What is absolute zero? Absolute zero: history of discovery and main application

The limiting temperature at which the volume of an ideal gas becomes equal to zero is taken as absolute zero temperature. However, the volume real gases At absolute zero the temperature cannot go to zero. Does this temperature limit make sense then?

The limiting temperature, the existence of which follows from the Gay-Lussac law, makes sense, since it is practically possible to bring the properties of a real gas closer to the properties of an ideal one. To do this, you need to take an increasingly rarefied gas, so that its density tends to zero. Indeed, as the temperature decreases, the volume of such a gas will tend to the limit, close to zero.

Let's find the value absolute zero on the Celsius scale. Equating volume VV formula (3.6.4) zero and taking into account that

Hence the absolute zero temperature is

* More accurate absolute zero value: -273.15 °C.

This is the extreme, lowest temperature in nature, that “greatest or last degree of cold”, the existence of which Lomonosov predicted.

Kelvin scale

Kelvin William (Thomson W.) (1824-1907) - an outstanding English physicist, one of the founders of thermodynamics and the molecular kinetic theory of gases.

Kelvin introduced the absolute temperature scale and gave one of the formulations of the second law of thermodynamics in the form of the impossibility of completely converting heat into work. He calculated the size of molecules based on measuring the surface energy of the liquid. In connection with the laying of the transatlantic telegraph cable, Kelvin developed the theory of electromagnetic oscillations and derived a formula for the period of free oscillations in a circuit. For his scientific achievements, W. Thomson received the title of Lord Kelvin.

The English scientist W. Kelvin introduced the absolute temperature scale. Zero temperature on the Kelvin scale corresponds to absolute zero, and the unit of temperature on this scale is equal to a degree on the Celsius scale, so absolute temperature T is related to temperature on the Celsius scale by the formula

(3.7.6)

Figure 3.11 shows the absolute scale and the Celsius scale for comparison.

The SI unit of absolute temperature is called the kelvin (abbreviated K). Therefore, one degree on the Celsius scale is equal to one degree on the Kelvin scale: 1 °C = 1 K.

Thus, absolute temperature, according to the definition given by formula (3.7.6), is a derived quantity that depends on the Celsius temperature and on the experimentally determined value of a. However, it is of fundamental importance.

From the point of view of molecular kinetic theory, absolute temperature is related to the average kinetic energy of the chaotic movement of atoms or molecules. At T = O K the thermal movement of molecules stops. This will be discussed in more detail in Chapter 4.

Dependence of volume on absolute temperature

Using the Kelvin scale, Gay-Lussac's law (3.6.4) can be written in a simpler form. Because

(3.7.7)

The volume of a gas of a given mass at constant pressure is directly proportional to the absolute temperature.

It follows that the ratio of volumes of gas of the same mass in different states at the same pressure is equal to the ratio of absolute temperatures:

(3.7.8)

There is a minimum possible temperature at which the volume (and pressure) of an ideal gas vanishes. This is absolute zero temperature:-273 °C. It is convenient to count the temperature from absolute zero. This is how the absolute temperature scale is constructed.

Absolute zero (absolute zero) - the beginning of the absolute temperature, starting from 273.16 K below the triple point of water (the equilibrium point of three phases - ice, water and water vapor); At absolute zero, the movement of molecules stops, and they are in a state of “zero” motion. Or: the lowest temperature at which a substance contains no thermal energy.

Absolute zero Start absolute temperature reading. Corresponds to –273.16 °C. At present, in physical laboratories it has been possible to obtain a temperature exceeding absolute zero by only a few millionths of a degree, but according to the laws of thermodynamics, it is impossible to achieve it. At absolute zero, the system would be in a state with the lowest possible energy (in this state, atoms and molecules would perform “zero” vibrations) and would have zero entropy (zero disorder). The volume of an ideal gas at the point of absolute zero must be equal to zero, and to determine this point, the volume of real helium gas is measured at sequential lowering the temperature until it liquefies at low pressure (-268.9 ° C) and extrapolates to the temperature at which the volume of gas in the absence of liquefaction would become zero. Absolute temperature thermodynamic scale is measured in kelvins, denoted by the symbol K. Absolute thermodynamic the scale and the Celsius scale are simply offset from one another and are related by the ratio K = °C + 273.16 °.

