Electromagnetic momentum in frontiers of modern physics

We review the role of the momentum of the electromagnetic (EM) fields P e in several areas of modern physics. P e represents the EM interaction in equations for matter and light waves propagation. As an application of wave propagation properties, a first order optical experiment which tests the speed of light in moving rarefied gases is presented. Within a classical context, the momentum P e appears also in proposed tests of EM interactions involving open currents and angular momentum conservation laws. Moreover, P e is the link to the unitary vision of the quantum effects of the Aharonov-Bohm (AB) type and, for several of these effects, the strength of P e is evaluated. These effects provide a quantum approach to evaluate the limit of the photon mass m ph . A new effect of the AB type, together with the scalar AB effect, provides the basis for table-top experiments which yield the limit m ph = 9.4 × 10 −52 g, a value that improves the results achieved with recent classical and quantum approaches.