The handedness and classification of materials

According to direction relationship among the triplet of vectors of electric field intensity, magnetic field intensity and wave vector of electromagnetic wave, materials have usually been classified as right- and left-handed material. Here, we shall strictly and systematically demonstrate that, in a linear isotropic homogeneous medium, the direction relationship among the triplet of vectors of electric field intensity, magnetic field intensity and wave vector of electromagnetic wave may generally alter between right-handedness and left-handedness with change of time except for the special cases. Thus the further classification of materials according to handedness and corresponding criterion are proposed.