Did you know we can thank World War II for microwave ovens?

The idea of heating up objects with radio waves had been around since around 1920. The 1933 Chicago World’s Fair featured a radio transmitter that could cook food placed between two metal plates, but this early technology was a far cry from our modern microwave ovens.

The 1933 predecessor of the microwave oven
(Photo: Short Range Craft magazine)

World War II gave many technologies a great boost, and radar, which is essentially radio waves bounced off a target, was no exception. In 1940, British physicists John Randall and Harry Boot invented the cavity magnetron, a device that could create very short-wavelength (high-frequency) radio waves called microwaves. The cavity magnetron was the size of a small book and could be combined with an antenna a few inches long to create much smaller and lighter radar systems than before, ones small enough to be equipped on night fighters, anti-submarine aircraft and small escort ships, giving the Allies a radar advantage the Axis powers could never match. The technology was shared with the United States, where it was manufactured by the Raytheon Company, a major defense contractor (also the manufacturer of civilian electronics and one of the predecessors of today’s Raytheon Technologies).

A cavity magnetron tube, the technology that made better radar (and microwave ovens) possible
(Photo: John Cummings / Wikipedia)

One day, a Raytheon employee called Percy Spencer was standing in front of an active radar device and noticed that a chocolate bar in his pocket started to melt. This had happened to others before, but Spencer was the first to investigate it. His experiments led to the creation of the world’s first bowl of popcorn, and an egg that blew up in the face of a colleague. His work quickly led to the invention of the microwave oven, the first model of which preserved its origins in its name: the RadaRange Oven.