Here is an interesting old fact

While preparing to do an assignment on Newton's Mechanics I decided to look it up in an old University physics book. Well it didn't have Newton's Mechanics but it did have Newton's Rings.
41.5 Interference in Thin Films
The brilliant colors that are often seen when light is reflected from a soap bubble or from a thin layer of oil floating on water are produced by interference effects between the two trains of light waves reflected at opposite surfaces of the thin films of soap solution or oil....The rays come together at a point on the retina of the eye, provided the film is thin enough to allow both rays to enter the pupil of the eye. hmmm ...wonder if that train of thought has changed since 1973.
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