Perspectives on Quantum Friction, Self-Propulsion, and Self-Torque

Kimball A. Milton, Nima Pourtolami, Gerard Kennedy

Published 2025-01-29Version 1

This paper provides an overview of the nonequilibrium fluctuational forces and torques acting on a body either in motion or at rest relative to another body or the thermal vacuum blackbody radiation. For a moving body, a retarding force emerges, called quantum or Casimir friction, which in vacuum was first predicted by Einstein and Hopf in 1907. Moreover, if a stationary body is not in thermal equilibrium with the blackbody vacuum, a self-propulsive force or torque can appear, resulting in a potentially observable linear or angular terminal velocity, even after thermalization.