# Electromagnetic attraction. How?

1. Jan 20, 2012

### salvestrom

Repulsion's got a nice, 'this emits that, hits this; see Newton's third Law' explanation. Attraction. I found one thing. It says this:

A virtual particle with momentum p corresponds to a plane wave filling all of space, with no definite position at all. It doesn't matter which way the momentum points; that just determines how the wavefronts are oriented. Since the wave is everywhere, the photon can be created by one particle and absorbed by the other, no matter where they are. If the momentum transferred by the wave points in the direction from the receiving particle to the emitting one, the effect is that of an attractive force.

I guess the first question should be: is this accurate?

I have others, but it would seem better to not voice them until someone can confirm, or put it in otherwords.

2. Jan 20, 2012

### tom.stoer

another example why the concept of virtual particles in laymen's terms is not sufficient to explain the forces and should therefore be avoided; you can understand attraction based on virtual particles only via the math

3. Jan 20, 2012

### maverick_starstrider

Yes, virtual particles are not real and should never leave their home in the math of perturbation series. That's why we call them virtual. Things attract because they are able to lower their potential energy by moving closer to one another.

4. Jan 20, 2012

### tom.stoer

even in QED there is a strict derivation of a "static Coulomb potential", i.e. there is a Coulomb force not mediated by virtual particles plus "virtual particles on top";

5. Jan 20, 2012

### salvestrom

I was under the impression they were called virtual simply because they never exist long enough to be observed, only their effects.

Your last sentence doesn't really explain anything and comes rather close to giving them an intent to their action.

Repulsion has an explanation that is a consequence of something that the particles are continuously doing that causes a certain reaction if they get close enough. I'm looking for a less general explanation than this of what action and reaction is taking place when attraction occurs. My original post contains someone elses explanation which seems to say that a photon emitted by an electron, such that the photon is headed away from, say, a proton can end up hitting the proton from 'behind' so that the electron's knockback from emission and the protons push forward from absorbtion push the pair closer.

Is the original explanation accurate? Is my interpretation accurate?

6. Jan 20, 2012

### Hydr0matic

7. Jan 20, 2012

### maverick_starstrider

No, virtual particles are not real. They're a mathematical artifact of how we solve certain equations in quantum field theory. That's why we call them virtual. The whole picture of "trading messenger particles" isn't physical. Far better to stay with the concept of a field.