Minimum entropy production of neutrino radiation in the steady state

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