[speculation alert]

here's a theory, and it's my theory: before the big bang there was no time (actually, there was virtually nothing). the big bang happened in no time at all. time started with the big bang and has been expanding (but you can't tell because everything is relative to the obvious observer) as the universe expands to fill the big void (see New Yorker link below). one day the universe will begin to contract and time (as we know it) will stop (this will also be the beginning of the end of the universe as we know it). that's the theory, and it's my theory. the fact that it makes no sense is a moot point and totally begs the question; ask a quantum mechanic.

ot, here is a shortened link if you want to remove that wiiiiiiiiide one...
http://www.cartoonbank.com/cartoonissue_closeup.asp?pf_id=46122&dept_id=1001