Classical Defocussing of world lines from Higher Dimensions

Abstract

A five-dimensional gravity theory, motivated by the brane-world picture, with Kaluza scalar in the 5 - dimensional metric as $g_{55}(r); r=\sqrt{x^2+y^2+z^2}$, is considered near the possible singularity (small distance scales where gravity is strong) and is shown to give rise to a positive contribution to the Raychaudhuri equation. This inhibits the focusing of world lines and contributes to non - focusing of the worldlines in the 5-dimensional space. It is also shown that the results extend to time dependent cases such as those relevant for black hole interiors and cosmology.