Non-linear electromagnetism and special relativity
The paper makes use of the assumption of Lorentz invariance and, in particular, shows that nonlinearity forbids the convexity of the energy density. This is used to justify the study of rank-one convex and polyconvex densities. It is also shown that either electrodynamics is linear, or that dispersion is lost as the intensity of the magnetic field increases.
scientific article; zbMATH DE number 5509444