The human eye can detect a single photon, study finds

Your eyes may be more sensitive than you ever thought possible. In a study published Tuesday in Nature Communications, researchers report that our warm, wet, multicellular eyes have evolved such a high level of sensitivity that they can, on occasion, detect a single photon aimed at the retina. Even the most sophisticated man-made devices require a cool, temperature-controlled environment to achieve the same feat. A single photon is the the smallest particle that light is made of, and it is extremely hard to see. "It's not like a dim flash of light or anything like that," said Alipasha Vaziri, a quantum physicist at Rockefeller University in New York City and the senior author on the paper.