Something new under the sun

[Ziggurat]

Pretty graphs.

I know what is claimed to be happening in magnetic reconnection.

[qimg]http://www.nature.com/nphys/journal/vaop/nprelaunch/images/nphys111-f1.gif[/qimg]

Look at the equation I posted before. Look at the graph I made. This is exactly an illustration of what happens when you vary the prefactors in my equation and look at field lines passing through (-1,1), (1,1), (-1,-1), and (1,-1). You have never been able to object to that equation, and you cannot say why the picture doesn't correspond to it.

When you draw in field lines, they are not an actual point on the field where anything is different, they are just describing the strength of a section of the field. However, the lines themselves do not actually exist in reality. They are simply a visualization device; a useful way to understand the properties of a vector field.

This is true, but it doesn't change anything. Look at my equation again. It's a continuous, smoothly varying vector field which satisfies Maxwell's equations. But when you change the prefactors, something does happen. The lines are a way of visualizing what happens. And the picture you linked to is a correct representation of part of what happens. Your objections have always and only been about the choice of language. You have never been able to take exception to the math. Because it's right, and you are wrong. Just as you were wrong when you claimed that the proposed alfvenons were particles.

I am not sure I know what "splicing" means, scientifically speaking.

I'm sure you don't. But in context it's been made quite clear.

 

[Zeuzzz]

YOU referenced that article, and claimed that the field configuration I posted did not coincide with the process described by it. Now that it is obvious you were wrong, you are attacking your own reference. Furthermore, not long ago I gave you a list of about 20 papers describing experimental observations of reconnection in a plasma lab, which you ignored.

I was the one that first quoted those papers at MRX.

Once i see the actual data from experiments that clearly shows the magnetic field lines reconnecting, not the just the mathematics of the theory, i will reconsider my opinion. So far i have not.

And yes, there are plenty of papers on 'reconnection'. Restricting ADS' search to just Astronomy, and just 2006 to 2008, and to only papers with the words 'magnetic reconnection' in their titles yields >2000 hits! Of course, some will be irrelevant, and many relate to indirect observations associated with various magnetic effects.

The main experiment to test mag' reconnection is at a small laboratory in Princeton, Magnetic Reconnection Experiment: "The goal of MRX is to investigate the fundamental physics of magnetic field line reconnection, an important process in magnetized plasmas in space and in the laboratory." Now they give a very detailed explanation about how the energy is created, and the mechanics of the equiptment and many other things. But the one quite amazing omission from any of those papers is any experimental evidence of magnetic field lines actually 'reconnecting' to create this effect.

And your graph and the graph on the wiki page are similar, but so they in any way show that field lines can release lots of energy? No. If you had read Alfvens comments on it in my previous post you would understand my position.


I am not saying tht your graph is wrong, but your graph does not explain how magnetic field lines can do the following required in magnetic reconnection:

"Exchange magnetic field lines"

What is being exchanged here?

"and are spliced one to the other"

What actually occurs when metaphysical lines are "spliced together"?

"release energy"

How do lines release energy?


Magnetic fields are not made up of field lines, every magnetic field is a continuum, a vector field. Each of the infinite points in this continuum has a magnitude, and a direction, that is associated with it. When you draw in field lines, they are not an actual point on the field where anything is different, they are just describing the strength of a section of the field. However, the lines themselves do not actually exist in reality. They are simply a visualization device that we put in; a useful way to understand the properties of a vector field. The loci are always endless (closed) loops. They are useful abstractions and nothing more.

 

[sol invictus]

And your graph and the graph on the wiki page are similar, but so they in any way show that field lines can release lots of energy?

OK, so you've changed your position completely. You've flipflopped and now admit magnetic field lines can reconnect in a way consistent with Maxwell, but you do not believe that process releases a lot of energy.

Correct?

If so, we can move on to the question of how much energy is released when this happens.

If not, you're back to the three options I posted above: either you don't believe your eyes (in which case plot the field yourself and show us), don't believe that this field satisfies Maxwell's equations (in which case show us why not), or shut up and admit you were wrong or lying.

 

[Zeuzzz]

OK, so you've changed your position completely. You've flipflopped and now admit magnetic field lines can reconnect in a way consistent with Maxwell, but you do not believe that process releases a lot of energy.

No. Maxwells theory implicitly states that at any instant of time, the net sum of all magnetic flux entering any closed surface, A, is zero, ie, ∇ · B = 0. Where the field is strong, such as at the poles of an electromagnet, the lines come close together. However, the lines themselves do not actually exist, and so a 'reconnection' process based on the lines themselves doing something physical is an erroneous concept from the start.

