What did people do before microwaves? Heat food over an open fire? Ok, probably not, but microwaves have revolutionized our eating habits. This is an interesting story about how microwaves were discovered along with how they got to the public.
Show Notes/TranscriptionWhat did people do before microwaves? How did they heat up their pizza rolls? They would probably rub two sticks together to start a fire and roast them on a stick one at a time.
Ok, probably not, but still, 90% of homes today have a microwave and they are sold in the millions yearly. Its discovery revolutionized the way we cook food and eat meals. It’s really an amazing gadget, full of science and engineering that we all take for granted.
Like almost all of the discoveries that I’ve talked about, this was another one that was found by accident. And also, once again, it was a result of research and development pressure from WWII, although maybe not as important as penicillin, which was an interesting podcast itself.
Microwave Radar Used In WWIIDuring WWII, there was a lot of research going on trying to figure out how to use microwave radiation from a magnetron to detect Nazi warplanes. Before we go any further, let’s clear up some definitions.
This is an awesome video of a tutorial on repairing magnetrons on planes in World War 2.
What is a Magnetron?First, what the heck is a magnetron? To me it sounds like a good name for a villainous transformer, but that’s not quite it. The lay person answer is that it is a vacuum tube that produces microwave radiation. It is the thing that takes the electrical energy from the wall and turns it into microwaves.
The actual definition is fairly complicated and involves cathodes, anodes, magnets, heat, electrons boiling off the cathode, resonant cavities cut in the anode and much more, so let’s stick with a vacuum tube that creates microwave radiation from electricity.
What Are Microwaves?Secondly, and probably more importantly, what are the microwaves themselves? A lot of different words are used to describe microwaves including nuking your food, radiation, and so forth, but is this true?
Not really. The word radiation gets a bad rap because of how it is used in the context of nuclear weapons, and rightly so. The radiation from nuclear weapons can cause a horrible, slow death. However, that form of radiation is much different than that in microwaves.
Radiation in this context simply means the emission of energy as a wave, whereas nuclear radiation specifically refers to energy particles or rays that are given off from a radioactive element. Huge difference.
Ok, now that we have that cleared up, let’s finally get to what a microwave is. There is this thing in physics called the electromagnetic spectrum. It is a continuous graph that contains all of the frequencies of waves that we know of.
The difference between the waves on this spectrum are the different energy levels given by frequency. The higher the frequency, the lower the energy and vice versa. Radio waves, infrared waves, all of the visible light and colors, the ultraviolet waves that cause sunburn, x-rays and many more are on this spectrum, along with microwaves.
Microwaves are just a wave on the spectrum that are surprisingly low in energy. They sit between radio waves and visible waves. They are invisible to us because we have no available sense to detect them the way our eyes detect visible waves, hence the name ‘visible’.
So, to wrap it up, the magnetron takes electrical energy and turns it into a directed beam of microwave radiation. Microwaves are just a low energy wave that sits between radio and visible on the electromagnetic spectrum. We’re still quite a way from cooking food, but don’t worry, we will get to it.
Percy Spencer And The Melted Candy BarAlright, back to the story. Scientists were trying to use magnetrons and microwave radiation to detect Nazi warplanes as a form of short distance radar. In 1946, a scientist named Percy Spencer at Raytheon was working on magnetrons and one day, he had a candy bar in his pocket. Dun dun dun.
I don’t know what kind of candy bar it was nor do I recommend eating them, especially in a lab, but this led to the development of one of the most widespread home devices ever. How, you may ask? As he was working on the magnetron, the candy bar melted in his pocket.
Instead of being angry that he ruined his pants, he did a bit of investigating and found that it was the microwaves that were the culprit. More experimenting led to him discovering that it would cook food much faster than a regular conventional oven.
He sent a boy to get a package of popcorn to try next and it popped all over the lab. The next morning, he brought in a kettle with a hole cut in the bottom and dropped an uncracked egg in it. He pointed the magnetron at it and gave it some power. The egg proceeded to explode.
Funny side story… One time I cooked some hard boiled eggs and brought them to work with me, only to realize that I hadn’t left them on the stove long enough. I thought it would be a good idea to microwave them, but to my surprise a couple seconds later, I heard an explosion come from the microwave. The inside was covered in egg and the break room stunk for quite a while.
Raytheon Scales Microwave DevelopmentAfter realizing the potential this could have, Spencer got the patent and Raytheon came out with the first commercial microwave in 1947. A lot of money was put into this project. They called it the RadaRange. Get it? Because they were using microwaves for radar? Anyways, they must’ve thought it was a clever name.
It was a huge machine at 6 feet tall and 750 lbs that was also very expensive. And by very expensive, I mean $64k in today’s money, or $5k back then. This model was meant to sit in the kitchen at a restaurant, not someone’s home.
It’s important to note that Dr. Spencer wasn’t the first person to find that some types of waves could heat food. It was already known that radio waves could heat food. Companies like Bell Labs, General Electric and RCA had been working on this for years beforehand, but nothing ever came of these. It was Dr. Spencer’s work with microwave radiation that pushed the industry forward.
First Uses Of The Commercial MicrowaveInitially, the few microwaves that were out there were being used to dry potato chips, roast coffee beans and peanuts, and defrost meat. They were also used outside of food to dry things such as cork, ceramics, paper, leather, tobacco and much more.
