Interestingly (well, interesting to me - probably very dull to many people), this is allegedly how Richard Feynman came up with his "sum over histories" approach to the motion of photons and electrons (whereby, to calculate how a photon/electron moves from point A to point B, you have to assume that it simultaneously moves via EVERY possible path through space between the two points).

He thought of a two slit experiment (where the particle follows the two paths - i.e. through the two slits - simultaneously), then 3 slits, then 4, ... and reasoned that, as the number of slits grows to infinity (i.e. the screen disappears and you're left with free space), you end up having to accept that the particle is effectively following every possible path simultaneously.

I'd strongly recommend Feynman's book "QED" for a nice short (and cheap) layperson's introduction to how light phenomena (slit experiments, reflection, diffraction, etc.) can be explained neatly and simply by quantum mechanics. (That is, after you've finished reading "Quantum", Neil.)

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