What temperature is called absolute zero. What is absolute zero and can it be reached

Any physical body, including all objects in the universe, has a minimum temperature index or its limit. For the reference point of any temperature scale, it is customary to consider the value of absolute zero temperatures. But this is only in theory. The chaotic movement of atoms and molecules, which give off their energy at this time, has not yet been stopped in practice.

This is the main reason why absolute zero temperatures cannot be reached. There are still disputes about the consequences of this process. From the point of view of thermodynamics, this limit is unattainable, since the thermal motion of atoms and molecules stops completely, and a crystal lattice is formed.

Representatives of quantum physics provide for the presence of minimal zero-point oscillations at absolute zero temperatures.

What is the value of absolute zero temperature and why it cannot be reached

At the General Conference on Weights and Measures, for the first time, a reference or reference point was established for measuring instruments that determine temperature indicators.

Currently, in the International System of Units, the reference point for the Celsius scale is 0 ° C when freezing and 100 ° C during the boiling process, the value of absolute zero temperatures is equal to −273.15 ° C.

Using temperature values on the Kelvin scale for the same International system units, boiling water will occur at a reference value of 99.975 ° C, absolute zero is equal to 0. Fahrenheit on the scale corresponds to -459.67 degrees.

But, if these data are obtained, why then it is impossible to achieve absolute zero temperatures in practice. For comparison, we can take the speed of light known to everyone, which is equal to a constant physical value of 1,079,252,848.8 km/h.

However, this value cannot be achieved in practice. It depends on the transmission wavelength, and on the conditions, and on the required absorption a large number particle energy. To obtain the value of absolute zero temperatures, a large return of energy is necessary and the absence of its sources to prevent it from entering atoms and molecules.

But even in conditions of complete vacuum, neither the speed of light nor absolute zero temperatures were obtained by scientists.

Why is it possible to reach approximate zero temperatures, but not absolute

What will happen when science can come close to achieving the extremely low temperature of absolute zero, so far remains only in the theory of thermodynamics and quantum physics. What is the reason why it is impossible to reach absolute zero temperatures in practice.

All known attempts to cool the substance to the lowest limit limit due to the maximum energy loss led to the fact that the value of the heat capacity of the substance also reached a minimum value. Molecules were simply not able to give the rest of the energy. As a result, the cooling process stopped before reaching absolute zero.

When studying the behavior of metals in conditions close to the value of absolute zero temperatures, scientists have found that the maximum decrease in temperature should provoke a loss of resistance.

But the cessation of the movement of atoms and molecules only led to the formation of a crystal lattice, through which the passing electrons transferred part of their energy to the immobile atoms. It failed to reach absolute zero again.

In 2003, only half a billionth of 1°C was missing from absolute zero. NASA researchers used the Na molecule to conduct experiments, which was always in a magnetic field and gave off its energy.

The closest was the achievement of scientists Yale University, which in 2014 achieved an indicator of 0.0025 Kelvin. The resulting compound strontium monofluoride (SrF) existed for only 2.5 seconds. And in the end, it still fell apart into atoms.

The term "temperature" appeared at a time when physicists thought that warm bodies were composed of more specific substance - caloric - than the same bodies, but cold. And the temperature was interpreted as a value corresponding to the amount of caloric in the body. Since then, the temperature of any body is measured in degrees. But in reality it is a measure of the kinetic energy of moving molecules, and, based on this, it should be measured in Joules, in accordance with the SI system of units.

The concept of "absolute zero temperature" comes from the second law of thermodynamics. According to it, the process of transferring heat from a cold body to a hot one is impossible. This concept was introduced by the English physicist W. Thomson. For achievements in physics, he was granted the noble title of "Lord" and the title of "Baron Kelvin". In 1848, W. Thomson (Kelvin) suggested using a temperature scale, in which he took the absolute zero temperature corresponding to the extreme cold as the starting point, and took degrees Celsius as the division price. The unit of Kelvin is 1/27316 of the temperature of the triple point of water (about 0 degrees C), i.e. temperature at which pure water It is immediately found in three forms: ice, liquid water and steam. temperature is the lowest possible low temperature, at which the movement of molecules stops, and it is no longer possible to extract from the substance thermal energy. Since then, the absolute temperature scale has been named after him.

