remember the big bang theory is just that a throry,they try to find some origen to the totality of all galaxys and thats the only knowk event that they think could have happened.but confining there minds to that singular event might prove to have been a lost cause eventualy.every thing is going some where and is leaving some where and we see no end in either direction so as a theory it puts minds at ease to think they have the right formula to the universe.but they still cannot explane much about whats really happening.some what like the delima ancient peoples had when they thought the world was flat.they used the best instruments available and the most educated minds to come to the conclusion that the world was indeed flat,some people still think that it is,but we now know differantly dont we?