Negative Entropies in Casimir and Casimir-Polder Interactions

TL;DR

This paper discusses the phenomenon of negative entropies in Casimir and Casimir-Polder interactions, exploring their conditions, implications, and the consistency with thermodynamic principles.

Contribution

It provides new calculations and insights into when negative entropies occur in quantum vacuum interactions, clarifying their physical interpretation.

Findings

Negative entropies occur in specific temperature and separation regimes.

Total entropy remains positive when including self-entropies.

New calculations support the physical consistency of negative entropies.

Abstract

It has been increasingly becoming clear that Casimir and Casimir-Polder entropies may be negative in certain regions of temperature and separation. In fact, the occurrence of negative entropy seems to be a nearly ubiquitous phenomenon. This is most highlighted in the quantum vacuum interaction of a nanoparticle with a conducting plate or between two nanoparticles. It has been argued that this phenomenon does not violate physical intuition, since the total entropy, including the self-entropies of the plate and the nanoparticle, should be positive. New calculations, in fact, seem to bear this out at least in certain cases.