[opportunity]

I see your point.

Quanta though as the concept of packaged light released from electron jumping can be thought of as a wave/field and a particle. It's only the notion of the Plank scale that gives it "particle" notoriety. I completely respect that, I can't not. Which.....beckons my bias (another post somewhere), but I won't let that interfere here.

[Colin2B]

It's only the notion of the Plank scale that gives it "particle" notoriety.

Well, more the fact that the quanta carries momentum. Which can be quantfied with the Planck constant, but that’s more of a conversion factor.

[opportunity]

Yes. I have an idea (theory) though about sub-elementary particle space that "provides" quanta with momentum, hence my bias, yet it re-proposes the whole idea of the Plank scale....which proposes a long discussion, yet I would be a fool if I didn't first consider how everything is thought to work.

[lightarrow]

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the field is not just model and  fit for scrap if superseded?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

No, the fact sources are spread out or not doesn't change the properties of the electrostatic/electromagnetic field outside of them; in case it changes the electrostatic's field energy inside the charge. This is an old problem, studied by Abraham - Lorentz, Dirac, Feynman and others and partially solved by Quantun Electrodynamics; look for electron's electromagnetic mass and the 4/3 problem, e. g.  https://en.m.wikipedia.org/wiki/Electromagnetic_mass
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lightarrow

[Graccer]

It is cool!

[lightarrow]

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!

But the device is switched off. If the electric current or other source of energy is not there any longer, you can destroy the device, vaporize it, and nothing changes: no field is generated.

The actual source of the field are the electric current's charges in the specific potential inside the light emitting diode (if it's a laser device of this kind). When you switches it off it's just as a piece of inert stone, for what concerns the laser beam, that is, the field.

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.   

In this case the ancient romans are the electric's current charges: once switched off, the laser beam remains (if you shooted it in the void, travelling in outer space) but the electric current which generated the field is gone.

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lightarrow

[Bill S]

Lightarrow. We seem to be in complete agreement on many points of our reasoning, but, somehow, we end up in different places. 

I’m going to try to clarify my position:-

A = cause.  B = effect.

A causes B, which is a continuing effect through time.

A is destroyed; giving rise to two lines of reasoning:

One might say that B no longer has a cause. 

The other might say that, although A no longer exists (at least, not in its original form), it remains the cause of B, and will always remain so.

I accept that each of these lines of reasoning is accurate, within its particular context; but each is the answer to a different question.

The second line of reasoning is the one I was following.

[Bill S]

Could be its silly to ask another question before the previous one has been addressed, but I'm slipping this one in before I forget about it.  Fixation amnesia, whatever that is. 

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

My understanding is that the electrostatic field must carry energy, therefore, according to E=mc² it must have “mass”.  However, would this equate to rest mass, or would it be better described in terms of inertia?

[lightarrow]

Could be its silly to ask another question before the previous one has been addressed, but I'm slipping this one in before I forget about it.  Fixation amnesia, whatever that is. 

 

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

My understanding is that the electrostatic field must carry energy, therefore, according to E=mc² it must have “mass”.  However, would this equate to rest mass, or would it be better described in terms of inertia?

Good question.
The first you wrote.
As you know, the more general equation is not E=mc² but is:
E² = (mc²)² + (cp)²
where p is the system's total momentum (vector).
If the electric field is stationary, and only in this case, its momentum is zero, so the equation reduces to the much known you wrote.

However I don't like to call m "rest" mass because nowadays it's simply called "mass" (the so called "relativistic mass" is an  obsolete term and concept).

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lightarrow   

[Colin2B]

As you know, the more general equation is not E=mc² but is:
E² = (mc²)² + (cp)²

@Bill S - as @lightarrow points out it’s important to bear in mind the full formula. Another example is the photon, having 0 mass so the first term in the equation is 0, leaving only the momentum contribution.

[Bill S]

However I don't like to call m "rest" mass because nowadays it's simply called "mass" (the so called "relativistic mass" is an  obsolete term and concept).

How far off the mark would I be if I interpreted this as saying: "rest" mass = total mass; "relativistic mass" = inertia? 

[Bill S]

If the electric field is stationary, and only in this case, its momentum is zero,

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

Isn't the electrostatic field always stationary?

