"In a multiverse, one cannot avoid infinity, and infinity does strange things. There are two types of possible infinities in a multiverse: Type I: A single universe may be infinite in size (e.g., in our universe, if space and galaxies would continue forever without end or closure), or Type II: All the separate universes in a multiverse can be infinite in number (irrespective of whether any or all of the universes are infinite in size themselves).
The consequences of either infinity become bizarre. First of all, even Tegmark's Level I multiverse, assuming it's infinite, must contain everything that's physically possible. This means, for example, that every "Star Wars" scenario really exists out there, including those that didn't make it into the films and even all those the writers didn't think of!
Similarly, as long as there is sufficient space for unending random shufflings of particles (and a universe of infinite size certainly has sufficient space), there would have to be a sector of space out there identical to our sector of space, with persons identical to you and to me. Tegmark estimates that our closest identical copy is 10^10^28 m away.
I'm not so impressed even by this bizarre proposition. There would also have to be a sector of space identical to our sector of space except for, say, one hair on the head of one person, which is skewed 1 nanometer to the right. And another sector of space in which all else is the same except for that same hair, which is now skewed 2 nanometers to the left. Then all the hairs on all the people, skewed this way and that way. And then all the things in whole sectors of space, arranged in every possible combination and permutation. There would be innumerable minute differences and innumerable large differences, with every one a separate sector of space — all enabled because the one infinite universe with infinite sectors of space goes on forever. Obviously, on this vision, randomized particles in the overwhelming majority of vast sectors of space yield nothing much at all.
To be clear, a truly infinite universe means that anything that is not impossible (no matter how obscure) will happen, must happen and must happen, weirdly, an infinite number of times. An infinite universe goes on forever, not only generating uncountable variations, but also requiring each of the uncountable variations to occur an infinite number of times. That's the strange nature of a true infinity."---
https://www.space.com/31465-is-our-unive...verse.html
Quote:My take is that there is no such thing as identical copies of things that have already existed.
Something with the same identical structure will always have a different history and so the apparent paradox in an infinite universe just does not present itself.
The different histories mean that any such identical structures will only exist for the shortest possible length of time and immediately evolve into something else.(differrent)
If the structure has any internal constituent parts then the same applies to them-in spades.
But in a truly infinite universe, one that goes on forever and ever, there would eventually have to be a universe where all the histories of every object in our universe would be identical, and an infinite number of such as well. But there would also exist an infinite amount of universes where the history of one given object is identical to one in our universe except for one event, and then except for two events, and so for all the events in all the histories of all the objects in our universe, and then for all possible combinations and permutations of those events for each and every history of all the objects, and all possible numbers and combinations and permutations of the set of all histories, and etc and etc! We are talking staggering numbers of universes at this point, the vast majority of which would be totally indistinguishable and superfluous.. Such a endless profusion of infinities becomes almost absurd at some point. One even has to go into Cantor's transfinite sets to make sense of it all. In any case, even if infinity isn't real, it is certainly a mind-boggling concept!