Story

The word “temperature” arose in those days when people believed that more heated bodies contained a larger amount of a special substance - caloric - than less heated ones. Therefore, temperature was perceived as the strength of a mixture of body matter and caloric. For this reason, the units of measurement for the strength of alcoholic beverages and temperature are called the same - degrees.

Since temperature is the kinetic energy of molecules, it is clear that it is most natural to measure it in energy units (i.e. in the SI system in joules). However, temperature measurement began long before the creation of the molecular kinetic theory, so practical scales measure temperature in conventional units - degrees.

Kelvin scale

Thermodynamics uses the Kelvin scale, in which temperature is measured from absolute zero (the state corresponding to the minimum theoretically possible internal energy body), and one kelvin is equal to 1/273.16 of the distance from absolute zero to the triple point of water (the state in which ice, water and water vapor are in equilibrium). Boltzmann's constant is used to convert kelvins into energy units. Derived units are also used: kilokelvin, megakelvin, millikelvin, etc.

Celsius

In everyday life, the Celsius scale is used, in which 0 is the freezing point of water, and 100° is the boiling point of water at atmospheric pressure. Since the freezing and boiling points of water are not well defined, the Celsius scale is currently defined using the Kelvin scale: a degree Celsius is equal to a kelvin, absolute zero is taken to be −273.15 °C. The Celsius scale is practically very convenient because water is very common on our planet and our life is based on it. Zero Celsius is a special point for meteorology because freezing atmospheric water changes everything significantly.

Fahrenheit

In England and especially in the USA, the Fahrenheit scale is used. In this scale, the interval from the temperature itself is divided into 100 degrees. cold winter in the city where Fahrenheit lived, to a temperature human body. Zero degrees Celsius is 32 degrees Fahrenheit, and a degree Fahrenheit is equal to 5/9 degrees Celsius.

The current definition of the Fahrenheit scale is as follows: it is a temperature scale in which 1 degree (1 °F) is equal to 1/180th the difference between the boiling point of water and the melting temperature of ice at atmospheric pressure, and the melting point of ice is +32 °F. Temperature on the Fahrenheit scale is related to temperature on the Celsius scale (t °C) by the ratio t °C = 5/9 (t °F – 32), 1 °F = 5/9 °C. Proposed by G. Fahrenheit in 1724.

Reaumur scale

Proposed in 1730 by R. A. Reaumur, who described the alcohol thermometer he invented.

The unit is the degree Reaumur (°R), 1 °R is equal to 1/80 of the temperature interval between the reference points - the melting temperature of ice (0 °R) and the boiling point of water (80 °R)

1 °R = 1.25 °C.

Currently, the scale has fallen out of use; it survived longest in France, the author’s homeland.

Comparison of temperature scales

Normal human body temperature is 36.6 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly quoted value of 98.6 °F is an exact conversion to Fahrenheit of the 19th century German value of 37 °C. Since this value is not within the normal temperature range according to modern ideas, we can say that it contains excessive (incorrect) precision. Some values ​​in this table have been rounded.

Comparison of Fahrenheit and Celsius scales

(oF– Fahrenheit scale, oC– Celsius scale)

To convert degrees Celsius to Kelvin, you must use the formula T=t+T 0 where T is the temperature in kelvins, t is the temperature in degrees Celsius, T 0 =273.15 kelvins. The size of a degree Celsius is equal to a kelvin.

What is absolute zero (usually zero)? Does this temperature really exist anywhere in the universe? Can we cool anything to absolute zero at real life? If you're wondering if it's possible to beat the cold wave, let's explore the furthest reaches of cold temperatures...

What is absolute zero (usually zero)? Does this temperature really exist anywhere in the universe? Can we cool anything to absolute zero in real life? If you're wondering if it's possible to beat the cold wave, let's explore the furthest reaches of cold temperatures...

