From: Hector Calderon Email: calderon@physics.montana.edu Affiliation: Montana State Univeristy, Dept. Physics (grad student) Title: Semiclassical back reaction on Schwarzschild-deSitter black holes Abstract: Using the semiclassical gravity approach on Schwarzchild-de Sitter spacetime, the perturbations to the metric caused by a quantized massive field with arbitrary curvature coupling are found to the lowest order in the inverse mass of the field. From studying the perturbations to the thermodynamical properties, we conclude that quantum perturbations cannot equalize the temperatures of the black hole and cosmological horizons.