Gravitational Instabilities of Spacetime

This lecture by the instructor explores the concept of gravitational instabilities in spacetime, focusing on the phenomenon of bubbles of nothing. The presentation covers the motivation behind studying vacuum stability, the semiclassical formalism for vacuum decay, and the implications of bubbles of nothing in various theoretical frameworks. The talk delves into the existence conditions and decay rates of these bubbles, emphasizing the effect of stabilizing potentials. The discussion extends to the tunneling process in the presence of gravity, the instability of the Kaluza-Klein vacuum, and the implications for vacuum selection and nucleation from 'nothing'. The lecture concludes with open questions regarding supersymmetry breaking and the nature of 'nothing' in a UV-complete theory of quantum gravity.