Even if you're not a physicist, you're probably familiar with the concept of temperature. Temperature is a measure of the amount of internal random energy of a material. The word "internal" is very important. Throw a snowball, and although the main movement will be quite fast, the snowball will remain quite cold. On the other hand, if you look at air molecules flying around a room, an ordinary oxygen molecule is frying at thousands of kilometers per hour.

We tend to stay quiet when it comes to technical details, so just for the experts, let's note that temperature is a little more complicated than we said. True Definition temperature refers to how much energy you need to expend for each unit of entropy (disorder, if you want a clearer word). But let's skip the subtleties and just focus on the fact that random air or water molecules in the ice will move or vibrate slower and slower as the temperature drops.

Absolute zero is a temperature of -273.15 degrees Celsius, -459.67 Fahrenheit and simply 0 Kelvin. This is the point where thermal movement stops completely.

Does everything stop?

In the classical consideration of the issue, everything stops at absolute zero, but it is at this moment that the terrible face of quantum mechanics peeks out from around the corner. One of the predictions of quantum mechanics that has spoiled the blood of more than a few physicists is that you can never measure the exact position or momentum of a particle with perfect certainty. This is known as the Heisenberg uncertainty principle.

If you could cool a sealed room to absolute zero, strange things would happen (more on that later). The air pressure would drop to almost zero, and since air pressure usually opposes gravity, the air would collapse into a very thin layer on the floor.

But even so, if you can measure individual molecules, you'll find something interesting: they vibrate and spin, just a little bit of quantum uncertainty at work. To dot the i's: if you measure the rotation of molecules carbon dioxide At absolute zero, you will find that oxygen atoms are flying around carbon at several kilometers per hour - much faster than you thought.

The conversation reaches a dead end. When we talk about quantum world, the movement loses its meaning. At these scales, everything is defined by uncertainty, so it's not that the particles are stationary, it's just that you can never measure them as if they were stationary.

How low can you go?

The pursuit of absolute zero essentially faces the same problems as the pursuit of the speed of light. To reach the speed of light requires an infinite amount of energy, and reaching absolute zero requires the extraction of an infinite amount of heat. Both of these processes are impossible, if anything.

Despite the fact that we have not yet achieved the actual state of absolute zero, we are very close to it (although “very” in this case is a very loose concept; like a nursery rhyme: two, three, four, four and a half, four on a string, four by a hair's breadth, five). The coldest temperature ever recorded on Earth was recorded in Antarctica in 1983, at -89.15 degrees Celsius (184K).

Of course, if you want to cool off in a childish way, you need to dive into the depths of space. The entire universe is flooded with remnants of radiation from Big Bang, in the emptiest regions of space - 2.73 degrees Kelvin, which is slightly colder than the temperature of the liquid helium we were able to obtain on Earth a century ago.

But low-temperature physicists are using freeze rays to take the technology to the next level. new level. It may surprise you to know that freeze rays take the form of lasers. But how? Lasers are supposed to burn.

Everything is true, but lasers have one feature - one might even say, the ultimate: all light is emitted at one frequency. Ordinary neutral atoms do not interact with light at all unless the frequency is precisely tuned. If an atom flies towards a light source, the light receives a Doppler shift and reaches a higher frequency. The atom absorbs less photon energy than it could. So if you tune the laser lower, fast-moving atoms will absorb light, and by emitting a photon in a random direction, they will lose a little energy on average. If you repeat the process, you can cool the gas to a temperature of less than one nanoKelvin, a billionth of a degree.

Everything takes on a more extreme tone. The world record for lowest temperature is less than one-tenth of a billion degrees above absolute zero. Devices that achieve this trap atoms in magnetic fields. “Temperature” depends not so much on the atoms themselves, but on the spin of atomic nuclei.

Now, to restore justice, we need to get a little creative. When we usually imagine something frozen down to one billionth of a degree, you probably get a picture of even air molecules freezing in place. One can even imagine a destructive apocalyptic device that freezes the backs of atoms.

