Everything Everywhere Daily: History, Science, Geography & More - Absolute Zero

Episode Date: June 25, 2021

One of the interesting things about temperature is that no matter how cold you’ve ever been, or how low of a temperature anyone has ever achieved, you can always get colder, if only by a little bit. That is because temperature has an absolute barrier that can never be broken. Learn more about absolute zero and the attempts to get ever close to the impossible temperature on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

One of the interesting things about temperature is that no matter how cold you've ever been or how low a temperature anyone has ever achieved, you can always get colder, if only by a little bit. That's because temperature has an absolute barrier that can never be broken. Learn more about absolute zero and the attempts to get ever closer to the impossible temperature on this episode of Everything Everywhere Daily. What if your perceptions about the past were wrong? ThruLine 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 and tonight.

And how it shaped the world now. Time travel with us every week on the Thulein podcast from NPR. This episode is sponsored by the Athletic Brewing Company. Athletic Brewing brews delicious craft beers that just happen to be non-alcoholic. Athletic Brewing founders Bill and John are craft beer lovers who wanted to cut back on alcohol without compromising on flavor. But the interesting flavors that they loved in other craft beers just weren't available in non-alcoholic beer.

So they brewed the beer that they wanted to drink. It turns out there are a lot of others looking to moderate or abstain, but are still thirsty for great beer. Order their amazing beers at athletic brewing.com. You can get free shipping on every order of two six-packs or more, and you can save 15% by using the code Everything 15 at checkout. Once again, that's athleticbrewing.com coupon code everything 15. The discussion of Absolute Zero can be a bit involved.

However, the definition of it is rather straightforward. Absolute Zero is defined as negative 273.5 degrees Celsius, or negative 459.67 degrees Fahrenheit. Or, to be more accurate, zero Kelvin. In fact, the entire Kelvin scale is based around Absolute Zero, and Zero. Zero Kelvin is the very definition of absolute zero. And just as a refresher, Kelvin units are the same size as Celsius units, the only difference being where they put zero. To understand why zero Kelvin is an absolute which can never be crossed,

we first have to understand exactly what temperature is. And to do that, we need to understand the kinetic theory of matter. The kinetic theory of matter states that all matter is made up of small particles, atoms and molecules, which are constantly in motion. The particles will all move randomly, bouncing off against other particles nearby. Some particles move much faster than other particles. The faster a particle is moving, the higher the temperature it's considered to have. The slower it moves, the lower the temperature it has.

The average of all the particles in a given system is considered the temperature of that system. Particles will move differently depending upon the state of matter that they're in. A particle in a gas will move much more than one that's in a liquid, which is more than one in a solid. At what temperature the particles break away to boil or melt will depend on the substance. As you get colder and colder, the movement of everything starts to slow down. However, the closer you get to Absolute Zero, the more work you have to put into the system to make it even colder. Eventually, the amount becomes so great that it would require an infinite amount of work to make the atoms completely stop moving. To this extent, Absolute Zero is to temperature what the speed of light is to velocity.

You can approach it, but the closer you get, the more energy is required, and ultimately getting there is impossible. The idea of absolute zero actually goes back to before modern science. English chemist Robert Boyle proposed that there was a premium frigidum back in 1665. French physicist Guillaume Admontons proposed an absolute coldness in 1702. However, none of them had a basic understanding of atoms like we do today. In the 19th century, there was a race amongst researchers to reach ever lower. temperatures. The way they were able to get low temperatures in a time before electricity was widely available is the same way that air conditioners and refrigerators work today. Evaporation. When a liquid

evaporates, it requires energy to convert it from a liquid to a gas. The energy that it takes will cool down the substance that it takes the energy from. That's why you can cool down when it's hot out by getting yourself wet, and it's why we sweat. You can also lower temperatures by decompressing a compressed gas. If you've ever blown compressed air out of a can to clean a keyboard or something, you'll notice immediately how cold it gets and that frost can quickly form on the can. In the laboratory, they had to cascade temperatures evaporating one substance down to cool another substance. They would have to do this again and again with different substances with different boiling points. Much of this was literally experimentation, trying different substances at different pressures.

