Constant mean curvature foliations of flat space--times

Abstract

Let $V$ be a maximal globally hyperbolic flat $n+1$--dimensional space--time with compact Cauchy surface of hyperbolic type. We prove that $V$ is globally foliated by constant mean curvature hypersurfaces $M_{\tau }$, with mean curvature $\tau$ taking all values in $(-\infty ,0)$. For $n\ge 3$, define the rescaled volume of $M_{\tau }$ by $\Ham = |τ|^n \Vol(M,g)$, where $g$ is the induced metric. Then $\Ham \geq n^n \Vol(M,g_0)$ where $g_0$ is the hyperbolic metric on $M$ with sectional curvature -1. Equality holds if and only if $(M,g)$ is isometric to $(M,g_0)$.

20 pages