Semiclassical perdurance of de Sitter space

We investigate the classical and semiclassical instabilities of de Sitter space. Due to the presence of a cosmological event horizon and its associated Hawking temperature, de Sitter space might be expected to behave in some respects like flat space at finite temperature. We use the euclidean formulation of quantum gravity to show that de Sitter space does exhibit a semiclassical instability to the nucleation of black holes. We find, however, no analog to the classical instability due to gravitational clumping of thermally excited gravitons.