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In the early 1900s, at age 12, Percy Spencer, an orphan, was a grammar school dropout working in a mill.   A castoff in the making, Spencer’s life diverted course when, at age 16, he joined the Navy.  Using the skills he developed there, Spencer (pictured above) parlayed himself into a job at Raytheon, working on magnetrons — a device which creates radio signals, in Spencer’s case, to power radars.

One of the side effects of working on these magnetrons: a pocket of melted chocolate.  One day, in 1945, Spencer noticed that the peanut bar in his pocket was hot and, in fact, the chocolate had melted.  This apparently was not the first time a Raytheon scientist noticed something similar, but Spencer’s curiosity was piqued.  Had the magnetron caused this?  He sent an assistant out for some popcorn — a test, of sorts.  Holding the popcorn near the magnetron created a violent reaction — an explosion of popcorn flew all over his lab.  The next day, he tested with a raw egg, poking a hole in the shell, and discovered that the magnetron was, in fact, cooking the food.

By 1947, his discovery, patented, was available for sale — as the microwave oven.

Bonus fact: Carrots and hot dogs sometimes “spark” in the microwave, as you may have noticed on occasion.  Why?  It’s called arcing, caused by how microwaves reacting to metal.  Is there metal in these foods?  Not exactly, the USDA explains: “In hot dogs, this can be due to the uneven mixing of salts and additives. In carrots, it can be due to the minerals in the soil in which they were grown.”  Either way, if it happens, the USDA advises you to remove the food from the microwave.

From the Archives: Baby Carrots aren’t babies.

RelatedAccidental Inventions That Changed our Lives by Birgit Krols.

Originally published

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