Talk:Magnetic monopole

‹See TfM›

Clean up

New minor changes:

• Clean up slightly.
• Re-section the lead into historical/recent developments sections, to break the long succession of paragraphs.
• Use the colspan="x" for equations repeated in the table, why write multiple times when the colspan implies the equations fall under all top headings?
• Remove some repetition of ρ_m and j_m in/after the Maxawell equation tables, re-stated 3 times in the article:
  • first table: "ρ_m and j_m are defined as above" then "in these equations ρ_m are...,
  • second table: "where ρ_m and j_m are...",

just once would be fine.

• Inserted Lorentz force into first table for consistent layout with other table, adjusted heading slightly
• Indent tables.
• Made dot product for divergence bigger for visibility, replace ∇⋅ with ∇•
• Moved the apparently out-of-place statement:

For a long time, the open question has been "Why does the magnetic charge always seem to be zero?"

randomly stuck before Maxwell's equations in cgs units, and moved it higher up since its a good start to the first (newly-headed) section.

F = q(E+v×B) ⇄ ∑_ic_i 07:42, 28 May 2012 (UTC)

Looks ok to me :-) --Steve (talk) 21:13, 31 May 2012 (UTC)

• In the section "Grand unified theories" there are two adjectives that should be reconsidered.

"most of which had the curious[according to whom?] feature of implying the presence of a real magnetic monopole particle"

I feel the use of 'curious' is intended to indicate irony, as if to say, although no monopoles are in evidence, most of the :GUTs require monopoles. I think the "according to whom" can be removed or at least satisfied with a footnote to this effect.

"the apparent problem of the observed scarcity of monopoles is resolved by..."

The adjective 'scarcity' should be changed to 'absence'. Although monopoles are expected to prove to exist and to be scarce, it is more precise and serves the article better to reiterate that monopoles remain unobserved. — Preceding unsigned comment added by Shellsunder (talk • contribs) 11:08, 28 October 2012 (UTC)

I reworded... --Steve (talk) 15:25, 28 October 2012 (UTC)

Marko Rodin

Not a single mention to Marko Rodin (http://www.youtube.com/watch?v=RnjW1zROJPc), one way or another - is there a reason for that? 89.153.150.71 (talk) 13:00, 1 July 2012 (UTC)

Yes, see WP:UNDUE. --Steve (talk) 17:55, 7 August 2012 (UTC)

"Appendix"

The newly added Appendix section is almost exactly copied from http://www.encyclopediaofmath.org/index.php/Magnetic_monopole, on the site that the poster described. It might be relevant material, but it should definitely be presented in a different format. Also, this article does not have anything like this addition in its 2006 history. Nat2 (talk) 00:22, 31 July 2012 (UTC)

I will clean up the referencing at least. It would help if people could actually reference properly, this has been done before (see for example the edit history of David Hestenes)... Maschen (talk) 11:28, 18 August 2012 (UTC)

Done, except I couldn't find [4] or [15] in the text so moved those references to the Notes section. Also cleaned up most of the formatting... Now to contact the editor/s responsible for the messy ref style, and notify others at Wikipedia talk:WikiProject Physics#Magnetic monopole and Yang-Mills theory so they can rewrite the section, as indicated by the above link... Maschen (talk) 12:10, 18 August 2012 (UTC)

The SpringerEOM license allows copying but requires attribution, and so this kind of copying should include a note along the lines of "tis article contains material from Springer EOM, licensed under the CC-by-SA and GFDL..etc." linas (talk) 14:04, 18 August 2012 (UTC)

Article is confusing

I wonder that an article like this,"Magnetic monopole" in the present form may still exist. In the light of the fact that there do not exist any real particles justified to be called so, it is confusing, and should be revised, rewritten.Caboz (talk) 14:10, 1 September 2012 (UTC)

Can you say more specifically what you found confusing? --Steve (talk) 13:15, 2 September 2012 (UTC)

The article should inform the reader that no particle of material substance as a source of magnetic field do exist and therefore can not be found. It should make clear, that all phenomena which we call "magnetic" are the consequence of the motion of electric field (charge). And this it does not.94.113.59.212 (talk) 16:55, 2 September 2012 (UTC)

See this section. Maschen (talk) 17:02, 2 September 2012 (UTC)

I agree: The introduction section, the figure and caption at the top, section 1.1, and section 2 state over and over, in extremely explicit terms, that magnetic monopoles are not the explanation for any magnetism phenomenon ever observed. Short of flashing lights and audio warnings, I can't think how to make it any clearer!! :-P

Caboz, how much time did you spend reading the article before you posted this comment? A few seconds? Minutes? Hours? Which sections were you mainly paying attention to? Did you read any of the text of Sections 1.1 or 2? Did you read the figure caption at the top? (Please don't think these questions are accusatory! I am asking in good faith to understand whether and how the article needs improvement.) --Steve (talk) 12:39, 3 September 2012 (UTC)

Does this drawing help (from field (physics))?

Electric fields E due to charged particles (black/white) and an electric dipole moment d, and magnetic fields B due to an magnetic dipole m and magnetic monopoles (red/blue). Particles with either electric or magnetic charge in motion (velocity v) induce an electromagnetic field.

Apart from the one in the lead there are no other diagrams... Maschen (talk) 08:24, 3 September 2012 (UTC)

I don't think it's relevant to the specific complaint of this section...is that what you're talking about?

More generally, I have mixed feelings, particularly I think the bottom right entry may cause confusion. For one thing, a magnetic dipole is not normally made of two magnetic monopoles (obviously), so depicting that unusual kind of dipole may cause confusion. For another thing, IF you made a magnetic dipole out of two magnetic monopoles, the B-field lines would not be closed loops as depicted, they would start at N and end at S exactly like the top-right entry. Other than the bottom-right entry, it's a nice demonstration of the classical behavior of a magnetic monopole, relevant to the Maxwell's equations section. --Steve (talk) 12:39, 3 September 2012 (UTC)

Yes I am referring to this thread/complaint. Also it explicitly states "magnetic dipole" and linked so I hoped people would see the magnetic dipole found in ordinary matter there, but to prevent the confusion you now pointed out I splitted the image into two new ones - one for monopoles and another for dipoles:

Left: Fields due to stationary electric and magnetic monopoles. Right: In motion (velocity v), an electric charge induces a B field while (in theory) a magnetic charge induces an E field. Conventional current is used.

Top: E field due to an electric dipole moment d. Bottom left: B field (in theory) due to a magnetic dipole m formed by two magnetic monopoles. Bottom right: B field due to a natural magnetic dipole moment m found in ordinary matter (not from monopoles).

The E fields and B fields due to electric charges (black/white) and magnetic poles (red/blue).

Maschen (talk) 16:42, 3 September 2012 (UTC)

Caboz, is the confusion that although we have not found natural magnetic monopoles, we can still theoretically define and use the mathematical definition of pole strength (redirected to magnetic moment), and then all the mathematical "hype" about Maxwell's generalized equations, the quantization condition, Dirac strings and topology... Is that it?

Forgive me, but what do you mean by "the article in the present form may still exist"? I have no clue what this means... just trying to understand where you are coming from...

Although I don't fully understand the QFT/topology of it all yet either - the absolute brilliance and fascination of the duality overwhelms the confusion IMO... Maschen (talk) 17:37, 3 September 2012 (UTC)

Maschen, since you seem to make the changes to the images so readily, what do you think of merging the dipole dots into a single one, half red and half blue? I think that way everyone should be happy, as it suggests the limiting condition more closely. — Quondum 18:28, 3 September 2012 (UTC)

Sure, they have been overlapped, but I would rather not blend too much (i.e. not into one pole) else it would look more like a neutral magnetic pole i.e. no magnetic charge (!). Is this ok? Maschen (talk) 18:47, 3 September 2012 (UTC)

Better. Let's see whether you get any other comments. — Quondum 18:59, 3 September 2012 (UTC)

No-one has objected to adding it in 8 days. I will do so. Maschen (talk) 09:47, 11 September 2012 (UTC)

It seems to me that the last discussion brings only more confusion and no clarification of the problem. The fact is that there are no "particle-like" magnetic poles, and this fact should be respected anywhere in this article. The first sentence in the present form: "A magnetic monopole is a hypothetical particle in particle physics that is an isolated magnet with only one magnetic pole...." is confusing. It should state: "Magnetic monopole is a misleading technical term inducing the idea of existence of material particles with magnetic properties (magnetic charge)...." The article should be re-written keeping this fact in mind. http://en.wikipedia.org/w/index.php?title=Talk:Magnetic_monopole&action=edit# — Preceding unsigned comment added by 94.113.59.212 (talk) 10:34, 13 September 2012 (UTC)

Again - it states from the very beginning that magnetic monopoles have not been found, and are not the sources of magnetism as we know it (who says they "don't exist"?).

They can be defined mathematically with the property of magnetic charge, as stated in the article, and there are sections on Maxwell's monopole equations (which reduce to the normal equations when magnetic charges and currents are zero for the system in analysis), Dirac quantization condition etc.

