TRIVIAL PURSUITS: From what did the idea for inventing the microwave oven come?

In 1945, engineer Percy Spencer was experimenting with a new vacuum tube called a magnetron while doing research for the Raytheon Corporation. He was intrigued when the candy bar in his pocket began to melt, so he tried another experiment with popcorn. When it began to pop, Spencer immediately saw the potential in this revolutionary process.

In 1947, Raytheon built the first microwave oven, the Radarange, which weighed 750 pounds, was 5 1/2 feet tall, and cost about $5,000. When the Radarange first became available for home use in the early 1950s, its bulky size and expensive price tag made it unpopular with consumers. But in 1967, a much more popular 100-volt, countertop version was introduced at a price of $495.