Feynman diagrams - electrical charges

Camille
Messages
20
Reaction score
3
I have a request for some explanation in Feynman diagram concerning repelling/attraction of electrical charges. I have been told that when two charges (say, e1(-) and the e2(-)) repel each other, a photon is being emitted from one of them, and the other charge is later being hit by this photon. There is some confusion I can see in this explanation.

First: Does the charge e1(-) emit just a beam of photons in the direction of charge e2(-)? If yes, then how is that this photons always hit charge e2(-) and never miss? Charge e2(-) could move before photons hit it.

Second: Or perhaps the charge e1(-) emitts photons constantly, in all directions. If that's so, what is the wavelength of those photons? Can we detect them?

Third: Does the interaction between charges is based purely on conservation of momentum? (I mean: charge e1(-) gives up some energy (mass of photon) and is therefore tilted outwards the system and charge e2(-), hit by the photon, also gets tilted - therefore we see the repelling.)

Fourth: In the system of e1(-) and e2(-), do they both emit photons in each other's direction?
 
Last edited:
Physics news on Phys.org
For one thing, a negative and a positive charge attract each other, not repel.

Feynman diagrams are just a convenient shorthand for a mathematical expansion. They shouldn't be taken too literally.
 
  • Like
Likes 1 person
Fair point, my error :D

But they must have something to do with the reality. Photons must be really emitted, right...?
 
Camille said:
But they must have something to do with the reality. Photons must be really emitted, right...?

Virtual photons are not really emitted. They are just terms in perturbation expansion. When 2 electrons meet, there is definitely something happening in the electromagnetic field between them, but the repulsive force is not caused by physical emission of photons.

The virtual photons (Green functions) are just a tool used to solve differential equations.
 
  • Like
Likes 1 person
Is it already known in physics what is happening in the electric field between the electrons? And I mean at the subatomic particles level.

Can someone share some materials from where I could learn to use and read Feynman diagrams in a more or less easy way?
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. Towards the end of the first lecture for the Qiskit Global Summer School 2025, Foundations of Quantum Mechanics, Olivia Lanes (Global Lead, Content and Education IBM) stated... Source: https://www.physicsforums.com/insights/quantum-entanglement-is-a-kinematic-fact-not-a-dynamical-effect/ by @RUTA
If we release an electron around a positively charged sphere, the initial state of electron is a linear combination of Hydrogen-like states. According to quantum mechanics, evolution of time would not change this initial state because the potential is time independent. However, classically we expect the electron to collide with the sphere. So, it seems that the quantum and classics predict different behaviours!

Similar threads

Replies
29
Views
3K
Replies
4
Views
2K
Replies
6
Views
2K
Replies
13
Views
3K
Replies
6
Views
2K
Replies
3
Views
2K
Replies
11
Views
3K
Back
Top