This gets hard, as you probably guessed.

This guy has written the book on magenetism.
https://www.youtube.com/user/kathodosdotcom/videos

and, the way he shows it working is through aether.
But, that is not a proof, that is a theory based off an assumption based off of observation.

Further than this, we have a bunch of theories.
All of them have some good points.

But, it really is testing something you cannot see.
And, no proof is available that proves that something exists.

The aether is probably were we will also find gravity.