What is the force carrier particle for magnetism?
I realize that the force carrier particle for electromagnetism is the photon, but the photon doesn't seem to me, to be attached to it's parent in the same way a gluon would be to it's parent-particle, the quark.
So this raises 2 questions I guess. The first would be.. do photons "exchange" with each other, and is that force felt by the parent particle? I'd guess the answer is no, and if so.. then the 2nd question is.. what is the force carrier for magnetism?
Thanks, and please excuse my ignorance, [Luna]
hikaruzero
the photon doesn't seem to me, to be attached to it's parent in the same way a gluon would be to it's parent-particle, the quark.
Yep, that's correct — this is because the photon does not carry electric charge, while gluons do carry colour charge. That causes gluons to interact with each other, binding into "flux tubes" that resemble strings. While photons don't interact with each other.
do photons "exchange" with each other, and is that force felt by the parent particle?
I'm not 100% what you mean by "exchange with each other." If you're asking "do photons interact with each other, and maybe exchange some information like charge or energy," similar to how gluons interact with each other and are constantly swapping colour charge between them, then the answer is no*.
If you mean, do two fermions (like electrons) exchange a photon between themselves, then the answer is yes, and the force is felt by the parent particle.
- Technically two photons can under some circumstances interact with each other, by one photon fluctuating into a fermion-antifermion pair, which then interacts with the other photon ... but this is a much rarer higher-order effect.
what is the force carrier for magnetism?
It's the photon, the same as for the electric force. A photon is a self-sustaining oscillation in the electric and magnetic fields. Without an oscillation in one field, the other field would also not oscillate, so the two fields are in a sense dual to each other.
Now, keep in mind that photons aren't necessarily constantly being exchanged between materials with electric or magnetic charge. It's not like a game of billiard balls where the balls are shooting photons directly at each other. Both the electric and magnetic forces are "felt" even without exchanging photons between the particles. For example, if you had two test charges, at rest with respect to each other, they would attract or repel even before absorbing or emitting photons. This is because it is the electromagnetic field itself which causes the attraction; photons are simply moving changes in the EM field values. So, the EM field itself will cause attraction or repulsion, but when it does, the moving of charged particles causes changes in the EM field (photons), and the photons then interact with other systems, effectively informing them of the field changes, and "adjusting"/"correcting" their motion to be consistent with the changed field configuration. That's the role of photons — they aren't "the force carrier" in the sense of "they cause all attraction and repulsion," rather they are are "the force carrier" in the sense of "they carry changes in the field values," and those changes in turn affects the force that charged particles feel.
Hope that all makes sense. [from https://www.reddit.com/r/askscience/comments/28s0io/what_is_the_force_carrier_particle_for_magnetism/]