The "misleading" part of your statement is not correct; if a magnetic monopole is found, it would be a new elementary particle (which would have mass). The first image clearly states this. Maschen (talk) 11:07, 13 September 2012 (UTC)

The IP presumably has an interpretation of the word "hypothetical" with the semantic of "suspected" rather than the absolutely neutral sense that it normally carries. Clarity would probably come to this discussion when differences in interpretation of the words being used are ironed out, not from arguments dealing with the article's content. — Quondum 12:18, 13 September 2012 (UTC)

Apologies to the IP if I sounded personally direct and irritated, it's certainly not my intension to patronize.

I can't really think how to make the wording clearer, and intend to leave it to those who are inclined and capable... Maschen (talk) 13:06, 13 September 2012 (UTC)

You're not the one who should be apologetic. IMO the IP is being excessively assertive/POV based on a misinterpretation; I was basically trying to suggest to you to avoid being baited. I (and evidently others) think the article is perfectly well worded in this respect. — Quondum 13:54, 13 September 2012 (UTC)

Note to the new drawings: In the new drawings the depiction of the electric field is OK, but that of the magnetic field is false, - the lines of magnetic induction B are not "product" of "magnetic monopoles N S" but of moving (orbiting) electrical particles (electrons), i.e. electrical current. So the drawings are not explaining reality but only the false idea of the author.94.113.59.212 (talk) 01:37, 14 September 2012 (UTC)

No. For the magnetic dipole from two monopoles: if you actually read the caption - you will find that it is the mathematical prediction of what the field would be if monopoles were found.

For the magnetic dipole in ordinary matter, that's just true. A magnet has a north pole AND a south pole. Yes it is a macroscopic effect and ultimately all magnetism results from currents.

Yes - I am well aware that electric currents are the source of magnetism, and have drawn a diagram of that too (a year ago, in fact):

Dipole moment m.

Electric current I.

The magnetic field and magnetic moment, due to an electric current or natural magnetic dipoles, either generates the same field profile.

I wish you would quit insinuating us that we "don't know magnetism arises from electric currents" and quit your false assertion that "magnetic monopoles do not exist". There is no conclusive experimental evidence that they exist - we haven’t found them yet. The laws of EM are not violated if they exist, so I have no clue why you keep saying magnetic monopoles are a false formality.Maschen (talk) 02:02, 14 September 2012 (UTC)

can you please 94.113.59.212 (talk) 06:12, 14 September 2012 (UTC)explain why should we talk about "hypothetical particles magnetic monopoles" when we know that they do not exist, and all magnetic phenomena can be explained by real effect of moving electrical particles ? 94.113.59.212 (talk) 06:12, 14 September 2012 (UTC)

"... when we know that they do not exist" – we do not know this; all our observations are consistent with them possibly existing or possibly not existing. As the old chestnut says, absence of evidence is not evidence of absence. So you cannot use this is a premise. Hypotheses are useful for investigating possibilities in the absence of knowledge as to the truth of the hypothesis.

"... and all magnetic phenomena can be explained by real effect of moving electrical particles" – again, this is only true within the scope of our observations. Should magnetic monopoles actually exist, there will be magnetic phenomena that cannot be explained in terms of moving electrically charged particles.

One of the strengths of hypotheses is that they allow us to speculate, and to explore the feasibility of the hypotheses. At the time of Dirac's invention of his equation, positrons could not have existed, by logic similar to yours. Fortunately Dirac did not dismiss his equation on the grounds that no then-observed particle fitted the bill of that solution to his equation. — Quondum 06:43, 14 September 2012 (UTC)

I agree that "...hypotheses may be useful for investigating possibilities in the absence of knowledge..." In the case of magnetic phenomena the knowledge is not absent, so why to use hypotheses when the reality is known ? is my question ?94.113.59.212 (talk) 11:01, 14 September 2012 (UTC)

It is clear that you asserting

"monopoles simply *cannot exist at all* and that we *know the only reality* is electric currents/quantum spin is the source of all magnetism".

(*Applause!* Do you think anyone knows what "reality is" anyway? That's philosophy...). Does extensive, painstaking, searching in excruciating detail automatically "prove" that monopoles do not exist? No.

As Quondum pointed out with the electron-positron prediction from Dirac's equation, just because no positron's were found at the time does not automatically "prove" that they do not exist - they were found later. Same for monopoles. Who knows, in the next century, millennium or beyond (assuming Humanity lasts) that someday a monopole is found? What then?

I withdraw from this thread... Maschen (talk) 11:20, 14 September 2012 (UTC)

I withdraw from this thread...(Maschen). So do I.(94.113.59.212 (talk) 08:51, 15 September 2012 (UTC)) Such a "discussion" leads nowhere.94.113.59.212 (talk) 13:41, 14 September 2012 (UTC)

I recommend to read also the discussion to the article Magnetischer monopol Ich empfehle auch die Disskusion : Magbetischer Monopol zu lesen.94.113.59.212 (talk) 14:05, 14 September 2012 (UTC)

I strongly disagree with the assertion that "magnetic monopoles do not exist" and that they are a "misleading technical term". I agree,we have not found them,many suspect they dont exist,the difficultly in finding them seems to indicate they may not exist,perhaps even they probably dont exist. All of those might be valid statements,but we dont KNOW they dont exist,until for instance,someone finds a charge thats not quantized like it should be. If charges there are magnetic monopoles,then charges have to be quantized in a certain way,therefore if charges are NOT always quantized that way,there must not be any monopoles. No one has found that charge yet either. Finding either that charge or a magnetic monopole gets you a nobel prize,but so far,we just dont KNOW,all we know is that if there ARE magnetic monopoles,they are hard to find. As for it being a misleading technical term,far from it. You might try to say the same thing about the vector potential. But in fact,like monopoles,the vector potential is a very useful thing when solving problems. Similarly,you can solve magnetic field problems by positing monopoles.In the end though,it turns out the vector potential IS physical,as it can affect a particle in places where its curl vanishes. Makes me a little less certain about the monopoles. — Preceding unsigned comment added by 67.2.240.140 (talk) 07:59, 13 September 2013 (UTC)

References

Covariant form of Maxwell's monopole equations?

See also: Talk:Covariant formulation of classical electromagnetism § Covariant form of Maxwell's monopole equations?

Here [1] is a paper (and here [2] are more related) on the covariant form of Maxwell's equations including monopoles (it's not hard to imagine a monopole 4-current and find a second inhomogeneous equation from the Faraday and electric Gauss equations for monopoles, though obviously OR without citations). The equations are:

$\partial _{\mu }F^{\mu \nu }=\beta J_{\mathrm {electric} }^{\nu }$

$\partial _{\mu }\star F^{\mu \nu }={\frac {\beta }{\gamma c}}J_{\mathrm {magnetic} }^{\nu }$

$\star F^{\mu \nu }=G^{\mu \nu }$

in more detail the vector set is:

$\nabla \cdot \mathbf {E} =\alpha \rho _{\mathrm {electric} }$

$\nabla \cdot \mathbf {B} ={\frac {\beta }{\gamma }}\rho _{\mathrm {magnetic} }$

$\nabla \times \mathbf {E} +\gamma {\frac {\partial \mathbf {B} }{\partial t}}=-\beta \mathbf {J} _{\mathrm {magnetic} }$

$\nabla \times \mathbf {B} -{\frac {\beta }{\alpha }}{\frac {\partial \mathbf {E} }{\partial t}}=\beta \mathbf {J} _{\mathrm {electric} }$

where:

Units	α	β	γ
SI	1/ε0	μ0	1
Gaussian	4π	4π/c	1/c
Heaviside-Lorentz	1	1/c	1/c

Any objections to inclusion (aside from those who think monopoles are "impossible"!)? Of course we can change the notation for α, β, γ to something less confusing with notation for the Lorentz factor... Maschen (talk) 06:41, 22 September 2012 (UTC)

The standard vector form (the second set of equations) is already adequately covered. The tensor form may be of interest, but to try and accommodate all systems of units is rather clumsy. — Quondum 11:14, 22 September 2012 (UTC)

The tensor (covariant) form is what I was emphasizing - obviously the vector equations are included in the article. We can just use the Gaussian and SI units for the appropriate sections, as you suggest. Maschen (talk) 11:27, 22 September 2012 (UTC)

Can you please explain how this contribution: "== Covariant form of Maxwell's monopole equations? == can help to explain the question of existence or non-existence of "magnetic monopoles?94.113.59.212 (talk) 13:07, 24 September 2012 (UTC)

It cannot. It is merely a mathematically equivalent rephrasing of existing formulae. — Quondum 13:49, 24 September 2012 (UTC)

Yes - exactly as Quondum says; the proposal here is for those interested in the covariant form of Maxwell's monopole equations, for use in special relativity for instance. They "explain/question/prove" nothing and no intension is made to do so. Maschen (talk) 18:07, 24 September 2012 (UTC)

New section: Duality transformation

Very nicely done (by ‎Sbyrnes321), but there seems to be no mention of the U(1) symmetry, if that is the symmetry group... Also maybe it could be a 2nd level section? Maschen (talk) 19:36, 24 September 2012 (UTC)

If it's ok I will align the formulae. Maschen (talk) 19:39, 24 September 2012 (UTC)

