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Inventions & Discoveries
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The Accidental Meal: How Military Radar Gave Us the Microwave Oven
In 1945, Raytheon engineer Percy Spencer noticed a candy bar melted in his pocket while working on military radar magnetrons. His subsequent experiments with popcorn and an egg revealed the culinary potential of microwaves, leading to the invention of the oven.
In kitchens across the world, a familiar hum signals that a meal is just moments away. The microwave oven is a cornerstone of modern convenience, so deeply integrated into daily life that we rarely consider its origin. Yet, this humble kitchen appliance wasn't born from a desire to reheat leftovers faster; its story begins with the high-stakes technology of World War II and a moment of pure, accidental discovery.
The Heart of the Machine: Radar and the Magnetron
The tale of the microwave starts not in a test kitchen, but in a lab focused on military defense. During World War II, a critical piece of technology for the Allied forces was radar, used to detect enemy planes from miles away. At the core of these systems was the cavity magnetron, a high-powered vacuum tube that generates the short-wavelength radio waves—microwaves—that make radar possible. The American company Raytheon was a leading manufacturer of these vital components, and one of their star engineers was a man named Percy Spencer.
A Sweet, Messy Discovery
Percy Spencer was a brilliant, self-taught engineer with over 100 patents to his name. In 1945, while working with an active magnetron, he reached into his pocket and made a peculiar discovery: a peanut cluster bar he had saved for a snack had completely melted into a gooey mess. While many might have simply cursed their luck, Spencer’s innate curiosity kicked in. He suspected the magnetron's microwave radiation was the culprit. He immediately decided to test his hypothesis. As one internet user recounted the now-famous story:
The story goes that Percy Spencer was working with a live radar set when he noticed the chocolate bar in his pocket melted. He then tried it on popcorn, then an egg (which exploded).
Spencer famously directed the magnetron's output towards a bag of popcorn kernels, which quickly began to pop all over the lab. Emboldened, his next experiment involved a whole egg, which cooked so rapidly from the inside out that it exploded, splattering a skeptical colleague. This messy but definitive result confirmed that low-density microwave energy could heat food rapidly.
From 'Radarange' to Kitchen Counter
Recognizing the groundbreaking potential of this discovery, Raytheon filed a patent for a microwave cooking process. In 1947, the world’s first commercial microwave oven, the “Radarange,” was released. However, it bore little resemblance to the sleek boxes we use today. The Radarange was a behemoth, standing nearly six feet tall, weighing a staggering 750 pounds, and requiring its own water-cooling system. With a price tag of around $5,000—equivalent to over $65,000 in today's money—it was sold not to homeowners but to large institutions like hotels, hospitals, and restaurants where large-scale, rapid cooking was a necessity.
It would take another twenty years of innovation to domesticate this military-grade technology. Engineers worked to make the magnetron smaller, safer, and cheaper. Finally, in 1967, the Amana Corporation, a subsidiary of Raytheon, released the first popular countertop microwave oven for home use, priced at a more accessible $495. From that point on, the accidental invention began its slow but steady march to becoming a fixture in nearly every American kitchen. The device born from war technology had become a symbol of domestic efficiency, forever changing our relationship with food preparation.