Popular Science (June 11) -- For decades researchers have been trying to find out the minimum number of photons our eyes can see--three photons is the eye’s lower limit. The study, which involves firing photons into the eyes of people sitting in a dark room, could ultimately show whether people can sense single photons, according to Rebecca Holmes, a physicist from the University of Illinois at Urbana-Champaign. Also: Nature News (June 11).