The Einstein static universe in extended theories of gravity

Abstract

In this thesis, the evolutionary dynamics of the early universe through an inflationary paradigm are discussed, prescribing the initial conditions for the primordial soup. The inability of General Relativity and its extensions to describe the early universe has led cosmologists to consider teleparallel geometry. Indeed, the stability of the Einstein Static Universe is analyzed by considering homogenous and isotropic scalar perturbations in the context of torsion functions of f (T) gravity. The stability regions are parametrized by a linear equation of state w = P for a perfect fluid, with the condition w > 0 marking an inflation epoch as in standard ACDM cosmology. The study reveals that in some f (T) models with the cosmological constant A > 0, a stable Einstein cosmos is feasible as the asymptotic origin of the universe.