THE 4TH LAW OF BLACK-HOLE THERMODYNAMICS

We show that black holes fulfill the scaling laws arising in critical transitions. In particular, we find that in the transition from negati ve to positive values the heat capacities C(JQ), C(OMEGAQ) and C(JPHI) give rise to critical exponents satisfying the scaling laws. The thre e transitions have the same critical exponents as predicted by the uni versality hypothesis. We also briefly discuss the implications of this result with regards to the connections among gravitation, quantum mec hanics and statistical physics.