Photon and physical phenomena responsible for its momentum

V.P. Torchigin, A.V. Torchigin

We derive a magnitude of the momentum of light in matter by means of matching two irrefutable not contradictory thought experiments where no preliminary assumptions about kinds of optically induced forces responsible for a change of the momentum of light in matter are made. The total momentum increases in the matter by n times due to the Coulomb kind of force in a dielectric investigated by Maxwell. There are two different component of the total momentum. These are the mechanical component arising due to a motion of conventional material objects, mass of whose is non-zero and the electromagnetic component produced by a travelling electromagnetic wave, mass of which is equal to zero. The following types of optically induced forces provide a redistribution of the total momentum between these components. These are the kind of the Abraham-like force produced in matter by an electromagnetic wave, intensity of which is changed in time and the Helmholtz-like force arising in a field of an electromagnetic wave due to an inhomogeneity of the electrostriction pressure produced by the light wave. The mechanical component of the momentum of the light is negative and the electromagnetic component is greater than the total momentum.

DOI