Heart Shades of Green

[Plenum]

sorta related:

White light passing through a slit or from air into a prism generates a spectrum (rainbow). This is due to the fact that different component frequencies/wavelengths of the light refract (bend) by different amounts as they cross the boundary between the rarefied phase (air) and the condensed phase (glass or water). The phenomenon is known as the index of refraction. The technical origin for this effect is that the phase velocity (speed) of light in a condensed medium depends on its wavelength/frequency.

Remember the album cover for Dark Side of the Moon? CD, I meant CD case! You can easily find the image on the net. White light enters the prism from the left and a spectrum of light exits from the left. From top to bottom the colors are red, orange, yellow, green, blue, and violet. Do you recall the mnemonic for the colors of the rainbow?




Roy G. Biv : Red, orange, yellow, green, blue, indigo, and violet, which is one more than on the Pink Floyd album cover. Why the difference? Well Isaac Newton made up this color series you see, and being a law-and-order sort of fellow he imagined that the light spectrum might be best understood by analogy to a musical (octave) scale.

To make this work out he artificially added a seventh designation, indigo, between blue and violet. Of course visible light can be anywhere between red and violet. By the way, almost nobody can distinguish indigo in rainbows or in other diffraction experiments.

has anybody here ever inverted violet and indigo in the past? For a long time, I thought of violet as being the much deeper shade, and indigo the lighter shade.