Hi... If we consider propagation of sound through a medium other than vacuum, we mean, when sound is produced by a vibrating speaker diaphragm, it gives periodic jolts to the molecules and atoms present in the medium or air. These "pushes" are transferred to all adjacent atoms until finally few manage to reach our ears, which is then perceived as sound. Now, in case of EM waves, the energy excites WHAT kind of matter so that the energy passes on to next? What is the medium of EM waves? What is it that's common in vacuum and matter? Dark matter/Dark energy? From Einsteins GR theory, if presence of matter curves or bends 3-D space, then is there a possibility that the electric charges, + and - produce curves or bends in dimensions other than what we can perceive? And do those particles which EM waves excite to propagate, probably exist in this imperceptible dimension?