Get the latest tech news
What's the Deal with Magnetic Fields?
I apologize, but there won't be any Insane Clown Posse jokes in this article.
The significance of the concept is sometimes misunderstood, but in the most basic sense, it appears to be a fundamental constraint on causality: you can’t exert influence at a distance any faster than it would take for a photon — a massless elementary particle — to travel from here to there. As we established, in the lab frame of reference, the length-contracted density of electrons and copper ions must stay the same as before — so there is no net electric field acting on a nearby stationary charge: Well, from its perspective, the conductor consists of a bunch of non-moving electrons spaced pretty far apart, and then a markedly higher density of positive ions moving the other way round!
Or read this on Hacker News
