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arXiv · 2501.17793

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

Kimball A. Milton·Nima Pourtolami·Gerard Kennedy
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Abstract

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 to the thermal vacuum blackbody radiation. We consider forces and torques beyond the usual static Casimir-Polder and Casimir forces and torques. For a moving body, a retarding force emerges, called quantum or Casimir friction, which in vacuum was first predicted by Einstein and Hopf in 1910. Nonreciprocity may allow a stationary body, out of thermal equilibrium with its environment, to experience a torque. Moreover, if a stationary reciprocal 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.

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Kimball A. Milton, Nima Pourtolami, Gerard Kennedy. 2025-01-29. Perspectives on Quantum Friction, Self-Propulsion, and Self-Torque. https://arxiv.org/abs/2501.17793

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