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Twin Paradox

  1. Sep 27, 2005 #1
    If the universe was closed and such that if one continued in a straight line they would arrive where they began eventually. Wouldn't the twins paradox still be a paradox as neither party is accelerating (are they?) and this would prove that such a universe doesn't exist?
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  3. Sep 27, 2005 #2
    hmmmmm time dilation, well who is to say that the universe is finite in the first place. considering that we know it is currently expanding(because the gallixys are moving apart) its not to hard to fathom the fact that it may be infinitely big in porportion and that it is getting biger even as we speak.
  4. Sep 27, 2005 #3
    As long as it isn't expanding faster then the traveller they will still met again if the universe is as suggested in my original post.
  5. Sep 27, 2005 #4


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    But if the universe is infinite the odds of a duplicate of your traveler existing is 1 , so you argument is not unique to a closed as the same result can be expected in an infinite universe.

    I do not see how the "twin paradox" enters into this. Proper application of Special Relativity resolves the "twin paradox", so it is not a paradox.
  6. Sep 27, 2005 #5
    The paper, "On the Twin Paradox in a Universe with a Compact Dimension" presents a very clear answer to your question:

    "We consider the twin paradox of special relativity in a universe with a compact spatial dimension. Such topology allows two twin observers to remain inertial yet meet periodically. The paradox is resolved by considering the relationship of each twin to a preferred inertial reference frame which exists in such a universe because global Lorentz invariance is broken. The twins can perform 'global' experiments to determine their velocities with respect to the preferred reference frame (by sending light signals around the cylinder, for instance)."

    See these references also:


    All this analysis has a pointed answer:

    When the two twins meet again, the youngest, least-aged twin will be the one who is moving the fastest with respect to the absolute frame of reference.

    Here's the main point:

    Spatially compact spacetimes break global Lorentz invariance and define absolute inertial frames of reference.
  7. Sep 27, 2005 #6


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