Black hole entropy from near-horizon microstates

Black holes whose near-horizon geometries are locally, but not necessarily globally, AdS3 (three-dimensional anti-de Sitter space) are considered. Using the fact that quantum gravity on AdS3 is a conformal field theory, we microscopically compute the black hole entropy from the asymptotic growth of states. Precise numerical agreement with the Bekenstein-Hawking area formula for the entropy is found. The result pertains to any consistent quantum theory of gravity, and does not use string theory or supersymmetry.