Generalized second law of thermodynamics in blackhole physics
Abstract
In previous work we introduced the concept of blackhole entropy, which we identified with the surface area of the black hole in question expressed in units of the Planck length squared. We suggested that the appropriate generalization of the second law for a region containing a black hole is that the blackhole entropy plus the common entropy in the blackhole exterior never decreases. Here we establish the validity of this law for the infall of an entropybearing system into a much larger and more massive generic stationary black hole. To do this we determine a general lower bound for the increase in blackhole entropy, and an upper bound for the entropy of the system, while allowing for quantum effects at each stage. In passing we show that the generalized second law is a statistical law which becomes overwhelmingly probable in the limit of a macroscopic system. We also consider briefly more general situations. Finally, we give two simple examples of predictions made by the generalized second law for blackhole formation processes.
 Publication:

Physical Review D
 Pub Date:
 June 1974
 DOI:
 10.1103/PhysRevD.9.3292
 Bibcode:
 1974PhRvD...9.3292B