Abstract: Black holes are believed to be described by a quantum system with a large number of degrees of freedom given, in the classical limit, by the area of the event horizon. This was verified extensively in string theory using the index of the putative quantum system since, in the context of supersymmetric theories, it can be computed at weak coupling. In the first part of the talk I describe how to compute the index of the black hole quantum system from a gravitational path integral. This was puzzling for some time since periodic fermions seem to be singular at the event horizon. In the second part of the talk I describe work in progress that uses this insight to compute "(-1)^F" in non-supersymmetric theories, giving us a gravitational prediction to the number of fermionic vs bosonic black holes in a theory of quantum gravity. Link to the Event Video |