Early one November evening, 1973: Gasoline supplies have been cut by the month-old Arab Oil Embargo and people wait in long lines to buy gas. Inside Lawrence Berkeley National Laboratories, particle physicist Art Rosenfeld’s office is lit by 12 dazzling 60-watt fluorescent lights, which allows him to make a startling calculation. The light bulbs in his office are burning the equivalent of .05 gallons of oil per hour, and if he leaves them on all weekend, as nearly everyone does, his empty office will have burned the equivalent of four gallons of gasoline by the time he returns on Monday morning. "So this was the funny thing," he says, "There are 20 lights filling the rooms between my office and the door of the building, and I figure it’ll save 60 gallons of oil if I switch them off." But he can’t—bookshelves and posters hide the switches. Forty-five minutes later, having rearranged the furniture and turned out the lights, he exits the building thinking "there’s something wrong."