Early Viscous Universe with Variable Cosmological and Gravitational Constants in Higher Dimensional Space Time

Abstract

In this paper we present a number of classes of solutions of the Einstein's field equations with variable G, and bulk viscosity for a Kaluza-Klein type of cosmological model. The solutions are obtained by using γ -law equation of state p = (γ − 1)ρ, where adiabatic parameter γ -varies continuously as the universe expand. A unified description of the early evolution of the universe is discussed with number of possible assumption on the bulk viscous term and gravitational constant in which an inflationary phase followed by radiation-dominated phase. We also investigate the cosmological model with constant and time dependent bulk viscosity along with constant and time dependent gravitational constant. In all cases, the cosmological constant found to be positive and decreasing function of time which supports the results obtained from recent supernovae Ia observations. The important physical behaviour of the early cosmological model has also been discussed in the frame work of higher dimensional space-time.

Five-Dimensional Space-Times with a Variable Gravitational and Cosmological Constant

“…A limited number of authors studied cosmological models in higher-dimensional space-time with variable gravitational constant " " and cosmological constant "Λ" [25][26][27][28][29]. Such five-dimensional space-times are also widely studied in the braneworld scenario and are useful to investigate ([30] and references therein) the geodesic deviation and the kinematics of geodesic flows in the background of such geometries.…”

Early-Universe and Evolution of the Present Universe: Exact Solution Models

“…The possibility of the creation field with G varying as some powers of t discussed by [8]. [10] also presented exact solutions for zero pressure Robertson-Walker cosmological models with G varying as some powers of R. A spatially flat FRW model wherein the vacuum energy density has been taken to vary as the radiation energy density discussed by [11,12] discussed about the effect of bulk viscosity on the early evolution of universe, [13] discussed about early universe with variable cosmological and gravitational constants in higher dimensional space time. [14,15] discussed about the cosmology of the very early universe and structures in the Universe by exact methods.…”