Absolute zero and its physical meaning. Why can't absolute zero temperatures be reached? Absolute zero temperature

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 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.

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). Large 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) little 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

The limiting temperature at which the volume of an ideal gas becomes zero is taken as absolute zero temperature.

Let's find the value of absolute zero on the Celsius scale.
Equating Volume V in formula (3.1) to zero and taking into account that

Hence the absolute zero temperature is

t= -273 °С. 2

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

The highest temperatures on Earth - hundreds of millions of degrees - were obtained during the explosions of thermonuclear bombs. Even higher temperatures are characteristic of the inner regions of some stars.

2A more accurate value for absolute zero: -273.15°C.

Kelvin scale

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

T = t + 273. (3.2)

On fig. 3.2 shows the absolute scale and the Celsius scale for comparison.

The SI unit of absolute temperature is called kelvin(abbreviated as K). Therefore, one degree Celsius equals one degree Kelvin:

Thus, the absolute temperature, according to the definition given by formula (3.2), is a derivative quantity that depends on the Celsius temperature and on the experimentally determined value of a.

Reader: What is the physical meaning of absolute temperature?

We write expression (3.1) in the form

Given that the temperature on the Kelvin scale is related to the temperature on the Celsius scale by the ratio T = t + 273, we get

where T 0 = 273 K, or

Since this relation is valid for an arbitrary temperature T, then the Gay-Lussac law can be formulated as follows:

For a given mass of gas at p = const, the relation

Task 3.1. At a temperature T 1 = 300 K gas volume V 1 = 5.0 l. Determine the volume of gas at the same pressure and temperature T= 400 K.

STOP! Decide for yourself: A1, B6, C2.

Task 3.2. With isobaric heating, the volume of air increased by 1%. By what percent did the absolute temperature increase?

= 0,01.

Answer: 1 %.

Remember the resulting formula

STOP! Decide for yourself: A2, A3, B1, B5.

Charles' law

The French scientist Charles experimentally found that if you heat a gas so that its volume remains constant, then the pressure of the gas will increase. The dependence of pressure on temperature has the form:

R(t) = p 0 (1 + b t), (3.6)

where R(t) is pressure at temperature t°C; R 0 – pressure at 0 °С; b is the temperature coefficient of pressure, which is the same for all gases: 1/K.

Reader: Surprisingly, the temperature coefficient of pressure b is exactly equal to the temperature coefficient of volumetric expansion a!

Let us take a certain mass of gas with a volume V 0 at temperature T 0 and pressure R 0 . For the first time, keeping the pressure of the gas constant, we heat it to a temperature T one . Then the gas will have volume V 1 = V 0 (1 + a t) and pressure R 0 .

The second time, keeping the volume of the gas constant, we heat it to the same temperature T one . Then the gas will have pressure R 1 = R 0 (1 + b t) and volume V 0 .

Since the gas temperature is the same in both cases, the Boyle–Mariotte law is valid:

p 0 V 1 = p 1 V 0 Þ R 0 V 0 (1 + a t) = R 0 (1 + b t)V 0 Þ

Þ 1 + a t = 1+b tÞ a = b.

So there is nothing surprising in the fact that a = b, no!

Let us rewrite Charles's law in the form

Given that T = t°С + 273 °С, T 0 \u003d 273 ° С, we get

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

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. It was they who played a key role in the creation of the main temperature scales still used 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 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 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 at a temperature equal to 0C.

The obvious conclusion followed from this law: the temperature equal to -2730C 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 one, therefore, the absolute temperature scale introduced by him in 1848 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, which, after numerous agreements, began to be considered equal to -273.150C.

It is also worth noting that absolute zero plays a very important role in the whole fact 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, only here the reference point “according to Kelvin” is considered to be absolute zero, that is, -273.150С.

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 described above.

Have you ever thought about how cold 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 inquisitive people.

What is absolute zero

Even if you didn’t like physics since childhood, you probably know 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 around -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 (the Kelvin scale), in which absolute zero is the reference point, and a 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 great prospects for mankind.

Why is it so important

Extremely low and extremely high temperatures are closely related to the concept of superfluidity and superconductivity. The disappearance of electrical resistance in superconductors will make it possible to achieve unthinkable values of efficiency and eliminate any energy losses. If it were possible to find a way that would allow one to freely reach the value of "absolute zero", many of the problems of mankind would be solved. Trains hovering over the rails, lighter and smaller engines, transformers and generators, high-precision magnetoencephalography, high-precision clocks are just a few examples of what superconductivity can bring to our lives.

