Big bang theory question?

The big bang created our universe; whatever caused it, if anything, happened outside our universe, and we can't see outside our universe. We have some ideas as to how it could have happened, but we can't currently test them. The scientific answer is 'we don't know - yet'. But it doesn't really matter; sure, we'd like to know, but the big bang works no matter how it came to be in the first place.