By 1845, Michael Faraday managed to liquefy most gases, except for six. Oxygen, hydrogen, hydrogen, carbon monoxide, methane, and nitric oxide. These six gases became known as permanent gases, and Faraday speculated that they might be impossible to liquefy. However, this wasn't the case. Scientists went to work to try to liquefy the remaining gases. In 1877, the first drops of liquid air were created. Liquid oxygen and nitrogen were first created in 1883 by Polish researchers. This got temperatures down to 90 Kelvin and 77 Kelvin, respectively.

In 1898, James Dewar managed to liquefy hydrogen, which brought temperatures down to 20.28 Kelvin. At the beginning of the 20th century, there was only one gas that hadn't been liquefied. The gas with the lowest boiling point of any element, helium. This finally happened in 1908 when Dutch physicist, Hinky Camerlane Onus managed to liquefy helium at 4.2222 Calvin. Onus went on to discover superconductivity and was awarded the 1913 Nobel Prize for his low-temperature work. 4.2212 Calvin seems like it's getting pretty close to absolute zero. However, there is a lot that goes on between 4.2 and 0, and the physics down there start to get really weird.

In 1937, they got liquid helium 4, and that's helium with two protons and two neutrons, down to 2.2 Kelvin. At that point, it becomes what's known as a superfluid. There is zero viscosity and friction at that temperature. That means if you stir something which demonstrates superfluidity, it will never stop rotating. In 1949, they got helium 3 down to 1 Kelvin. Even at one single Kelvin of temperature, there was still a lot to learn. The next big breakthrough in low temperatures occurred in 1978, with the discovery of laser cooling. This uses the light-absorving and light-emitting properties of atoms to capture and slow a very small number of atoms at a single time.

One of the weird things which happens below 1K is that there is a whole other state of matter known as a Bose-Einstein condensate. This was theorized by Satyanda, Nath-Bos, and Albert Einstein. It was first created in 1995 when rubidium atoms were cooled down to 170, now. That's 170 billionth of a Calvin above absolute zero. The current world record for the coldest temperature ever cratered in a laboratory is 100 pico-calvins, which was done in the International Space Station. It's theoretically possible in space to possibly get as low as one pico-calvin, or one trillionth of a degree above absolute zero.

Now you might be wondering, if there's an absolute limit for cold, is there an absolute limit for hot. And the answer is, yes, at least in theory. However, unlike absolute zero, there's no way to even approach absolute hot. There's a theoretical temperature known as the Plunk temperature, named after a quantum physicist Max Planck. That temperature would be 14,000 quintillion Kelvin. The only point where such a temperature would even be theoretically possible would have been in the tiniest fraction of a second after the Big Bang. However, ordinary matter can't even get to the plonk temperature, only some atomic particles can. There's another temperature called the Hegdorn temperature, and that is basically the temperature

where hedronic matter, aka the stuff we and our world is made of, just fall apart. And that is about 1.7 trillion Kelvin. This temperature has actually been achieved at the Large Hadron Collider in Europe with subatomic particles. In 2012, they announced they very briefly got subatomic particles to reach 5.5.5. trillion Kelvin. To put this in perspective, the surface of the sun is only 5,700 Kelvin, and the interior of the sun is believed to be around 15 million Kelvin. A record was recently set in a Chinese fusion reactor experiment where they reached a temperature of 120 million Kelvin for over

100 seconds, which is still nowhere close to either the Planck or Hagdorn temperatures. The quest to reach Absolute Zero is one that will never achieve. However, it's a quest that has rewards for just coming close. We've made huge advances in physics in our understanding of the universe by coming absurdly close to absolute zero, but never quite touching it. The associate producer of Everything Everywhere daily is Thor Thompson.

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