Originally posted by finnegan
I just read The Hidden Reality, a book by Brian Greene published in 2011 which explores the concept of the multiverse and the possibility of parallel universes. It is very readable and is the first that has made me appreciate what is going on here. He offers a range of parallel universes, not just one, each as persuasive as the others, all capable of existi ...[text shortened]... hing that is really hard to accept is the idea that there is only one universe and we are in it.
There is more than one valid way of using Occam’s razor in this case. You can either say the assumption that “all possible universes exists” is the least assumptive hypothesis (because it does not assume that there are 'possible' universes that don't exist and we already know at least ONE 'possible' universe exists; our own ) and we are in just one possible universe out of a vast (possibly infinite) number.
Or you can say “there is only one universe, the one we know” is the least assumptive hypothesis (because it doesn't assume the existence of universes that we have yet to observe).
Purely on the bases of this Occam’s razor logic, I would say there is no more reason to believe the only-one universe theory than the multi-universe theory.
However, having said that, if we eventually discover that, despite the universe being so big with many Earth-like planets in the inhabitable zone, the probability of life emerging and existing ANYWHERE in the universe is extremely small, then that could be seen as good evidence for the multi-universe theory. This is because there being a vast number of universes so great in number that it is, mathematically, virtually inevitable or inevitable that life will emerge in some of them, despite a tiny probability of it doing so in each one universe, would mathematically explain why there is life and why we exist -whichever universe we came to exist in, we could say “isn't it an astonishing coincidence that we exists in THIS universe! “
-of course, it would be no big coincidence because their would be nothing 'special' about this universe other than it would be one of the one-in-a-zillion universes that life just happened to emerged in.
Else, if there is only one universe and if the probability of life emerging ANYWHERE in the universe is extremely small then it would be a strange coincidence that life formed in the only universe to exist despite a tiny probability of that happening anywhere within it!