Here's another theory to add to the list.

Now you know that when they make an A bomb, the nuclear material is forced together to cause fission? Fusion is created in an H bomb in a blink after fission.

So, in thinking about the Universe as we know it, "our" Universe could have been created by two lots of the "right" material slamming in to each other?

OK, so you're gonna ask where those things came from and the answer is "I dunno". Except....... it leads to another theory that ove eons of time, all the material in "A" Universe comes back together getting compressed smaller and smaller under immense gravity. When two of those collide.......****BINGO**** it all kicks off again.