Electric universe theories here.

[Ziggurat]

He doesn't like how things are being described.

Like gas is a plasma?

No. Gas is not a plasma, but plasma is a gas. Like squares are rectangles. But rectangles are not squares. This is like the most basic concept of subsets, which most children can grasp by the first grade. Why do you still struggle with it?

Use the correct terminology, its not scary at all.

"Gas" is correct, even when talking about a plasma. It's less specific, and you might prefer "plasma" as a result, but that's a different complaint.

Magnetic reconection is a great example.

EU describes the same phenomena using electric current short circuits (everyone understands a short circuit) and you use tangle snappy elastic figment s of your imagination.

Your analogy is even worse.

 

[hecd2]

The Great mystery. Where are we from...ah, to ponder.

Abject inability to answer the basic key physics question "what is the energy source for stars" noted.

 

[hecd2]

Do you understand the difference between an electric and magnetic field?

Yes I do, but you obviously don't. They are both vector fields which can be illustrated by lines that show the vector direction with separation that represents magnitude. The specific difference claimed by the ignoramus Scott in his silly little video does not exist.

 

[W.D.Clinger]

Do you understand the difference between an electric and magnetic field?

Some of us know the electromagnetic field is a unified field whose decomposition into electric and magnetic fields depends upon the coordinate system(s) you choose to use.

In particular, if you find yourself in an electric field where the magnetic field is zero, you can create a magnetic field by moving at a steady rate across the electric field while thinking of yourself at rest. As illustrated by that particular situation, the difference between an electric field and a magnetic field is partly to be found within the head of the observer.

Yes I do, but you obviously don't. They are both vector fields which can be illustrated by lines that show the vector direction with separation that represents magnitude. The specific difference claimed by the ignoramus Scott in his silly little video does not exist.

I'm pretty sure Sol88 has not been aware that the gradient of a scalar field is a vector field.

 

[Ziggurat]

Yes I do, but you obviously don't. They are both vector fields which can be illustrated by lines that show the vector direction with separation that represents magnitude. The specific difference claimed by the ignoramus Scott in his silly little video does not exist.

There are some differences in ways magnetic and electric fields can be graphically depicted which are interesting but above Sol88's ability to understand, and likely Scott's too.

Field line depictions are especially useful for depicting fields, or at least field regions, where the divergence is zero. In that case, field lines never start or end. Magnetic fields always have zero divergence, so that always works, electric field lines only have zero divergence in charge-free regions. This isn't a problem if the charges are confined to specific areas, but it doesn't work as well when you need to draw your fields in regions that have volume charges throughout them.

If the field is curl-free (not the case for magnetism, often but not always the case for electric fields) but not necessarily divergenceless, then it can be better to depict the field as covariant vectors, where the direction is given not by an arrow but by an oriented pair of parallel planes, and magnitude is given by the inverse separation between the two. When curl is zero, the planes of of the covector field produce equipotential surfaces, and the field strength is basically just the gradient of the potential they represent. That doesn't work when the curl is nonzero, though.

 

[W.D.Clinger]

A minor correction...

Field line depictions are especially useful for depicting fields, or at least field regions, where the divergence is zero. In that case, field lines never start or end.

The highlighted sentence is untrue. It is a white lie often told by physics teachers as a way to avoid the calculus involved in the true definition of divergence. It has been repeated so often that some competent physicists have come to believe it as well.

That white lie has confused Donald Scott, who has used it to argue that magnetic reconnection (in which oppositely directed field lines may fade to zero at the point or surface where they end) is impossible.

A technical discussion of this would start with the proper definition of a magnetic field line as a curve that satisfies the geodetic equation. As there is no hope of explaining any of this to Sol88, and my previous exposition became almost unreadable when ISF dropped its support for LaTeX^*, I'd suggest we start a separate thread if anyone wants to pursue this further.

^*Yes, I know ISF eventually began to support LaTeX again, but changed the markup tags in the process, so the old posts that used LaTeX remain unreadable.

 

[Ziggurat]

The highlighted sentence is untrue. It is a white lie often told by physics teachers as a way to avoid the calculus involved in the true definition of divergence. It has been repeated so often that some competent physicists have come to believe it as well.

That white lie has confused Donald Scott, who has used it to argue that magnetic reconnection (in which oppositely directed field lines may fade to zero at the point or surface where they end) is impossible.

