ONE WILD WORLD — NEWSLETTER

Issue #006 | This Changed Everything | April 2026

In 1945, an engineer with a fifth-grade education walked past a radar machine with a candy bar in his pocket. It melted. And that one moment of curiosity changed how 90% of American households cook their food.

BY THE NUMBERS

Percy LaBaron Spencer was born on July 19, 1894, in Howland, Maine. His father died when he was 18 months old. His mother couldn’t care for him, so he was sent to live with an aunt and uncle. His uncle died when Percy was seven.

He left school after the fifth grade and started working at a spool factory at age 12, working from sunrise to sundown. At 18, he joined the U.S. Navy, where he became fascinated by radio technology. During night shifts, he taught himself calculus, trigonometry, physics, and chemistry from borrowed textbooks.

He never returned to school. But by the time he was in his 30s, he was one of the most respected engineers at Raytheon, a Massachusetts defense contractor. He eventually held over 300 patents.

During World War II, Spencer’s specialty was magnetrons — vacuum tubes that generate microwaves and power radar systems. Radar was critical to the Allied war effort, used to detect enemy aircraft and submarine periscopes.

When Spencer arrived, Raytheon was producing 17 magnetrons per day. Spencer figured out that stamping and soldering the components was faster than machining them. Production rose to 2,600 per day. Raytheon ended up producing 80% of all magnetron tubes used by the U.S. and British military during the war.

For this work, the Navy awarded Spencer its Distinguished Public Service Award — their highest civilian honor.

One day in 1945, Spencer was standing near an active magnetron in one of Raytheon’s laboratories when he noticed something strange. The candy bar in his pocket — a Payday bar, his usual snack — had started to melt.

Other engineers had noticed similar effects near magnetrons before. They dismissed it. Spencer didn’t.

Raytheon filed a patent for a “microwave cooking process” on October 8, 1945. Two years later, they released the first commercial microwave, the RadaRange. It stood nearly six feet tall, weighed 750 pounds, required water cooling, and cost about $5,000 — roughly $73,000 in today’s money.

The early RadaRange was marketed to restaurants, hospital kitchens, ship galleys, and military installations. It could boil water faster than a stove and reheat food in seconds. But it was enormous, expensive, and had clear limitations — it couldn’t brown meat or crisp fries.

Raytheon even hired a chef to cook exclusively with the RadaRange to prove its versatility. The chef quit.

The turning point came in 1967, when Amana (a Raytheon subsidiary) introduced the first countertop microwave for home use, priced at $495. It was compact, ran on standard household power, and was affordable for middle-class families.

Adoption was slow at first, but by 1975, microwave ovens were outselling gas ranges. By the mid-1980s, over half of all U.S. households had one. Today, the number exceeds 90%.

For inventing one of the most widely used kitchen appliances in history, Percy Spencer received Raytheon’s standard inventor’s bonus: a one-time payment of $2. That’s about $29 in today’s money.

He never profited from the microwave patent. He continued working at Raytheon, rising to Senior Vice President and Senior Member of the Board of Directors. He died on September 8, 1970, at the age of 76.

Today, a building at Raytheon’s Missile Defense Center in Woburn, Massachusetts, is named in his honor. One of the original RadaRange ovens sits in the lobby.

The microwave oven is a reminder that the most transformative inventions don’t always come from labs with billion-dollar budgets or teams of PhD researchers. Sometimes they come from someone who notices something everyone else ignored.

Percy Spencer wasn’t the first person to feel warmth near a magnetron. He was the first person to ask why.

A man with no formal education. A war machine repurposed for popcorn. A $2 bonus for an invention worth billions.

The microwave didn’t come from a plan. It came from a pocket.

SOURCES

MIT Technology Review — “Melted Chocolate to Microwave”

HISTORY.com — “Who Invented the Microwave Oven?”

New England Historical Society — “Percy Spencer Melts a Chocolate Bar, Invents the Microwave Oven”

Lemelson-MIT Program — Percy Spencer inventor profile

Wikipedia — Percy Spencer (verified against multiple primary sources)