"Spacetime topology and chaos in quantum black holes"

The thermal nature of black holes indicates that their underlying dynamics is chaotic. Chaotic quantum systems are believed to exhibit certain universal behaviors related to the statistics of their spectrum of microstates, sometimes known as 'RMT universality'. I explain how spacetimes with nontrivial topology ('spacetime wormholes') explain many of these features for black holes in low-dimensional toy models, though the essential ingredients have clear generalizations to higher-dimensional black holes. These explanations come at a price: spacetime wormholes seem to give an inherently statistical picture of black hole microstates, inconsistent with a description of black holes as conventional quantum systems with fixed microstates (as opposed to, for example, an ensemble of systems). I address this issue in some toy models, motivating a proposal for reconciling wormholes with black hole microstructure.