Eli5: How does the colour purple “not exist”?
In: Physics
Purple does exist. There isn’t a single wavelength of light that is purple you can have a wavelength that is red, orange, yellow, green, blue… but you cannot have single wavelength that appears purple. That’s because our eyes basically see in buckets of wavelengths of Red, Green, and Blue and the red and green buckets overlap a little as do the green and blue. So while we can’t exactly tell what wavelength something is, we see something that really lights up our Red cone and slightly lights up our green it looks a bit orange. The thing is for something to appear purple it has to light up Red and Blue but those don’t overlap so there’s no one wavelength that lights both of those up. We need to see red and blue but no green. So the way purple is usually seen is either white light (pretty much ”all the wavelengths”) where green is blocked out or absorbed so that only red and blue comes through or with LEDs sometimes it will just be one (or a small group) of red wavelengths and another or blue.
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