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Same person, doing same thing?

  1. Dec 29, 2008 #1
    I once heard somewhere that due to some physics theory, there is someone out there in the universe doing exactly the same thing as you and looking exactly the same as you. I cant remember the details though... Anyone heard of this before and can clarify?

    I don't think it seems plausible though..
  2. jcsd
  3. Dec 29, 2008 #2
    Mathematically, if the universe is infinite, that would have to be the case, because the probability of there being somebody somewhere in the infinite universe doing the same thing would be 1. However, if the big-bang theory is correct, our universe is not infinite, so the probability of that happening would drop dramatically - so close to zero we could say for sure it's not the case.
  4. Dec 30, 2008 #3
    even if the universe is infinite, why can't there be an infinite number of possible combinations for "things"?
  5. Dec 30, 2008 #4


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    Science Advisor
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    Then it should be possible to show the existence (with probability 1) of a person 'arbitrarily similar' to you by any reasonable metric.
  6. Dec 30, 2008 #5


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    Staff: Mentor

    You're thinking of MWI (Many-Worlds Interpretation). Here are two links you can read about it.


  7. Jan 1, 2009 #6
    Thanks Evo!

    I don't really seem to understand it though haha... But i guess its something to do with probability too?

    Happy New Year anyway!
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