During the World War II years, Percy Spencer, a self-taught engineer leading the power tube division at defense contractor Raytheon, focused his efforts on the magnetron—the core tube that made radars so powerful they enabled U.S. bombers to spot periscopes on German submarines. Standing next to a magnetron one day, Spencer noticed that a candy bar in his pocket had melted. He then wondered, Could the energy from the radio waves be used to actually cook food? He placed some popcorn kernels near the tube and soon was munching on the world’s first microwave popcorn. In 1947, Raytheon put the first Radarange microwave ovens on the market—but it took another 20 years before the appliances were small enough to fit on a countertop.
