In the middle of World War II the most brilliant engineers in the world were frantically trying to figure out how to spot enemy airplanes. They were playing with invisible radio waves and building massive military radar systems. Absolutely nobody in these top secret labs was thinking about how to heat up leftover food.
But a self taught scientist named Percy Spencer accidentally created the most common kitchen appliance on the planet. And he did it without even trying.
The Sticky Snack That Changed Everything
Spencer was working for a major defense contractor called Raytheon. He was standing in a lab testing a powerful piece of technology called a magnetron. This was a heavy metal vacuum tube that pumped out high density microwave radiation to bounce signals off distant targets. He was just doing his normal daily checks on the machinery.+1
Then he reached into his pocket for a quick snack. He had a peanut cluster candy bar sitting in his pants. But when he touched it his fingers just sank into a warm sticky mess. The candy had completely melted into liquid goo.
The Exploding Egg Experiment
Spencer was a highly curious guy. He knew the room was completely cold. His own body temperature felt totally normal. He was not sweating. He immediately realized the invisible waves shooting out of the active magnetron were actively cooking the food in his pocket. He decided to test this crazy theory right away.
He grabbed some raw popcorn kernels and placed them near the active tube. Within seconds the kernels aggressively popped into white fluffy snacks all over the expensive lab floor.
Then he decided to try something a little more dangerous. He brought in a raw egg and placed it near the machine. One of his curious coworkers leaned in closely to see what was happening. The extreme internal heat built up massive pressure inside the shell. The egg violently exploded right into the poor guy’s face. Spencer realized the invisible waves were vibrating the water molecules inside the food and cooking it from the inside out in a matter of seconds.
A Giant Metal Monster
Spencer quickly built a closed metal box to trap the energy and keep it completely safe. He pumped the microwave power directly into the metal square. This was the very first working prototype of the modern oven. His company realized the massive potential and patented the idea very quickly. But the earliest commercial versions were absolutely terrifying.
They released a machine called the Radarange in 1946. These early models were massive. They stood almost six feet tall and weighed over seven hundred pounds. They were so incredibly powerful that they had to be hooked directly up to massive water plumbing lines just to keep the heavy machinery from melting itself. They cost the equivalent of tens of thousands of dollars. Regular people could never put one of these giant metal boxes inside a normal house. They were only sold to giant commercial restaurants and massive cruise ships.+1
Changing How The World Eats
It took decades for engineers to figure out how to shrink the military technology down to a normal size. By the late 1960s they finally managed to make a small affordable version that could sit safely on a kitchen counter.
People were completely terrified of the invisible cooking waves at first. They thought the boxes would leak deadly radiation into their homes. But the sheer convenience of heating up a meal in sixty seconds was just too powerful to ignore. The technology completely revolutionized the way human beings prepare their meals. Today there is one in almost every single home on the planet. And this entire global industry only exists because a radar engineer decided to bring a cheap piece of candy to work.
References: You can read more about Percy Spencer and his famous melted candy bar in this historical breakdown by Popular Mechanics.