Why don't EM waves need any medium?

Yes you are completely right, but it took an intellectual revolution for physicists to realise that it made sense to have a wave that wasn't the motion or jiggling of some physical medium, a wave that could exist equally well in empty space. All light is electromagnetic radiation. But to ask « How do they contain ... read more

For like the medium water oscillates when a water wave is observable after throwing a stone, so the electromagnetic field oscillates when excited by an antenna, say. If nothing oscillates there are no waves, neither in water nor in the electromagnetic field. read more

No, we do not need any medium in order for electromagnetic waves to move. There was a time where people believed that you needed a medium, which made many think there was some sort of medium in space called the “luminiferous Ether”. read more

EM waves are fluctuations in the universal EM field, but sound waves are just lots of molecules in the air bumping into each other. The sound needs a medium (by definition), but the EM waves are just part of the universe. read more