Proven Existence in Modern Physics

I've never worked this before, so I apologize beforehand if I mess this up. I've found these two intriguing articles and moves magnetic monopoles into the realm of reality (albeit not a very practically useful one at present; still better than hypothetical). I'm not qualified to provide any real text submissions/editions to Wikipedia, so if someone would be kind enough to appropriately create and word the new section, it'd be appreciated.

http://www.nature.com/news/2009/090903/full/news.2009.881.html http://www.sciencedaily.com/releases/2009/09/090903163725.htm http://arxiv.org/abs/0908.3568v2 — Preceding unsigned comment added by 111.68.108.82 (talk) 05:02, 1 March 2013 (UTC)

I can't find those articles you link to above in the references (may have missed), but spin ices are already discussed in this section and linked to. I'll put these links in the external links section. Thanks, M∧Ŝc²ħεИ_τlk 10:32, 1 March 2013 (UTC)

"Nearly 85 years after pioneering theoretical physicist Paul Dirac predicted the possibility of their existence, an international collaboration led by Amherst College Physics Professor David S. Hall '91 and Aalto University (Finland) Academy Research Fellow Mikko Möttönen has created, identified and photographed synthetic magnetic monopoles in Hall's laboratory on the Amherst campus. The groundbreaking accomplishment paves the way for the detection of the particles in nature, which would be a revolutionary development comparable to the discovery of the electron." http://phys.org/news/2014-01-physicists-synthetic-magnetic-monopole-years.html Thangalin (talk) 10:17, 30 January 2014 (UTC)

@Thangalin -- The "detection of the particle in nature" is what this wikipedia article is about, and it hasn't happened yet. The David Hall work is not it. Otherwise they would have said "the accomplishment is a revolutionary development comparable to the discovery of the electron..." rather than saying "the accomplishment paves the way for..." (And by the way, "paves the way for" is actually a euphemism for "does not make any progress towards".) The David Hall article is quite deceptive, and the press is gullible ... See discussion below. --Steve (talk) 17:24, 31 January 2014 (UTC)

New monopole demonstration videos

Here we have a demonstration of monopoles being created; and here is a more thorough demonstration of their monopole nature (a compass is circulated completely around the object, showing that it has only a south pole and no north).

Is it the opinion of the editors of this article that these videos are a hoax? 71.219.201.182 (talk) 20:59, 18 May 2013 (UTC)

It must be a hoax, as no "magnetic monopoles" do exist ! I shall try to find out where the dupery is. 62.245.107.32 (talk) 13:30, 13 July 2013 (UTC)

Wow, that comment sounds a lot like "Mr. Galileo's claim of moons orbiting Jupiter must be a hoax, as Jupiter does not have moons!" 75.163.204.203 (talk) 13:45, 23 July 2015 (UTC)

The video seemingly demonstrating the "creation south poles" on one drip tray, and "north poles" on the other by passing the drops of melted metal through two coils of wire is nothing but fake abusing the visual similarity with Lord Kelvin Generator (see Wikipedia). Prove of the fake: 1. In "the demonstration" video no connection of the coils to electric current source is shown, so no magnetic field which should influence the melted metal passing through the coils exists. 2. The fact, that the needle of the compass when moved under the tray points always in the direction to the tray is no proof of "monopole". Such an effect has a small permanent magnet pasted to the bottom underneath the tray.(notice, that the compass was moved only under the tray, not also above it, where the magnetic field has opposite direction). The video is nothing but poor fake.62.245.107.32 (talk) 07:05, 14 July 2013 (UTC)

In popular culture

Many years ago this article had an "In popular culture" section. It was entirely deleted, which is a pretty common fate for these kinds of sections -- See WP:POPCULTURE! But now it has been recreated and is steadily growing.

For what it's worth, here is the old version, immediately before it was deleted: [3].

I personally think that these sections can be nice when they are done well (not a list), but they tend to get flooded with trivia, and it's so much trouble to maintain that it's better to delete the section altogether. --Steve (talk) 17:11, 12 November 2013 (UTC)

It has been deleted. M∧Ŝc²ħεИ_τlk 21:09, 5 January 2014 (UTC)

Discovery

The new paper is: Observation of Dirac monopoles in a synthetic magnetic field

in Nature

http://www.nature.com/nature/journal/v505/n7485/full/nature12954.html

This is just... they exist?? arghhhhhhhh — Preceding unsigned comment added by Waylah (talk • contribs) 14:11, 30 January 2014 (UTC)

Magnetic monopoles can theoretically be of two types: having electric charge, or not having electric charge. It would be good to clarify which kind the recently-discovered ones are.Anythingyouwant (talk) 17:17, 30 January 2014 (UTC)

No, they don't exist, not as particles. The discovery of a true magnetic monopole would be a news event no less significant than that of the Higgs boson. —Quondum 05:54, 31 January 2014 (UTC)

The Nature paper set up a chamber full of protons, neutrons, electrons, photons. They did not discover any new elementary particle besides those. The press descriptions from this paper are extremely misleading, bordering on dishonest. --Steve (talk) 13:38, 31 January 2014 (UTC)

In the article is clear that authors used superfluid helium, not BEC condensed matter and surely not decoupled protons, neutrons and electron. Furthermore in the presentation there is a clear phrase: "These real-space images provide conclusive and long-awaited experimental evidence of the existence of Dirac monopoles". The question is only "are they right"? --Pippo skaio (talk) 16:04, 31 January 2014 (UTC)

The paper is shamelessly sensationalist in its description. I am surprised (and disgusted) that Nature published the paper without demanding a rewording. It is not only the popular press at fault here. Read the text carefully: they do make it clear that no actual fundamental particles were created, and no true monopoles created. There is nothing new over the spin ice "magnetic monopole", except that the medium and detailed mechanism is different. So, if you are asking about whether they are right about discovering what physicists refer to as a magnetic monopole, i.e. what is described in this article (i.e. Magnetic monopole), the answer is a very clear "no". —Quondum 16:26, 31 January 2014 (UTC)

Pippo -- I never said the protons, neutrons and electrons were "decoupled" -- obviously they are interacting with each other!! I just said that there are not other elementary particles in the chamber besides those (plus photons, gluons, gravitons, etc.). I was wrong before: It is not just the press release that is deceptive, but also the paper itself. You can find more clarity by reading Nature's own description of this article, in the very same issue. The title is "Quantum cloud simulates magnetic monopole" not "Quantum cloud contains magnetic monopole". Quote from the article: ""There’s a mathematical analogy here, a neat and beautiful one. But they’re not magnetic monopoles," Bramwell says. "You have to do a sideways jump — a bit of lateral thinking in your mind — to project these onto magnetic monopoles,"" --Steve (talk) 17:07, 31 January 2014 (UTC)

Domains?

Should the article perhaps contain a brief explanation of why monopoles are not possible within normal matter? Perhaps with reference to magnetic domains, and/or to magnetic moment as an extensive property? (Please forgive any vocabulary glitches; my degree is in chemistry, not physics) DS (talk) 14:57, 18 February 2014 (UTC)

It sounds like you're discussing this section...

I don't understand the relevance of magnetic domains. A single-domain magnet is not a monopole, and a multi-domain magnet is not a monopole either.

I don't understand the relevance of "Magnetic moment as an extensive property". Magnetic moment is short for magnetic dipole moment, which is irrelevant because the issue under discussion is magnetic monopoles not dipoles. Right?

I guess it could be worthwhile to say something like "As with electric charge, the magnetic charge of a system is the sum of the magnetic charges of its component particles, i.e. all the electrons and protons etc. in the system. Since the magnetic charge of each of those particles is zero, the magnetic charge of any system made of ordinary matter is zero." That sort of discusses extensive-ness but I don't know if that's what you had in mind... --Steve (talk) 15:51, 18 February 2014 (UTC)

Why is "magnetricity" not mentioned in this article?

This article is currently the target of a redirect of Magnetricity, and yet does not appear to be mentioned, let alone defined, explained, or bolded as a redirect. I found a layman's description of this term (which has apparently been gracing the headlines of both science and pop-sci articles for years) as "the magnetic equivalent of electricity", which sounds fascinating without being at all illuminating.

Someone apparently believes that "magnetricity" or its related concepts are discussed here. Could that someone or other informed party make this connection explicit? Thank you in advance. ~ Jeff Q (talk) 22:33, 12 March 2014 (UTC)

I just added it in bold in the appropriate place.

Another choice for that redirect is Spin_ice#Spin_ices_and_magnetic_monopoles. I don't know which is better. Neither is a very thorough description. --Steve (talk) 23:16, 12 March 2014 (UTC)

I wonder how the evident nonsenses about nonexisting "magnetic monopoles" can be "upgraded" by new expressions, like "magnetricity". All "electromagnetic phenomenon" in the universe are explaned by properties of electrons. Exisitence of "magnetic monopoles" as elelemntary particles is not "needed", so why are they supposed to exist and searched for? Can someone explaine ?

14:14, 18 November 2014 (UTC)94.113.58.149 (talk)

The term "magnetricity" is related to the so-called magnetic monopoles in spin ice, which are not hypothetical, they have actually been observed. But they're not real magnetic monopoles either. Why did somebody invent the term "magnetricity"? I don't know, maybe it sounds cool. I think that using the term "magnetricity" for spin ice is better than using the term "magnetic monopoles", because the latter is (in my opinion) deliberately misleading.

