The physical concept of “absolute zero temperature” is very important for modern science: it is closely related to such a concept as superconductivity, the discovery of which made a splash in the second half of the 20th century.
To understand what absolute zero is, one 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 creating the basic temperature scales used so far.
The first to offer his temperature scale in 1714 was the German physicist G. Fahrenheit. In this case, 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 the normal temperature of the human body, which began to equal 1000. Accordingly, each division of this scale was called "Fahrenheit degrees", and the scale itself was called "Fahrenheit scales."
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 is called the “Celsius scale”, it is still popular in most countries of the world, including Russia.
In 1802, 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 interesting thing was that when the temperature changed by 10 on the Celsius scale, 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 gas volume at a temperature equal to 0C.
From this law the obvious conclusion followed: a temperature equal to -2730 is the lowest temperature, even if you come close to it, it is impossible to achieve it. This temperature was 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 lower than absolute zero. Moreover, he actively used the second law of thermodynamics, therefore, the absolute temperature scale, introduced by him in 1848, became known as the thermodynamic or “Kelvin scale”.
In the following years and decades, only a numerical refinement of the concept of “absolute zero” occurred, which after numerous approvals became considered equal to -273.150.
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 measures and weights, 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 of Kelvin is numerically equal to one degree Celsius, only here the absolute zero, that is -273.150, is considered to be the reference point “according to Kelvin”.
The main physical meaning of absolute zero is that, according to the basic physical laws, at this temperature the energy of motion of elementary particles, such as atoms and molecules, is zero, and in this case any chaotic motion of these particles should stop. At a temperature equal to absolute zero, atoms and molecules should occupy a clear position at the main points of the crystal lattice, forming an ordered system.
Currently, using special equipment, scientists have been able to obtain a temperature that is only a few millionths of a fraction higher than absolute zero. It is physically impossible to reach this very value because of the second law of thermodynamics described above.