The Abraham–Minkowski controversy is a physics debate concerning electromagnetic momentum within dielectric media.
[1][2] Two equations were first suggested by Hermann Minkowski (1908)[3] and Max Abraham (1909)[4][5] for this momentum.
[7][8][9][10] The two points of view have different physical interpretations and thus neither need be more correct than the other.
[11] David J. Griffiths argues that, in the presence of matter, only the total stress–energy tensor carries unambiguous physical significance; how one apportions it between an "electromagnetic" part and a "matter" part depends on context and convenience.
[13][14][15][16][17][18] The controversy is still claimed to have importance in physics beyond the Standard Model where electrodynamics gets modifications, like in the presence of axions.