Minimum Entropy Production of Neutrino Radiation in the Steady State

A thermodynamical minimum principle valid for photon radiation is shown to hold for arbitrary geometries. It is successfully extended to neutrinos, in the zero mass and chemical potential case, following a parallel development of photon and neutrino statistics. This minimum principle stems more from that of Planck than that of classical Onsager- Prigogine irreversible thermodynamics. Its extension from bosons to fermions suggests that it may have a still wider validity.