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Michelson-Morley Experiment

  1. Dec 28, 2007 #1
    Since this experiment was done long before lasers were invented, what did they use as a coherent light source? All the explanations of the experiment I can seem to find skip this detail and I am curious.
     
  2. jcsd
  3. Dec 28, 2007 #2

    mathman

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    They didn't need a coherent light source. A narrow beam sufficed.
     
  4. Dec 29, 2007 #3
    I suppose the important bit wouldn't be the coherent bit, but having a light source with a limited range of frequencies so that the change in intensity due to the change in interference in one wavelength wasn't canceled out by an opposite change in intensity from other wavelengths interfering differently. A light source like an oil lamp would have too large a range of frequencies for the interference effects to not wash each other out wouldn't it?
     
  5. Dec 29, 2007 #4

    mathman

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    I don't know what they used as a light source, but whatever they used, the problem you raised didn't seem to be an issue.
     
  6. Dec 30, 2007 #5

    uart

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    For monchromatic light something like a gas discharge tube that emits a line spectrum would do the job.
     
  7. Dec 31, 2007 #6
    They used a carbide bicycle lamp for the experiments. They sometimes used a sodium-vapor lamp to help set up.
     
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