Isolated gravitational systems such as stars, galaxies and black holes are modeled by asymptotically flat initial data sets. In 1981 Schoen-Yau and Witten showed that such initial data sets with vanishing energy must be contained in Minkowski space. We show that if such initial data sets have vanishing mass, they must be contained in pp-wave spacetimes. This is based upon joint work with Yiyue Zhang from UCI.
Sven Hirsch (Princeton): Initial data sets with vanishing mass are contained in pp-waves.
