I'm trying to understand Young's experiment and have been unable to find a clear, precise, historically accurate description of what Young actually did.

Specifically, discussion in Young's double slit experiment with a single photon does not make it clear Young used monochromatic light or sunlight. It also cites Tony Rothman's book Everything's Relative and Other Fables from Science and Technology (which I haven't read) which, according to what is currently footnote a, Rothman claims that there is no historical evidence that Young actually conducted his experiment.

I find it hard to believe that Young didn't actually conduct his experiment. Presumably, an answer to my question will also answer Rothman.

The reason that I want this precise description is that Young would have had to assume that either all of the light coming form his source was a single wave, or else that all of the different light emitters in his source somehow produced waves that were phase aligned. Otherwise, the light from different waves would cancel out, would they not?

I'd like to ask Young what was going through his mind, but it's currently not possible to do so...

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    $\begingroup$ I think this is a history question rather than a science question. It would be an ideal question for the History of Science Stack Exchange. $\endgroup$ Oct 27, 2019 at 15:56
  • $\begingroup$ There is a sense in which (a) you shouldn't care what Young did and (b) you shouldn't care about "the two-slit experiment" as an isolated thing. Not that what Young thought, did and observed in uninteresting, but the physics doesn't care who did it, exactly how they did it, or what they were thinking when they did it. Physics isn't the history of physics, and you can do diffractive scattering experiments (one way to describe the general class that includes "the two-slit experiment") lots of different ways. $\endgroup$ Oct 28, 2019 at 1:38
  • $\begingroup$ I care because I'm writing a history of science. $\endgroup$
    – vy32
    Oct 28, 2019 at 2:44

1 Answer 1


You can refer to the Feynman lectures on Physics. Volume 2 gives a historically accurate description with Interesting insights on the topic


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