Science Broadens Our Vision of Reality
There are many scientists and philosophers who've talked about this concept of a multiverse. But this is a very strict, very sober understanding of what a multiverse is. All of these universes in this multiverse obey the same laws of physics. We're not talking about universes where there are other laws of physics.
This should be no more surprising than historically when it used to be thought that the universe consisted of our planet, and around our planet orbited everything else: other planets, stars, the sun, and the moon orbited around us. We existed on this tiny planet. Then our vision of reality got expanded a little bit. We realized, in fact, we were not at the center of the universe; the sun was at the center, and these other planets were, in fact, bigger—in some cases, in the case of Jupiter and Saturn and the gas giants—bigger than what our planet, Earth, is. The sun was a lot bigger than what we are, so our universe became larger.
Then we realized that we were just one star system among many in a huge galaxy of hundreds of billions of stars. Later, we realized that this galaxy is one of hundreds of billions of galaxies. So the history of ideas and the history of science is a history of us broadening our vision of exactly how large physical reality is. This is another step in that general trend, and we should expect it to continue.
It shouldn't be that hard for people to accept that this is the way to understand things. Do we know everything about quantum theory and how this multiverse works? No, we haven't united this multiverse with general relativity. We need a space-time or a geometry of the multiverse, which we don't have yet.