What is absolute zero temperature in degrees? Absolute zero

> Absolute zero

Learn what it's equal to absolute zero temperature and the value of entropy. Find out what the temperature of absolute zero is on the Celsius and Kelvin scales.

Absolute zero– minimum temperature. This is the point at which entropy reaches its lowest value.

Learning Objective

Understand why absolute zero is a natural indicator of the zero point.

Main points

Absolute zero is universal, that is, all matter is in the ground state at this indicator.
K has quantum mechanical zero energy. But in interpretation, kinetic energy can be zero, and thermal energy disappears.
The lowest temperature in laboratory conditions reached 10-12 K. The minimum natural temperature was 1 K (expansion of gases in the Boomerang Nebula).

Terms

Entropy is a measure of how uniform energy is distributed in a system.
Thermodynamics is a branch of science that studies heat and its relationship with energy and work.

Absolute zero is the minimum temperature at which entropy reaches its lowest value. That is, this is the smallest indicator that can be observed in the system. This is a universal concept and acts as the zero point in the system of temperature units.

Graph of pressure versus temperature for different gases with constant volume. Note that all graphs extrapolate to zero pressure at one temperature

A system at absolute zero is still endowed with quantum mechanical zero-point energy. According to the uncertainty principle, the position of particles cannot be determined with absolute accuracy. If a particle is displaced at absolute zero, it still has a minimum energy reserve. But in classical thermodynamics, kinetic energy can be zero, and thermal energy disappears.

The zero point of a thermodynamic scale, such as Kelvin, is equal to absolute zero. International agreement has established that the temperature of absolute zero reaches 0K on the Kelvin scale and -273.15°C on the Celsius scale. The substance exhibits quantum effects at minimum temperatures, such as superconductivity and superfluidity. The lowest temperature in laboratory conditions was 10-12 K, and in the natural environment - 1 K (rapid expansion of gases in the Boomerang Nebula).

Rapid expansion of gases leads to minimum observed temperature

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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 releases into the 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, even in 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 that they cannot have under ordinary 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. The atoms of the crystal lattice vibrate with less amplitude, electron scattering decreases, and therefore electrical resistance decreases. The metal acquires superconductivity, the practical application of 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 of a material point, but additionally it 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. The opposite of an absolutely rigid body is a deformable body,

Absolute zero corresponds to a temperature of −273.15 °C.

It is believed that 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 in the nodes of the crystal lattice. However, in fact, even at absolute zero temperature, the regular movements of the particles that make up matter will remain. The remaining oscillations, such as zero-point oscillations, are due to the quantum properties of the particles and the physical vacuum that surrounds them.

At present, in physical laboratories it has been possible to obtain temperatures exceeding absolute zero by only a few millionths of a degree; to achieve it itself, according to the laws of thermodynamics, is impossible.

Notes

Literature

G. Burmin. Assault on absolute zero. - M.: “Children’s Literature”, 1983.

Temperature, which expresses the absence of heat, is equal to 218° C. Dictionary of foreign words included in the Russian language. Pavlenkov F., 1907. absolute zero temperature (physical) - the lowest possible temperature (273.15°C). Big dictionary... ... Dictionary of foreign words of the Russian language

absolute zero- The extremely low temperature at which the thermal movement of molecules stops; on the Kelvin scale, absolute zero (0°K) corresponds to –273.16±0.01°C... Dictionary of Geography

Noun, number of synonyms: 15 round zero (8) small man (32) small fry ... Synonym dictionary

The extremely low temperature at which the thermal movement of molecules stops. The pressure and volume of an ideal gas, according to Boyle-Mariotte’s law, becomes equal to zero, and the beginning of the absolute temperature on the Kelvin scale is taken to be... ... Ecological dictionary

absolute zero- - [A.S. Goldberg. English-Russian energy dictionary. 2006] Energy topics in general EN zeropoint ... Technical Translator's Guide

The beginning of the absolute temperature reference. Corresponds to 273.16° C. Currently, in physical laboratories it has been possible to obtain a temperature exceeding absolute zero by only a few millionths of a degree, and to achieve it, according to the laws... ... Collier's Encyclopedia

absolute zero- absoliutusis nulis statusas T sritis Standartizacija ir metrologija apibrėžtis Termodinaminės temperatūros atskaitos pradžia, esanti 273.16 K žemiau vandens trigubojo taško. Tai 273.16 °C, 459.69 °F arba 0 K temperatūra. atitikmenys: engl.… … Penkiakalbis aiškinamasis metrologijos terminų žodynas

absolute zero- absoliutusis nulis statusas T sritis chemija apibrėžtis Kelvino skalės nulis (−273.16 °C). atitikmenys: engl. absolute zero rus. absolute zero... Chemijos terminų aiškinamasis žodynas

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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) is the minimum limit of temperature that a physical body in the Universe can have. 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: closely related to it is such a concept as 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, in which the English physicist W. Thomson, also known as Lord Kelvin, took an active part. 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 of elementary particles, such as atoms and molecules, is zero, and in this case any chaotic movement of these same particles should cease. 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 recent years superfluidity has been discovered in other systems: in rarefied atomic Bose condensates, 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 strongly cooled state, a sufficiently large number of 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

http://wikipedia.org
http://rudocs.exdat.com
http://fb.ru

Short description

Have you ever thought about how low the temperature can be? What is absolute zero? Will humanity ever be able to achieve it and what opportunities will open up after such a discovery? These and other similar questions have long occupied the minds of many physicists and simply curious people.

What is absolute zero

Even if you didn’t like physics since childhood, you are probably familiar with the concept of temperature. Thanks to the molecular kinetic theory, we now know that there is a certain static connection between it and the movements of molecules and atoms: the higher the temperature of any physical body, the faster its atoms move, and vice versa. The question arises: “Is there such a lower limit at which elementary particles will freeze in place?” Scientists believe that this is theoretically possible; the thermometer will be at -273.15 degrees Celsius. This value is called absolute zero. In other words, this is the minimum possible limit to which a physical body can be cooled. There is even an absolute temperature scale (Kelvin scale), in which absolute zero is the reference point, and the unit division of the scale is equal to one degree. Scientists around the world do not stop working to achieve this value, as this promises enormous prospects for humanity.

Why is this so important

Extremely low and extremely high temperatures are closely related to the concepts of superfluidity and superconductivity. The disappearance of electrical resistance in superconductors will make it possible to achieve unimaginable efficiency values and eliminate any energy losses. If we could find a way that would allow us to freely reach the value of “absolute zero,” many of humanity’s problems would be solved. Trains hovering above the rails, lighter and smaller engines, transformers and generators, high-precision magnetoencephalography, high-precision watches - these are just a few examples of what superconductivity can bring to our lives.

Latest Scientific Advances

In September 2003, researchers from MIT and NASA were able to cool sodium gas to a record low. During the experiment, they were only half a billionth of a degree short of the finish line (absolute zero). During the tests, the sodium was constantly in a magnetic field, which kept it from touching the walls of the container. If it were possible to overcome the temperature barrier, molecular motion in the gas would completely stop, because such cooling would extract all the energy from the sodium. The researchers used a technique whose author (Wolfgang Ketterle) received the Nobel Prize in Physics in 2001. The key point in the tests was the gas processes of Bose-Einstein condensation. Meanwhile, no one has yet canceled the third law of thermodynamics, according to which absolute zero is not only an insurmountable, but also an unattainable value. In addition, the Heisenberg uncertainty principle applies, and atoms simply cannot stop dead in their tracks. Thus, for now, absolute zero temperature remains unattainable for science, although scientists have been able to approach it to a negligible distance.