I have often read that the electromagnetic force is transmitted by photons. My understanding is that when two magnets are pulling on each other (for example) they do so by exchanging photons. Are these photons the same kind of photons that make up electromagnetic radiation? If so, what part of the electromagnetic spectrum do they belong to? How can you detect them? And how does a photon emitted by an electron cause a proton to move towards the electron? Aren’t photons supposed to push on things?
The difference between the photons that carry force and the ones that you see is that the force-vector particles are virtual particles, and the detected ones are real particles. It’s a difficult concept to grasp: Basically, a virtual particle is a particle that doesn’t have enough energy to exist, but does anyway. You can’t detect a particle that doesn’t have enough energy to exist, so the process of detection will somehow give the particle enough energy to make up the difference, at which point, the particle becomes real.
As for attractive forces produced by particle exchange, the key is that unlike real particles, a virtual particle is allowed to have momentum in the opposite direction from its direction of movement. In effect, it does push, but by a negative amount.
Note that everything I’ve said here is only an analogy, and not strictly correct. In order to correctly talk about real and virtual particles, and particles mediating forces, you need to go pretty deep into the mathematics of quantum mechanics, and that’d take a whole book to explain.
You can think of photons that are interacting with the attractive magnets (or to simplify, between two particles) as carrying messages. If the two particles are negative, the message is “go away”. If the two particles are opposite charges, the message is “come closer”.
I don’t know if that helps at all in addition to Chronos’ explanation
Holy cow
I understood electromagnetism until just now.
Thanks. I’m glad to know those photons aren’t normal photons. That had been bugging me for years.
Nobody knows de trouble Bob Scene.