You hear sounds by detecting vibrations. Sounds can be either loud or quiet, high-pitched or low-pitched. Every sound you could listen to appears somewhere in this box.
These vibrations usually travel from the source, through the air, to our ear. There is a general pattern: source → medium → detector.
An explanations seeing uses the same source → medium → detector Pattern. Everything detected again falls into a box.
But what is detected? The best answer we have is that photons are detected.
Physicists can count photons(but it is hard)—if it's brighter more are arriving in each second. The colour you see says something about the inbound photons, not how many of them. A spinning arrow best models this. (Why
best?Because of what you can explain—coming right up). Rapid spinning for blue, about twice as fast as the spinning for red.