The Accidental Invention of the Microwave

This one isn’t about rice. It’s about the box next to the rice cooker that reheats your leftovers in ninety seconds flat, and the way the story goes, it exists because a man stood near a running radar tube during World War Two and, by his own account, the candy bar in his pocket melted.

Nobody designed this thing on purpose. Nobody sat down and said “let’s cook food with radar.” A snack melted, an engineer got curious instead of annoyed, and forty years of trial, failure, and one very expensive flop later, there’s a box on your counter. Here’s how it actually happened.

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Meet Percy Spencer, Self-Taught Radar Engineer

The man was Percy Spencer, an engineer at Raytheon in Massachusetts. He’d had a rough start: orphaned young, out of school by around age seven to help support his family, working a spool mill by twelve. From there he was self-taught, trigonometry, physics, electronics, learned from library books while he stood night watch in the Navy, reportedly after reading about the wireless operators aboard the Titanic.

By World War Two, Spencer was one of the country’s top experts on the magnetron, the tube that generates radar’s microwaves. Production was stuck at about seventeen a day, nowhere near what the war effort needed. He redesigned the manufacturing process himself and pushed output to roughly two thousand six hundred a day, the tubes that helped win the radar war, years before anyone thought to point one at food.

1945: The Candy Bar That Started It All

As Spencer later told it, one day in 1945, testing an active magnetron, he felt something odd in his pocket: the candy bar he’d brought for later had melted. Curious, not alarmed, he sent someone for popcorn kernels and held them near the tube. They popped, right there in the lab.

Then he tried an egg in a kettle, magnetron aimed straight at it. A coworker leaned in for a closer look. The egg exploded, and the coworker got a face full of hot yolk. Spencer had his proof: this thing cooked. It’s worth noting that this origin story comes mostly from Spencer’s own account, so treat the candy-bar detail as the story he told rather than a documented lab record.

October 8, 1945: The Patent, and a Two-Dollar Payout

Raytheon filed the patent on October 8, 1945: “Method of Treating Foodstuffs,” Percy Spencer listed as inventor. It was granted in 1950, patent number 2,495,429.

For an idea that would end up in nearly every kitchen on Earth, Spencer got Raytheon’s standard employee-invention bonus: two dollars. Same as any other employee. He kept working there anyway, and racked up over a hundred more patents before he was done.

1947: The RadaRange, Six Feet Tall and 750 Pounds

Two years later, Raytheon put the discovery on the market: the Radarange. Almost six feet tall, about 750 pounds, water-cooled, and somewhere around three to five thousand dollars, or roughly a hundred fifty a month to lease. Raytheon reportedly tried one out in a Boston restaurant kitchen first, to see if it could survive dinner service.

Nobody was putting that in a home kitchen. It went to restaurants, ocean liners, and hospital kitchens, where cooking fast mattered more than counter space, and where “six feet tall and needs a water line” wasn’t a dealbreaker.

1955: The $1,295 Home Microwave That Flopped

In 1955, Tappan licensed the technology and built the first microwave meant for an actual house: the Tappan RL-1, wall-mounted, wired for 220 volts, priced at $1,295, something like fifteen thousand of today’s dollars.

It was a disaster. Tappan built only 34 of them that first year. Buyers didn’t understand what the box did to their food, didn’t want to rewire their kitchen, and didn’t trust it. By the time Tappan gave up in 1964, fewer than 1,400 had sold in total. The technology worked. The pitch to actual households did not.

1967: Amana Shrinks It to $495, and It Works

Raytheon bought Amana Refrigeration and put its engineers on one problem: take the same idea that filled a restaurant kitchen and shrink it small enough for a countertop, cheap enough for a family, and pluggable into a normal wall outlet, no electrician required.

In 1967, the Amana Radarange countertop model launched at $495, about ninety percent cheaper than the original commercial unit. This is the one that actually got adopted, the one that finally looked like a kitchen appliance instead of restaurant equipment someone had wheeled into your house.

How It Actually Won: Laws, Prices, and TV Dinners

It still wasn’t easy. A 1968 federal law set leak limits for microwave ovens, and a share of older units needed retrofitting, which spooked buyers all over again right after Amana had gotten them interested.

But three things kept pushing it forward. Japanese manufacturers drove magnetron costs way down. Prices fell under three hundred dollars by the mid-1970s, then kept falling as mechanical dials gave way to electronic control panels. And frozen-food companies started selling meals built specifically to be microwaved, which meant the box finally had something to do besides reheat coffee.

In 1970, about one percent of American homes had one. By 1975, microwaves were reportedly outselling gas ranges. By 1997, it was over ninety percent. A machine that flopped at $1,295 became a machine almost nobody’s kitchen was without.

Today: The Most-Used Appliance Nobody Thinks About

So the next time that thing beeps at you, remember: it exists because a man with a melted candy bar decided to point a radar tube at an egg on purpose, got yolk on a coworker’s face, and got two dollars for changing how the entire planet reheats leftovers.

That’s the accidental, mostly-true history of the microwave. It sits on the counter next to the rice cooker, the other appliance that quietly automated a job people used to have to stand over. The refrigerator is the third box in that set: leftover rice has to get cold on purpose after the cooker is done. We test the rice side of that counter here.

Microwaves and Rice Cookers Worth a Look

If this sent you shopping for the box on your counter, or the one next to it:

• Browse countertop microwaves on Amazon
• Tiger JBV-A10U fuzzy logic rice cooker
• Browse fuzzy logic rice cookers on Amazon

Keep reading:

• The Strange History of the Rice Cooker →
• Fuzzy Logic Explained →
• Is a Rice Cooker Worth It? →