The Reality of Casimir Friction

TL;DR

This paper reviews the history and current theoretical understanding of Casimir friction, a quantum electromagnetic phenomenon that causes tiny dissipative forces between moving bodies, and discusses prospects for experimental observation.

Contribution

It consolidates and clarifies the theoretical predictions of Casimir friction, highlighting emerging consensus and potential for experimental verification.

Findings

Theoretical predictions for Casimir friction are converging.

Casimir friction forces are extremely small but potentially measurable.

Experimental confirmation of Casimir friction remains a future goal.

Abstract

For more than 35 years theorists have studied quantum or Casimir friction, which occurs when two smooth bodies move transversely to each other, experiencing a frictional dissipative force due to quantum electromagnetic fluctuations, which break time-reversal symmetry. These forces are typically very small, unless the bodies are nearly touching, and consequently such effects have never been observed, although lateral Casimir forces have been seen for corrugated surfaces. Partly because of the lack of contact with phenomena, theoretical predictions for the frictional force between parallel plates, or between a polarizable atom and a metallic plate, have varied widely. Here we review the history of these calculations, show that theoretical consensus is emerging, and offer some hope that it might be possible to experimentally confirm this phenomenon of dissipative quantum electrodynamics.