Everything Everywhere Daily: History, Science, Geography & More - All Hail the Microwave Oven!

Episode Date: June 15, 2021

According to legend, in 1945 an engineer by the name of Perry Spencer was working in front of an active radar installation. As he was working, he noted that a candy bar that he had in his shirt pocket started to melt. His investigation into the phenomenon resulted in a new technology that has radically change how we cook and live. Learn more about microwaves, how they were invented, and how they work, on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

According to legend, in 1945, an engineer by the name of Percy Spencer was working in front of an active radar installation. As he was working, he noticed that a candy bar he had in his shirt pocket started to melt. His investigation into the phenomenon resulted in a new technology that has radically changed how we cook and live. Learn more about microwave ovens, how they were invented, and how they work on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? throughline is a podcast that takes you back in time to uncover the parts of the story that may have gone unnoticed. It effectively turned day into night and how it shaped the world now. Time travel with us every week on the ThruLine podcast from NPR.

This episode is sponsored by Expedia's OutTravel the System podcast. I know you'll love to hear the story behind the story. So let me tell you why I think you might want to listen to the speedy a podcast, Out Travel the System. This season alone, the show talks to someone on a mission to visit every country in the world. In case you're wondering, the tally stands at 194 out of 197 countries. There's the man who's visited and stayed at literally thousands of hotels, who shares some of his favorite unique accommodations and experiences.

Or how about the woman who has reached some deep philosophical conclusions about travel and privilege in no small part because of the pandemic? Get all of this and more when you tune into the show, including larger insights about the future of travel, as well as tips and tricks to maximize your savings for your next trip, whenever you feel ready to head out into the world again. You can find out-travel the system on your podcast platform of choice. The development of the microwave goes back to the early days of radio. Experimenters learn that if used the proper frequency and enough power, the radio waves could make your hands warm. This phenomenon is due to something

called diletric heating. Before we get into too much of this discussion, I'm might as well explain how dielectric heating works, and hence how microwaves work. Certain molecules are known as polar molecules. One end of the molecule will have a slightly positive electrical charge, and the other end will have a slightly negative electrical charge. The best known polar molecule is water. If you think of a water molecule as looking like Mickey Mouse's head, the ears which have the hydrogen atoms, have a slightly positive charge, and the bottom of the face, which is the oxygen atom has a slightly negative charge. These polar molecules will want to align themselves when exposed to an electromagnetic field. If you oscillate the electromagnetic field, the polar molecules

will move to adjust themselves to the field. This movement is what creates heat. This effect, after it was first discovered, was used for a whole bunch of quack medicines known as diathermy. They used microwaves to heat people's bodies as if that would do something. Once dielectric heating was known, the next step towards using it to cook food was soon followed. At the 1933 World's Fair in Chicago, the Westinghouse company demonstrated cooking steaks and potatoes between two metal plates that were connected to a shortwave transmitter. In 1937, Bell Labs, which, if you remember from my previous episode, invented everything, received a patent for diletric heating. Beyond novelty uses of cooking a steak between two pieces of metal, not much was done with the concept of diletric heating until 1945.

That was when the previously mentioned Pertsey Spencer melted the candy bar in his pocket. While he didn't discover dielectric heating, he did something that no one else bothered to seriously do before. He wondered if this could be turned into a product. Spencer was an employee of the Raytheon Corporation and was working on a radar installation and standing in standing front of a magnetron. A magnetron is the thing inside of every microwave today and is at the heart of radar systems. It converts electricity to electromagnetic waves. He immediately sent an assistant out to get some popcorn, and he tried to make it pop by placing it in front of the magnetron. And it worked. Popcorn went flying all over the place.

Next, he tried to cook an egg. He put a raw egg in a teapot and placed a magnetron directly overhead. One of his associates looked into the teapot at the exact moment the egg exploded, and he got a face full of egg. The egg exploded because the inside was cooking, and it built up too much pressure. The next step in his tinkering was to focus the waves coming out of the magnetron, into a metal box. The metal box wouldn't allow any of the electromagnetic waves coming out of the magnetron to escape, greatly increasing the intensity of the waves inside the box.

This was effectively the first microwave oven. And by the way, for all his efforts for creating one of the most popular cooking appliances in the world, Percy Spencer received a whopping $2 from Raytheon. It only took two years from Percy Spencer's cooking popcorn in front of a radar to the release of the first commercial microwave oven. In 1947, Raytheon released the radar range. Compared to modern microwaves, it was huge. It was basically the size of a refrigerator and weighed 750 pounds.

