Thermodynamics of Radiation Pressure and Photon Momentum

TL;DR

This paper offers a novel thermodynamic perspective on radiation pressure and photon momentum, emphasizing blackbody radiation and thermal equilibrium rather than classical electrodynamics.

Contribution

It introduces a thermodynamics-based approach to radiation pressure, integrating blackbody radiation properties with quantum concepts like entropy and Einstein's coefficients.

Findings

Provides a thermodynamic framework for understanding radiation pressure.

Connects photon momentum with blackbody radiation properties.

Offers insights into energy and momentum transfer in thermal equilibrium.

Abstract

Theoretical analyses of radiation pressure and photon momentum in the past 150 years have focused almost exclusively on classical and/or quantum theories of electrodynamics. In these analyses, Maxwell's equations, the properties of polarizable and/or magnetizable material media, and the stress tensors of Maxwell, Abraham, Minkowski, Chu, and Einstein-Laub have typically played prominent roles. Each stress tensor has subsequently been manipulated to yield its own expressions for the electromagnetic (EM) force, torque, energy, and linear as well as angular momentum densities of the EM field. This paper presents an alternative view of radiation pressure from the perspective of thermal physics, invoking the properties of blackbody radiation in conjunction with empty as well as gas-filled cavities that contain EM energy in thermal equilibrium with the container's walls. In this type of analysis, Planck's quantum hypothesis, the spectral distribution of the trapped radiation, the entropy of the photon gas, and Einstein's A and B coefficients play central roles.