## Theory Seminar (High Energy/Cosmology) |

**Observations of Hawking radiation: the Page curve and baby universes**

**Date:**

**Friday, December 18th**

**Time:**2:00 pm

**Place:**For zoom link, sign up at: https://groups.google.com/a/g-groups.wisc.edu/d/forum/theoryseminars/join

**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.