Your other question is, if we have never seen experimental evidence of magnetic monopoles, why do we bother talking about them and writing articles and books about them? The answer is, theoretical physicists spend a lot of time predicting whether or not things exist that have never been seen. Why do they do that? Because maybe we'll see them someday if we know where to look, and maybe they help explain how the universe works. If you find that kind of thing to be a stupid waste of time, then you shouldn't become a theoretical physicist. It may seem like a waste of time to you, but historically a lot of wonderful things have come from theoretical physicists making predictions about things that had not yet been seen experimentally. --Steve (talk) 17:31, 18 November 2014 (UTC)

Hello Steve. here I am again with my doubts about any sense of looking for "magnetic monopoles" or "magnetricity". May be it is so because I am not, and I even do not want to be, a theoretical physicist, looking for something the nature did not find to be necessary for the existence of the universe. And so it is with the "magnetic monopoles". Evidentaly the nature does with electrones, without "magnetrons". It makes without the kind help of theoretical physicists living on a planet in the universe. Nevertheless they, the physicists, should be thanked for their good will.94.113.58.149 (talk) 10:53, 4 December 2014 (UTC)

Claim

A magnetic monopole is a hypothetical elementary particle in particle physics that is an isolated magnet with only one magnetic pole (a north pole without a south pole or vice versa).[1][2] In more technical terms, a magnetic monopole would have a net "magnetic charge". In fact, all electro-magnetic phenomena are the result of natural properties of electrons, depending on their relative velocity. When the velocity, relative to the observer is zero, he observes what we call electrostatic field. The electric charges are attracted/repelled by a force given by Coulomb law. If the same electric charges are moving the forces are given by Lorentz law, depending on their relative velocity, without any other “elementary particles with magnetic properties - magnetic monopoles”. That is why they can never be found.

This article has already been two times deleted!!! Why?! 78.45.207.57 (talk) 14:53, 6 May 2015 (UTC)

The reason for deletion was given in the View history tab, which you might not be looking at. Please review WP:FORUM. You should also use the "New section" tab to start a new topic, not append an unrelated post to an existing thread – this helps in including a heading for the new thread etc. —Quondum 15:30, 6 May 2015 (UTC)

I can not agree with the allegation that the „append is unrelated post to an existing thread“. It concernes the question of existence of „manetic monopoles“ as elementary paricles, which is discused in the article! 78.45.207.57 (talk) 16:22, 6 May 2015 (UTC)

The thread that I referred to is the one above: "§ Why is "magnetricity" not mentioned in this article?", to which you appended your post, and to which your post does not seem to relate. With that I was merely pointing out show to use talk pages, though you seem to have misunderstood me. —Quondum 18:07, 6 May 2015 (UTC)

I really do not understand your argumentation. I see no reason to change my view on the problem. What I have written in my append is true and relevant,78.45.207.57 (talk) 18:50, 6 May 2015 (UTC)

It is true that bar magnets, and electromagnets, and every other magnetic phenomenon that humans have ever observed, all have absolutely no involvement of magnetic monopoles in how they work. If you believe this (and it sounds like you do), then you are correct about that. Everyone else believes it too. In my opinion, this wikipedia article explains this fact very clearly. I find that the article states this fact over and over and over again, at least 10 or 15 times (e.g. the top figure and its caption, the first sentence, the second paragraph, Section 1.1, and Section 2). If I had to guess, I would say that the article is so clear about this point, that nobody reading this article could possibly wind up misunderstanding this point. But who knows, maybe I'm wrong. Do you think that the article is unclear or confusing on this point? If so, how would you suggest making it clearer? Thanks in advance, --Steve (talk) 23:34, 6 May 2015 (UTC)

The article "Magnetic monopole" begins:

A magnetic monopole is a hypothetical elementary particle in particle physics that is an isolated magnet with only one magnetic pole (a north pole without a south pole or vice versa).[1][2] In more technical terms, a magnetic monopole would have a net "magnetic charge". Modern interest in the concept stems from particle theories, notably the grand unified and superstring theories, which predict their existence.[3][4] Magnetism in bar magnets and electromagnets does not arise from magnetic monopoles, and in fact there is no conclusive experimental evidence that magnetic monopoles exist at all in the universe.

So we know that ".... there is no conclusive experimental evidence that magnetic monopoles exist at all in the universe." In addition, we know the Maxwell's theory of electromagnetic phenomena which explains all of them with existence of electrical charges, in practice mainly electrons, without some "special elementary particles! called magnetic monopoles. Why then should we assume the existance of such particles, and try to find them? Can you explain why?

In my append I state the fact that the search of "magnatic monopoles" is fruitless.78.45.207.57 (talk) 00:28, 7 May 2015 (UTC)

If you are the same person from Czechoslovakia, who has come back to this page for almost three years to say that monopoles cannot be found or it's pointless to search for them, then please desist. You keep demanding to change the article along these lines, and it's using up other editors' time (not mine). Thanks, M∧Ŝc²ħεИ_τlk 09:59, 7 May 2015 (UTC)

Dear И_τlk, I do not demand to change the article. I only publish the fact that the "magnetic monopoles" do not exist in the nature and therefore can never be found. 78.45.207.57 (talk) 11:51, 7 May 2015 (UTC)

The sole purpose of this talk page is for improvement of the article, and most definitely not for publishing anything. Hence, by your admission, you concede that your post does not belong here. This has been pointed out to you several times. The original deletion of your post was appropriate. If you wish to publish anything, Wikipedia is not the place to do it. You are also not educating any of the editors here: we are all fully aware of the point you are making, so all you are doing is airing your opinion of "Why bother?" to people who have a far deeper interest in physics than you display. —Quondum 13:06, 7 May 2015 (UTC)

I understand finaly: The reality that there are no „magnetic monopoles“,- the fact revealing that the talk about these not-existing „elementary particles“ is the talk about nothing, may not be published on these pages.78.45.207.57 (talk) 16:16, 7 May 2015 (UTC)

Evidently, magnetic monopole hunt is finished. No magnetic monopole in the universe found. Amen78.102.206.211 (talk) 16:20, 28 October 2015 (UTC)

Rewrite needed

Hello!

@Quondum, Maschen, and Sbyrnes321: I've read the article and while parts are good there are a lot of errors creeping in. In particular conflating philosophical considerations with scientific ones. The idea that the discovered monopoles are not "fundamental" is reductionist ideology and it is not a scientifically testable idea or concept. There is no physical measurable property, part of the electromagnetic field's ontology, that can tell you whether you have finally found the ultimate elementary particle. In Quantum spin liquids and the Fractional quantum Hall effect "elementary particles" ( i.e. the electrons) become fractions of themselves - in this case it is the electrons that are the quasiparticles. This is due to a deep mathematical distinction between linear and nonlinear systems. We know know that fundamental aspects of nature can not only be described in terms of symmetries and broken symmetries (Noether) but in terms of topology (The subject of the 2016 Nobel Prize). In fact they form a duality, I'm recently been working on the Montonen–Olive duality article (not perfect and a lots still to do on it but...} it should hopefully give you a better overview as to why point particles (described by Noether charges) and topological solitons (described by topological charges) can be interchanged depending on the duality.

The Dirac monopole contains a point singularity. It is important to note that Dirac was only able to derive his equation for the electron by adding a non-commutative quantities to the equations; it was these non-commutative quantities that turned out to describe the physical spin of a particle. U(1) is a commutative group and the fact it need to contain a non-commutative element for the formal constancy for Dirac's equation (and Maxwell's) is indicative that a higher dimensional generalization allowing this singularity to be removed. This is the 't Hooft–Polyakov monopole and are equivalent to what has been discovered in experiments. Saying, as the article does, that a "fundamental" monopole will violate gauss's law is like saying we will discover a square triangle, it's not going to happen! It is in fact the act of setting ∇⋅B = 0 which restricts monopoles from existing by stating that only divergence-less solenoidal magnetic fields can exist (no nonlinear solitons allowed!)

I'm redrafting the page here - its currently full of mistakes and not even half done - but would welcome your comments on the above points in the paragraphs above.

--Sparkyscience (talk) 20:42, 20 February 2017 (UTC)

You've pinged me, but I would not add value here. —Quondum 22:24, 20 February 2017 (UTC)

@Quondum: No worries. I saw your comment on the Nature article above and that you're pretty active compared to others on the revision stats so thought it important to get your perspective before I start chopping up the article in any big way.--Sparkyscience (talk) 23:20, 20 February 2017 (UTC)

Good call to ping people. I've largely withdrawn from editing physics articles. I do not have your courage. —Quondum 00:40, 21 February 2017 (UTC)

I'm trying to understand what you're saying. The article is kinda contrasting GUT monopoles with spin ice monopoles by saying that the former is a real elementary particle magnetic monopole and the latter is merely a quasiparticle (kinda fake) monopole. But you're saying that this is misleading because the GUT monopoles are also quasiparticles in the high-energy theory. Is that what you're saying? If so, I'm OK with changing a few words here or there to avoid being technically inaccurate.

