Source of light in Michelson-Morley experiment

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Discussion Overview

The discussion revolves around the source of light used in the Michelson-Morley experiment, particularly focusing on whether sunlight could be used and the specific type of light employed by Michelson. Participants explore historical context and technical details related to the experiment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the specific source of light used by Michelson and whether sunlight could be a viable option, referencing Young's earlier work with sunlight in double-slit experiments.
  • Another participant provides a link to a historical resource about Michelson, but does not address the question directly.
  • Some participants assert that Michelson was not measuring the speed of light but rather the effects of ether drift, with references to specific pages in Michelson's work.
  • There is a suggestion that Michelson used yellow light in his calculations, but the exact source remains unspecified, leading to speculation about the use of sodium light.
  • One participant proposes that salt crystals might have been burned in the lamp to produce the sodium light, which is known to emit a bright yellow light from the Sodium D lines.
  • Another participant mentions that Michelson may have returned to using white light for measurements, suggesting a temporary use of sodium light.

Areas of Agreement / Disagreement

Participants express differing views on the nature of Michelson's measurements and the source of light used in the experiment. There is no consensus on the specific source of light or the implications of Michelson's findings regarding ether drift.

Contextual Notes

There are unresolved questions regarding the assumptions made about the light source and the historical context of Michelson's work, as well as the implications of using different types of light for the experiment.

nikolafmf
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Hi

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. Nikola
 
Science news on Phys.org
https://www.aip.org/history/exhibits/gap/Michelson/Michelson.html#michelson1

Zz.
 
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).
 
ZapperZ said:
https://www.aip.org/history/exhibits/gap/Michelson/Michelson.html#michelson1

Zz.

Thank you very much.

As far as I can see, he uses the wavelength of yellow light in his calculations, but doesn't' state what is the source of light?
 
carl susumu said:
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).

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.
 
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.
 
nikolafmf said:
Thank you very much.

As far as I can see, he uses the wavelength of yellow light in his calculations, but doesn't' state what is the source of light?

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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