Five dimensional Gravity and Big Bang Singularity

TL;DR

This paper explores a five-dimensional gravity model inspired by brane world scenarios, demonstrating how it can lead to a universe with no initial singularity by preventing geodesic focusing.

Contribution

It introduces a 5D gravity framework with a Kaluza scalar that modifies the Raychaudhuri equation, suggesting a universe without a big bang singularity.

Findings

Positive contribution to Raychaudhuri equation inhibits geodesic focusing

Universe can have infinite age, avoiding big bang singularity

Provides a theoretical basis for non-singular cosmological models

Abstract

A 5-dimensional gravity theory, motivated by the brane world picture, with factorisable metric and with Kaluza scalar $G_{55}(r)$, is shown to give rise to a positive contribution to the Raychaudhuri equation. This inhibits the focusing of geodesics and possibly cause non-focusing of the geodesics. This feature is translated into the situation in which the universe has an infinite age and hence no beginning avoiding the big bang singularity.