But you need to understand where that came from. For many decades, people like Alvarez and Cabrera and many others were searching for magnetic monopoles. Then these spin ice and other papers came along and the popular press reported that the long search is over, they found literally exactly the thing that Alvarez and others spent so long looking for. Would you agree with me that this popular press account is misleading?

I am willing to believe that there is no principled mathematical distinction between a quasi-particle in condensed matter physics (e.g. a hole) and the elementary particles of the effective field theory that emerges from a more accurate high-energy particle physics theory in the low energy limit (e.g. the W bosons that emerge as low-energy excitations in electroweak theory). But there's a giant distinction in practice!! Here on Earth, it is very easy and practical to take your system and change it so that the hole excitation loses its identity (melt the solid, chemically react it, etc.), but we cannot create any system that is so hot that the W boson ceases to be an appropriate low-energy excitation to base your analysis on. (Requires temperature of 10^15 K...).

So here on Earth, where we can and should draw a practical distinction between "the kinds of particles that particle physicists talk about", vs. "quasi-particles in condensed matter". This is currently an article about the intersection of the former category with magnetic monopoles. It could be converted to cover both, but I remain to be convinced that this is wise. I would prefer two separate articles. (Monopoles in spin ice does not have its own article to speak of, last I checked.)

I tried to read your draft text. I find it very confusing and hard to read—and I am way more qualified than the typical Wikipedia reader (including this particular article). It's too abstract. People understand better when you start from concrete things and work your way up to abstract things. It also assumes way too much background. There are sci-fi novels that use magnetic monopoles as plot points. People read them and then look up "magnetic monopole" on Wikipedia. These people have never heard of a gauge theory or non-trivial topology or anything like that. They'll be totally lost!

I find that it reads like a review article or textbook chapter, not an encyclopedia article. For example, I have a hard time seeing how a "quaternionic electromagnetism" section should be more than 1 paragraph. If there's more to say than that, it should be its own separate article. Same with many other things in the draft. It's just way more detail than you can expect people to absorb, too many steps removed from magnetic monopoles, and not properly laid out with the most concrete and non-technical stuff first.

(Please excuse any technical mistakes in this response, my QFT is rusty.) --Steve (talk) 03:41, 21 February 2017 (UTC)

I'm also confused by your statement about ∇⋅B = 0. My understanding is that (A) if you draw a sphere around a GUT monopole, and calculate the flux of B through the sphere, it's nonzero. And (B) the analogous statement is false for a spin ice monopole (unless you replace B with H). Do you agree with (A) or (B) or both or neither? (I'm pretty sure I can find textbooks and other reliable sources backing up (A).) --Steve (talk) 11:55, 21 February 2017 (UTC)

@Sbyrnes321:Apologies for getting my wires crossed here: My understanding is that in Ray et al. (2015) a Dirac monopole with no connecting nodal line was confirmed. The experiment the previous year in Ray et al. (2014) does not contain topological point defect in the order parameter and is "almost" a monopole like those in a spin ice (though even here i disagree that these "almost" monopoles can be defined in terms their of "real" particles that surround them. Their existance is distinct. In this regard the Nature articles like this one were not misleading...) The monopole is singular and embedded in U(1) and thus a Dirac version. The 't Hooft–Polyakov monopole, which i thought they found, is U(2) and can be non-abelian (this is where all the maths gets more complex then standard vector analysis and requires gauge theory), here there seems to be a few interesting papers on these in topological insulators....

In answer to your question: Ray et al. (2015) experiment will (1) violate ∇⋅B = 0 as there is no connecting node and is embedded in U(1) (2) it is not a spin ice analogue.

The central point is: Have “fundamental” monopoles been discovered? The only difference i can see here is that the means of discovery are topological rather then by symmetry breaking. Topology is just as fundamental an aspect as geometry. The idea of discrete categorisation into what is "fundamental" is embedded in the idea of reductionism, the point I was trying to get across earlier is that the monopole soliton is just as fundamental as a particle. Roderich Moessner who was part of the team that discovered monopoles in spin ices Castelnovo et al. (2008) explicitly warns against the dangers of reductionism in this piece here and in a journal article here. There seems to be many many different types of possible magnetic monopoles (i.e dyons, anyons etc...) in the same vien there are many different "types" of electron in things like quantum spin liquids.

Reductionism is is hugely successful ideology and which has been the driving force behind the amazing success with the Standard Model. But it has limits: The core tenant of the idea is that we can reduce things into individual fundament parts and if we understand the functioning of these individual parts we can understand the functioning of a whole system; there is no mode of existence which cannot be defined as a composite function of the underlying parts. This works very well in linear situations, as we can isolate variables and define them analytically and make predictions. It does not work when we enter the realm of nonlinearity, because we cannot separate the variables. We cannot define an emergent structure as a linear function of its parts, the whole and the parts are one in the same. Monopoles do not fit into a linear paradigm.

Let us quickly define "fundamental" particles as those discovered in accelerators. If thats our definition, then it definition raises questions: Have we really discovered fundamental particles called quarks? If they only exist as confined pairs, will we ever “reduce” them to something more fundamental?....will we actually gain any knowledge by doing this process? are quarks not a form of quasiparticle? It turns out quarks can be viewed, in some sense, as monopoles(!) with fractional charges There is nothing “fake” about quasiparticles they are just as real as fundamental particles, our best thoeries in physics are not to do with particles or parts but fields: contious forms where everything is connected. When the field is homogenous it behaves linearly, when it isn't it doesn't. The fundamental laws of nature and the particles are can or cant exist are determined entirely by the geometry and topology of the field.

How would you tell the difference between a "mathamatical analogue" and a “real” particle? You can’t! because all properties we can assign physical meaning to are based the objective mathematics alone. The rest is subjective. The idea that we haven’t discovered the monopole is untenable given it behaves exactly as the model predicts. That being said i appreciate both perspectives, the article perhaps should strike more of the tone found in the Majorana fermion article?--Sparkyscience (talk) 18:43, 21 February 2017 (UTC)

Let's put on hold the discussion of fundamental particles and reductionism. I shouldn't have gone off on that tangent. The crux of the issue is very very simple. Draw a sphere. Calculate the flux of B. If it's nonzero, then there is a magnetic monopole inside the sphere. That's the definition currently used in the article, and I strongly believe that it is the traditional and best and most common definition of "magnetic monopole".

If that's the definition, then I think the article (as currently written) is correct: None of the condensed matter experiments (spin ice, Ray et al., etc.) have shown the existence of magnetic monopoles.

Ray et al. 2015 found a topological defect that acts as a source for a field, but the field in question is NOT the magnetic field B. They call it a "synthetic magnetic field", a bizarre and unnecessarily confusing term. It is the BEC's spin-1 order parameter, or something like that. The math is similar to the GUT magnetic monopoles, but it is not a magnetic monopole, because if you draw a sphere and calculate the flux of B, it's zero, just like normal. (The flux of the spin-1 order parameter through the sphere is nonzero. That's all they're claiming!)

The spin-ice monopoles are likewise not monopoles of the magnetic field B. We have plenty of sources already in the article for the claim that spin ices contain no B source. In fact, take the arxiv paper you linked, which you said was written by one of the spin-ice people [4] The paper explicitly says that B is divergenceless. It also says that the (super-misleadingly-named) Dirac strings are observable, and that the systems in question "manage to emulate Maxwell electromagnetism". Note that they say emulate, not modify!! There is only one real B-field. You can spend your life finding field after field that "emulates" B or is a "synthetic" B or whatever, but if it's not the real B-field, then it's not the basis for real magnetic monopoles!

But really it's pretty obvious: Every electron and proton and neutron has zero contribution to the divergence of B, and therefore, by the superposition principle, no possible condensed-matter configuration combining these three ingredients could have sources of sinks of B either—no matter how gloriously complicated its many-body wavefunction is, and no matter how nonlinearly the system behaves. Really, the math is airtight: Take an arbitrary many-body wavefunction, consisting of protons and neutrons and electrons in any configuration whatsoever, and you can calculate the expectation-value divergence of B, and it's zero. Doesn't matter whether the low-energy excitations are anyons or whatever.

Please let me know where you agree and disagree. :-D --Steve (talk) 03:45, 22 February 2017 (UTC)

@Sbyrnes321:I think we're getting somewhere: On emulate vs. modify point, this source here in Physics Today states "Maxwell's laws of electromagnetism are dramatically altered by an additional topological term". To my mind the word "emulate" is doublespeak and sounds like an immaterial virtual reality: surely the electromagnetic field is either modified or it is not, we can't have the laws of the familiar "real" electromagnetic field running in parallel with the rules of a concocted "emulated" field in the same area of space at the same time: If an electromagnetically interacting particle is traveling through such an area where we have created an "emulation"... which laws of electromagnetism does it follow? both?! Clearly there is only one electromagnetic field and its rules are modified depending on its topology i.e. it may be more general then that usually described in the U(1) case. The description that it is "synthetic" is empty verbiage, it is just as real as the surrounding electromagnetic field in other areas of more normal space...

