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Relativity time and length

  1. Apr 7, 2009 #1
    when using lorentz factor in time dilation and length contraction... are those phenomenon only considered when the velocity is comparable to the speed of light or does it happen all the time and extremely negligeable in all cases other than when v~c? thanks.
  2. jcsd
  3. Apr 7, 2009 #2
    effects usually seem noticeable at about .5c
  4. Apr 7, 2009 #3


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    It happens all the time; it is just harder to measure with smaller velocities.

    A classic experiment in 1971 involved flying atomic clocks around the world on regular aircraft flights. It's the Hafele and Keating Experiment. The consequences are calculated from a combination of general and special relativity. You need the general relativity because flying at altitude makes a difference. In any case, after clocks flying east-west, and clocks flying west-east, were all back home and compared again with a clock left at home, time dilation was able to be checked with these clocks.

    The various contributions (from gravitation and velocity effects) were all of the order of magnitude 100 nano seconds; easily measured with the clocks. More details at the link.

    If you've ever taken a long haul airflight, then you've experienced a different length of time from your folks at home, by an amount that is tiny but measurable with decent equipment.

    Cheers -- Sylas
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