Communications in Analysis and Geometry
Volume 11 (2003)
Mean Curvature Flow of Spacelike Hypersurfaces near Null Initial Data
Pages: 181 – 205
We prove an interior estimate for the gradient function of spacelike hypersurfaces which move by mean curvature in a Lorentzian manifold. This estimate depends only on a time function which measures how far the hypersurfaces are from being null. As a consequence, we show that under mean curvature flow a weakly spacelike initial hypersurface instantaneously becomes smooth and strictly spacelike except along null geodesics which extend to its boundary.