Macroscopic short-time electrodynamics for conductors

In the macroscopic electrodynamics (MED) of good conductors (metals) based on Ohm's law j=σE, the momentum relaxation time τ=σm/ne² of the electrons limits the application to electromagnetic (EM) processes with characteristic times t≫τ. An interesting physical difficulty occurs in MED since the EM field damping time τ_R=e{open}/σ of metals is very small compared with the minimum macroscopic time scale, τ_R≪τ. Consequently, the damping and propagation of EM waves and pulses in good conductors cannot be correctly described within the frame of conventional MED. New hyperbolic EM wave equations with relaxation and memory are proposed, which no longer exhibit the τ_R≪τ deficiency. The latter is caused by Ohm's law, which breaks down for short-time processes, due to neglect of electron inertia. The advantages of the proposed and the disadvantages of the conventional EM wave equations for good conductors are discussed in applications.