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Has light wavelength compression been proven?

  1. Apr 11, 2004 #1
    has there been an experiment verifying the compressing of light's wavelength by gravity? i thought i heard of one verifying light's wavelength lengthening (redshift) by the earth back in the 60's or something, i was wondering if we'd proved the compression(blueshift)?
  2. jcsd
  3. Apr 11, 2004 #2


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    The X-rays emitted by matter falling into black holes were a prediction of gravitational redshift via GR. They have been observationally verified.

    For earth, I don't know - not a lot of gravity here (relatively speaking).
  4. Apr 11, 2004 #3
    Is there any other way to speak about gravity? :wink:
  5. Apr 12, 2004 #4


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    Good question! One of the early 'gravitational redshift' experiments was (IIRC) a 57Fe gamma Mossbauer effect, over a vertical distance of several (tens of?) metres. I don't know if the experimenters went on to put the source on a higher storey of the lab building, and the detector at a lower one ... :smile:
  6. Apr 13, 2004 #5


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    If I'm not mistaken, Nereid, the Pound & Rebka experiment you cite (the one performed at the Harvard tower) involved beams going in both directions.

    - Warren
  7. Apr 13, 2004 #6
    excellent, so obviously compression has been pretty well proved, thanks guys
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