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Thought Experiment

  1. Oct 28, 2011 #1
    Let's say two people are born in a hospital at the same time.

    Now person A spends his entire life sitting around his house and not moving much.

    Person B spends most of his life traveling around in high speed cars/planes/and even takes a few trips to space.

    Considering time slows down the faster you go, does this mean that Person B would be younger than person A by an extremely small amount of time?

    I'm not sure if you want to take in the effects of gravity on time but I'm sure that makes a difference as well.

    What I am trying to say is, is everyone on a different time so to speak?
  2. jcsd
  3. Oct 28, 2011 #2


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    If these two people ever come back together again, then all Frames of Reference will agree that the one who traveled more will be younger that the couch potato. But you can only say that when they reunite.
  4. Oct 28, 2011 #3
    Atoms of the human body get replaced all the time, and some less frequent than otherts so even a body has not one unique time.
  5. Oct 28, 2011 #4
    How could you possibly prove that?

    You can prove that two very accurate atomic clocks show a different time but not a human body, unless the time factor is very significant which is not the case in this example.
  6. Oct 28, 2011 #5
    And even if they both carried high precision clocks to register the exact time flow, the difference will be extremely small, a fraction of a second.
  7. Oct 28, 2011 #6
    Basically, the human body has too many variables to give an educated answer, but theoretically, given that the two bodies had the exact same health, genetic build and atom replacement, the one travelling would age slower.
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