Temperature is measured on different scales

The most commonly used temperature scale is called the Celsius scale. It is built on two points: on the temperature of the phase transition of water from liquid to vapor and water to ice. A. Celsius in 1742 proposed to divide the distance between reference points into 100 intervals, and take water as zero, while the freezing point is 100 degrees. But the Swede K. Linnaeus suggested doing the opposite. Since then, water freezes at zero degrees A. Celsius. Although it should boil exactly in Celsius. Absolute zero Celsius corresponds to minus 273.16 degrees Celsius.

There are several more temperature scales: Fahrenheit, Réaumur, Rankine, Newton, Roemer. They have different and price divisions. For example, the Réaumur scale is also built on the benchmarks of boiling and freezing of water, but it has 80 divisions. The Fahrenheit scale, which appeared in 1724, is used in everyday life only in some countries of the world, including the USA; one is the temperature of the mixture of water ice - ammonia and the other is the temperature of the human body. The scale is divided into one hundred divisions. Zero Celsius corresponds to 32 The conversion of degrees to Fahrenheit can be done using the formula: F \u003d 1.8 C + 32. Reverse translation: C \u003d (F - 32) / 1.8, where: F - degrees Fahrenheit, C - degrees Celsius. If you are too lazy to count, go to the online Celsius to Fahrenheit conversion service. In the box, type the number of degrees Celsius, click "Calculate", select "Fahrenheit" and click "Start". The result will appear immediately.

Named after the English (more precisely Scottish) physicist William J. Rankin, a former contemporary of Kelvin and one of the creators of technical thermodynamics. There are three important points in his scale: the beginning is absolute zero, the freezing point of water is 491.67 degrees Rankine and the boiling point of water is 671.67 degrees. The number of divisions between the freezing of water and its boiling in both Rankine and Fahrenheit is 180.

Most of these scales are used exclusively by physicists. And 40% of American high school students surveyed these days said they don't know what absolute zero temperature is.

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 the extrapolation of the observed physical phenomena, while such extrapolation shows that at absolute zero, the energy of the thermal motion of molecules and atoms of a substance must be equal to zero, that is, the chaotic motion of particles stops, and they form an ordered structure, occupying a clear position at 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 fluctuations, such as zero-point vibrations, are due to the quantum properties of the particles and the physical vacuum that surrounds them.

Currently in physical laboratories it was possible to obtain a temperature exceeding absolute zero by only a few millionths of a degree; it is impossible to achieve it, according to the laws of thermodynamics.

Notes

Literature

G. Burmin. Storming absolute zero. - M .: "Children's literature", 1983.

Temperatures are the origin of the temperature reading on the thermodynamic temperature scale. Absolute zero is located 273.16.C below the temperature of the triple point of water, for which the value of 0.01.C is accepted. Absolute zero is fundamentally unattainable (see ... ... Big Encyclopedic Dictionary

The temperature expressing the absence of heat is 218 ° C. Dictionary of foreign words included in the Russian language. Pavlenkov F., 1907. absolute zero temperature (phys.) – 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, in the Kelvin scale absolute zero (0°K) corresponds to -273.16 ± 0.01°C ... Geography Dictionary

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

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 reference point for the absolute temperature on the Kelvin scale is taken ... ... Ecological dictionary

absolute zero- - [A.S. Goldberg. English Russian Energy Dictionary. 2006] Topics energy in general EN zeropoint … Technical Translator's Handbook

Absolute temperature reference point. Corresponds to 273.16 ° C. At present, in physical laboratories, it was possible to obtain a temperature exceeding absolute zero by only a few millionths of a degree, but to achieve it, according to the laws ... ... Collier 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 aiskinamasis 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 aiskinamasis žodynas

- 48.67 Kb

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 Alexandrovna

Checked by: Assistant of the Department of General

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 attacking the absolute zero temperature. As you know, the temperature equal to absolute zero characterizes the ground state of a system of many particles - the state with the lowest possible energy, at which atoms and molecules perform the so-called "zero" vibrations. Thus, deep cooling close to absolute zero (it is believed that absolute zero itself is unattainable in practice) opens up unlimited possibilities for studying the properties of matter.

