What is absolute zero?




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What is absolute zero (most – zero)? Is this temperature there is anywhere in the universe? Can we cool anything to absolute zero in real life? These and other interesting questions we will try to answer in this article.

There are many reasons for deciding to take an interest in the cold outside. Perhaps you incredible supervillain who uses the power of freezing, and want to understand the extent of your power. Or you’re wondering whether you can outrun a wave of cold. Let’s explore the farthest limits of the cold temperature.

“Is the traffic stops, reaching absolute zero? Can we reach that level? ”

Let’s start with the obvious.
What is absolute zero?

Even if you are not a physicist, you are probably familiar with the concept of temperature. But if all of a sudden you’re unlucky, you grew up in the woods or on another planet, here’s a brief overview.

Temperature – this is a measure of the amount of random internal energy of the material. The word “domestic” is very important. Throw a snowball, and, although the movement is fast enough, the snowball will be quite cold. On the other hand, if you look at the molecules in the air, flying across the room, the usual oxygen molecule fries at thousands of miles per hour.

We usually fall silent when it comes to the technical details, so especially for the experts note that the temperatures are a bit more difficult than we were told. The true definition of temperature implies how much energy you need to spend on each unit of entropy (disorder, if you want a more meaningful word, about the entropy ). But let’s drop the niceties and just dwell on the fact that the random molecules of air or water in the ice will move or vibrate slower and slower as the temperature.

Absolute zero – the temperature is -273.15 degrees Celsius, -459.67 Fahrenheit and just 0 Kelvin. This is the point where the thermal motion stops completely.
All the stops?

In a classic considering at absolute zero all the stops, but at this moment because of the angle looks scary face of quantum mechanics. One of the predictions of quantum mechanics, which spoiled the blood of a considerable number of physicists , is that you can never measure the exact position and momentum of a particle with perfect certainty. This is known as the Heisenberg uncertainty principle.

If you could cool the sealed room to absolute zero, stranger things have happened (more on this later). The air pressure dropped to almost zero, and as the air pressure is generally opposed by gravity, air collapses into a very thin layer on the floor.

But even in this case, if you can measure individual molecules, you’ll find something curious: they vibrate and rotate quite a bit – in the quantum uncertainty. To dot the i: if you measure the rotation of the molecules of carbon dioxide at absolute zero, you will find that overfly the carbon atoms of oxygen at a rate of several kilometers per hour – much faster than you expected.

The conversation comes to a standstill. When we talk about the quantum world, the movement loses its meaning. In such a scale is determined by all the uncertainty, so it is not that the particles are fixed, you simply will never be able to measure them as if they were still.
How low can fall?


The quest for absolute zero essentially found the same problems as the aspiration to the speed of light . To dial the speed of light, it will take an infinite amount of energy, and achieving absolute zero requires an infinite amount of heat extraction. Both of these processes are not possible, if that.

Despite the fact that we have not yet achieved the actual state of absolute zero, we are very close to it (although the “extreme” in this case is a loose concept, as a child’s Counting: two, three, four, four and a half, four by a thread, four the balance, five). The lowest temperature ever recorded on Earth was recorded in Antarctica in 1983, at around -89.15 degrees Celsius (184K).

Of course, if you want to cool off is not a child, you need to dive into the depths of space. The entire universe is filled with remnants of the radiation from the Big Bang, in most regions of empty space – 2.73 degrees Kelvin, which is a little colder than the temperature of liquid helium, which we were able to get the world a century ago.

But physicists nizkotemperaturschiki freeze rays used to bring the technology to a whole new level. It may surprise you that the freezing takes the form of laser beams. But how? Lasers have to burn.

All true, but there is one feature of lasers – one might even say ultimatum: all the light emitted at the same frequency. Conventional neutral atoms do not interact with light, if the frequency is not set up in a precise manner. If the atom is flying to the light source, the light is Doppler shift and goes to a higher frequency. Atom absorbs less energy photon than it could be. So if you configure a laser lower, fast-moving atoms will absorb light and emitting a photon in a random direction, will lose a bit of energy on average. If we repeat the process, you can cool the gas to a temperature of less than one nanokelvin, a billionth of a degree.

Everything becomes more extreme color. The world record of the lowest temperature of less than a tenth of a billion degrees above absolute zero. Devices that achieve this, grab the atoms in a magnetic field. “Temperature” depends not so much on the atoms themselves, but on the back of atomic nuclei.

Now, for the restoration of justice, we need to dream a little. When we usually imagine something frozen up to one-billionth of a degree, you will probably draw a picture of how even the air molecules are frozen in place. You can imagine the devastating doomsday device that freezes the atomic spins.

In the end, if you really want to experience the low temperature, all you have to do is wait. After about 17 billion years of background radiation in the universe cooled down to 1K. After 95 billion years, the temperature will be about 0.01 K. After 400 billion years deep space will be as cold as the coldest experiment on Earth, and after that – even colder. If you’re wondering why the universe cools so fast, say thank you to our old friend: the entropy and dark energy. The universe is in acceleration, entering into a period of exponential growth that will last forever. Things will freeze very quickly.
Why should we care?


All this is well and good, and beat records is also nice. But what’s the point? Well, there are lots of good reasons to understand the temperature in the lowlands, and not only on the rights of the winner.

The good guys from the National Institute of Standards and Technology, for example, would just like to make a class hours. Time standards are based on such things as the frequency of the cesium atom. If cesium atom moves too much, there is uncertainty in the measurements, which ultimately lead to failure hours.

But more important, especially from the point of view of science, materials behave madly at extremely low temperatures. For example, the laser consists of photons that are synchronized with each other – at the same frequency and phase – and a material known as Bose-Einstein condensation, can be created. It all atoms are in the same state. Or imagine an amalgam in which each atom loses its identity, and the whole mass reacts as a zero-super-atom.

At very low temperatures, many materials become superfluid, which means that they can totally have a viscosity stacked ultrathin layers and even defy gravity to achieve the minimum energy. Also at low temperatures, many materials are superconducting, means that the absence of any electrical resistance. Superconductors are able to respond to external magnetic fields in such a way as to cancel them inside the metal. As a result, you can combine the cold temperature and the magnet and get some kind of levitation.
Why is absolute zero, but there is no absolute maximum?

Let’s take a look at the other extreme. If the temperature – it is simply a measure of energy, it is possible to simply introduce the atoms which are selected closer to the velocity of light. Yet it can not go on indefinitely?

There is a short answer: we do not know. It is possible that there is literally such thing as infinite temperature, but if there is an absolute limit, young universe provides enough interesting clue as to what it is. The highest temperature ever existed (at least in our universe) is likely to happen in the so-called “Planck time”. It was a long moment in the 10 ^ -43 seconds after the Big Bang, when gravity separated from quantum mechanics and physics became just be what is today. The temperature at the time was about 10 ^ 32 K. This septillion times hotter than the inside of our sun.

Again, we’re not sure if this is the hottest temperature of all that could be. Since we do not even have a large model of the universe at the time of the Planck time, we’re not even sure that the universe is boiled to such a state. In any case, the absolute zero we many times closer than the absolute heat.
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Tags: absolute zero , quantum mechanics , temperature , Physics .


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