Thread: Seriousness Is Time Travel possible
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Old 04-08-2009, 08:16 PM   #58
kovidgoyal
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Quote:
Originally Posted by Xenophon View Post
Various science fiction authors have observed that a system (universe) in which it is possible to
  1. Travel back in time
  2. Change something
  3. Return to the (possibly modified) "present"
is not stable. With all possible time travelers from the entire future available to meddle, eventually (in terms of iterations of the above actions, not "elapsed time") someone will make a change that causes time travel to not be invented. From that system state, no one will travel backwards in time and make a change... so the "time travel never invented" state is the only stable state for the system!

Xenophon
A time traveler might well change the state of the future to one where time travelling is not invented at a *particular period* of history, but to say that he will change it to a state where it is never invented is about the same as saying that he wipes out the solar system or some such catastrophic event. Basically the usual "kill my gradfather" paradox.
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