What is absolute zero in thermodynamics?

This concept developed by Lord Kelvin establishes the lowest possible temperature.

The temperature of the environment is and has been throughout history a very determining element for the survival of different living beings, and something that has marked the evolutionary evolution and, in the case of human beings, the way of understanding the world around us.

In fact, much of the known life can only live within thermal limits, and even the movement and energy of particles is altered at the molecular level. It has even been stipulated that there are extreme temperatures that can cause the motion of subatomic particles to cease completely, as they are in total absence of energy. This is the case of absolute zero, a concept developed by Kelvin and whose research has great scientific relevance.

But... what exactly is absolute zero? Throughout this article we are going to find out.

Absolute zero: what does this concept refer to?

We call absolute zero to the unit of lowest temperature that is considered possible, the -273,15ºCThis is a situation in which the subatomic particles themselves would be without any kind of energy and would not be able to make any kind of movement.

This occurs due to the fact that the fact of decreasing the temperature of an object implies subtracting energy, so absolute zero would imply the total absence of this.

This is a temperature that is not found in nature. and which is assumed to be hypothetical for the time being (in fact, according to Nernst's principle of unaffordability, reaching this temperature is impossible), although scientific experimentation has succeeded in reaching very similar temperatures.

However, the above description is linked to a perception of this concept from the viewpoint of classical mechanics. from the viewpoint of classical mechanics. Later investigations that would leave classical mechanics aside to enter quantum mechanics propose that in reality at this temperature there would still exist a minimum amount of energy that would keep the particles in motion, the so-called zero-point energy.

Although, according to the first classical views, in this hypothetical state matter should be in a solid state since there is no motion, or it should disappear since mass is equivalent to energy and the latter is totally absent, quantum mechanics proposes that since energy exists, other states of matter could exist.

Kelvin's research

The name and concept of absolute zero comes from the research and theory of William Thomson, better known as Lord Kelvin, who based his elaboration of this concept on the observation of the behavior of gases and the behavior of energy. the observation of the behavior of gases and how they vary their volume proportionally as the proportionally to the decrease in temperature.

Based on this, this researcher began to calculate at what temperature the volume of a gas would be zero, reaching the conclusion that it would correspond to the aforementioned.

Based on the laws of thermodynamics, the author created his own temperature scale, the Kelvin scale, placing the point of origin at this lowest possible temperature, absolute zero. Thus, a temperature of 0ºK corresponds to absolute zero, -273.15ºC. This is part of the creation by this author of a temperature scale generated from the laws of thermodynamics. from the laws of thermodynamics of the time (in 1836). (in 1836).

Is there anything beyond that?

Considering that absolute zero is a temperature at which there would be no particle motion or only a residual energy of absolute zero, it is worth asking whether something beyond this temperature could exist.

Although logic might lead us to think that it does not, research carried out by different investigators at the Max Planck Institute seem to indicate that in fact an even lower temperature could exist, and that it would correspond to negative temperatures on the Kelvin scale (i.e. below absolute zero). This is a phenomenon that could only occur at the quantum level.

This would occur in the case of some gases, which through the use of lasers and experimentation were able to go from being somewhat above absolute zero to negative temperatures below zero. These temperatures would ensure that the gas in question, prepared in such a way that it should contract at high speed, would remain stabilized. In this sense it resembles dark energy, which according to some experts prevents the universe from collapsing in on itself.

What can it be useful for?

Knowing the existence of absolute zero has repercussions not only on a theoretical level but also even on a practical level. And it is that when exposed to temperatures close to absolute zero, many materials change their properties to a great extent.

An example of this can be found in the fact that at these temperatures the subatomic particles condense into a single large atom called a Bose-Einstein condensate. Likewise, some particularly interesting properties for their practical application are found in the superfluidity or superconductivity that certain elements can reach under these thermal conditions.

Bibliographical references:

• Braun, S. et al. (2013). Atoms at negative absolute temperature- the hottest systems in the world. Science, 4. Max Planck Society.
• Merali, Z. (2013). "Quantum gas goes below absolute zero". Nature. doi:10.1038/nature.2013.12146.