Electrodynamics and rational thermodynamics

The electromagnetic fields (D, H) represent contravariant components of an antisymmetric 4-tensor, while the (E, B) covariant same 4-tensor. Both sets are identical in Lorentz frames. governing equations for them balance flux D and B across open surfaces they invariant under arbitrary analytic transformation space time. This convenient property has motivated mechanicians to reformulate mechanics thermodynamics terms symmetric 4-tensor energy-momentum so as exhibit, perhaps, invariance electromagnetism: general relativity. interpretation electromagnetism carries theory a long way. But it breaks down when absorption emission radiation by bodies is concerned. In this case proper view that photon gas. Also elegant union meets practical difficulties with internal structure, like electric magnetic dipoles or mixtures charged constituents. description such limited velocities much smaller than light. Still those entropy inequality implies severe interesting restrictions on dependence material properties fields. It will be evaluated using Lagrange multiplier method. early days there was confusion among physicists engineers about different formulation dimensions units. dilemma also briefly explained article.