Ultimately, if you really want to experience low temperatures, all you have to do is wait. After about 17 billion years, the background radiation in the Universe will cool down to 1K. In 95 billion years the temperature will be approximately 0.01K. In 400 billion years, deep space will be as cold as the coldest experiment on Earth, and even colder after that.

If you're wondering why the universe is cooling so quickly, thank our old friends: entropy and dark energy. The universe is in acceleration mode, entering a period of exponential growth that will continue forever. Things will freeze very quickly.

What do we care?

All this, of course, is wonderful, and breaking records is also nice. But what's the point? Well, there's a ton good reasons understand the low temperatures, and not only as a winner.

The good folks at NIST, for example, would just like to do cool watch. Time standards are based on things like the frequency of the cesium atom. If the cesium atom moves too much, it creates uncertainty in the measurements, which will eventually cause the clock to malfunction.

But more importantly, especially from a scientific perspective, materials behave crazy at extremely low temperatures. For example, just as a laser is made of photons that are synchronized with each other - at the same frequency and phase - so a material known as a Bose-Einstein condensate can be created. In it, all atoms are in the same state. Or imagine an amalgam in which each atom loses its individuality and the entire mass reacts as one null-super-atom.

At very low temperatures, many materials become superfluids, meaning they can have no viscosity at all, stack in ultra-thin layers, and even defy gravity to achieve a minimum of energy. Also, at low temperatures, many materials become superconducting, meaning there is no electrical resistance.

Superconductors are able to respond to external magnetic fields in such a way as to completely cancel them inside the metal. As a result, you can combine cold temperature and a magnet and get something like levitation.

Why is there absolute zero, but not absolute maximum?

Let's look at the other extreme. If temperature is simply a measure of energy, then we can simply imagine atoms getting closer and closer to the speed of light. This can't go on forever, can it?

The short answer is: we don't know. It's possible that there literally is such a thing as infinite temperature, but if there is an absolute limit, the young universe provides some pretty interesting clues as to what it is. The most heat ever existed (at least in our universe), probably happened in the so-called “Planck time”.

It was a moment 10^-43 seconds after the Big Bang when gravity separated from quantum mechanics and physics became exactly what it is now. The temperature at that time was approximately 10^32 K. This is a septillion times hotter than the inside of our Sun.

Again, we're not at all sure if this is the hottest temperature it could be. Since we don't even have a large model of the universe at Planck's time, we're not even sure the universe boiled to such a state. In any case, we are many times closer to absolute zero than to absolute heat.

Federal State Budgetary Educational Institution of Higher Professional Education

"Voronezh State Pedagogical University"

Department of General Physics

on the topic: “Absolute zero temperature”

Completed by: 1st year student, FMF,

PI, Kondratenko Irina Aleksandrovna

Checked by: assistant of the general department

physicists Afonin G.V.

Voronezh-2013

Introduction……………………………………………………. 3

1.Absolute zero…………………………………………...4

2.History………………………………………………………6

3. Phenomena observed near absolute zero………..9

Conclusion…………………………………………………… 11

List of used literature…………………………..12

Introduction

For many years, researchers have been advancing towards absolute zero temperature. As is known, a temperature equal to absolute zero characterizes the ground state of a system of many particles - a state with the lowest possible energy, at which atoms and molecules perform so-called “zero” vibrations. Thus, deep cooling close to absolute zero (absolute zero itself is believed to be unattainable in practice) opens up unlimited possibilities for studying the properties of matter.

1. Absolute zero

Absolute zero temperature (less commonly - absolute zero temperature) - the minimum limit of temperature that can be physical body in the Universe. Absolute zero serves as the origin of an absolute temperature scale, such as the Kelvin scale. In 1954, the X General Conference on Weights and Measures established a thermodynamic temperature scale with one reference point - the triple point of water, the temperature of which was taken to be 273.16 K (exact), which corresponds to 0.01 °C, so that on the Celsius scale the temperature corresponds to absolute zero −273.15 °C.