With the technology being so new, there was no reason to just stick to heating food. However, cooking food proved to be the most beneficial use. According to the manual given with the Radarange, it could cook an egg in just 12 seconds.
People were warming up (no pun intended) to the idea of microwaves despite initial fears of it being unsafe. They saw its practical uses and along with this, the device itself kept getting better. One example was the switch from water cooling to fan cooling of the magnetron. The machine didn’t need to be hooked to water and it was much lighter.
The first model for consumers came out in 1955, called that Tappan RL-1. It cost $1,295, or $11,000 today which still made it too expensive for most people. Then in 1967, Amana, which was a division of Raytheon, became the first company to make a household version of a microwave.
It cost $495 which was still expensive for the time, but revolutionary. Despite this, sales were slow at first. However, around the same time, other companies in the US and worldwide joined the race and competition for a better product started.
By 1971, prices started to drop and quality of the machines increased as well. This is the best case scenario for the consumer and it was from increased competition and advances in technology. Then in 1975, microwave sales actually passed conventional stove sales. In Japan, 17% of all households were cooking with microwaves compared to just 4% of American.
Practicality Outweighs Health ConcernsIn 1975, the New York Times Stated, “After testing 15 microwave ovens…Consumers Union warned in March, 1973, that none could be considered ‘completely safe,’ in part because there was no solid data on safe levels of radiation emission.”
It’s amazing how fast the panic about health issues smoothed over in the face of convenience. I’m not anti-microwave, but I didn’t really see anywhere that tested the safety of microwaved food before they went viral. All that was done were regulations put in place to ensure microwave radiation didn’t leak out.
Microwaves Keep Gaining PopularityThings kept pushing forward and by 1976, nearly 60% of American homes were using microwaves. The cooking routine of Americans was completely changing. Like most technology, microwaves started off as being too expensive, but as the development progressed and there was more competition, prices dropped and everyone could afford them.
Dr. Spencer would go on to have over 150 patents and become a legend at Raytheon. He extremely boosted their sales with the invention of the microwave. Not only did they profit from microwave sales, but they could also use up their stores of magnetrons leftover from WWII.
In addition to the initial invention, Spencer also found more efficient ways to make magnetrons. Because of this, Raytheon went from making 17 per day to 2600 per day. Raytheon is still up and running today and even has a building named after Spencer.
The invent of the microwave also coincided well with an increasingly fast world. Faster cooking meant less time on meals that could be spent elsewhere. I don’t necessarily know if that’s a good thing, but to each their own. There were also entire instant food industries that were formed around microwaves as well.
Microwaves In The Current DayLike I said in the beginning, 90% of American homes have a microwave, and honestly, I don’t know who the 10% without them are. A late 1990’s survey showed that Americans rated the microwave as the most important gadget in their life. Despite this large percentage, the sale of microwaves is currently dropping significantly in the United States.
One reason for this is that the health fear still lingers despite microwaves being deemed safe by the FDA. Also, and thankfully, Americans are becoming more aware of what they are putting into their bodies in an attempt to be healthy. The fact of the matter is that there are very few microwaveable foods that are healthy.
With the downfall of microwaves, many microwaveable foods are losing sales as well. In addition to this, the elephant in the room is that microwaves are no longer cool to have on your countertop. When they first came out, it was a new and novel tech gadget that you could show off. Now, that is not really the case.
So How Do Microwaves Cook The Food?Before we head out, I don’t want to leave you without saying how microwaves actually heat up the food! It’s sort of mystical, isn’t it? You put your food in, it spins on a plate, and only the food gets hot. There are special rules like no metal and no plastic that can melt.
Here’s the scoop. When the magnetrons emit microwaves, the food is heated through radiation. And no, not the nuclear bomb kind. The microwaves have the right frequency to ‘excite’ the molecules, specifically the water in the food. They are given energy, which causes friction which leads to heat.
That happens on the outside, but the microwaves lose momentum fast and don’t make it to the inside. They really only go an inch or two in. So, this is where convection takes over. Essentially, the stuff that was heated on the outside just transfers heat to the inside.
This video is a great quick summary of how microwaves work!
Some plastics are microwave safe and some aren’t, so what’s the difference? Well, some plastics are able to absorb microwave energy, and some aren’t. It’s that simple.
Also, metal doesn’t always cause sparks and ruin the microwave, but when it does, it’s from a buildup of charged particles. When the charge gets high enough, it causes a spark.
Now, You Know About Microwaves!Microwave ovens are an often-overlooked part of the kitchen that have had an impact on our meals, families, and even lives. When they were made, the world was modernizing. Astronauts were going into space, computers were rising, and the microwave perfectly fit into that vision of progress.
Now, we have that technology as a staple in our lives and it’s all because of one man’s candy bar.
Referenceshttp://www.smecc.org/microwave_oven.htm
https://www.explainthatstuff.com/how-magnetrons-work.html
https://www.explainthatstuff.com/microwaveovens.html
https://spectrum.ieee.org/tech-history/space-age/a-brief-history-of-the-microwave-oven
https://qz.com/187743/the-slow-death-of-the-microwave/?
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