Speaker: Nicky Kamran (McGill)

Title: A rigorous treatment of energy extraction from a rotating black 
hole.

Abstract: We prove that by choosing a suitable wave packet as initial data 
for the scalar wave equation in Kerr geometry, one can extract energy from 
the black hole, thereby putting superradiance, the wave analogue of the 
Penrose process, into a rigorous mathematical framework. We quantify the 
maximal energy gain, and we also estimate the infinitesimal change of mass 
and angular momentum of the black hole, in agreement with Christodoulou's 
result for the Penrose process. This is joint work with Felix Finster, 
Joel Smoller and Shing-Tung Yau.