EDIT: Let’s cool it with the downvotes, dudes. We’re not out to cut funding to your black hole detection chamber or revoke the degrees of chiropractors just because a couple of us don’t believe in it, okay? Chill out, participate with the prompt and continue with having a nice day. I’m sure almost everybody has something to add.
I believe one of the theories for a multiverse is that Inflation never ended, it is just a continually ongoing process in which out universe “bubbled” out of it. Other universes would have bubbled up too, and we “should” be able to see evidence of collisions between those other bubbles and our own bubble in the CMB, which there has been a little bit of success in finding.