Ok, if the big bang theory is correct, the universe was created by something smaller than an atom exploding and all the matter contained inside expanded and is still to this day (14.8 billion years later) still expanding, what is it expanding into and what was the matter originally inside and created by. Because NOTHING can exist without something else existing before it.

i was thinking, that there were multiple universes in forms of spheres inside of some type of void and that each universe expands until it becomes too dense then collapses and then everything ceases to exist for the rest of eternity and beyond. but if there were multiple universes inside of a void, what is the void in?

what do you think?
i want what you think, not something off of google