  From information theory and thermodynamic considerations a universal bound on
the relaxation time $\tau$ of a perturbed system is inferred, $\tau \geq
\hbar/\pi T$, where $T$ is the system's temperature. We prove that black holes
comply with the bound; in fact they actually {\it saturate} it. Thus, when
judged by their relaxation properties, black holes are the most extreme objects
in nature, having the maximum relaxation rate which is allowed by quantum
theory.

General Relativity and Quantum Cosmology;Astrophysics;Statistical Mechanics;High Energy Physics - Theory;Nuclear Theory;Quantum Physics