Percy L. Spencer was a grammar school dropout who became Raytheon's chief engineer. Late in 1945, the homegrown engineering genius reportedly was standing near an operating radar transmitter when a candy bar in his pocket began to melt. Fascinated, he sent out for popcorn and watched kernels pop wildly when placed next to the device—and the microwave oven was born. Spencer's creation, christened the Radarange, debuted later that decade in industrial kitchens. After Raytheon bungled the marketing, Japanese companies came to dominate the industry. Today, World War II-type microwave transmitters—called magnetrons—still form the heart of this popular appliance.

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