On Monday, June 28, 2021 at 5:30:43 AM UTC+2 Bruce wrote: > > Why should we ever be led to consider the set of all logically possible > worlds? >
Because why does this particular world exist instead of some other? And what is the difference between a possible world that exists and a possible world that doesn't, anyway? What does it mean "to exist"? I see no difference between possibility and existence. > I doubt that such a set can ever be well-defined. > Maybe it can't. All possible concrete worlds might be identical to all possible pure sets, which would need uncountably many axioms to define, as per Godel's first incompleteness theorem. But there are some more limited sets of possible worlds that are closely connected to known physics that might be easier to define: possible worlds beyond the horizon of our observable universe (but still in our universe), possible worlds of inflationary multiverse, of string theory multiverse and of quantum mechanical multiverse. > Current evidence is against the existence of these other worlds -- we have > evidence only for our world. > What about worlds beyond the horizon of our observable universe (but still in our universe)? By definition, we don't have direct observational evidence for them. We do have indirect observational evidence that they exist because they seem to be predicted by known physics. One might argue that known physics also predicts some types of multiverse, although the matters are not so clear there. -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/f6ef064b-3498-4457-af11-845200b38cf4n%40googlegroups.com.
