system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why mixing all colours of the rainbow creates white but mixing lots of paints creates brown

Bonus: why does the mixing of, say, red and blue create purple, even though red and blue both have greater wavelengths?
gpt
Subtractive vs additive light. Paint absorbs all light but the color they emit (red paint absorbs all light but red), light emits only the color (red light emits red light). When you mix two lights, you mix the wavelengths, when you mix paints you are combining what colors they absorb, mixing more colors means they absorb more colors, leading the color they emit to turn very brown.