Everything Everywhere Daily: History, Science, Geography & More - Superconductivity

Episode Date: November 13, 2021

In 1911, a Dutch physicist named Heike Kamerlingh Onnes was experimenting with ultra low-temperature metals. He was measuring the electrical resistance of mercury to find out what would happen What he found was shocking and totally upended everything we know about physics and electricity. Learn more about superconductivity, how it works, and its applications, on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

In 1911, a Dutch physicist named Heinka Kammeling Onus was experimenting with ultra-low temperature metals. He was measuring the electrical resistance of mercury to find out what would happen. What he found was shocking and totally upended everything we know about physics and electricity. Learn more about superconductivity, how it works, and its applications on this episode of Everything Everywhere Daily. Do you ever climb into bed ready to sleep only to have your mind start racing the moment your head hits the pillow? Thoughts bouncing around, replaying the day or jumping ahead to tomorrow. That is exactly why Catherine Nikolai created Nothing Much Happens. Each episode is a gentle, cozy bedtime story where, well, nothing much happens. No drama,

no tension, nothing you need to follow closely. Just soft narration, calming repetition, and soothing sensory details designed to help your mind slow down and your body relax. It's not about entertainment, it's about rest. And millions of listeners around the world use it every night to quiet their thoughts and finally fall asleep. If you've ever seen, you've ever seen, struggle to shut your brain off at night, this might be exactly what you've been missing. You can listen to Nothing Much Happens wherever you get your podcasts. Episodes are every Monday and Thursday. To understand what superconductivity is, we first have to understand what conductivity is,

and its reciprocal value, resistance. When an electrical current passes through something, usually a metal, the ease with which it passes through is called its connectivity. Each substance will have a different level of conductivity. Silver and copper have very high conductivity, which is why they're often used for electrical wiring or for electrical contacts. Likewise, substances with poor conductivity and high resistance have a use as well. Incandescent light bulbs work because they provide electrical resistance. The resistant causes the filament to get hot and glow. Likewise, the burner of an electrical stove or an electrical

space heater both produce heat from electrical resistance. So high conductivity is great for things like wires where you want to transmit electricity, and high resistivity is great for other applications like producing heat. However, even a great conductor like copper doesn't have perfect conductivity. When you have more of a substance like a very long wire, you'll have more resistance. This becomes a huge problem for things like long-distance electrical transmission. The longer the distance you want to transmit electricity, the more of that will be lost during the transmission. And here I'm going to skip back to the physicist I mentioned in the introduction. Hinky Camerling Onus. Prior to his experiments, there was debate amongst physicists

as to what would happen to metals at very low temperatures when a current was run through them. William Thompson, aka Lord Calvin, thought that all electrical current would stop at very low temperatures. Any conducting substance would become a perfect resistor at some point. However, other physicists like Onus thought the exact opposite would happen, that any metallic conductor would instead become a perfect conductor. On April 8th, 1911, at 4 p.m., Onus resolved the question once and for all. He was running an experiment on a wire made of solid mercury, which was in a bath of liquid helium. He was measuring the current on the wire as the temperature kept dropping. When the temperature hit exactly 4.19 Kelvin, something amazing happened. All electrical resistance in the wire

suddenly disappeared. Once it hit that temperature, the resistance to the the wire went to zero, and the mercury wire became a perfect electrical conductor. Onus had discovered superconductivity. He continued to investigate this strange phenomenon. A year later, he tried a circular loop that was cooled down to near absolute zero. He put an electrical charge on it and removed the battery. What he found was that over time, the current in the loop never decayed. The current just kept going around and around and around the loop. He initially called it supra-conductivity, and later changed it to

superconductivity. Onus was awarded the Nobel Prize for physics in 1913 for his discoveries. Over time, more and more substances were cooled down to extreme temperatures and tested for superconductivity. Most became superconductoring at temperatures lower than mercury, but a few, like lead and niobium, were slightly higher in temperature, but still had very low temperatures in the big scheme of things.

In 1961, it was found that a substance made of three parts niobium and one part 10 could create incredibly powerful electromagnets, up to 10 or 20 times the strength of the most powerful natural magnets. Superconductivity clearly had several amazing properties, but there was one massive problem. It only worked at extremely low temperatures around the boiling point of helium at 4 Kelvin, not far from absolute zero. It was difficult to come up with practical applications for something which required temperature so low. Despite all of the tests done in materials to check for superconductivity, it was believed going into

the 1980s that nothing could be superconducting at a temperature higher than 30 Kelvin, and the highest temperature superconductor known at that time was around 25 Kelvin. In 1986, however, all of this changed. A team at IBM managed to find a new type of copper oxide ceramic that achieves superconductivity at 35.1 Kelvin. Once the 30 Kelvin threshold was passed and researchers knew it could be done, the race was on for the Holy Grail of superconductivity. A room temperature superconductor.

A room temperature superconductor doesn't, as the name implies, necessarily have to be at room temperature, although if that did happen, it would be incredible. What it mostly means is finding a superconducting material that is superconducting above 77 Kelvin, or 196.2 Celsius or 321.1 Fahrenheit, which is the boiling point of liquid nitrogen. Liquid nitrogen is relatively easy and cheap to make and store. If a true room temperature semiconductor were to be developed, it would revolutionize the world. It would allow for

lossless transmission of electricity, reducing the amount of electricity that's needed to be generated. It would allow us to connect the electrical grids of entire continents. It could create amazing batteries that never lost their charge. Extremely powerful magnets could make magnetically levitating trains economically possible. It could radically improve the efficiency of electrical power generation using turbines, create incredibly powerful quantum computers, and make the containment of plasma in a fusion reactor more efficient, as well as a host of applications we haven't even thought of yet. Over the last 35 years, a race has been on to try to find a room-temperature semiconductor,

and a lot of progress has been made. There's a category of materials called coop rates which have achieved superconductivity at 138 Kelvin or minus 135 Celsius at normal atmospheric pressure. If you're willing to increase pressure, by a whole lot, there have actually been superconductors found at temperatures above the freezing point of water. In October of 2020, researchers announced that they had created a carbonaceous sulfur hydride compound that was a superconductor at 15 degrees Celsius or 59 degrees Fahrenheit. However, it was only superconducting at 270 gigapascals, which is the equivalent of the pressure inside the core of the Earth. Progress is slowly being made on the creation of a room temperature semiconductor. The upper temperatures of superconductivity keep increasing as new and innovative materials are tested. Nonetheless, even though they aren't as efficient as maybe

they one day might be, superconductors are in use today. The biggest practical application of superconductors today is in magnetic resonance imaging, or MRI machines. They require incredibly powerful magnets, and only superconducting magnets can really create that sort of magnetism. The large Hadron Collider in Europe uses superconducting magnets, as do many of the experimental fusion reactors reactors now being tested. There are a handful of experimental projects around the world using superconducting cables for electrical transmission, and so far the longest is only one kilometer. Until the temperature of superconductivity can be raised substantially, it'll be difficult to find use cases for it. The cost of cooling simply makes it too difficult to use for all but the biggest

budget projects. Hopefully one day soon we'll have a room temperature superconductor breakthrough, and the benefits to humanity might be as great as that from the internal combustion engine. The associate producers of Everything Everywhere Daily are Peter Bennett and Thor Thompson. If you'd like to support the show, please join the list of patrons over at patreon.com. And also remember, if you leave a review or send me a question, you two can have it read on the show.