(published on 12/04/07)
It seems as if we've gotten this same good question numerous times, but since I can't find the answers, we'll have another round at it. Both the Big Bang picture and the black hole picture are solutions of exactly the same equations: General Relativity. A black hole is not just a region in which the mass within some volume exceeds a partcular threshold. That gives a black hole solution under the condition that the mass density outside that region is low. That condition was not even approximately met in the Big Bang, in which the density everywhere was high but nearly uniform. Different starting conditions give different solutions.
You may wonder how the mass density could have been high and nearly uniform. There are basically two ways. Either the universe is finite, wrapping around on itself, or it's infinite, extending without end. Either way is consistent with the equations. Current data do not tell us which is correct.
(published on 09/14/13)