1. Absolute zero

Absolute zero temperature (more rarely - absolute zero temperature) is the minimum temperature limit that a physical body in the Universe can have. Absolute zero serves as the reference point for 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 is taken to be 273.16 K (exactly), which corresponds to 0.01 ° C, so that on the Celsius scale absolute zero corresponds to temperature -273.15°C.

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

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

The absolute zero temperature is unattainable in practice, and obtaining temperatures approaching it as close as possible is 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 by equating the volume V to zero and taking into account that

Hence the absolute zero temperature is -273°C.

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

Fig.1. Absolute scale and Celsius scale

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

Thus, the 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 random motion of atoms or molecules. At T = 0 K, the thermal motion of molecules stops.

2. History

The physical concept of "absolute zero temperature" is very important for modern science. importance: such a concept as superconductivity is closely connected with it, the discovery of which made a splash in the second half of the 20th century.

To understand what absolute zero is, one should refer to the works of such famous physicists as G. Fahrenheit, A. Celsius, J. Gay-Lussac and W. Thomson. They are the ones who played key role in the creation of the basic temperature scales still in use today.

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

After 30 years, 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 mass 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 the 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 gas. From this law, the obvious conclusion followed: the temperature equal to -273 ° C is the lowest temperature, even approaching which it is impossible to reach it. This temperature is called "absolute zero temperature". Moreover, absolute zero became the starting point for creating the absolute temperature scale, in which the English physicist W. Thomson, also known as Lord Kelvin, took an active part. His main research concerned the proof that no body in nature can be cooled below absolute zero. At the same time, he actively used the second law of thermodynamics, therefore, introduced by him in 1848 absolute scale temperature became known as the thermodynamic or "Kelvin scale". In subsequent years and decades, only a numerical refinement of the concept of "absolute zero" took place.

Fig.2. Relationship between 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 - kelvin - became one of the six basic units of measurement. At the same time, it was specifically stipulated that one degree Kelvin

is numerically equal to one degree Celsius, only here the reference point "according to Kelvin" is 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 equal to zero, and in this case, any chaotic motion of these very particles should stop. At a temperature equal to absolute zero, atoms and molecules should take a clear position in the main points of the crystal lattice, forming an ordered system.

Currently, using special equipment, scientists have been able to obtain a temperature only a few millionths higher than absolute zero. It is physically impossible to achieve this value itself because of 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 - the property of some materials to have strictly zero electrical resistance when they reach a temperature below a certain value (critical temperature). Several hundreds of compounds, pure elements, alloys and ceramics are known that pass into the 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 bulk 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 (HTSCs) pushed far the temperature limit of superconductivity and allowed the practical use of 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 slots 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, 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 the 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 fluid will flow without friction.

3. Bose - Einstein condensate - state of aggregation a substance based on 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 to science and technology.

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

At low temperatures, the properties of materials change dramatically. Some metals increase their strength, become ductile, 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 construction of spacecraft, stations and instruments.

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

Low temperature electrical and magnetic properties metals, semiconductors and dielectrics make it possible to develop fundamentally new radio engineering devices of microscopic dimensions.

Extremely low temperatures are used to create the vacuum required, for example, for the operation of giant nuclear particle accelerators.

Bibliography

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

Short description

Absolute zero temperature

Absolute zero temperature is the minimum temperature limit that a physical body can have. Absolute zero serves as the reference point for an absolute temperature scale, such as the Kelvin scale. On the Celsius scale, absolute zero corresponds to -273.15 °C.

It is believed that absolute zero is unattainable in practice. Its existence and position on the temperature scale follows from the extrapolation of the observed physical phenomena, while such extrapolation shows that at absolute zero, the energy of the thermal motion of molecules and atoms of a substance must be equal to zero, that is, the chaotic motion of particles stops, and they form an ordered structure, occupying a 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 fluctuations, such as zero-point vibrations, are due to the quantum properties of the particles and the physical vacuum that surrounds them.

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

Notes

Literature

G. Burmin. Storming absolute zero. - M .: "Children's literature", 1983.

What temperature is called absolute zero. What is absolute zero and can it be reached

What is the value of absolute zero temperature and why it cannot be reached

Why is it possible to reach approximate zero temperatures, but not absolute

Notes

Literature

see also

See what "Absolute Zero" is in other dictionaries:

Notes

Literature

see also

See what "Absolute Zero Temperature" is in other dictionaries: