Percy Spencer, an American engineer and inventor, was working for Raytheon, a leading electronics company, in 1946. One day, while testing a magnetron, a high-powered microwave generator, he noticed that a chocolate bar in his pocket had melted. Intrigued, Spencer began experimenting with popcorn kernels and an egg. He placed them near the magnetron and watched as they rapidly heated up. This led him to wonder if microwaves could be used to cook food more quickly and efficiently.
Spencer built the first microwave oven using a modified magnetron and a wooden box. He tested it with popcorn kernels and an egg again, and was thrilled to see them cook in just seconds. The first microwave oven was about 5 feet tall and weighed over 750 pounds.
Raytheon filed for a patent in 1947, and the microwave oven was officially born. The first commercial microwave oven was released in 1954, but it was expensive and not widely adopted. It wasn't until the 1960s that microwave ovens became a common kitchen appliance.