  Chapter 3 of S. Lloyd's 1988 Ph.D. thesis, `Black Holes, Demons, and the Loss
of Coherence: How complex systems get information and what they do with it,'
supervisor Heinz Pagels. Reformulates statistical mechanics in terms of pure
states and shows that (a) quantum statistics of typical pure states are very
close to the mechanics of statistical mechanical ensembles; (b) if a system is
in a typical state with energy E, then the reduced density matrix of a
subsystem is very close to a thermal state. (A similar result was derived using
Levy's lemma some years later by S. Popescu, A.J. Short, A.Winter, Nature
Physics 2, 754-758 (2006).) Pure state quantum statistical mechanics is applied
to black holesto show that for typical states of matter insideand outside a
black hole, the external state is likely to be thermal. Proposes novel
interpretation of probabilities in quantum statistical mechanics. Full thesis
available at http://meche.mit.edu/documents/slloyd_thesis.pdf. This chapter was
submitted for publication to Physical Review in 1988 but rejected by one
sentence referee report: `There is no physics in this paper.' You be the judge.
