Friction, Free Axes of Rotation and Entropy

TL;DR

This paper investigates how friction forces can induce alignment and negentropy in systems of rotators, with implications for phase equilibrium and motion in colloidal and granular systems.

Contribution

It demonstrates experimentally and theoretically that friction can generate negentropy, promoting alignment and reducing entropy in rotator systems, a novel insight into friction's role in statistical mechanics.

Findings

Friction promotes alignment of rotators, reducing system entropy.

Negentropy generated by friction depends on temperature.

Friction-induced negentropy may influence phase behavior in colloidal systems.

Abstract

Friction forces acting on rotators may promote their alignment and therefore eliminate degrees of freedom in their movement. The alignment of rotators by friction force was demonstrated by experiments performed with different spinners, demonstrating how friction generates negentropy in a system of rotators. A gas of rigid rotators influenced by friction force is considered. The orientational negentropy generated by a friction force was estimated with the Sackur-Tetrode equation. The minimal change in total entropy of a system of rotators, corresponding to their eventual alignment, decreases with temperature. The reported effect may be of the primary importance for a phase equilibrium and motion of ubiquitous colloidal and granular systems.