I think you might want to raise this question in the highly technical forum but, as far as I know as a layman who isn't particularly interested in this subject. We can never know what happened before the big bang. It's quite likely that time is an artifact of that explosion. What existed before is not something we can deal with. There is (or used to be) a big argument about whether the universe was positively or negatively curved. It has implications for whether the universe is bounded. I don't know what the current state of knowledge is, but it's my belief that the universe is positively curved and will eventually collapsed. My only evidence of that is that everything that I know about has a finite life but continues on in some form. Sort of the Tao of the universe.
By the way, take your last good look at the sun; another 5 billion years and it won't support us.