# Does the electromagnetic force "split" at lower than normal energies?

Since we have working models for forces "combining" or being describable via a single framework at higher energies (such as the "electroweak" force and the aim of GUTs), does electromagnetism split into an "electric" force and a "magnetic" force at lower energies, or is this simply a misnomer in the English language born of the order in which the behaviors where discovered and related?

As an aside, the main reason I ask is because I have heard "spin" (the quantum number; which I might add in hindsight was badly named if considering the laymen such as myself) described as a "magnetic moment", and something entirely disconnected from "electric charge" (another quantum number); to my limited knowledge, there is no known meaningful correlation between the two properties (though obviously I might have just not read about/understood such).

I'm a confused layman, and any answers will be much appreciated!

• Since electric fields and magnetic fields trasform into each other under changes in inertial frames, there is no reason that they would split seperately. Commented Jan 24, 2016 at 2:57
• Thanks for the reply! I've heard about this before in a classical context, but I suppose I'm wondering more in terms of quantum theory. Could you elucidate any further on the "magnetic moment/spin" and "electric charge" and why there is or isn't (as I seem to read), a relationship between the two? Commented Jan 24, 2016 at 3:40
• The "splitting of forces" in general is a misnomer, already. While it is convenient in high energy physics to think about effective fields in that way, in general the situation is much more complicated. Entire libraries full of literature about solid states physics can show you just how complicated it is at low energies. The electroweak scale is, at most, a lucky example among a sea of non-trivial counterexamples. Commented Jan 24, 2016 at 4:21
• @machinemessiah It is true that charged particles with spin (a completely quantum phenomena) have an associated magnetic moment, but uncharged particles (neutrinos, for example) also have spin so I don't believe the existence of quantum spin has any implications for how electromagnetism decouples from the other forces in the early universe. Commented Jan 26, 2016 at 2:14

Whereas the electroweak force has lots of bosons. And when you go to low energy the electromagnetic force gets just one boson, the photon. Whereas the weak force gets three, the $W^+$ boson, the $W^-$ boson, and the $Z$ boson. There are always lots of bosons. And they have to go somewhere.