Yet they also showed that there are limits here, as well. The scientists showed that lower temperatures can be obtained with only a modest increase of resources. The new result led the physicists to a second question: If we can't reach absolute zero, then how close can we get (with finite time and resources)? It turns out that the answer is closer than might be expected. This finding is in agreement with the widely accepted physical explanation of the unattainability of absolute zero: As the temperature approaches zero, the system's entropy (disorder) approaches zero, and it is not possible to prepare a system in a state of zero entropy in a finite number of steps.

The physicists showed that cooling a system to absolute zero requires either an infinite amount of work or an infinite reservoir. When applied to cooling, the question becomes how much work must be done and how large must the cooling reservoir be in order to cool an object to absolute zero (0 Kelvin, -273.15☌, or -459.67☏)? There, a common problem is to determine the amount of resources required to perform a certain task. To prove the third law, the physicists used ideas from computer science and quantum information theory. Personally, I love that the whole of thermodynamics (including the third law) has been derived from more fundamental principles.' In addition, this derivation unveils the strong connections among the limitations of cooling, the positivity of the heat capacity, the reversibility of microscopic dynamics, etc. 'The goal of fundamental physics is to derive all the laws of nature and to describe all phenomena by only assuming a small set of principles (like quantum mechanics, the Standard Model of particle physics, etc.),' Masanes told.

After more than 100 years, the result finally puts the third law on the same footing as the first and second laws of thermodynamics, both of which have already been proved. Now for the first time, physicists Lluís Masanes and Jonathan Oppenheim at the University College of London have derived the third law of thermodynamics from first principles.

Absolute zero from entropy derivative