The human eye is sensitive enough pick out a single photon of light in otherwise complete darkness.
Light-sensitive cells called rods, located in the back of your eye, can react to single photons, but that’s not the same as actually seeing the light. Sight, in the way that we think of consciously perceiving a visual, requires the retina and the brain to process those signals. For decades, researchers have wondered how little light the human eye could actually detect. Now, it turns out tha