According to Horizon it's no longer scientifically illiterate to wonder what happened before the Big Bang. A convenor asked a room full of mega brains, "Who believes there was something before the Big Bang?" and every hand went up- though some only to half mast. There are many theories to be considered. The one that sticks with me- probably because its so simple- is that the universe expands, contracts and expands again- like breathing in and out.