Some Estimates for the Curvatures of Spacelike Hypersurfaces in de Sitter Space

Abstract

In this paper we will report on our recent studies on curvature properties of space-like hypersurfaces in de Sitter space. In particular, we will state certain estimates for the higher order mean curvatures, the scalar curvature and the Ricci curvature of complete space-like hypersurfaces in de Sitter space. We will also establish a sufficient condition for a compact space-like hypersurface in de Sitter space to be spherical in terms of a lower bound for the square of its mean curvature.