Nonperturbative Instability of Black Holes in Quantum Gravity

The decay rate for a black hole to decay nonperturbatively via tunneling is shown to be related to the Bekenstein-Hawking black hole entropy $S_{bh}$. This new physical interpretation of the black hole entropy was presented first in 1988 in this paper. I quote here the relevant statement: ``It should be noticed that the decay rate of a black hole due to nonperturbative instability is proportional to $\exp(-S_{bh}$, where $S_{bh}$ is the Bekenstein-Hawking entropy. This seems to indicate that the Bekenstein-Hawking entropy is the measure of the ability of a black hole to disappear from our Universe in the one quantum jump, with the simultaneous production of particles carrying away its total energy.''