It cost $5,000 in 1947, which would be over $58,000 today. It consumed three kilowatts of electricity and had to be water-cooled because it got so hot. The initial market for these huge microwave devices was restaurants and believe it or not airplanes. The idea behind using it on an airplane, is that it eliminated the heating unit, which on a regular oven would have been a safety concern, and it could also quickly reheat meals for passengers. However, the huge size of this appliance and the weight of the device probably overwhelmed any of the benefits. One of the earliest surviving commercial microwaves sits on the NS Savannah,

which was the world's first nuclear-powered merchant ship. Today, the ship is a museum in Baltimore Harbor, but you can still see the original Raytheon radar range in the galley. As with most technology, microwaves got smaller and cheaper. In 1955, Raytheon licensed its technology to the Tappin Corporation, which made kitchen appliances. Tappan introduced the Tappin RL1, which was the size of a regular oven, and it cost $1,295, or about $11,000 today. Other companies such as Sharp in Japan and Lytton also produced microwaves in the 1960s, but they were still big and expensive and not something you would find in a normal home. home. That all changed in 1967. Raytheon purchased the Amata Corporation, which was a manufacturer of

residential refrigerators, and it released the Amana Radar Range. It only cost $495, and it could fit on a countertop. It was the first microwave, which was small enough and cheap enough for the home. In addition to the countertop microwaves, in the late 60s and early 70s, there were many models which were integrated into a normal convection oven. You almost never see these sorts of. You almost never see these sorts of ovens anymore, but they actually make a lot of sense. It's the best of both worlds. You can get the speed of cooking with a microwave, yet you can still bake and broil things to get a crust that you can't do with a microwave. The 1970s saw an explosion in sales of microwave ovens. In 1971, only about 1% of U.S. households owned a microwave oven, and there were only

about 40,000 sold per year. By 1975, there were a million microwaves sold annually in the United States. Today, 90% of American homes have a microwave. Microwave sales have actually gone down in recent years. They hit their peak in 2004. While they're fast and convenient, there has been a movement back towards slower food cooking for yourself. You'll never be able to properly cook a steak or bake bread in a microwave. Since microwaves have become a common household item, there are several beliefs about microwaves that have floated around. Some are true and some are not. For starters, what's the deal with putting metal in a microwave. If you've ever put a piece of metal in a microwave, either on purpose or by accident, you've probably noticed that sparks will begin shooting out. What's

happening is that electrical fields at the corners of metallic objects become concentrated, which is why you see the sparks. Much of this has to do with the shape of the object. It is actually safer to put a spoon in a microwave than it is a fork for this reason. Technically, you can put some metals in a microwave, and some products actually do this. microwavable soup container will have a thin metal layer that is actually used to heat the soup. However, you can't leave it in longer than the recommended time or you're going to have problems. Nonetheless, not putting metal in a microwave is still a very good rule to follow. Are microwaves harmful?

The answer is simple. No. For starters, the radiation inside of a microwave is non-ionizing radiation. It won't break apart molecules. X-rays and gamma rays are ionizing radiation and those are dangerous. Microwaves fall between radio and infrared light on the electromagnetic spectrum. Also, a microwave oven is basically a Faraday cage. The microwaves inside bounce around and can't get out.

The next time you look through the window of a microwave, you'll notice there's actually a wire mesh you're looking through. Modern microwaves basically let out none of the electromagnetic radiation. You can tape a candy bar to the window and it will not melt. Why do microwaves heat food unevenly? This is due to the electromagnetic waves, inside of the microwave cancelling each other out. There are some great experiments online where people put a tray of shredded cheese in a microwave

and heat it. When they take it out, some parts are melted and some parts are not. The distance between the melted parts is the same as the wavelength of the microwaves. You can actually use your microwave oven to calculate the speed of light. And this is also why many microwaves have a rotating base. Do microwaves destroy the nutrients and food? No, they do not, and actually they preserve nutrients. better than most conventional cooking does.

This is because cooking times are shorter, and you aren't leaching away nutrients in water if you're doing something like boiling. And the only thing you really don't want to do with a microwave is to take it apart and start munking with electronics. The magnetron inside of a microwave requires very high voltages, and there are capacitors inside that can give you a very nasty shock, even if it's unplugged. So whether you're heating up a cup of coffee at the office,

a cup of ramen in your dorm room, or a TV dinner at home, take a moment to thank Perry Spencer, whose curiosity took us from a melted candy bar to a ubiquitous household appliance. The associate producer of Everything Everywhere Daily is Thor Thompson. If you'd like to support the show, please donate over at patreon.com.

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