Physics will be and is increasingly being applied to biology and the brain, so it's not necessarily sci-fi thinking even though I think the idea of multiverse is sci-fi thinking since we can't prove it anyway. We know a lot about the brain for the past 300 or so years of research that has gone into it but who knows if that's a lot or nothing depending on the future of these disciplines - we've not scratched the surface of a lot of things, things that require huge interdisciplinary approaches and in some cases revolutionary thinking and engineering. The idea of quantum states being mediated by brains is a working hypothesis by some* physicists in an attempt to try and explain emergence. And I've used this example before but appropriating the idea of bit flips to brains/biology and even interactions across the universe, sure there'd be repetition, but repetition of exact same elements, evolutions, and histories? Can only see that as unlikely unless there truly is infinity "out there"; the chances of the same/similar things happening become close to zero but not zero (ever with infinity). And in the end, imo this whole thread is pretty speculative.