On the Casimir entropy between 'perfect crystals'

TL;DR

This paper reinterprets the Casimir entropy in perfect crystals, showing it as a finite, disorder-related contribution that challenges the applicability of the third law of thermodynamics.

Contribution

It offers a new perspective on the electromagnetic Casimir effect in perfect crystals, linking entropy to electron gas disorder and questioning the Nernst theorem's relevance.

Findings

Finite Casimir-like entropy in perfect crystals

Disorder in electron gas contributes to entropy

Nernst theorem does not hold in this context

Abstract

We give a re-interpretation of an `entropy defect' in the electromagnetic Casimir effect. The electron gas in a perfect crystal is an electromagnetically disordered system whose entropy contains a finite Casimir-like contribution. The Nernst theorem (third law of thermodynamics) is not applicable.