  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.
