That's only if you subscribe to the many-worlds theory being the only way with which to accomplish time travel (which I do, but for the sake of argument, let's say I don't).
One could subscribe to Gödel's CTCs as being a possible if not plausible method of time travel -- punch holes in the Universe and space-time travel becomes possible; apply Visser's words on Roman rings (a configuration of n black holes in a polygonal formation acting as a time machine and ignore his caveats about it not being a flaw in classical quantum gravity theory) and Bob's your uncle. In the same universe, no less.
Granted, such a solution is practically impossible and ignores Occam's Razor wrt. the many-worlds theory, but this is magic we're talking about. ;) And to stave off paradoxes, one could also throw in Novikov's self-consistency principle, which along with Thorne's calculations seem to indicate that large masses passing through wormholes for purposes of time travel could never produce paradoxes (i.e. once time travel is brought into the picture, conditions generating paradoxes could not be introduced).
Anyway. Gödel and multiverses aside, I take Hawking's expansion of the Fermi paradox, i.e. that we haven't had chrononauts from the future visiting us is the strongest proof that time travel is impossible, at least in large numbers. And I better stop before I babble all day...
(Disclaimer: IANAP; astrophysics, not quantum mechanics, is my darling.)
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timeasmymeasure
no subject
Date: 2005-03-23 12:42 am (UTC)That's only if you subscribe to the many-worlds theory being the only way with which to accomplish time travel (which I do, but for the sake of argument, let's say I don't).
One could subscribe to Gödel's CTCs as being a possible if not plausible method of time travel -- punch holes in the Universe and space-time travel becomes possible; apply Visser's words on Roman rings (a configuration of n black holes in a polygonal formation acting as a time machine and ignore his caveats about it not being a flaw in classical quantum gravity theory) and Bob's your uncle. In the same universe, no less.
Granted, such a solution is practically impossible and ignores Occam's Razor wrt. the many-worlds theory, but this is magic we're talking about. ;) And to stave off paradoxes, one could also throw in Novikov's self-consistency principle, which along with Thorne's calculations seem to indicate that large masses passing through wormholes for purposes of time travel could never produce paradoxes (i.e. once time travel is brought into the picture, conditions generating paradoxes could not be introduced).
Anyway. Gödel and multiverses aside, I take Hawking's expansion of the Fermi paradox, i.e. that we haven't had chrononauts from the future visiting us is the strongest proof that time travel is impossible, at least in large numbers. And I better stop before I babble all day...
(Disclaimer: IANAP; astrophysics, not quantum mechanics, is my darling.)