Everett and time travel

  • #1
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Main Question or Discussion Point

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?
 

Answers and Replies

  • #2
Sunfist
Considering an infinite number of alternative universes, all possiblities of all outcomes are possible. It would essentially be childsplay to avoid the grandfather paradox in such a situation.
 
  • #3
selfAdjoint
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Suppose you had one of those FTL send-messages-to-the-past devices that works by sending an instantaneous message to a remote frame moving away at a high sublight speed, converting the message to that frame (e.g. by reflection) and sending it back, still instantaneous but now in the remote frame's spacelike slice which intersects the past of your worldline. What would you get back in an Everett universe? White noise? For in interacting with the remote frame certainly many branches could be created and they would all be relected back.
 

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