Abstract

We investigate the recent black hole firewall argument. We argue that unitarity requires every quantum of radiation leaving the black hole to carry information about the initial state. Unitary evaporation is thus inconsistent with an information-free horizon at every step of the evaporation process. The required horizon-scale structure is manifest in the fuzzball proposal. To address the experience of an infalling observer, we argue for fuzzball complementarity. Unlike black hole complementarity and observer complementarity which postulate asymptotic observers experience a hot membrane while infalling ones pass freely through the horizon, fuzzball complementarity postulates that fine-grained operators experience the details of the fuzzball microstate and coarse-grained operators experience the black hole. In particular, this implies that an infalling detector tuned to energy E ∼ TH, where TH is the asymptotic Hawking temperature, does not experience free infall while one tuned to E ≫ TH does.