How the idea of force-carrying particles acts in real-world?

Question

The idea of "force-carrying particles" is insane to me. Because if I hold two magnets near each other, probably zillionths of photons are constantly being exchanged bwteen them. In extreme form, two stationary electrons can be the source of infinite photons exchange. Or protons in nucloes must constantly exchange gluons. I don't know how many million times per second.

This means that we have infinite amount of force carrying particlea. Which I simply can not comprehend.

Have I understood it right? Can you please explain it to me?

Answer 1

I have been asking some questions around this issue but there seems to be no clean answer.

These particles are in some sense "virtual". According to quantum theory, vast numbers of such particles can exist. But of course, they are not what one classically means by a solid "particle", they are possibility waves describing where they would probably be found if one were to interact with them.

In quantum field theory (QFT) they are perturbations of the zero-point field for that type of particle. But QFT has no coherent model (that anybody here can offer) for how to handle static fields which do not transfer energy, such as the force between two electrons, just a rather vague idea that virtual particles must get "exchanged", or one electron would gain energy from the other. Most commentators refer for the maths to classical electromagnetism, which of course is all waves and no particles.

At least one can say that each virtual photon exchange represents a quantised and therefore finite force, so the total cannot be infinite.

Gluons are highly energetic, so much so that e=mc² means that they form a significant amount of the mass of a nucleon or massive boson. Again, they are quantised and therefore finite in number at any given moment. (I don't know how bosons are supposed to carry the weak nuclear force, I suppose most of them must be virtual too).

The fourth fundamental force, gravity, ought in theory to describe gravitons as perturbations of the zero-point graviton field. But nobody has a clue how to reconcile that with General Relativity. My feeling is that, since GR and electromagentism have very similar equations, this constitutes an elephant in the room when it comes to describing electro- and magnetostatic forces.

I look forward to the comments explaining any downvotes this answer receives, maybe we'll both learn something from them.

Answer 2

The idea of exchange particles is a purely quantum mechanical concept and does not extend to macroscopic bodies where we have the concept of classical fields.

Your assumption about an infinite amount of particles being exchanged giving an infinite force is incorrect. Perhaps you mean infinite sums in QFT? The answer to this is in a process called renormalisation. Nevertheless, the numbers of particles is not infinite and so there is no need to think about infinite forces.

You can read about renormalisation on Wikipedia.