[lightarrow]

Secondly I should have described my potential sensors as "conductive" rather than "charged".

Then that's not a problem too: a piece of dielectric material which has a charge separation (let's say a plastic or glass stick with a charge + at one end and a charge - at the other) or a simple molecular dipole (e.g. a water molecule) will rotate in an electric field which is not parallel to its axis.

Apologies :-(

No problems at all... 

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lightarrow

[lightarrow]

With energy annihilation, as for instance to resolve Dirac's postulate,

What do you mean with "Dirac's postulate"?

  does field annihilation propose a source?

Sorry I can't understand what you mean here too.

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lightarrow

[Colin2B]

as for instance to resolve Dirac's postulate,

Which postulate and what do you mean by resolve?

[Bill S]

As I understand it, a field needs no source. A field just is. It's a sort of accounting or mapping tool that we can use to describe the universe. Every field exists everywhere, even if it has zero amplitude at specific places, or even everywhere.

You are saying, quite specifically, that a field (e.g. the electron field?) is the pre-existing entity – it needs no source.

If this is so, what meaning does it have to talk of the electron as the source of the field? 
Is that just sloppy terminology; or is the term "field" used in more than one sense; like "vacuum" or "nothing"?

[geordief]

I think I understand a field to just be a mathematical object whereas the electron is physical in the sense it can be measured

You can't detect or measure a mathematical object ( an idea)

Does that make sense? Is it right?

[jeffreyH (OP)]

The energy of a field exists. Otherwise we wouldn't have any forces. It isn't tangible. That does not mean that it is simply an abstract concept.

[petelamana]

I confess that I have not read, or scanned all 40+ replies to this topic, so I am not sure if what I am about to proffer has already been so.  At any rate...

What about the force field on an electron caused by two nearby protons?  I believe the field strength is the vector sum of the two individual protons.  If so, then there wouldn't be any single source to the field.

I may be wrong, and if so, please tell me.  I strive to learn.

[lightarrow]

As I understand it, a field needs no source. A field just is. It's a sort of accounting or mapping tool that we can use to describe the universe. Every field exists everywhere, even if it has zero amplitude at specific places, or even everywhere.

You are saying, quite specifically, that a field (e.g. the electron field?)

"electron field" is something else, let's call it with a better name: electric (or electromagnetic) field generated by the electron.

 is the pre-existing entity – it needs no source.

The fact it needs a source doesn't mean it can't exists after being generated by it. You switch on a laser device: it generates a light beam; you switch off the device: the light beam keeps going towards its target.

If this is so, what meaning does it have to talk of the electron as the source of the field?

The ancient romans created the Adrian wall; the wall is still there, but the ancient romans don't exists anymore   

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lightarrow

[geordief]

The energy of a field exists. Otherwise we wouldn't have any forces. It isn't tangible. That does not mean that it is simply an abstract concept.

the field is not just model and  fit for scrap if superseded?

[lightarrow]

The energy of a field exists. Otherwise we wouldn't have any forces. It isn't tangible. That does not mean that it is simply an abstract concept.

the field is not just model and  fit for scrap if superseded?

Probably I'll amaze you now, but did you know that an electrostatic field has a mass too?

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lightarrow

[geordief]

i

The energy of a field exists. Otherwise we wouldn't have any forces. It isn't tangible. That does not mean that it is simply an abstract concept.

the field is not just model and  fit for scrap if superseded?

Probably I'll amaze you now, but did you know that an electrostatic field has a mass too?

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lightarrow

Can I rationalize that by saying (correctly I hope) that the source  of this effect (the source =the charges)  is not local but spread out in a wave form?

That might be word salad  as..... (well you can probably guess   )

[Bill S]

The fact it needs a source doesn't mean it can't exists after being generated by it. You switch on a laser device: it generates a light beam; you switch off the device: the light beam keeps going towards its target.

Sorry, this makes no sense to me. 

“You switch on a laser device: it generates a light beam”.  The device is the source of the beam.
“you switch off the device: the light beam keeps going..”.  Of course, but the device is still the source of the beam!

The ancient romans created the Adrian wall; the wall is still there, but the ancient romans don't exists anymore.

Surely, the ancient Romans remain the “source” of Hadrian’s Wall; even if they are no longer with us.   

[Bill S]

Is the field something that exists in its own right, irrespective of whether or not any electron is “active” within it?

I’m going to attempt an answer to my own question.

The term “electron field” is used in two different ways:

1) A field which exists, and has probably existed since the BB, or very soon after.  The electron is not the source of this field; it is a quantum of the field.

