
Title: Geometric restrictions imposed on spacetime by the Einstein equations
Speaker: Richard Schoen (University of California - Irvine)
Abstract: The Einstein equations together with energy conditions on the matter fields lead to geometric and topological restrictions on spacetime. In many cases these restrictions are imposed through lower bounds on the scalar curvature of the Riemannian manifolds which arise as spacelike hypersurfaces in spacetime. Physical considerations of energy and momentum lead to mathematical conjectures about such manifolds. Some of these, such as positive energy theorems, have been rigorously proven and others are unresolved. We will describe results and techniques which have bearing on such questions.