From: utzoo!decvax!cca!tzs@mit-ccc@sri-unix
Newsgroups: net.physics
Title: Black holes
Article-I.D.: sri-unix.4307
Posted: Mon Nov 22 17:45:07 1982
Received: Wed Nov 24 08:25:37 1982

Lot of the questions out there happen to be cofcerning the thermodynamics 
of black holes. Well, Kip Thorne wrote a very good article for  Sci Am 
which ended up in the "Cosmology +1" collection. Pretty much, there are 
only three quantities of a mass that can be conserved after it falls into
a black hole--better yet, say that are conserved--the mass of the object, the charge, and the angular momentum. (This was all summed up in the statement "Black 
holes have no hair." It turns out that black holes do decay over time. You can 
think of this as a virtual particle-antiparticle pair being created right
near the boundary of the black hole--one of the two gets snarfed in, and the
other is free to go whither it will. To an outsider, this looks like a particle
is being emitted from the black hole. The rate of decay varies inversely with 
the mass of the black hole. I seem to remember that your average ordinary 
black hole was supposed to not be at absolute zero, but at app. 0.0001 degrees
Kelvin. It also turns out that the baby black holes that were supposedly
created in the Big Bang are supposedly reaching the end of their decay and if 
such a decay were seen, it would liberate approximately the energy in a 
supernova.) I'll check my numbers---it's been a few years since I read it.
                                   --tzs---