2008/03/31 by Stephen D. H. Hsu, David Reeb
Physics and Astronomy · #hep-th #gr-qc
paper · pdf · doi:10.1088/0264-9381/25/23/235007
published as Class.Quant.Grav.25:235007,2008 · 7 pages, 3 figures, revtex; minor changes in v2 (version published in Class. Quant. Grav.)
arxiv created 2008/11/21 · arxiv updated 2009/12/01
Under the premises that physics is unitary and black hole evaporation is complete (no remnants, no topology change), there must exist a one-to-one correspondence between states on future null and timelike infinity and on any earlier spacelike Cauchy surface (e.g., slices preceding the formation of the hole). We show that these requirements exclude a large set of semiclassical spacetime configurations from the Hilbert space of quantum gravity. In particular, the highest entropy configurations, which account for almost all of the volume of semiclassical phase space, would not have quantum counterparts, i.e. would not correspond to allowed states in a quantum theory of gravity.