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Riding on a light beam

  1. Sep 1, 2008 #1
    Riding on a light beam....

    Einstein, i believe, famously wondered what riding on or next to a light beam would be like. I'm just curious, since at the speed of light the time frame collapses, so time ceases to move or exist, would Einstein actually "see" light that was "frozen"? doesn't this violate the uncertainty principle as well??
  2. jcsd
  3. Sep 1, 2008 #2


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    Re: Riding on a light beam....

    In relativity the thought-experiment doesn't exactly make sense, since an object moving at light speed doesn't have its own rest frame so you can't really talk about what it would observer. It might be seen as something more like an attempt at a reductio ad absurdum of other theories which say it should be possible, like the aether model of light. Go here for a good discussion of the history of this thought-experiment and what role it may have played in Einstein's thinking about relativity:

  4. Sep 5, 2008 #3


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    Re: Riding on a light beam....

    In quantum mechanics, the probability amplitude evolves deterministically, so we just treat the electromagnetic wave as a probability amplitude, and it doesn't violate the uncertainty principle. In this view, the typical plane electromagnetic wave doesn't contain a definite number of photons.

    For another discussion about how to make sense of the idea that light does not "experience" time, look at posts #24 and after on https://www.physicsforums.com/showthread.php?t=252523.
    Last edited: Sep 5, 2008
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