On the nature of black hole entropy

Abstract

I argue that black hole entropy counts only those states of a black hole that can influence the outside, and attempt (with only partial success) to defend this claim against various objections, all but one coming from string theory. Implications for the nature of the Bekenstein bound are discussed, and in particular the case for a holographic principle is challenged. Finally, a generalization of black hole thermodynamics to "partial event horizons" in general spacetimes without black holes is proposed.

13 pages, 2 figures; references added, almost same as version published in General Relativity And Relativistic Astrophysics: Eighth Canadian Conference, AIP Conference Proceedings 493, eds. C.P. Burgess and R.C. Myers (AIP, 1999)