Cosmologists are in almost complete agreement that our universe is expanding from an original explosion ("Big Bang") and subsequent inflation. This is evidenced by the fact that all of the galaxies are moving away from each other like the dots on the skin of an inflating balloon. Wind the film backwards and you arrive at an original point from whence the universe originated. Nuclear physicists tell us that point would have been microscopically small.
My questions for discussion are these:
1. What did our universe explode into? And the same question put another way is: What is our universe continuing to expand into? Or to put the same question in different words again: What lies outside our universe? If there is an expanding edge to our universe, what is beyond that edge and what are it's properties?
2. Is it theoretically possible for another big bang to occur within our own universe?
3. What would happen to our universe if another universe exploded into existence within our universe?
Answers and discussion in the comments below please.