# Feynman diagrams - electrical charges

1. May 26, 2013

### Camille

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 therfore 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: May 26, 2013
2. May 26, 2013

### VantagePoint72

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.

3. May 26, 2013

### Camille

Fair point, my error :D

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

4. May 26, 2013

### mpv_plate

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.

5. Jun 6, 2013

### Camille

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?