The principle that unitarity must be preserved in all processes, no matter
how exotic, has led to deep insights into boundary conditions in cosmology and
black hole theory. In the case of black hole evaporation, Horowitz and
Maldacena were led to propose that unitarity preservation can be understood in
terms of a restriction imposed on the wave function at the singularity.
Gottesman and Preskill showed that this natural idea only works if one
postulates the presence of "conspiracies" between systems just inside the event
horizon and states at much later times, near the singularity. We argue that
some AdS black holes have unusual internal thermodynamics, and that this may
permit the required "conspiracies" if real black holes are described by some
kind of sum over all AdS black holes having the same entropy.Comment: Various minor improvements, references added, 25 page