Black holes must die

In light of recent evidence suggesting a nonzero present-day cosmological constant [S. Perlmutter et al. (The Supernova Cosmology Project), Astrophys. J. 517 (1999) 565], Adams, Mbonye, and Laughlin [Phys. Lett. B 450 (1999) 339] have considered the evolution of black holes in the presence of vacuum energy. Using the assumption that Λ remains constant with time and a conjecture based on a paper by Mallett [Phys. Rev. D 33 (1986) 2201], they reach the remarkable conclusion that black holes with current mass greater than ∼2×10−9M⊙ will not Hawking evaporate in the distant future, but will instead absorb vacuum energy and grow to roughly the de Sitter horizon size. In this letter we reexamine black hole evaporation in the presence of a cosmological constant, and find instead that all known black holes will eventually evaporate.