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I Source of light in Michelson-Morley experiment

  1. Apr 1, 2016 #1

    I wonder if anyone can tell me what was the source of light Michelson and Morley used when they did the experiment(s) to measure the (difference of) speed of light in different directions? And can it be done with sunlight? Young observed interference patterns with sunlight in 1801 in double-slit experiments.

  2. jcsd
  3. Apr 1, 2016 #2


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  4. Apr 1, 2016 #3
    Michelson was not determining the speed of light he was determining the effects of the ether drift (wind) of Fresnel's optical ether, composed of matter (Michelson, p. 120) (Michelson-Morley, p. 334).
  5. Apr 1, 2016 #4
  6. Apr 1, 2016 #5
    I see, it was my mistake. He was determining the relative speed between the ether and the Earth, as far as I can see. So he found that it should be much less than Earth's orbital speed.
  7. Apr 1, 2016 #6


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    Yes, I'd never heard of an argand burner before.
    As far as I can see he does not say what the source of his sodium light was. Perhaps he just put some salt in the flame? Since it seems he then returned to using white light for the measurements, some such temporary expedient seems plausible.
  8. Apr 4, 2016 #7

    Andy Resnick

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    As best I can tell, salt crystals could be burned in the lamp- Sodium produces a bright yellow light from the Sodium D lines, which were known at least since Fraunhofer. The lamp was probably also outfitted with a slit (Mathven screen?) to increase fringe visibility.
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