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450 THz electromagnetic waves are unambiguously red light, you can nitpick about the shade of red, how people perceive it, etc... but it is red. It may look dif
by GuB-42 4y ago
450 THz electromagnetic waves are unambiguously red light, you can nitpick about the shade of red, how people perceive it, etc... but it is red. It may look differently to colorblind people, or dogs, but it is red. The electromagnetic spectrum of frequencies just lower than red is called infra-red, don't tell me that physicists don't talk about infrared.
If you look up some colors in Wolfram-Alpha you will have precise ranges of frequencies, I am not sure they are officially defined ranges, but colors, at least pure colors correspond to physical quantities.
There is some overlap with biology, and there are some colors are special (brown, purple, ...) and can't be defined by a single frequency. Then you can introduce color perception, and how very real and physical red photons are perceived as red, why a combination of red and green photons are perceived the same way as yellow photons and how spectrometers reveal the difference, and how there are no purple photons.
Composite colors are a bit more complicated, you need to add a bit of math (namely, a color space) in order to formally define them from physical quantities, but saying that it is not a physical concept is going a bit far.
No need to make physics more abstract than it is. Because what's next? Temperature is not a physical concept because we don't all agree on how hot something is? Like color, temperature is a well defined physical concept that is based on our perception.
- throwaway1851 4y agoI think with color, it’s important to appreciate the irregularity that exists in this domain. You’re right that colors are defined as ranges of wavelengths or blends of ranges of wavelengths. And so there is a mathematical component to color. Yet, the mathematical view of color is imperfect if you ultimately are concerned with the perceptual end result. People are always trying to create better, more perceptually accurate color spaces, but all of them have their issues and weird corners where the adjusting the values in a certain direction doesn’t yield the expected result.
- BrandoElFollito 4y agoIn that case, what is the frequency of the light needed to create "salmon"? Or in other words: is "salmon", "fuschia" and other colors located on the frequency spectrum? If so - why do we have zillions of color spaces instead of just a simple frequency? (or wavelength) At the moment when you introduce color spaces, you start accounting for how our eye receptors are sensitive to frequencies and leave the realms of physics (mostly because the receptors differ from person to person) When you take a 450 THz wave, you say it it is "unambiguously red" because it is what happens to be the word for the signal which is triggered by that wave. In most of the people. Roughly the same way. What I am trying to say here is that a color is a concept as well defined as "pain". You can have all sorts of measures, but none is strict. Finally, there are no "red photons", or green or blue (you mention them) - this simply does not exist at all as a concept.