Fermi–Dirac and Bose–Einstein distributions and the interaction of light with matter

Einstein’s treatment of stimulated emission, spontaneous emission, and absorption yields the Planck distribution law for photons if the ‘‘atoms’’ with which the photons interact are described by the Boltzmann distribution. We show that the Planck law is also obtained when the photons interact with matter that is described by either Fermi–Dirac or Bose–Einstein distributions.