I am not disputing that you can mathematically model the situation where lines appear to reconnect, but that no different to when you are modelling a saddle point on a hill, the lines appear to reconnect, but nothing actually happens at this point, because the field itself is not made of lines that can 'do' anything.

Its like the centre of gravity of an object. You would never say that the centre of gravity of an object can do something physical, ie, "the centre of gravity of an object is responsible for creating energy at the core of a planet", because the centre of gravity is not a physical thing that can do anything. It is a useful point to use for mathematical calculations about mechanics, but has no physical properties. The same applies with magnetic field lines, they do not exist in that sense, and so they can not do anything physical like reconnect, or release energy.

 

[sol invictus]

Please give yes or no answers to the following four questions. I'm trying to find out where you are confused, or if you are simply trolling. I'm rapidly losing my patience with this - any more evasions and this conversation is over (permanently this time). It's hard to imaging a clearer or better defined question than this one. If you will not admit you are wrong here, you will never admit you are wrong on anything, and there is no point at all in any further exchange.

No. Maxwells theory implicitly states that at any instant of time, the net sum of all magnetic flux entering any closed surface, A, is zero, ie, ∇ · B = 0.

That equation is satisfied for the field Zig and I have posted. Do you or do you not dispute that?

1) Yes or no?

Do you agree that given a magnetic field, we can unambiguously draw the field lines and use them to answer the question of whether two points are or are not connected by a field line? And do you further agree that the plot I posted above is correct for that field, and that it shows that as we vary the values of a and b over time, some pairs of points go from being connected by a field line to not connected by a field line (and some other pairs the opposite)?

2) Yes or no?

Where the field is strong, such as at the poles of an electromagnet, the lines come close together. However, the lines themselves do not actually exist, and so a 'reconnection' process based on the lines themselves doing something physical is an erroneous concept from the start.

The statement we are discussing is whether the magnetic field lines for a magnetic field which satisfies ∇ · B = 0 can reconnect. There is nothing ill-defined or "erroneous" about that question. It doesn't make any difference if the lines physically exist - the field exists, and given a field we can draw field lines and see what they do. We have given you an example of such a field. Do you or do you not dispute that the lines of the field Zig and I posted reconnect? (This is the same question as 2).)

3) Yes or no?

I am not disputing that you can mathematically model the situation where lines appear to reconnect, but that no different to when you are modelling a saddle point on a hill, the lines appear to reconnect, but nothing actually happens at this point, because the field itself is not made of lines that can 'do' anything.

The field in question is not a mathematical model - it is a physical field configuration which satisfies Maxwell's equations, and which we could create in a lab (and has been, many many times). Do you agree that magnetic reconnection - which means that the MAGNETIC FIELD LINES associated with a physical magnetic field RECONNECT - can occur? If you have answered "yes" to the other three questions, the answer to this one must also be yes - but consistency is not your strong suit, so...

4) Yes or no?

 

[Dancing David]

That's like asking "Is a 500 meter mountain 'very high'?" It depends what you're doing with it---climbing it, bulldozing it, falling off of it, etc. Yes, 1% ionization is enough to show some plasma behaviors on some scales. That'd be (I think) an incredibly high degree of ionization for, e.g., a flame or a spark on Earth, but incredibly low for a Lyman-Alpha Forest cloud or a neutron star accretion disk.

Thanks, that puts it and me in perspective, I already knew that temperature was not always related to the ionization, but thaht is cool about the Alpha-Lymans forest.

Thanks

 

[Dancing David]

.
My understanding, and I am happy to be corrected, is that the ionized component responds strongly to electromagnetic forces (as illustrated by the previous example from Alfvén), and then the ions affect the non-ionized component through collisions. Alfvén actually writes:

When a plasma is only partially ionized, the electromagnetic forces act on the nonionized components only indirectly through the viscosity between the ionized and non-ionized constituents. -- Hannes Alfvén, Cosmic Plasma, (1982) Page 95​

So when Alfvén says in a particular example, that a 1% partially ionized plasma should be treated as if though it was fully ionized, he is implying that we use the equations that model plasmas (eg. magnetohydrodynamics) (I don't have a reference for this), and consequently they will be strongly influenced by electromagnetic forces. As for whether electromagnetic or gravitational forces dominate:

"Stars are dominated by gravitation, but their surface activity is due to electromagnetic forces. Similarly, the interstellar and intergalactic matter are shaped by plasma forces; and galaxies also show plasma collective behavior where long-range forces are gravitational forces acting on a gas of stars. Active stars (pulsars, X-ray binaries, transient sources, etc) and active galactic nuclei appear to be dominated by plasma effects" -- B. Coppi, Attilio Ferrari, Elio Sindoni, Plasmas in the Universe, (2000) in "Astrophysical Plasmas", ISBN 1586030736, (page 1)​

Thanks for the response Ian, i would again be very cautious about treating a 1% ionizatioin as fully ionnised but it will take considerable reading and learning on my part to tell you how accurate that statement might be.