This paper in Science by Qi et al. (2009) who wrote the above article in Physics Today is particularly enlightening:

“ Since we started with the Maxwell’s equation, which includes $\nabla \cdot B=0$, the magnetic flux integrated over a closed surface must vanish. We can indeed check that this is the case by considering a closed surface, for example a sphere with radius a, which encloses a topological insulator. Inside the closed surface, there is not only a image magnetic monopole charge, but also a line of magnetic charge density whose integral exactly cancels the point image magnetic monopole. However, when the separation between the electric charge and the surface, d, is much smaller than the spherical radius a, the magnetic field is completely dominated by the image magnetic monopole, and the contribution due to the line of magnetic charge density is vanishingly small. Therefore, we propose here to experimentally observe the magnetic monopole in the same sense as we can experimentally observe other fractionalization, or deconfinement, phenomena in condensed matter physics. In any closed electronic system, the total charge must be quantized to be an integer. However, one can separate fractionally charged elementary excitations arbitrarily far from each other, so that fractional charge can have well defined meaning locally. Similar situation occurs in spincharge separation. While the total charge and the total spin of a closed system must be linked to each other, spin and charge can occur as well separated local excitations. In our case, as long as d is much smaller than the radius of curvature of a topological surface a, the local magnetic field is completely determined by a single image magnetic monopole. ” — Qi et al. (2009), pp. 2–3

My reading is that outside a closed sphere where the field is homogenous and normal Maxwells laws apply, ∇ · B = 0, but inside this sphere the non-trivial topology prevents us from subdividing it further via simple vector analysis; the monopole is the result of more complex mathematics required of gauge theory (Witten 1979). Now in the above sources we are talking about a 't Hooft-Polakov monopole, the Ray et al. (2015) is a Dirac monopole which apparently is singular (I'm not sure how) but i imagine that the flux of the synthetic magnetic field is canceled out elsewhere such that any closed linear system will show ∇ · B = 0. But to state that somehow these particles that arise within this more complex "synthetic" space are mathematical fictions with no physical existence is clearly not true - they is really something there... and they are not dipoles...and they are electromagnetic. Surrounding this complex space with homogeneous space enforces ∇ · B = 0 and the flux of monopole is cancelled out...but we can imagine a universe where the EM field is nearly always topologically non-trivial, where monopoles are abundant and only small spheres of synthetic homogeneous space exist: In these strange areas of space we think we have discovered the elusive "electron" that explains the magnetic charge of the monopole, but we conclude that since its charge is canceled out by fractional monopoles (quarks), its only a fake kind of particle and not a real one... this admittedly completely contrived overly simplified example hopefully underlines the nature of duality and the distinction between what is synthetic and what is not is merely relative and arbitrary.--Sparkyscience (talk) 14:48, 22 February 2017 (UTC)

I'm not sure you understand the term "synthetic magnetic field" correctly. (Again, in my opinion, the term is extremely and maybe even deliberately misleading.) The so-called synthetic magnetic field is a misleading name for the spin-1 BEC order parameter quantum field (or something like that). Let's go one step at a time. We learn in QFT that there are many distinct quantum fields in the world. There is a positron field, there is a neutrino field, there is an electric field, there is a magnetic B field (the latter two intimately related to the photon field), etc. These are not arbitrary but have fixed identities by convention. If I point at the positron field and tell you it's actually the neutrino field, you should tell me I'm nuts. Similarly, if Ray et al. take a spin-1 BEC order parameter quantum field and say it's actually the magnetic field, we should say, "no it isn't". The thing is a real quantum field, it's not a mathematical artifact, it's a fascinating and important quantum field, and I have nothing against it. But it is not the magnetic B field. (Indeed, this is indicated by the word "synthetic".) Do you agree that the "synthetic magnetic field" is not the actual magnetic B field? If so, can we acknowledge that sources or sinks of the "synthetic magnetic field" are not actual magnetic monopoles?

I agree that B is not well defined right at a GUT monopole (a.k.a. 't Hooft-Polyakov monopole). But draw a sphere around the monopole, far enough away that B is well defined again, and the B flux through the sphere is nonzero. That's why I phrased it in terms of flux rather than divergence in my second post. I disagree with your suggestion that B may not be well defined in a condensed matter system, in a way that is analogous to what happens at a GUT monopole. I think that B is universally well defined and well behaved in any condensed matter system. In GUTs, electromagnetism emerges from a more complicated configuration of fields, and the emergent description of electromagnetism (i.e. the QED we know and love) is universally valid except (A) at very very very high energy where those other fields can get excited, or (B) at those special locations (probably less than one per galaxy) where there is a knot (nontrivial topology) in those normally-inaccessible-and-irrelevant GUT fields. There is nothing you can do in a condensed matter laboratory that disrupts the inaccessible GUT fields, and therefore, there is nothing you can do to insert anything new into the normal laws of electromagnetism governing E and B, with their normal trivial topology. Right? --Steve (talk) 16:25, 22 February 2017 (UTC)

@Sbyrnes321:I really appreciate you taking the time and patience to go back and forth on this -I think its really important to get this right and will clear things up for myself and future editors. Great work! You've said you believe the "synthetic magnetic field" referenced in Ray et al. (2015) to be a "spin-1 BEC order parameter quantum field" or something to that effect, whatever it is, you claim that distinct from the real B field which is well defined and does not change. So what really is this strange "synthetic magnetic field" referenced and is it misleading? In Ray et al. (2014), p. 2 they elaborate what synthetic E* and B* fields are, referencing the review article by Dalibard et al. (2011). Given this review article is in Reviews of Modern Physics and has apparently been cited over 1000 times by Google Scholar I'm going to take what is in this review says about "synthetic magnetic fields" as gospel. As I understand, the B field is usually defined by a scalar potential A, when A cannot be set to zero by a gauge transformation, it gives us things like the Aharonov–Bohm effect and Berry phase. The review article defines an "artificial (synthetic) magnetic field" in terms of effects similar to AB effect stating on p. 2 "Therefore the quest for artificial magnetism amounts to realize situations where a neutral particle acquires a geometrical phase when it follows the contour C [...] This phase has a geometric origin and does not depend on the duration needed" Can we use simple vector analysis to understand these effects? No because in general they are path dependant, noncommutative phenomena. So synthetic B* field is still very much the B field but it is no longer topologically trivial due to a gauge potential with non vanishing curl. It is potentials that define E and B, so if strange things happen to the potentials strange things will happen to the E and B field. I'm pretty sure what i said in my previous comment is still correct...--Sparkyscience (talk) 18:59, 22 February 2017 (UTC)

OK let's talk about Dalibard et al. [5]. It has lots of citations, it is in a reputable journal, and I am confident that it is technically sound. But it's not discussing the magnetic B field. Did you read the abstract?

"When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium we present the physical principles at the basis of this artificial (synthetic) magnetism..."

Note the key words like "mimic" and "Lorentz-like force". The text of the paper is similar. In the systems they discuss, there are phenomena that resemble magnetism, but are not actually magnetism. There's nothing inherently wrong with trying to learn about magnetism by studying something else which is not magnetism but which resembles magnetism. ...As long as we don't get confused about what we're actually doing! :-D --Steve (talk) 19:54, 22 February 2017 (UTC)

C'mon :-) ...The order parameter is the virtual thing here - it does not represent any real space it is just an abstraction like a Phase space to help understand classification of the system - it can be made of any variable or field needed! You said that "artificial magnetic field" was almost deliberately misleading... I am confident the RS states that what they mean by artificial magnetic fields are those that arise when the potentials cannot be set to zero by gauge transformation. And i can understand why they want to call artificial given it arrises in limited circumstances...but that doesn't mean it is not real. If its not the definition of what artificial magnetic field is...then what is?! The RS doesn't mention the word "order parameter" once(!)... Are you basically saying that the AB effect is not a real electromagnetic effect? That when a particle experiences such an effect it is not the result of EM... but the result of some synthetic illusion by other non-EM forces? Or that the B field is not defined by the potentials??...--Sparkyscience (talk) 20:48, 22 February 2017 (UTC)

The exact meaning of the "artificial magnetic field", at least in section 1, is given by Eqs. (7-8) and the text after Eq. (2). There is an atom in a strong laser field, and the "artificial magnetic field" is a slightly complicated function of the laser frequency, phase, and intensity. The actual magnetic field is very very different than that: It is mainly oscillating back and forth at hundreds of terahertz (as with any light wave) (perhaps with a small contribution from the magnetic moment of the atom itself).

Both the artificial magnetic field and the real magnetic field are determined by the laser frequency, phase, and intensity, but that does not mean that the two are the same thing. Look at the formulas. If the laser phase and/or intensity is the same everywhere, the artificial magnetic field is zero, but the real magnetic field is still oscillating back and forth at hundreds of terahertz. If you start with a constant laser intensity and frequency profile, then you decrease the intensity everywhere, but in an inhomogeneous way, it obviously reduces the RMS real magnetic field everywhere, but greatly increases the magnitude of the artificial magnetic field! I can go on and on. They are simply different fields.

I am not arguing that the "artificial magnetic field" is not a real field, merely that it is not the real magnetic field. The motion of the two-level atom in the laser field is indeed driven by electromagnetism (certainly not by the strong or weak or gravitational force!!), but again, the "artificial magnetic field" is a complicated function of the real electric and magnetic field.