Within the framework of the applicability of thermodynamics, absolute zero is unattainable in practice. Its existence and position on the temperature scale follows from extrapolation of observed physical phenomena, and such extrapolation shows that at absolute zero the energy of thermal motion of molecules and atoms of a substance should be equal to zero, that is, the chaotic movement of particles stops, and they form an ordered structure, occupying clear position at the nodes of the crystal lattice (liquid helium is an exception). However, from the point of view of quantum physics, and at absolute zero temperature, there are zero oscillations, which are caused by the quantum properties of particles and the physical vacuum surrounding them.

As the temperature of a system tends to absolute zero, its entropy, heat capacity, and coefficient of thermal expansion also tend to zero, and the chaotic movement of the particles that make up the system stops. In a word, the substance becomes a supersubstance with superconductivity and superfluidity.

Absolute zero temperature is unattainable in practice, and obtaining temperatures extremely close to it represents a complex experimental problem, but temperatures have already been obtained that are only millionths of a degree away from absolute zero. .

Let us find the value of absolute zero on the Celsius scale, equating the volume V to zero and taking into account that

Hence the absolute zero temperature is -273°C.

This is the extreme, lowest temperature in nature, that “greatest or last degree of cold”, the existence of which Lomonosov predicted.

Fig.1. Absolute and Celsius scale

The SI unit of absolute temperature is called the kelvin (abbreviated K). Therefore, one degree on the Celsius scale is equal to one degree on the Kelvin scale: 1 °C = 1 K.

Thus, absolute temperature is a derivative quantity that depends on the Celsius temperature and on the experimentally determined value of a. However, it is of fundamental importance.

From the point of view of molecular kinetic theory, absolute temperature is related to the average kinetic energy of the chaotic movement of atoms or molecules. At T = 0 K, the thermal movement of molecules stops.

2. History

The physical concept of “absolute zero temperature” is very important for modern science. important: closely related to it is the concept of superconductivity, the discovery of which created a real sensation in the second half of the twentieth century.

To understand what absolute zero is, you should turn to the works of such famous physicists as G. Fahrenheit, A. Celsius, J. Gay-Lussac and W. Thomson. They played a key role in the creation of the main temperature scales still in use today.

The first to propose his temperature scale was the German physicist G. Fahrenheit in 1714. At the same time, the temperature of the mixture, which included snow and ammonia, was taken as absolute zero, that is, as the lowest point of this scale. The next important indicator was the normal human body temperature, which became equal to 1000. Accordingly, each division of this scale was called “degree Fahrenheit”, and the scale itself was called “Fahrenheit scale”.

30 years later, the Swedish astronomer A. Celsius proposed his own temperature scale, where the main points were the melting temperature of ice and the boiling point of water. This scale was called the “Celsius scale”; it is still popular in most countries of the world, including Russia.

In 1802, while conducting his famous experiments, the French scientist J. Gay-Lussac discovered that the volume of a gas at constant pressure is directly dependent on temperature. But the most curious thing was that when the temperature changed by 10 Celsius, the volume of gas increased or decreased by the same amount. Having made the necessary calculations, Gay-Lussac found that this value was equal to 1/273 of the volume of the gas. This law led to the obvious conclusion: a temperature equal to -273°C is the lowest temperature, even if you come close to it, it is impossible to achieve it. It is this temperature that is called “absolute zero temperature.” Moreover, absolute zero became the starting point for the creation of the absolute temperature scale, Active participation which was attended by the English physicist W. Thomson, also known as Lord Kelvin. His main research concerned proving that no body in nature can be cooled below absolute zero. At the same time, he actively used the second law of thermodynamics, therefore, the absolute temperature scale he introduced in 1848 began to be called the thermodynamic or “Kelvin scale.” In subsequent years and decades, only a numerical clarification of the concept of “absolute zero” occurred.

Fig.2. The relationship between the Fahrenheit (F), Celsius (C) and Kelvin (K) temperature scales.

It is also worth noting that absolute zero plays a very important role in the SI system. The thing is that in 1960, at the next General Conference on Weights and Measures, the unit of thermodynamic temperature - the kelvin - became one of the six basic units of measurement. At the same time, it was specially stipulated that one degree Kelvin

is numerically equal to one degree Celsius, but the reference point “in Kelvin” is usually considered to be absolute zero.

