The quantization of a massless conformally coupled scalar field on the 2+1
dimensional Anti de Sitter black hole background is presented. The Green's
function is calculated, using the fact that the black hole is Anti de Sitter
space with points identified, and taking into account the fact that the black
hole spacetime is not globally hyperbolic. It is shown that the Green's
function calculated in this way is the Hartle-Hawking Green's function. The
Green's function is used to compute ⟨Tνμ⟩, which is
regular on the black hole horizon, and diverges at the singularity. A particle
detector response function outside the horizon is also calculated and shown to
be a fermi type distribution. The back-reaction from ⟨Tμν⟩ is calculated exactly and is shown to give rise to a curvature
singularity at r=0 and to shift the horizon outwards. For M=0 a horizon
develops, shielding the singularity. Some speculations about the endpoint of
evaporation are discussed.Comment: CTP 2243, 24 pages, RevTex. (The backreaction section is extended,
and some confusing notation has been changed