I was just thinking about the concept of magnetism and about particle theory. My understanding is that the current standard model links a particle to each force: gravity/graviton, EM/photon, strong force/gluon, etc.
Now, these particles carry their force … but what, exactly, does this mean? Do permanent magnets shoot out photons that affect other objects?
Explaning what, exactly, it means calls for a textbook on particle physics and quantum field theory. Approximately, though, you can say that a force is something which transfers momentum, and that the momentum is transfered in the form of those particles.
Thanks, Chronos.
Isn’t electro-magnetism linked with electrons, not photons?
Nope. Electrons are not force carriers, as demonstrated by this tabular depiction of the Standard Model.
(As an amusing side note, searching for a table of the Standard Model also got me this and this.)
Eeek! Trying to understand quantom physics makes me appreciate how hard it must have been for the Newtonian generation to accept Einstein!
Permanent magnets are indeed a weird beast. The rely on things called “bound currents” which make absolutely no sense but give you the right answer. In any case, these currents behave similarly to other “free” currents in that there are magnetic fields associated with them. Of course, in the unification of electricity and magnetism in QED (and standard model physics) the force carrier is still the photon. However, force carrier exchange is a bit more delicate than simply having particles “shoot out” of sources. This is very un-Quantum Mechanical. Instead, think about wavefunctions that represent (when squared) probabilities. These are really what are interacting over various spaces. The photon is then a result of an interpretation of a “quantum state” of a system that involves charge.