If I were an experimental geologist, I might do an experiment using a diamond anvil cell that is supposed to imitate conditions in the Earth's mantle. I might call my apparatus an "artificial mantle" or "synthetic mantle". It is a real environment, and the experimental results is really useful for understanding the mantle, but it is not literally a mantle!! Is the term "artificial mantle" or "synthetic mantle" misleading? In this context, nobody would be dumb enough to think that my apparatus is literally a mantle, so it's probably OK. But still, I think those terms are not the clearest. Something like "imitation mantle" or "mantle-like environment" would be clearer, I think. :-D --Steve (talk) 14:35, 23 February 2017 (UTC)

@Sbyrnes321:I think what you're trying to say is that you finally agree that the "synthetic magnetic field" is a indeed actually a magnetic field (not a "order parameter quantum field") that interacts with matter magnetically? If i label one half of the field left and the other half right and this labeling helps me calculate things better then thats fine....if you divide it up another way we can disagree forever over the definition but if both models predict the same thing who cares....the underling physical reality certainly doesn't care about what you labelled it. You can go on believing there are two distinct magnetic fields at each point in space rather then one unified field whose geometry and topology is dynamical if you want...i'm not going to waste time arguing that that view is not valid if it gives correct predictions. Do you agree on the following definitions for the article:

Magnetic field B - a magnetic field that is topologically homogenous

Synthetic magnetic field B* - a magnetic field which is topologically inhomogeneous.

--Sparkyscience (talk) 18:16, 23 February 2017 (UTC)

In regards to your statement the "synthetic magnetic field" is a indeed actually a magnetic field, I cannot disagree more!! I'm not sure what I wrote that led you to misunderstand me so extremely. I'll say it again. There is one and only one magnetic B field in the universe. There are an infinite number of fields in the universe (E and B and (E + 4*B) and (∇×B + 0.36 * ∂E/∂t) are just a few of the infinitely many electromagnetism-related fields), but only one of these fields is the magnetic B field.

Dalibard et al. has taken some other field (specifically, a complicated function of E and B and their spatial-derivatives and time-derivatives) and called it an "artificial magnetic field". Well, they can call it whatever they want, but it is not the magnetic B field. If Dalibard defined a certain quantum field and called it a gorilla, well, that doesn't make it a gorilla. I am unhappy that they called it an "artificial magnetic field". The term is misleading. How do I know that it's misleading? Because you, Sparkyscience, have been misled by it! And why is it misleading? Because artificial light is still real light, and artificial insemination is still real insemination, and artificial sweetener is still real sweetener, but Dalibard's so-called "artificial magnetic field" is definitely not a real magnetic field. (There are examples in the other direction too—an artificial heart is not a real heart, an artificial leaf is not a real leaf, etc.—so I wouldn't say that their choice of terminology is wrong, just misleading or sub-optimal. They should have called it a "magnetic-like field" or something like that.)

Again, if you can't follow all the details of section 1 of Dalibard, let me know how I can help you. Shine a focused laser beam. Everyone knows what the B field is: It is proportional to sqrt of intensity, it oscillates back and forth at 400THz or whatever the frequency is, and its time-average value is zero. OK, then you read section 1 and estimate what the "artificial magnetic field is". It's totally different. It has a node instead of a peak in the center, it doesn't oscillate, it points in the wrong direction, etc. etc. Therefore, the "artificial magnetic field" is definitely not the magnetic B field.

There is one and only one magnetic B field, and it is the one defined discussed in all the physics textbooks, the one involved in hard disk drives and electric motors, the one which is measured by magnetometers. A magnetometer cannot measure the specific field defined by the formulas in Dalibard section 1, so that field is not the magnetic B field, no matter what terminology they use to describe it. Simple as that! :-D --Steve (talk) 03:00, 24 February 2017 (UTC)

@Sbyrnes321:Haha... oh wow. You hit the nail on the head! It is exactly analogous to artificial light or artificial insemination!! Couldn't have put it better myself! Happy to put apply WP:IAR and have you down as a cited source on the article itself! Now... I've no doubt there are an infinity of fields in the platonic sense...This diagram here from the first few pages of Roger Penrose's book the Road to Reality illustrates it perfectly. There is a correspondence between mind, mathematics and matter but not all mathematical fields are manifestly physical. QED is highly accurate, highly successful mathematical model that attempts to explain electromagnetic phenomena we se in reality...it does not mean the mathematical model itself is reality! Consider the Mandelbrot set: if all atoms in the universe were made into one giant quantum computer - would we ever be able to capture the true essence of the infinite complexity of this mathematical object? Or simpler then this, can we ever make a true perfect triangle from elementary particles? No! We can only ever approximate. Reality and mathematics are distinct, both have an exististance, but you are completely conflating the two! You can invent whatever model you want but physics is about the rules of the game in which we play: If you have a model, an idea, that disagrees with what reality says you should change your model, if the the rules don't correspond to the game it is physically meaningless...putting the idea above reality is ideology. Your reverence to the almighty B field is a physically meaningless idea inside the areas of space we are considering! It is both limited and simplistic... it is completely unable to describe the Aharonov–Bohm effect and phenomena found in these experiments. It need to be broadened, as there is no notion of topology in QED.

Any good textbook will tell you the field is defined in terms of its vector potential, and this can be generalised to a situation where it is not a vector but a gauge. A different model, say topological quantum field theory may define the mathematic field that describes the physical phenomena of magnetism very differently to another physics model...but where the two models of TQFT and QED agree with observation they are both valid ...but all mathematical models have limitations no matter how accurate they are... we know that from Gödel's incompleteness theorems! I think it sensible to define the magnetic field as the field that has physically meaningful magnetic effect B present at each point in reality...I could define the real field as B + c...where c is some constant... and it is clear there are an infinity of such fields.. but in general when deciding what value to set the field at we declare merely by fiat the value of the ground state of a vector field be set to zero (this is what Wick ordering is!!) to make things simple. The situation of defining the B field is no different.

It is so clear in Dalibard et al. (2011) (I don't know how you can miss it!) that they are defining the a magnetic B* field in terms of its vector potential A which is not gauge invariant. A cannot be both gauge invariant and not gauge invariant at same set of coordinates, it is or it is not, thus B as defined by you is physically meaningless inside this space. But lets look at the other source referenced in Ray et al. (2014) about synthetic magnetic fields Lin et al. (2009) to get a clearer picture:

“ To generate a synthetic magnetic field $B^{*}$ for neutral atoms, we engineered a Hamiltonian with a spatially dependent vector potential $A^{*}$ producing $B^{*}=\nabla \times A^{*}$ ” — Lin et al. (2009), p. 628

We can elucidate this a little from another cited source:

“ B is a sum of magnetic field configurations which can be static or dynamic. ” — Ho & Shenoy (1996), p. 3

In other words, yet again, this is no different a situation to that of the Aharonov–Bohm effect or Berry phase where the vector potential cannot be trivially defined. The Qi et al. (2009) paper you glossed over earlier doesn't even mention the word artificial/synthetic... they state the "the local magnetic field is completely dominated" by a monopole. Penrose's book recommends Chan & Tsou (1993) as a textbook on monopoles...this book again describes the Aharonov–Bohm effect as equivalent situation, underlying the importance of topology and gauge theory, but not one mention of the word artificial/synthetic. Why? because such a distinction is in practice meaningless...The fact is this: a source of magnetism in a magnetic field that is not a dipole has been discovered, it might not be the magnetic field as defined by the model you are wedded to, but it is a magnetic field nonetheless. Your insistence of living in Flatland blinds to these truths...come out Plato's cave and see the light Steve!

You said your QFT was rusty, but after the "order parameter quantum field" blunder it looks increasingly like you're making it up as you go along!... your unsourced and uncited belief that there is only one true almighty B field whose topology must never vary throughout all of space is completely at odds with cited sources and your argument is increasingly relying on the notion that the academic articles written by the scientific community are some sort of conspiracy against us to mislead and misinform (they must be "nuts" to call it a magnetic field!). This is dangerously close to crackpot territory - don't do it! you're better than this Steve! I want to help!

In short a magnetic monopole has been discovered, reality likely has many types of possible magnetic monopole, but that which we have discovered is not the magnetic monopole that violates Gauss's law due to the inhomogeneity of the field present. Surely you agree with this statement? --Sparkyscience (talk) 19:09, 24 February 2017 (UTC)

(1) I don't understand your phrase "that which we have discovered is not the magnetic monopole that violates Gauss's law". I believe that a magnetic monopole by definition is a thing that, if you draw a sphere around it, has an inward or outward net flux of B. So a "magnetic monopole that does not violate Gauss's law for magnetism" is an oxymoron.