The saddle point involved in magnetic reconnection has a field line that can go infinitesimally close to the saddle point. I guess you could say that they're gone at that point, but you get lines going into and out of that point in equal measure, so... it's like they don't end. Is that all you mean? If so, that's a minor technicality in my book, of relevance to actual mathematicians (like the difference between [0,1] and [0,1) ) but not something a more general audience need dwell on. Are there any scenarios you can think of where it's more pronounced than that?

Scott seems like he could be confused by the instructions on a bag of instant ramen noodles.

 

[MRC_Hans]

When the magnetic field decays, what happen to the moving electric charge? It’s still creating a magnetic field.

Or the electric current? No magnetic field no current?

In the context of astronomical fields, it is a tad complicated, but essentially the current continues to flow till it has exhausted its energy, and only then can the magnetic field decay. In the world of wires, it is called self-induction. It is part of the mechanism causing magnet lines to "snap" to new fields, as they can't just disappear.

There it was again: Energy. Where do you imagine that energy comes from?

Hans

 

[MRC_Hans]

Trying to shroud your ignorance in gibberish? You fail.
Trying to baffle others with your BS? You fail.

The Great mystery. Where are we from...ah, to ponder.

Anyhoo, back to actual plasma, electric currents, electric fields....blah blah blah plasma blah blah blah...

Brave enough to tackle a Bennet a pinch in an astrophysical plasma passing an electric current?

Gibberish.

Or are you implying, that because there is no apparent “battery” there can be no electric currents, electric fields, plasma instabilities...so on an so forth?

Ah, a fair question, albeit naive.

Yes, electric currents, electric fields, magnetic fields, and indeed the existence of plasma all depend on the presence of an energy source. What did you think?

Once upon a time, long long time ago, stuff happened. Much the same as the Big Bang. Once there was nothing....

At this time, it’s not relevant. We are still getting over words to mean things.

Gibberish.

Plasma is not gas.

It is a subset of gas. Get over it.

Magnetic reconnection is actually electric fields, diamagnetic cavity is inside a double layer...so on and so forth.

No, magnetic fields are .... drum roll .... magnetic. In fact, a magnetic field is where a current can in theory be maintained without a charge difference.

You may then move onto advanced plasma physics!

Dusty plasma anyone? Kink or pinch instability in a dusty plasma stream if anyone’s keen on joust?

A dusty thought stream, more likely.

Hans

 

[W.D.Clinger]

The saddle point involved in magnetic reconnection has a field line that can go infinitesimally close to the saddle point. I guess you could say that they're gone at that point, but you get lines going into and out of that point in equal measure, so... it's like they don't end. Is that all you mean? If so, that's a minor technicality in my book, of relevance to actual mathematicians (like the difference between [0,1] and [0,1) ) but not something a more general audience need dwell on. Are there any scenarios you can think of where it's more pronounced than that?

It is, as you almost say, a mathematical fact that magnetic field lines can end. It is also, as you do say, an empirical fact that some physicists don't care or regard that as "a minor technicality in my book".

That becomes a problem when, as stated by Zilberti:

Many textbooks support the idea that B-field lines are always closed (or, at most, extend to infinity). Among them, we may mention those by Stratton [1941], Morse and Feshbach [1953], Sommerfeld [1964], Weber [1965] (who associates closed lines to any solenoidal vector), Paul and Nasar [1982], and Griffiths [1999]. The same happens in many handbooks of electrical engineering (see for instance Laughton [2003] and Schmitt [2002]).​

The idea that magnetic field lines "are always closed (or, at most, extend to infinity)" is not only out-and-out false, but an impediment to understanding the genuine meaning of ∇∙B=0.

That false explanation of Gauss's law for magnetism is very common. For example, it shows up in Wikipedia's current article on the magnetic field:

...magnetic B-field lines neither start nor end (mathematically, B is a solenoidal vector field); a field line may only extend to infinity, or wrap around to form a closed curve, or follow a never-ending (possibly chaotic) path.^[33]

As seen in that quotation, the false idea that magnetic field lines neither start nor end leads immediately to a false understanding of what it means to be a solenoidal vector field, as in this Wikipedia article:

A common way of expressing this property is to say that the field has no sources or sinks.^{[note 1]}

Happily, the superscript "note 1" amends that false statement by saying

This statement does not mean that the field lines of a solenoidal field must be closed, neither that they cannot begin or end. For a detailed discussion of the subject, see J. Slepian: "Lines of Force in Electric and Magnetic Fields", American Journal of Physics, vol. 19, pp. 87-90, 1951, and L. Zilberti: "The Misconception of Closed Magnetic Flux Lines", IEEE Magnetics Letters, vol. 8, art. 1306005, 2017.

