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

In fact, much of 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 extreme temperatures can cause the movement of subatomic particles to cease completely, as they are left in total absence of energy. This is the case of absolute zero, a concept developed by Kelvin and whose research is of great scientific relevance.

But… what exactly is absolute zero? Throughout this article, we’re going to check it out.

Absolute zero: what does this concept refer to?

We call absolute zero the lowest temperature unit considered possible, the -273.15ºC , a situation in which the subatomic particles themselves would be without any energy and would not be able to make any kind of movement.

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

This is a temperature that is not found in nature and is assumed for the moment to be hypothetical (in fact, according to Nernst’s principle of unavailability, reaching this temperature is impossible), although scientific experimentation has managed to reach very similar temperatures.

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

Although before the first classic visions in this hypothetical state, matter should be presented in a solid state since there is no movement 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 started to elaborate this concept of the observation of the behaviour of gases and how these vary their volume in a proportional way when faced with a 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 temperature.

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

Is there anything else beyond that?

Considering that absolute zero is a temperature at which there would be no movement of particles or only a residual energy of absolute zero, it is worth asking whether there could be anything beyond this temperature.

Although logic may lead us to believe that it is not, research carried out by different researchers at the Max Planck Institute seems to indicate that in fact there could be an even lower temperature, 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 happen in the case of some gases, which through the use of lasers and in 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 would have to contract at high speed, would remain stabilised. In this sense it is similar to dark energy, which according to some experts prevents the universe from collapsing in on itself.

What can it be used for?

Knowing the existence of absolute zero has repercussions not only on a theoretical level but also on a practical level. 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 subatomic particles condense into a single large atom called Bose-Einstein condensate. Likewise, some particularly interesting properties due to their practical application can be found in the superfluidity or superconductivity that certain elements can reach under these thermal conditions.

Bibliographic 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.