And again I would be very cautious about making statements about general conditions in the interstellar medium or intergalactic medium, because there are a variety of things that can happen and the particulars will determine which forces dominate in which situations.

 

[Dancing David]

See here is where I get stupid Ian, I go and have been reading today and obviously will have to do a lot more reading. Plasma are way cool, especially the collective effects which i am still digesting and the cool way that parameters are defined and measured. I am way over my head for an introductory physics web site but learning more. however here is a quote from the wiki page , which may be wrong, i don't think so.

For plasma to exist, ionization is necessary. The word "plasma density" by itself usually refers to the "electron density", that is, the number of free electrons per unit volume. The degree of ionization of a plasma is the proportion of atoms which have lost (or gained) electrons, and is controlled mostly by the temperature. Even a partially ionized gas in which as little as 1% of the particles are ionized can have the characteristics of a plasma (i.e. respond to magnetic fields and be highly electrically conductive). The degree of ionization, α is defined as α = n_{i/(ni + na) where ni is the number density of ions and na is the number density of neutral atoms. The electron density is related to this by the average charge state <Z> of the ions through ne=<Z> ni where ne is the number density of electrons.}

_{So yes a gas with 1% ionization might act like a plasma, which is cool, but it would appear to be related to density, I think because of debye length and from the above equations it would also be dependant upon the charge, I think. So I am saying that I would be cautious about saying that a gas with 1% ionization will always act as a plasma, because if it is not dense or has a low charge then it will sit respond to the magnetic field and carry current, but maybe to a lesser extent. So I would not say that it is ‘highly ionized’ if the ratio of alpha is (alpha)=1/1+99, unless the Z is really large. Especially since there is also something about the electron density and the collision ratio as well. Does that make sense?}

 

[ben m]

I am not disputing that you can mathematically model the situation where lines appear to reconnect, but that no different to when you are modelling a saddle point on a hill, the lines appear to reconnect, but nothing actually happens at this point, because the field itself is not made of lines that can 'do' anything.

Hey Zeuzzz, remember the four-magnet experiment I asked you to do? Do it again, this time without drawing the field lines. There, you've solved your problem---you haven't drawn any "lines that don't do anything" and you don't have to overtax yourself with a mathematical model.

Nonetheless, you have just run the magnetic fields (which can do things) through a set of transformations we call "reconnection". Agreed? And in those transformations, it so happens, the fields can release energy.

 

[iantresman]

So I am saying that I would be cautious about saying that a gas with 1% ionization will always act as a plasma, because if it is not dense or has a low charge then it will sit respond to the magnetic field and carry current, but maybe to a lesser extent.

.
Yes, a 1% ionized gas is not necessarily a plasma.

While it is related to density and other factors, its more complicated than that. It's not a case that a plasma has to be of a certain density, but that plasmas at different densities have other different characteristics.

Hannes Alfvén and Carl-Gunne Fälthammar classify plasmas into three density regions, high-, medium-, and low-density plasmas. See "Astrophysical plasma: Characteristics". And then there are magnetized vs non-magnetized plasmas, active vs passive plasmas, hot vs warm vs cold plasmas, collisionless vs collisional plasma, neutral plasmas vs charged plasmas, etc etc.

It's certainly interesting, complicated, and difficult to generalize.

 

[sol invictus]

double post

 

[sol invictus]

So? Are any of the anti-magnetic reconnection woos going to answer these four simple yes/no questions?

Please give yes or no answers to the following four questions. I'm trying to find out where you are confused, or if you are simply trolling. I'm rapidly losing my patience with this - any more evasions and this conversation is over (permanently this time). It's hard to imaging a clearer or better defined question than this one. If you will not admit you are wrong here, you will never admit you are wrong on anything, and there is no point at all in any further exchange.



That equation is satisfied for the field Zig and I have posted. Do you or do you not dispute that?

1) Yes or no?

