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Marlsfarp t1_iucumd8 wrote

Reply to comment by blow_up_the_outside in ELI5: Why are the colours in rainbows in separate lines? by Oheligud

The idea that the rainbow has seven colors actually comes from Isaac Newton, who greatly advanced our understanding of light. He understood that it was a continuous spectrum, but made many analogies to musical notes. The wavelengths of the “seven colors” are proportional to the wavelengths of the notes of one octave of a major scale.

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RRumpleTeazzer t1_iucwxo8 wrote

This is more than just artistic. Blue and red are close to an octave apart (a factor of 2 in frequency).

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JudgeAdvocateDevil t1_iudnjzy wrote

Moving on from Newtons work, James Clerk Maxwell developed the understanding that all light we detect is a combination of red, green, and blue (excluding tetrachromats). Even thought we see the rainbow, that's all made up by our brain using RGB data.

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Omphalopsychian t1_iudqjry wrote

The light in a rainbow is made up of many more wavelengths than red, green, and blue. Indeed, every color and shade in the rainbow is a distinct wavelength. Our eyeballs have three different kinds of color receptors. Each receptor responds to visible light, but more strongly to certain wavelengths. You can trigger any color that we can perceive using 3 wavelengths such as red, green, and blue (some other combinations can also be used). We can perceive many more wavelengths than that; we just can't distinguish them.

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SelfDistinction t1_iudqtzd wrote

Technically we're all seeing in XYZ , which can then be mapped onto RGB. Mostly.

If an optical illusion tells you "you're going to see a colour that doesn't exist!", It's because by staring at a colour for long exhausts some of the detectors, and then the remaining detectors will send a colour in XYZ space that doesn't properly map to RGB.

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