Latest scientific achievements

In September 2003, researchers from MIT and NASA managed to cool sodium gas to an all-time low. During the experiment, they were only half a billionth of a degree short of the finish line (absolute zero). During the tests, sodium was always in a magnetic field, which kept it from touching the walls of the container. If it were possible to overcome the temperature barrier, the molecular movement in the gas would completely stop, because such cooling would extract all the energy from sodium. The researchers applied a technique whose author (Wolfgang Ketterle) received the Nobel Prize in Physics in 2001. The key point in the tests carried out were the gaseous Bose-Einstein condensation processes. 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 the time being, the absolute zero temperature for science remains unattainable, although scientists have been able to approach it at a negligibly small distance.

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 motion of molecules stops, and they are in a state of "zero" motions. Or: the lowest temperature at which a substance contains no thermal energy.

Absolute zero Start absolute temperature reading. Corresponds to -273.16 ° С. At present, physical laboratories have managed 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 make “zero” vibrations) and 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 consistent lowering the temperature until it liquefies at low pressure (-268.9 ° C) and extrapolates to the temperature at which the volume of gas would go to zero in the absence of liquefaction. Absolute temperature thermodynamic The scale is measured in kelvins, denoted by the symbol K. Absolute thermodynamic the scale and the Celsius scale are simply shifted relative to each other and are related by the relation K = °C + 273.16 °.

Story

The word "temperature" arose at a time when people believed that hotter bodies contained a greater amount of a special substance - caloric than less heated ones. Therefore, temperature was perceived as the strength of a mixture of body substance and caloric. For this reason, the units of measure for the strength of alcoholic beverages and temperature are called the same - degrees.

From the fact that 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

In thermodynamics, the Kelvin scale is used, in which the temperature is measured from absolute zero (the state corresponding to the minimum theoretically possible internal energy of the 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 couples are in equilibrium. The Boltzmann constant is used to convert kelvins to energy units. Derived units are also used: kilokelvin, megakelvin, millikelvin, etc.

Celsius

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

Fahrenheit

In England, and especially in the USA, the Fahrenheit scale is used. This scale is divided by 100 degrees from the temperature of the coldest winter in the city where Fahrenheit lived to the temperature of the human body. Zero degrees Celsius is 32 degrees Fahrenheit, and a degree Fahrenheit is 5/9 degrees Celsius.

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

Reaumur scale

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

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

1°R = 1.25°C.

At present, the scale has fallen into disuse; it has been preserved for the longest time in France, in the author's homeland.

Comparison of temperature scales

Description	Kelvin	Celsius	Fahrenheit	Newton	Réaumur
Absolute zero		−273.15	−459.67	−90.14	−218.52
Melting point of Fahrenheit mixture (salt and ice in equal amounts)			0	−5.87
Freezing point of water (normal conditions)		0	32	0
Average human body temperature¹		36.8	98.2	12.21
Boiling point of water (normal conditions)		100	212	33
Sun surface temperature	5800	5526	9980	1823

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 Fahrenheit conversion of the 19th century German value of 37 °C. Since this value does not fall within the range of normal temperature according to modern concepts, it can be said that it contains excessive (incorrect) accuracy. Some values in this table have been rounded.

Comparison of Fahrenheit and Celsius scales

(oF- Fahrenheit scale, o C- Celsius scale)

oF	oC		oF	oC		oF	oC		oF	oC
-459.67 -450 -400 -350 -300 -250 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -95 -90 -85 -80 -75 -70 -65	-273.15 -267.8 -240.0 -212.2 -184.4 -156.7 -128.9 -123.3 -117.8 -112.2 -106.7 -101.1 -95.6 -90.0 -84.4 -78.9 -73.3 -70.6 -67.8 -65.0 -62.2 -59.4 -56.7 -53.9		-60 -55 -50 -45 -40 -35 -30 -25 -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5	-51.1 -48.3 -45.6 -42.8 -40.0 -37.2 -34.4 -31.7 -28.9 -28.3 -27.8 -27.2 -26.7 -26.1 -25.6 -25.0 -24.4 -23.9 -23.3 -22.8 -22.2 -21.7 -21.1 -20.6		-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19	-20.0 -19.4 -18.9 -18.3 -17.8 -17.2 -16.7 -16.1 -15.6 -15.0 -14.4 -13.9 -13.3 -12.8 -12.2 -11.7 -11.1 -10.6 -10.0 -9.4 -8.9 -8.3 -7.8 -7.2		20 21 22 23 24 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 125 150 200	-6.7 -6.1 -5.6 -5.0 -4.4 -3.9 -1.1 1.7 4.4 7.2 10.0 12.8 15.6 18.3 21.1 23.9 26.7 29.4 32.2 35.0 37.8 51.7 65.6 93.3

To convert degrees Celsius to kelvins, use the formula T=t+T0 where T is the temperature in kelvins, t is the temperature in degrees Celsius, T 0 =273.15 kelvin. A degree Celsius is equal in size to a kelvin.