Wave optics of Young and Fresnel and the luminiferous ether
An optics in which light is explained as a wave rather than a stream of particles: interference and diffraction find a simple explanation through the superposition of waves. The theory requires a carrier medium, the luminiferous ether, filling all space.
The English natural philosopher Thomas Young explained interference by the superposition of waves (double-slit experiment, 1804). The Frenchman Augustin Fresnel in his memoir on diffraction (1818, Academy prize 1819) gave the wave theory its mathematical form and by 1822 introduced transverse waves in an elastic ether.
As historians note, the formalism of the theory 'did not stand or fall' with any particular interpretation of the ether.
Why this date
exact for the publications: Young 1802/1804, Fresnel 1818 (prize 1819), transverse waves suggested by Young in 1817 and incorporated by Fresnel by 1822 (Encyclopedia.com)
Other links
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The Michelson-Morley experiment
refuted by · Confidence: high
The null result refuted the specific model of Fresnel's stationary ether that the experiment was designed to test.
Dispute: The experiment refuted not "the ether as such" but Fresnel's stationary-ether hypothesis; Lorentz and FitzGerald kept the ether via contraction, and Michelson himself, after repeating Fizeau's experiment (1886), held Fresnel's theory to be correct (Wikipedia "History of special relativity": "Michelson was now of the opinion that Fresnel's stationary aether theory was correct").
Link sources
- Michelson & Morley 1887, Am. J. Sci. 34 (1887) Verified 20 Sep 2026, quotation assembled from fragments
It appears, from all that precedes, reasonably certain that if there be any relative motion between the earth and the luminiferous ether, it must be small...
- Michelson 1881 (1881) Verified 20 Sep 2026
The result of the hypothesis of a stationary ether is thus shown to be incorrect, and the necessary conclusion follows that the hypothesis is erroneous.
- Britannica «Michelson-Morley experiment» (2024) Verified 24 Sep 2026
This null result seriously discredited the ether theories
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong. "Assembled from fragments" means the words do not stand together on the page: we found each fragment separately and joined them with an ellipsis.
- Michelson & Morley 1887, Am. J. Sci. 34 (1887) Verified 20 Sep 2026, quotation assembled from fragments
Links under review
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Maxwell's electromagnetic theory of light
influenced · Confidence: medium
The only source (Michelson 1881) describes the ether of the wave theory, not its inheritance by Maxwell; no historian (Buchwald, Hunt, Darrigol) is cited.
Maxwell's electromagnetic theory of light inherited from wave optics the idea of the ether as the carrier of waves.
Dispute: No direct statement by a historian on the continuity of the ether from Fresnel to Maxwell could be found; it is visible in the texts themselves (Maxwell 1878, Michelson 1881). Encyclopedia.com stresses: "the formalism of the theory did not stand or fall with a particular interpretation" of the ether.
Link sources
- Michelson 1881, Am. J. Sci. 22 (1881) Verified 20 Sep 2026
The undulatory theory of light assumes the existence of a medium called the ether, whose vibrations produce the phenomena of heat and light, and which is supposed to fill all space.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Michelson 1881, Am. J. Sci. 22 (1881) Verified 20 Sep 2026
Node sources
- Encyclopedia.com «Revival of the Wave Theory of Light in the Early Nineteenth Century» (Science and Its Times) (2001) Verified 20 Sep 2026
While its proponents continued to invoke the ether to interpret the theory and facilitate its assumptions, the formalism of the theory did not stand or fall with a particular interpretation.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
Further reading
Not evidence: these carry no quotation and support nothing we wrote. They are books and scans to read next.