A comment on a fine-grained description of evaporating black holes with baby universes

Abstract

We study a partially fine-grained description of an evaporating black hole by introducing an open baby universe with a boundary. Since the Page's calculation of the entropy of Hawking radiation involves an ensemble average over a class of states, one can formally obtain a fine-grained state by purifying this setup. For AdS black holes with a holographic dual, this purification amounts to introduce an additional boundary (i.e., baby universe) and then connect it to the original black hole through an Einstein-Rosen bridge. We uncover several details of this setup. As applications, we briefly discuss how this baby universe modifies the semi-classical gravitational Gauss law as well as gravitational dressing of operators behind the horizon.

Effective reflected entropy and entanglement negativity for general 2D eternal black holes

“…For other relevant comments on island, please see Refs. [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59].…”