Do you agree that given a magnetic field, we can unambiguously draw the field lines and use them to answer the question of whether two points are or are not connected by a field line? And do you further agree that the plot I posted above is correct for that field, and that it shows that as we vary the values of a and b over time, some pairs of points go from being connected by a field line to not connected by a field line (and some other pairs the opposite)?

2) Yes or no?



The statement we are discussing is whether the magnetic field lines for a magnetic field which satisfies ∇ · B = 0 can reconnect. There is nothing ill-defined or "erroneous" about that question. It doesn't make any difference if the lines physically exist - the field exists, and given a field we can draw field lines and see what they do. We have given you an example of such a field. Do you or do you not dispute that the lines of the field Zig and I posted reconnect? (This is the same question as 2).)

3) Yes or no?



The field in question is not a mathematical model - it is a physical field configuration which satisfies Maxwell's equations, and which we could create in a lab (and has been, many many times). Do you agree that magnetic reconnection - which means that the MAGNETIC FIELD LINES associated with a physical magnetic field RECONNECT - can occur? If you have answered "yes" to the other three questions, the answer to this one must also be yes - but consistency is not your strong suit, so...

4) Yes or no?

 

[iantresman]

So? Are any of the anti-magnetic reconnection woos going to answer these four simple yes/no questions?

.
Not while you continue to use derogatory and dismissive terms.

 

[sol invictus]

.
Not while you continue to use derogatory and dismissive terms.

OK, fine with me. That just makes you easier to ignore.

You don't seem to be as bad as the other two, but you still run a website full of lies and false information which probably misleads quite a few people. You don't deserve the slightest bit of sympathy.

 

[MattusMaximus]

.
Not while you continue to use derogatory and dismissive terms.

That's right Ian. Don't answer the tough questions... just expect the scientific community to take it easy on you and roll out the red carpet just because you say you're right.

Hark - I think I hear the Nobel Prize committee calling...

 

[Zeuzzz]

That's right Ian. Don't answer the tough questions... just expect the scientific community to take it easy on you and roll out the red carpet just because you say you're right.

Hark - I think I hear the Nobel Prize committee calling...

Why would Ian recieve a Nobel prize for simply re-stating the work of someone who already did win a Nobel prize for the exact work Ian is referencing in plasma physics?

 

[iantresman]

You don't seem to be as bad as the other two, but you still run a website full of lies and false information which probably misleads quite a few people. You don't deserve the slightest bit of sympathy.

.

That's right Ian. Don't answer the tough questions... just expect the scientific community to take it easy on you and roll out the red carpet just because you say you're right.

.
Insults and glib quips are hardly tough questions, and more at home in a tabloid newspaper than from the scientific community.

 

[Belz...]

Yes i have heard of escpace velocity, i had to recapp it a few days ago infact. And what that that have to with the solar wind acceleration problem? Its how these particles reach escape velocity in the first place which is the big mystery.

If they're not charged particles, it probably isn't by EM.

 

[sol invictus]

Why would Ian recieve a Nobel prize for simply re-stating the work of someone who already did win a Nobel prize for the exact work Ian is referencing in plasma physics?

So you, too, refuse to answer those four yes/no questions?

Is it really so hard to admit you were wrong? It's not like this is a subject you're knowledgeable in.

 

[ben m]

If they're not charged particles, it probably isn't by EM.

Belz, watch out for the trap that DD fell into: disagreeing with Zeuzz every time he says something is "electromagnetic". The solar wind is, in fact, a highly-ionized plasma and thus consists of charged particles. The mainstream model of the wind's acceleration is a mixture of (a) simple thermal escape from the hot corona, with the corona heated magnetically, and (b) occasional large flares or CMEs, accelerated by large magnetic reconnection events. It's a very complicated system, but it's definitely an active topic of study for mainstream plasma physics. Coronal heating is thought to be done via some combination of reconnection and plasma waves which couple in from below the photosphere.

Remember, there are three sides to plasma cosmology:

1) restating ordinary space plasma physics results and claiming (falsely) that there's overlooked new physics involved,
2) cooking up a steady-state (?) dark-matter-free cosmology by adding unspecified "plasma" forces on everything
3) powering the Sun with external currents, z-pinches and/or alien mind beams.

The assertion that the Solar Wind is accelerated or heated "electromagnetically" falls squarely in category 1. Of course, I don't doubt that when Zeuzzz is thinking of electromagnetism, he's probably picturing some transparently-wrong mechanism involving strong static electric fields, but we can cross that bridge when we come to it.