Speaker: Henry Maxfield, University of California, Santa Barbara
Abstract: I'll discuss recent progress in black hole information, using semiclassical gravity to compute the entropy of Hawking radiation and finding the "Page curve" associated with a unitary quantum system with density of states given by the Bekenstein-Hawking formula. I will formulate this in terms of an operationally-defined notion of entropy, using a Lorentz-signature gravitational path integral in asymptotically flat spacetimes. I'll then explain the Hilbert space interpretation of these calculations, which requires the introduction of a Hilbert space of baby universes, and results in superselection sectors for asymptotic observers.