[lightarrow]

However I don't like to call m "rest" mass because nowadays it's simply called "mass" (the so called "relativistic mass" is an  obsolete term and concept).

How far off the mark would I be if I interpreted this as saying: "rest" mass = total mass;

Ok, unless you give particular interpretations to "total" mass. Better to say "system" mass.

  "relativistic mass" = inertia? 

Do you like a concept of inertia which is different along different directions? Along the direction of the body's velocity you have a value of inertia, that is: γ³m, where γ is the gamma Lorentz factor:
γ = 1/sqrt[1-(v/c)²];
in the ortogonal direction you have a different value, that is: γm.
Conclusion: better not to talk about relativistic mass at all.
IMHO.

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lightarrow

[Bill S]

Conclusion: better not to talk about relativistic mass at all.

I expressed my intended meaning badly.  By "relativistic mass" = inertia, I meant something like: If you meet the term relativistic mass, it is better to think of it as inertia.

Would that be better?

[alancalverd]

Sorry to pick this one up so late.

Say we have a universe that contains only one electron and one positron. They collide and annihilate producing two gamma rays. Since the sources of the fields are gone how are the gamma rays propagating? Does the electromagnetic field, or any other field, require a source?

What field? An electromagnetic wave is selfpropagating. Nothing to do with an external field.

[opportunity]

This subject is moot. It is counterproductive to a theory of everything. A theory of everything would require everything to require everything.

Of course if reality just comes and goes, anything and everything requires nothing and vice versa.

[lightarrow]

Conclusion: better not to talk about relativistic mass at all.

I expressed my intended meaning badly.  By "relativistic mass" = inertia, I meant something like: If you meet the term relativistic mass, it is better to think of it as inertia.
Would that be better?

IMHO it would be better "energy" (in the sense "total energy") since relativistic mass is just energy/c².
Concerning "inertia", not, for what I wrote: you should remember that you have *two* different inertias simultaneously in the same body:
1) tangential inertia = γ³m
2) transversal inertia = γm
where m is the body's (rest/proper/invariant) mass.

If you are sure to remember that, ok, but when you talk of "inertia" you always have to specify *which of the two*

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lightarrow

[geordief]

Sorry to pick this one up so late.

Say we have a universe that contains only one electron and one positron. They collide and annihilate producing two gamma rays. Since the sources of the fields are gone how are the gamma rays propagating? Does the electromagnetic field, or any other field, require a source?

What field? An electromagnetic wave is selfpropagating. Nothing to do with an external field.

Yes ,can we talk about fields without specifying?

Any detail by the way on the way em  fields "self propagate"?

Is any energy involved ?

Do the 2 constituent waves interact with each other continuously?  (I have only a very sketchy understanding of what might be going on)

Unless I am digressing a lot.....

[Colin2B]

Yes ,can we talk about fields without specifying?

We can but only in general terms.

Any detail by the way on the way em  fields "self propagate"?

@alancalverd  didn’t say the em field propagates, he said the em wave propagates. The field does not propagate, as we’ve said before a field is a set of measurements over time and space, a description. Try not to make it more than it is.

Is any energy involved ?

Yes, the wave transfers energy

Do the 2 constituent waves interact with each other continuously?  (I have only a very sketchy understanding of what might be going on)

You have to be much more specific about which waves and what circumstances.

[geordief]

Any detail by the way on the way em  fields "self propagate"?

@alancalverd  didn’t say the em field propagates, he said the em wave propagates. The field does not propagate, as we’ve said before a field is a set of measurements over time and space, a description. Try not to make it more than it is.

Is any energy involved ?

Yes, the wave transfers energy

Do the 2 constituent waves interact with each other continuously?  (I have only a very sketchy understanding of what might be going on)

You have to be much more specific about which waves and what circumstances.

Yes I apologize (again    )for saying the em field propagates.I have a mental block with the words "wave" and "field" and keep confusing them (and you)

Still interested to learn in a little more detail possibly  , how this "self propagating" mechanism  of the em wave works .

Same question : is any energy involved(between the two component waves)

? The electrical wave seems to "feed" the magnetic wave

Any detail on that ?