2) An electron is a disturbance in the field described.  This disturbance “influences” the field.  That influence is what we identify as a field, of which the electron is the source. 

Does that make any sense?

[jeffreyH (OP)]

Is the field something that exists in its own right, irrespective of whether or not any electron is “active” within it?

I’m going to attempt an answer to my own question.

The term “electron field” is used in two different ways:

1) A field which exists, and has probably existed since the BB, or very soon after.  The electron is not the source of this field; it is a quantum of the field.

2) An electron is a disturbance in the field described.  This disturbance “influences” the field.  That influence is what we identify as a field, of which the electron is the source. 

Does that make any sense?

It makes sense to me.

[Colin2B]

The term “electron field” is used in two different ways:

1) A field which exists, and has probably existed since the BB, or very soon after.  The electron is not the source of this field; it is a quantum of the field.

2) An electron is a disturbance in the field described.  This disturbance “influences” the field.  That influence is what we identify as a field, of which the electron is the source. 

Does that make any sense?

I wouldn’t make that distinction. I would say there is an electron field, the electron is a quantum of that field and a disturbance of the field. It isn’t so much that the disturbance influences the field, as that disturbance is what we detect and call an electron. There are other fields which the electron influences such as the electromagnetic field.
Does that make sense?

[geordief]

I wouldn’t make that distinction. I would say there is an electron field, the electron is a quantum of that field and a disturbance of the field. It isn’t so much that the disturbance influences the field, as that disturbance is what we detect and call an electron. There are other fields which the electron influences such as the electromagnetic field.
Does that make sense?

What causes disturbances in the electron field that you say we call electrons when detected ?

Does one disturbance cause another?

[Colin2B]

What causes disturbances in the electron field that you say we call electrons when detected ?

Does one disturbance cause another?

QFM is a descriptive and predictive tool, it doesn’t assign causes, in the same way that Newton’s law of gravity describes the interaction of 2 masses but says nothing about the cause.

Clearly an electron can ‘cause’ an electrostatic field by its presence, but what causes the charge that causes the field? What is the root cause?
I’m not offering answers, i’m just trying to explain how the term field is used. As @chiralSPO said “It's a sort of accounting or mapping tool that we can use to describe the universe”.

[geordief]

As @chiralSPO said “It's a sort of accounting or mapping tool that we can use to describe the universe”.

Yes ,I have accepted that definition (have come across it elsewhere) but I must have/seem to have  taken my eye off the ball and regressed into attributing a physicality to the field.

If I think of an electron as being extensive  rather than local  does that mean that its associated field (as we would measure ** it ) is correspondingly  extensive although still centred at the same point? (perhaps in practice we wouldn't notice the difference and the field would have the same form as if the electron was actually a localized object)


**the field is the measurements, I keep trying to tell myself

[opportunity]

as for instance to resolve Dirac's postulate,

Which postulate and what do you mean by resolve?

Apologies for not responding sooner (and I think this also addresses light arrow's question).

Dirac knew that with an electron, as it speeds up under the influence of a field that the speed itself represents a feature that puts the normal relativistic energy of the system in focus above  the normal energy of the field and that relativistic energy environment in play, and thus his postulate was that there must be a sea of negative energy to keep the idea of energy creation at bay. It was then suggested that associated with elementary particles were anti-particles to accommodate for this, and thus the idea of particle annihilation. Whether that addresses negative energy is another story, yet "here" "purposefully" and as a proven idea anti-particles can annihilate standard elementary particles and thus aim to resolve the Dirac "sea" issue. Of what is being suggested in the context of this topic is that a particle, something substantiative, is directly responsible for the idea of energy and thus a field, whether creation or destruction.

[Colin2B]

his postulate was that there must be a sea of negative energy to keep the idea of energy creation at bay. ......yet "here" "purposefully" and as a proven idea anti-particles can annihilate standard elementary particles and thus aim to resolve the Dirac "sea" issue. Of what is being suggested in the context of this topic is that a particle, something substantiative, is directly responsible for the idea of energy and thus a field, whether creation or destruction.

OK, I understand, it’s just that he has 10 other postulates.
The Dirac Sea idea was that there is a sea of particles over all space and antiparticles are holes in this sea. He originally thought the hole was a proton, but the discovery of the positron gave a candidate.
This thread won’t resolve that as the concept has been overtaken in particle physics by the current use of fields, where a particle, or wave quanta, is substantive but is not held responsible ‘for the idea of energy’.
Certainly the quanta, and thus the field, do transfer energy.