The main physical meaning of absolute zero is that, according to the basic physical laws, at such a temperature the energy of motion elementary particles, such as atoms and molecules, is equal to zero, and in this case any chaotic movement of these same particles should stop. At a temperature equal to absolute zero, atoms and molecules must take a clear position at the main points of the crystal lattice, forming an ordered system.

Nowadays, using special equipment, scientists have been able to obtain temperatures only a few parts per million above absolute zero. It is physically impossible to achieve this value itself due to the second law of thermodynamics.

3. Phenomena observed near absolute zero

At temperatures close to absolute zero, purely quantum effects can be observed at the macroscopic level, such as:

1.Superconductivity is the property of some materials to have strictly zero electrical resistance when they reach a temperature below a certain value ( critical temperature). Several hundred compounds, pure elements, alloys and ceramics are known that transform into a superconducting state.

Superconductivity is a quantum phenomenon. It is also characterized by the Meissner effect, which consists in the complete displacement of the magnetic field from the volume of the superconductor. The existence of this effect shows that superconductivity cannot be described simply as ideal conductivity in the classical sense. Opening in 1986-1993. a number of high-temperature superconductors (HTSC) has pushed back the temperature limit of superconductivity far and has made it possible to practically use superconducting materials not only at the temperature of liquid helium (4.2 K), but also at the boiling point of liquid nitrogen (77 K), a much cheaper cryogenic liquid.

2. Superfluidity - the ability of a substance in a special state (quantum liquid), which occurs when the temperature drops to absolute zero (thermodynamic phase), to flow through narrow slits and capillaries without friction. Until recently, superfluidity was known only for liquid helium, but in last years superfluidity was also discovered in other systems: in rarefied atomic Bose condensates and solid helium.

Superfluidity is explained as follows. Since helium atoms are bosons, quantum mechanics allows an arbitrary number of particles to be in the same state. Near absolute zero temperatures, all helium atoms are in the ground energy state. Since the energy of states is discrete, an atom can receive not any energy, but only one that is equal to the energy gap between adjacent energy levels. But at low temperatures, the collision energy may be less than this value, as a result of which energy dissipation simply will not occur. The liquid will flow without friction.

3. Bose - Einstein condensate - a state of aggregation of matter, the basis of which is bosons, cooled to temperatures close to absolute zero (less than a millionth of a degree above absolute zero). In such a very cool state, it is enough big number atoms find themselves in their minimum possible quantum states and quantum effects begin to manifest themselves at the macroscopic level.

Conclusion

The study of the properties of matter near absolute zero is of great interest for science and technology.

Many properties of a substance, veiled at room temperatures by thermal phenomena (for example, thermal noise), begin to become more and more apparent as the temperature decreases, making it possible to study in their pure form the patterns and connections inherent in a given substance. Research in the field of low temperatures has made it possible to discover many new natural phenomena, such as the superfluidity of helium and the superconductivity of metals.

At low temperatures, the properties of materials change dramatically. Some metals increase their strength and become ductile, while others become brittle, like glass.

The study of physicochemical properties at low temperatures will make it possible in the future to create new substances with predetermined properties. All this is very valuable for the design and creation of spacecraft, stations and instruments.

It is known that during radar studies of cosmic bodies, the received radio signal is very small and difficult to distinguish from various noises. Recently created molecular oscillators and amplifiers by scientists operate at very low temperatures and therefore have a very low noise level.

The low-temperature electrical and magnetic properties of metals, semiconductors and dielectrics make it possible to develop fundamentally new microscopic radio devices.

Ultra-low temperatures are used to create the vacuum needed, for example, to operate giant nuclear particle accelerators.

Bibliography

1. http://wikipedia.org
2. http://rudocs.exdat.com
3. http://fb.ru

Short description

For many years, researchers have been advancing towards absolute zero temperature. As is known, a temperature equal to absolute zero characterizes the ground state of a system of many particles - a state with the lowest possible energy, at which atoms and molecules perform so-called “zero” vibrations. Thus, deep cooling close to absolute zero (absolute zero itself is believed to be unattainable in practice) opens up unlimited possibilities for studying the properties of matter.

