system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Are there genuinely 7 different colours? Or are these somewhat arbitrary divisions, and there's actually infinitely many colours?

Also, if you look at a colour spectrum or rainbow, what happens at the point where one of the main 7 colours merges into another? It seems like we get a lot of blues that are pretty similar, then the change accelerates as we move into green.

Also, I wondered, I read that some objects will for example absorb green light while reflecting all other colours. In practice would an object absorb/reflect coloured light in terms of the 7 main colours as nice clear lines, or could it absorb say half of the green frequencies?

Thanks!
gpt
It's subjective. Some languages see green as a shade of blue, for example.

Many languages also don't have a word for "pink," and it's instead called "white-red." It's not that the color (or a specific band of wavelength) doesn't exist in the cultures, they just don't have a separate name for it.