Null Hypersurfaces in Lorentzian Geometry and Their Applications

In this expository paper‎, ‎a description of null hypersurfaces in space forms and some of their applications have been given‎. ‎Such hypersurfaces are of special interest in geometry and physics‎. ‎Among other results of the paper‎, ‎geometric properties of black holes‎, ‎event horizons‎, ‎the important Cheeger–Gromoll splitting theorem and some famous space-forms such as asymptotically flat/de Sitter space forms have been stated and considered‎. ‎Finally‎, ‎null submanifolds in pseudo-Riemannian manifolds have been described shortly.