Absolute temperature zero corresponds to 273.15 degrees Celsius below zero, 459.67 below zero Fahrenheit. For the Kelvin temperature scale, this temperature itself is the zero mark.

The essence of absolute zero temperature

The concept of absolute zero comes from the very essence of temperature. Any body that gives away external environment during . At the same time, body temperature decreases, i.e. less energy remains. Theoretically, this process can continue until the amount of energy reaches such a minimum that the body can no longer give it away.
A distant harbinger of such an idea can already be found in M.V. Lomonosov. The great Russian scientist explained heat by “rotary” movement. Consequently, the maximum degree of cooling is a complete stop of such movement.

According to modern concepts, absolute zero temperature is at which molecules have the lowest possible energy level. With less energy, i.e. at a lower temperature, no physical body can exist.

Theory and practice

Absolute zero temperature is a theoretical concept; it is impossible to achieve it in practice in principle, even in conditions scientific laboratories with the most sophisticated equipment. But scientists manage to cool the substance to very low temperatures, which are close to absolute zero.

At such temperatures substances acquire amazing properties, which they cannot have under normal circumstances. Mercury, which is called "living silver" because it is in a state close to liquid, becomes solid at this temperature - to the point that it can be used to drive nails. Some metals become brittle, like glass. Rubber becomes just as hard. If you hit a rubber object with a hammer at a temperature close to absolute zero, it will break like glass.

This change in properties is also associated with the nature of heat. The higher the temperature of the physical body, the more intense and chaotic the molecules move. As the temperature decreases, the movement becomes less intense and the structure becomes more orderly. So a gas becomes a liquid, and a liquid becomes a solid. The ultimate level of order is the crystal structure. At ultra-low temperatures, even substances that normally remain amorphous, such as rubber, acquire it.

Interesting phenomena also occur with metals. Atoms of the crystal lattice vibrate with less amplitude, electron scattering decreases, and therefore decreases electrical resistance. The metal acquires superconductivity, practical use which seems very tempting, although difficult to achieve.

Sources:

• Livanova A. Low temperatures, absolute zero and quantum mechanics

Body– this is one of the basic concepts in physics, which means the form of existence of matter or substance. This is a material object that is characterized by volume and mass, sometimes also by other parameters. The physical body is clearly separated from other bodies by a boundary. There are several special types of physical bodies; their listing should not be understood as a classification.

In mechanics, a physical body is most often understood as a material point. This is a kind of abstraction, the main property of which is the fact that the real dimensions of the body can be neglected for solving a specific problem. In other words, a material point is a very specific body that has dimensions, shape, and other similar characteristics, but they are not important in order to solve the existing problem. For example, if you need to count an object on a certain section of the path, you can completely ignore its length when solving the problem. Another type of physical body considered by mechanics is an absolutely rigid body. The mechanics of such a body are exactly the same as the mechanics material point, but additionally has other properties. An absolutely rigid body consists of points, but neither the distance between them nor the distribution of mass changes under the loads to which the body is subjected. This means that it cannot be deformed. To determine the position of an absolutely rigid body, it is enough to specify a coordinate system attached to it, usually Cartesian. In most cases, the center of mass is also the center of the coordinate system. There is no absolutely rigid body, but for solving many problems such an abstraction is very convenient, although it is not considered in relativistic mechanics, since with movements whose speed is comparable to the speed of light, this model demonstrates internal contradictions. Absolutely the opposite solid body is a deformable body that can be displaced relative to each other. There are special types of physical bodies in other branches of physics. For example, in thermodynamics the concept of an absolutely black body was introduced. This is an ideal model, a physical body that absorbs absolutely all electromagnetic radiation that hits it. At the same time, it itself may well produce electromagnetic radiation and have any color. An example of an object that is closest in properties to an absolutely black body is the Sun. If we take substances that are common beyond the Earth, we can recall soot, which absorbs 99% of the radiation that falls on it, except for infrared, which it copes with absorption much worse.

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