Division of the energy and of the momentum of electromagnetic waves in linear media into electromagnetic and material parts

摘要

We defend a natural division of the energy density, energy flux and momentumdensity of electromagnetic waves in linear media in electromagnetic andmaterial parts. In this division, the electromagnetic part of these quantitieshave the same form as in vacuum when written in terms of the macroscopicelectric and magnetic fields, the material momentum is calculated directly fromthe Lorentz force that acts on the charges of the medium, the material energyis the sum of the kinetic and potential energies of the charges of the mediumand the material energy flux results from the interaction of the electric fieldwith the magnetized medium. We present reasonable models for linear dispersivenon-absorptive dielectric and magnetic media that agree with this division. Wealso argue that the electromagnetic momentum of our division can be associatedwith the electromagnetic relativistic momentum, inspired on the recent work ofBarnett [Phys. Rev. Lett. 104, 070401 (2010)] that showed that the Abrahammomentum is associated with the kinetic momentum and the Minkowski momentum isassociated with the canonical momentum.