22 October 2014
Venue: Room 516
The collision of two plane gravitational shock waves propagating in a vacuum generates a cosmological constant. When the plane gravitational waves are accompanied by plane electromagnetic shock waves then fine tuning of the amplitudes results in, arguably, the simplest post-collision space-time ever found. Finally a study of the histories of plane waves in space-times of constant curvature distinguishes de Sitter space-time from Anti de Sitter space-time in a natural way.