Is the current mainstream thinking that spacetime was created with or by the big bang? I've read many posts about a "wrap-around" universe in which there is no border, and traveling to the "edge" of the universe would pop you out on the other side. I've done some brain-wracking, and I haven't yet been able to conceive of how that's possible, though it seems like there's much evidence for it. If wrap-around universe is what's actually out there, and the answer to, "what is outside of the universe?" is "nothing" (not "nothing" as in space, but nothing as in complete non-being), then wouldn't that rule out a level I multiverse? If there is literally nothing outside of our known universe, then how could there be any other cluster of energy (i.e. a universe) very far away from our known universe? Basically I'm wondering what the mainstream theory is about the nature of spacetime its boundaries, and how travelling to, or past, the boundaries our universe would work. Why couldn't we just go past the boundary of the known universe into space unoccupied by any energy at all? Isn't void infinite? As always, thank you for your time and energy.