On the unattainability of absolute zero temperature and the Nernst heat theorem

TL;DR

This paper clarifies the relationship between the unattainability of absolute zero, the second law of thermodynamics, and the Nernst heat theorem, resolving long-standing contradictions and refining the third law of thermodynamics.

Contribution

The author refines the statement of the third law, demonstrating the independence of zero temperature unattainability from the second law and its equivalence to the Nernst heat theorem.

Findings

The unattainability of zero temperature is independent of the second law.

The unattainability of zero temperature is equivalent to the Nernst heat theorem.

The refinement resolves contradictions involving residual entropy and the third law.

Abstract

It is sometimes argued that the unattainability of zero temperature is a consequence of the second law of thermodynamics. Historically, the independence of the unattainability of zero temperature from the second law was proven more than 80 years ago, yet this assertion was repeated in the literature. This assertion naturally leads to a doubt that the unattainability of zero temperature is not equivalent to the Nernst heat theorem. The apparent contradiction between the Nernst heat theorem and residual entropy further complicates the problems of the third law. Totally, the validity of the third law seems to lose, giving an impression of somewhat ambiguous hypothesis to it. The author has recently settled the apparent contradiction between residual entropy and the Nernst heat theorem by refining the statement of the third law. Based on this refinement, two controversial problems, the independence of the unattainability of zero temperature from the second law and the equivalence of the unattainability with the Nernst heat theorem, have been solved.