Can a Human See a Single Photon? (1996)
Would there be any interest in a series I've been thinking of putting together about all the fantastically counterintuitive ways your eye fools you without you even noticing? Example:https://media.giphy.com/media/3o7btPOMufN5FziFWg/giphy.gifThe fact that colors influence colors around them means that there are far more than 256^3 viewable colors: the spatial axis is like a fourth channel.Another fun one: If you take a paper plate and poke a hole in it, then take a toothpick and stick it in front of the hole, from the bottom, pointing upwards.... Then it'll look like it's coming down from the top! It's very hard to explain in words, but basically it's a pinhole camera, so everything appears upside-down. Your brain tries to compensate and flips it right side up, but it can't quite do that with the toothpick-hole scenario. So when you push the toothpick up from the bottom, it looks like it's coming down from the top.Lastly: https://i.imgur.com/epXYhJd.png If you cover up the top half of the image, the bottom looks gray. But the strawberries look red.A fun puzzle is, how do you see an individual pixel? Can you think of any common object that would help you do this?
 (No magnifying lenses, for example, and using a phone is sort of cheating.) Answer below....Answer: pluck a hair out of your head and put it on your screen. The line along the edge of the hair will turn into a stairstep pattern, which is just another way of saying you can see individual pixels.