system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is it just a coincidence that the color spectrum "loops" around?

May have worded this poorly, but when you look at the color spectrum, it appears (to me, my thinking may be flawed) to be the primary colors red, yellow, and blue and their intermediates. Red to yellow with orange in the middle, yellow to blue with green in the middle, and blue to what would be red, with purple in the middle. Except there is no red at the end of the natural spectrum, just at the beginning. So is it just a nice coincidence that it wraps around perfectly?
gpt
Actually it doesn't loop around, but due to some clever hardware exploiting our visual sensory organs, it can be made to seem that way. In our eyes we have 3 types of sensors, reacting to (grossly) simplified red, green and blue. The bands of the sensors overlap slightly giving us the ability perceive 'colors" of the spectrum as ratios of stimulation in each band. By having 3 light sources corresponding to the center frequency of each sensor, we can generate the perception of any color simply by varying the intensity of those three light sources. By modulating them with 3 sine waves 120 degrees out of phase, you can get the effect of a color wheel that perfectly loops around.