General upper limits to the age of the universe

Abstract

An inhomogeneous and anisotropic universe is modeled by means of a general class of relativistic space-times, and conclusions are derived concerning the most general upper bounds that can be set on the age of the universe. In this model the universe need not be an exact Friedmann type. Within the present globally hyperbolic framework, the extension into the past of timelike geodesic trajectories is investigated by considering the gravitational focusing effect on the matter in a space-time