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

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.