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Seeking clarification of time dilation

  1. Jun 27, 2013 #1
    "Since we are always at rest with respect to ourselves, ignoring the effects of acceleration, our lifetime, as measured by us, will always appear shorter than it appears to others. To others our clocks will seem to run slow. But we will die, alas, on the cue of the internal timer that travels with us. In special relativity the grass is greener on the other person's lawn." - Euclid's Window, PG 188

    I've been under the impression that when you are moving, your clock will slow down; however, the above passage seems to imply that being at rest is what slows your clock down.

    What's going on here?
  2. jcsd
  3. Jun 27, 2013 #2


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    To start with, all motion is relative. There is no absolute at rest.

    When you observe a clock moving close to the speed of light it appears to be going slower. However someone traveling with that clock looking at your clock will observe it is going slower.


    See above for a detailed description.
  4. Jun 27, 2013 #3


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    hi acesuv! :smile:
    suppose you live 70 years, on a spaceship, and you return to earth to die

    you will return more than 70 years later according to an earth clock, so an observer who stays on earth will say that you lived for more than 70 years :wink:
  5. Jun 27, 2013 #4
    If you observe other clocks as going slower when they move relative to you, then why are they the ones that age faster? The passage implies that I should be the one whose clock is slowing down from my frame of reference, I think.
  6. Jun 27, 2013 #5
    Sorry guys; I got myself confused! I was associating a slowing of time with less aging; however, the opposite is actually true. "Slowing", meaning "less speed", I got myself confused...

    Thanks for the help
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