Pragmatically, the confusion caused by these false claims (that magnetic field lines can neither start nor end, are always closed or go to infinity, etc) has been an impediment to understanding some real physical phenomena, such as magnetic reconnection.

Donald Scott may be unusually susceptible to confusion, but he is not the only one who has been confused by this. Consider, for example, a stackexchange discussion of "Is magnetic reconnection reconcilable with magnetic field lines neither starting nor ending?" The answers given by @DavidHansen are incorrect. The highest rated answer, by tok3ratOr, is correct, and the second highest rated answer, by Kyle Kanos, is mostly correct but unnecessarily complex as it brings in matters that are not needed to answer the question that was asked.

 

[tusenfem]

Righto, “slave” is the correct word to use? Even demagnetised?

Did you actually READ and UNDERSTAND what I wrote?
Don't bother anwering, because the answer is no.
Otherwise you would not aks this (stupid) question.
The rest is just your lack of knowledge.

 

[Sol88]

An electron that is no longer "slave" to the magnetic field.
Where the magnetic field gets so weak it is no longer the major controlling factor of the motion of the electron.
Usually, "unmagnetized" is used.

Yeah, nah I got it.

Demagnetised electrons...that’s a good one.



Charge seperation anyone?

 

[Sol88]

Seems snapping magnetic field lines is not locked in yet.

Reconfiguration of electric currents and double layers are involved here.

We ALL agree the main player in “magentic reconnection” are ELECTRIC FIELDS.

Propa words here, as they actually mean stuff.

Plasma is not a gas.

 

[Sol88]

Ah, a fair question, albeit naive.

Yes, electric currents, electric fields, magnetic fields, and indeed the existence of plasma all depend on the presence of an energy source. What did you think?

Me personally think the universe is infinite in size and age, so...energy source??? Its the big battery at the other end on the Universe.

Big questions grasshopper. Maybe you should stick trying to comprehending charge seperation in astrophysical plasma’s.

 

[Sol88]

In the context of astronomical fields, it is a tad complicated, but essentially the current continues to flow till it has exhausted its energy, and only then can the magnetic field decay. In the world of wires, it is called self-induction. It is part of the mechanism causing magnet lines to "snap" to new fields, as they can't just disappear.

There it was again: Energy. Where do you imagine that energy comes from?

Hans

Most sense you’ve made so far.

Do you think all the magnetic fields we observe, in space, are the result of moving charged particles?

PS, tusenfem would then call those electrons demagnetised.

But if they are moving....ahhh fogedaboutit.

 

[Ziggurat]

Pragmatically, the confusion caused by these false claims (that magnetic field lines can neither start nor end, are always closed or go to infinity, etc) has been an impediment to understanding some real physical phenomena, such as magnetic reconnection.

I think those folks aren't going to understand this stuff anyways. Even when given a simple magnetic field that's very easily provable to have no divergence that shows reconnection, they'll still balk at it. I get your point, but I don't think that the lack of explicitly stating you can start AND stop (and you have to do both, not one or the other) magnetic field lines at null points is the real source of the problem.

 

[Sol88]

Proven correct, I see. Remembering the following, every double layer is an electric field but not every electric field is a double layer.

But an electric field will accelerate charged particles, electrons in particular (less mass) more better’r than null point mag fields snapping, stretching and reconnecting.

Good now we can move on. Reconnection (particle accelerators) are electric fields.

Thanks for the heads up, ziggurat.

 

[MRC_Hans]

Most sense you’ve made so far.

Do you think all the magnetic fields we observe, in space, are the result of moving charged particles?

PS, tusenfem would then call those electrons demagnetised.

But if they are moving....ahhh fogedaboutit.

I asked you a question. In fact several. It is your turn to answer questions.

Hans

 

[tusenfem]

PS, tusenfem would then call those electrons demagnetised.

No, I would use the correct UNMAGNETIZED, thank you very much.

 

[Sol88]

Sorry my bad. Unmagikitised.

Not demajikcised.

And in the real world this is observed mainly in, what exactly?

Link or source?