Robert Abbott Posted almost 3 years ago If the universe is expanding - what is it expanding into? There is a theory that there are multiple "verses," which are alternately expanding and contracting. Think of it as a bunch of unpopable bubbles in a bath tub. As some get bigger, some get smaller, and the smaller they get, the closer they get to "bursting" back into expansion. However, that leaves the question of what is outside the tub. I don't rightfully know. There are other theories that the Universe is curved and is expanding in the sense that it is completing the "curve," which is four or five dimensional. I think that outside of the Universe, there is nothing. And humans cannot understand that concept, so they choose not to believe it.