On October 8, 1945, Raytheon Manufacturing Company filed a patent for what’s now a staple kitchen appliance in homes around the world: the microwave oven. The appliance, invented by Raytheon employee Percy Spencer, now sits in more than 90 percent of American homes.
Spencer, who dropped out of grammar school at the age of 12 to work at a weaving mill, joined the U.S. Navy at the age of 18 as a radio operator. While in his post, he self-studied various subjects: trigonometry, calculus, physics and more.
After World War I, he was honorably discharged and landed a job at the Raytheon Company, a U.S. defense manufacturer, with the knowledge he learned while on duty. There, he worked with his colleagues to produce equipment for radios and radars—specifically the magnetron, which emits microwaves. Spencer also led the way in developing methods to mass produce smaller magnetrons, which historically were larger and difficult to manufacture in large quantities.
But as with many inventions, sometimes accidents at work lead to major discoveries. Spencer was a lover of PAYDAY candy bars, often bringing them to work. One day, while experimenting with a magnetron, he found that the microwave radiation emitted melted the peanut and caramel-filled chocolate bar in his pocket. He then tried other consumables, like unpopped popcorn, cold food and water. He found the microwaves could cook—or reheat—them through materials like wax paper, plastic and glass.
After this discovery, the first microwave was built: a 6-foot, over 750-pound appliance dubbed the “Radarange,” which was installed on a nuclear-powered cargo ship. Eventually, the patent was granted to Raytheon on January 24, 1950.
At the time, the original Radarange cost $5,000, around $52,000 in today’s currency. But due to public concerns about microwave radiation, as well as the size and high price point, the microwave remained absent in the average household. It wasn’t until 1967, when Amana—a company owned by Raytheon at the time—debuted the first tabletop microwave costing $495. And by 1975, the Amana Radarange became more common in homes than gas-powered ovens.
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