Global Nonlinear Stability of Minkowski Space for the Massless Einstein-Vlasov System

Given an initial data set for the vacuum Einstein equations which is suitably close to that of Minkowski space, the monumental work of Christodoulou—Klainerman guarantees the corresponding solution exists globally and asymptotically approaches the Minkowski solution.  The aim of the talk is to put this theorem in context, emphasising the importance of the null condition, before briefly discussing a new result on the corresponding problem in the presence of massless matter described by the Vlasov equation.