Multiple universes give a good answer to the anthropic principle. If there's only one universe then the probability it would have the physical laws necessary to support intelligent life are not good. If there's billions of universes then the probability one of them could support intelligent life are much better. It's even possible that universes evolve. For example, suppose our universe was spawned by a black hole in another universe and our universe inherited most of the physical laws of its parent but with some random modification. Then the universes which had the physical laws necessary to create lots of black holes would be the more successful universes at "reproducing". And some of their offspring would likely be even more successful at "reproducing". Eventually this evolution would arrive at a universe with the ideal physical laws for creating the most black holes. This could be the universe we find ourselves in. All the galaxies in our universe could be a spandrel effect due to fine tuning the physical laws to create black holes. But, of course, this is all speculation.