" Inflation is continuous and eternal, with big bangs happening all the time, with universes sprouting from other universes. In this picture, universes can “bud” off into other universes, creating a “multiverse.” In this theory, spontaneous breaking may occur anywhere within our universe, allowing an entire universe to bud off our universe. It also means that our own universe might have budded from a previous universe. In the chaotic inflationary model, the multiverse is eternal, even if individual universes are not. Some universes may have a very large Omega, in which case they immediately vanish into a big crunch after their big bang. Some universes only have a tiny Omega and expand forever. Eventually, the multiverse becomes dominated by those universes that inflate by a huge amount.
In retrospect, the idea of parallel universes is forced upon us. "

― , Parallel Worlds: A Journey through Creation, Higher Dimensions, and the Future of the Cosmos