A common claim is that in the many-worlds interpretation of quantum mechanics, grandfather paradoxes are avoided because you end up in a different universe when you travel back in time. Does anyone here know whether this is true, and how it works? Is there a web site that explains it well? I'm suspicious because it seems to me it would give you a way to test which interpretation of quantum mechanics is true. Also, aren't there just as strong consistency constraints on a "wave function of the universe" as on a classical, single universe? Does this lead to a global version of the grandfather paradox across all Everett-worlds?