0
$\begingroup$

I've heard over and over an electron described as a source of the electric field, but that is a misleading term. Source makes one thing of a tap, with a constant flow of something coming out of it. This is clearly not the case for an electron.

I am trying to ascertain the validity of the following statement

'A charge for e.g. an electron is a perpetual emitter of an electromagnetic potential flow [in the form of polarised virtual particle pairs popping into and out of existence] and is therefore a permanent creator, or rather a consistent initiator of a virtual flow of energy.'

This intuitively sounds wrong to me, I think the author is taking the mathematical concept of virtual particles too far.

$\endgroup$
  • $\begingroup$ How do virtual particles come into play here? $\endgroup$ – Kyle Kanos Aug 21 '15 at 23:39
  • $\begingroup$ @KyleKanos Ahh I couldn't include the whole quote as it was a few pages of work so I have added paraphrased context in square brackets. Thanks, hopefully it's clearer what the author means to say. $\endgroup$ – Dan Aug 21 '15 at 23:47
  • $\begingroup$ I imagine that paraphrasing 'a few pages' probably eliminated the physical content. It may be useful to include the author & title of the source. $\endgroup$ – Kyle Kanos Aug 21 '15 at 23:49
2
$\begingroup$

There is a grand tradition in electromagnetism to talk about the electric fields using the same terminology as we use for velocity fields.

For instance we talk about the flux which rightly is a flow per area (and sometimes we multiply by the area and still call it a flux, which is even more confusing to call two things a flux) but it isn't a flow because it isn't a velocity field.

We also borrow other terminology, we call thing potentials even though they aren't potential energy per charge and in fact it is really a gauge dependent scalar field at best and not an energy associated with a system.

We sometimes call an emf a work per charge or power per current even if the circuit is moving and therefore the current and therefore the charges aren't going in the direction of the circuit (the emf is integrated in the instantaneous direction of the circuit).

These last two are really just wrong except that we introduce them in statics and usually don't warn people that the power and energy ideas will not generalize.

So calling things a source is the least bothersome. We aren't using the same name to mean two different things. We aren't spending a huge time building up relations that will not generalize later. Because is it really so wrong to imagine something traveling along a field line with a source and a sink? We have a vector field that has places of positive divergence and places of negative divergence. It seems small harm talk of them as sources and sinks.

Sure, there really aren't little bits of electric and magnetic stuff travelling along the field lines because then you couldn't have the field be zero in one frame and nonzero in another.

But that's because rightly it is one electromagnetic field and just breaking into two fields was wrong. But as long as you broke it I don't see the harm in describing it like a velocity so you can talk about flux and how it relates to the net source enclosed.

The part about energy flow sounds outright wrong, energy objectively flows orthogonal to the fields.

$\endgroup$
0
$\begingroup$

The source and sink phenomenological description of charge - how realistic is it?

It isn't realistic at all. To be perfectly honest it's totally misleading.

I've heard over and over an electron described as a source of the electric field, but that is a misleading term.

Yes it is, because like Timaeus said, it's the electromagnetic field. See Minkowski talking about it in Space and Time:

"In the description of the field caused by the electron itself, then it will appear that the division of the field into electric and magnetic forces is a relative one with respect to the time-axis assumed; the two forces considered together can most vividly be described by a certain analogy to the force-screw in mechanics; the analogy is, however, imperfect".

Note how he said the field? It's one field and two forces. The electron doesn't have an electric field or a magnetic field, it has an electromagnetic field. So depictions like this one in Andrew Duffy's Physics 106 are misleading:

enter image description here

What's gone wrong is that there's this confusion between field and force. That's why you can read "lines of force are also called field lines". Electromagnetic field interactions result in linear "electric" force and/or rotational "magnetic" force. When we only see linear force we talk of an electric field, when we only see rotational force we talk of a magnetic field. Then when you make allowance for this error, the source-and-sink description is still wrong. Look at the directions of the arrowheads, and note that two electrons repel, two positron repel, and an electron and positron attract. There is no way those arrowheads "work" for that.

Source makes one thing of a tap, with a constant flow of something coming out of it. This is clearly not the case for an electron.

Clearly. Nor is it true for a positron.

I am trying to ascertain the validity of the following statement: A charge for e.g. an electron is a perpetual emitter of an electromagnetic potential flow [in the form of polarised virtual particle pairs popping into and out of existence] and is therefore a permanent creator, or rather a consistent initiator of a virtual flow of energy.

It's nonsense I'm afraid.

This intuitively sounds wrong to me, I think the author is taking the mathematical concept of virtual particles too far.

Agreed. When the electron and the proton attract one another they "exchange field" such that the hydrogen atom doesn't have much of a field left. This is the reality that underlies virtual particle exchange.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.