ◽  
Linear Case ◽  
Conformal Metric ◽  
Curvature Invariants ◽  
Metric Function ◽  
Big Bang Singularity

We present a model for an inhomogeneous and anisotropic early universe filled with a nonlinear electromagnetic field of Born–Infeld (BI) type. The effects of the BI field are compared with the linear case (Maxwell). Since the curvature invariants are well behaved then we conjecture that our model does not present an initial big bang singularity. The existence of the BI field modifies the curvature invariants at t=0 as well as sets bounds on the amplitude of the conformal metric function.

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 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.

C-field cosmology for barotropic fluid distribution with variable bulk viscosity and vacuum energy (Λ) in Friedmann–Robertson–Walker (FRW) space–time

2015 ◽  
Vol 93 (1) ◽  
pp. 14-17
Author(s):  
Raj Bali ◽  
Seema Saraf
Keyword(s):  
Bulk Viscosity ◽  
Vacuum Energy ◽  
Big Bang ◽  
Negative Energy ◽  
Space Time ◽  
Energy Conditions ◽  
Fluid Distribution ◽  
Massless Scalar ◽  
Barotropic Fluid ◽  
Friedmann Robertson Walker

A cosmological model that admits barotropic fluid distribution and a negative energy massless scalar creation field as a source in the presence of bulk viscosity and vacuum energy (Λ) in Friedmann–Robertson–Walker space–time is investigated. It has been shown that the model satisfies observational tests and is thus an alternative to the standard Big Bang model. The model is free from real singularity and particle horizon. The creation field increases with time, which matches Hoyle and Narlikar (Proc. Roy. Soc. A, 282, 178 (1964). doi:10.1098/rspa.1964.0225 ). To get the deterministic results, we have assumed that the coefficient of bulk viscosity, ζαρ1/2, where ρ is the matter density, ρ = 3H2, Λ ∼ H2, where H is the Hubble parameter. The model satisfies the energy conditions (weak, dominant, and strong). The deceleration parameter, q < 0, shows that the model represents an accelerating phase of the universe.

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.

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