James Dreben Apr 30, 2023

#ELI5 Why is water see through?

I'd never thought about it like this. Wow.

Show threadsqueakyearsMay 1, 2023

@Jdreben

I am reminded of the question, "If plants don't want to be eaten, why aren't all plants poisonous?" I *think* the answer is that they are, but it's advantageous for herbivores to resist the poison, so they evolve to.

Also, "Why are there three primary colors, not two or four?" This one I'm more confident about: Most humans have three types of color sensors, so some mix of three primary colors can reproduce those sensors' response to any "natural" color.

Show threadSörenMay 1, 2023

@squeakyears @Jdreben it depends on whether you’re in an additive (starts with black; colors add up to white) color system such as a screen, or a subtractive (starts with white; colors add up to blank) one such as a printer. The latter typically has four colors; sometimes six or more to make mixing more precise. And the former these days also sometimes has four; some TVs use RGBW.

And I think you need three for a proper gamut (a triangle-like shape that shows which colors can be mixed).

Show threadUli Kusterer (Not a kitteh)Jul 3, 2023
@chucker @squeakyears @Jdreben Yeah, RGB (red green blue) for screens, red yellow blue for paint/printing (though most printers use CMYK, cyan, magenta, yellow, black).
Show threadSören

@uliwitness @squeakyears @Jdreben I was confused as a kid who was told in kindergarten that the “basic colors” are red, yellow, blue (RGB in German), then found that displays used red, green, blue (again, RGB, but a different G).

It clicked once I realized additive and subtractive are opposite starting points, so blending colors also accomplishes the opposite.

Jul 3, 2023 at 10:09pmWeb
Show threadUli Kusterer (Not a kitteh)Jul 3, 2023
@chucker @squeakyears @Jdreben We had an arts teacher who once insisted you could mix yellow from red and green … refused to listen to my objections until we'd experimentally proven that it'd result in a bad shade of brown. No idea how that happens in that job.