Great question! Is the B field defined inside the Meissner effect? in a very loosely qualitative way, the situation is similar: Imagine an arbitrary sphere: outside the sphere and inclusive of the sphere boundary the field admits Maxwell's equations of U(1) abelian symmetry inside the sphere the topology admits Maxwell's equations of SU(2) abelian symmetry in the presence of a Dirac Monopole or SU(2) non-abelian symmetry in the case of a GUT monopole. Since outside of the sphere we have the standard Maxwell equations and therefore by definition Gauss's law must hold, inside the sphere Gauss's law no longer can be derived in the same way. Absolutely a monopole present in this field will have a flux going through it but this flux cannot be trivially derived in the usual way and it must be canceled out elsewhere within the sphere to ensure the space outside it is homogenous. I go into how this set up is possible in my longer answer in the below.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(1A): Try reading this whole wikipedia article, but everywhere that you see the phrase "magnetic monopole", starting from the title all the way down, try mentally replacing that phrase with the alternate phrase "source or sink of the magnetic B field". If you do that, then do you endorse the current article and its conclusions (including the statement that such "sources or sinks of the magnetic B field" are believed by particle physicists to exist but have never been seen despite decades of searching, etc. etc.)? If so, that's great! We are graduating from a conceptual disagreement to a terminology disagreement (and article scope disagreement). That would be a big step forward, if true!!

I do believe our difference is largely terminological. The biggest area of disagreement is what the "synthetic magnetic field" actually represents.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(2) Have you read Nature magazine's own (non-technical) description of Ray et al 2014? [6]. Note how the title is "Quantum cloud simulates magnetic monopole" not "Quantum cloud contains magnetic monopole". Why do you think they phrased it that way? Read the whole article, I think it will help reassure you that my opinion is the dominant mainstream physics opinion, not my own quirky thoughts.

Because the literature refers to "synthetic magnetic fields". It is crucial we establish what this actually means in the below.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(3) My references to "spin-1 BEC order parameter" were not a "blunder" but a reference to a Ray et al 2015, which we were discussing earlier. Read it yourself. IIRC the spin-1 order parameter is analogous to A, and therefore topological defects (i.e. vortices) in the spin-1 order parameter are analogous to magnetic monopoles. (Note the term "analogous". They are not a manifestation of magnetism but rather an analogue of magnetism, i.e. a different system which is in some respects mathematically similar to magnetism.)

The spin affects the definition of A, it is not analogous to A, more detail in the below.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(4) Believing that the gauge fields related to B cannot possibly have topological defects is equivalent to believing that there cannot be any magnetic monopoles. I do not have this belief. I do believe that there cannot be any magnetic monopoles in any region of space in which QED is applicable, because the quantum field structure of QED is indeed topologically trivial. (Do you agree?) Such regions of space include, most likely, everywhere in the solar system, but not everywhere in the universe. (Counterexamples include: around an evaporating black hole, or right after the big bang, or in the vicinity of a GUT monopole...) (Again, a real GUT magnetic monopole would entail a small region of space around the monopole where QED is no longer applicable, because the very very high energy fields which normally simplify / spontaneously-symmetry-break to QED are instead in an unusual configuration.) QED is the most precisely tested theory in the history of physics, with experiments probing it to sub-parts-per-billion levels. Nobody has ever created any experimental apparatus in which any violation of QED could be found. Ray et al and any of these papers are no exceptions. Again, since the field structure of QED admits no topological defects, it follows that there are no real magnetic monopoles in the experiments of Ray et al. or any similar paper. :-D

I agree with your first question. But as I am sure you will agree there are plenty of electromagnetic phenomena which QED is not a good model including plasmas, nonlinear solitons, superconductors etc. I have no doubt QED can give us an accurate value to one part in a zillion or whatever of the anomalous magnetic moment of the electron, because we are using the correct tool to analysis the issue... namely QED is linear and reductive, it is compatible with special relativity but is not compatible with general relativity or indeed QCD (i.e how charges of quarks interact inside an atom) both of which are nonlinear. the linear vs nonlinear aspect is the crux of the unification problem with with gravity. Your last sentence is incorrect: QED does not hold in the monopole field around Ray et al etc. the field electromagnetic field really is topologically altered it is not merely a computer simulation.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(5) Did you read Qi et al.? I quote: "Since we started with the Maxwell's equation, which includes ∇·B=0, the magnetic flux integrated over a closed surface must vanish". I don't know how it could be any clearer! :-D

Indeed. goes back to the point in (1)--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(6) Did you read the Rehn paper? I quote: "Demanding that the field B be divergenceless, implies for its Fourier modes...". I don't know how it could be any clearer! :-D

Yes... this is imposed at the so called pinch points not within them. see reply to (1).--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(7) You said that Dalibard is "defining the a magnetic B* field in terms of its vector potential A". You bolded the term "magnetic". What is your basis for saying and emphasizing that it is magnetic? On the contrary, I find that the paper is extremely clear that the fields under discussion are not magnetic: (A): In the abstract, they say that an atom may "mimic the dynamics of a charged particle in a magnetic field". If it were really a magnetic field, they would have said the atom "has the dynamics of a charged particle in a magnetic field". (B) In the abstract, they call it a "Lorentz-like force". If it were really a magnetic phenomenon, they would have simply said "Lorentz force". (C) Their first example in Section I is based on the AC stark effect, a type of electrical force! (They don't state explicitly that this particular system is based on AC stark, but I can vouch for this as a professional atomic physicist who works every day with this exact type of system.) (D) Their whole long first paragraph sets out how this paper is all about "simulating" a magnetic field. A simulation of an ocean wave is not itself an ocean wave. Similarly, a simulation of magnetism is not itself magnetism! :-D

You've gone from "the term is extremely and maybe even deliberately misleading" to "extremely clear that the fields under discussion are not magnetic". Cognitive dissonance if ever i saw it! :-) :-) We need to flesh out the definition of "synthetic magnetic field" in the below.--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(8) In QED, there is a single, well-defined, unambiguous quantum field called B. QED is also perfectly capable of describing the Aharonov–Bohm effect. Therefore I think I am entitled to both believe that there is a single unambiguous field called B, which obeys [the QED generalizations of] Maxwell's equations etc., and also simultaneously understand exactly how the Aharonov–Bohm effect works. Can you explain in more detail why you think that these two things are incompatible?? :-D

There is an inherent non-locality to the AB effect that cannot be described by QED. See [6] and [7].--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

(9) When you say "all mathematical models have limitations no matter how accurate they are... we know that from Gödel's incompleteness theorems", you are confusing two very different things. The first thing is the Fundamental Laws of the Universe - a set of equations that describe how any physical configuration will evolve in time from one moment to the next. The second thing is the Behavior of Systems Following These Laws. Conway's game of life is a good example of this concept: In Conway's Game of Life, The Fundamental Laws of the Universe can be described completely in one sentence, but the Behavior of Systems Following These Laws is so endlessly complicated that Gödel's incompleteness theorems applies to them. In real-world physics, we do not yet know the Fundamental Laws of the Universe, but we have made remarkable progress. We have found an approximation which is so accurate that it is compatible with literally every experiment that physicists have ever done so far here on Earth!! That approximation is the standard model (QED, QCD, etc.) plus general relativity. So in the present context (again, we are specifically trying to interpret various condensed-matter and atomic physics experiments conducted here on Earth), we cannot possibly go wrong by treating {standard model & GR} as a substitute for the true Fundamental Laws of the Universe. Gödel's incompleteness theorems does not undermine the previous sentence, nor give us any reason to think that the Fundamental Laws of the Universe are forever beyond reach, nor make us doubt that we really understand how {standard model / GR} works. Gödel's incompleteness theorems merely say that there are certain (rather contrived) unanswerable questions about the Behavior of Systems Following the Laws of Physics (e.g. if I set these particles in motion, and wait an infinitely long time, will such-and-such ever happen?) Anyway, there is a real universe, it has real laws, a major goal of physics is to learn about them, we have made remarkable progress towards that goal, and there is no reason to expect that the goal is unreachable (though of course we cannot know for sure unless we do). Anyway, in the standard model there is (among many other things) a specific quantum field that people call the magnetic B field, and since the standard model is an appropriate and predictive model to use in the context of any experiment ever performed on Earth, one can always understand exactly what one means by the magnetic B field. And you will never find an electromagnetism or any other physics textbook that uses the term "magnetic B field" willy-nilly to refer to any old field that has anything to do with magnetism, just like textbooks will never use the term "positron" to refer to anything other than the unique, specific particle species of that name. --Steve (talk) 04:14, 25 February 2017 (UTC)

I think it best for us to agree to disagree on the implications of Godel's theorem. Lets stay focused on magnetic monopoles! :-).--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

Ok lets focus this a little! Sorry if my last previous comments have touched a nerve it was all meant in good humour and not to be taken to seriously :-) I know we both want the same thing which is an understanding of what so called "synthetic magnetic fields" are and how they relate to magnetic monopoles.

Weyl spin-orbit coupled system

Lets start with some simplified semiclassical basics: consider a "spinning" charged particle, i.e. an electron, this intrinsic spin gives rise to a tight toroidal magnetic field around the electron. If this electric charge is then locked into an orbit whose axis is orthogonal to the spin, say around an atom such the spin is pointing away from the centre of the orbit, this will give rise to a more complex magnetic field where the toroidal magnetic field of the spin is interlaced with a toroidal magnetic field generated by the orbit. Its not quite as classical as this in a quantum system, as we have complex numbers that describe rotations in Gamma matrices (this is where the quaternion, Clifford algebra stuff comes in! I'm pretty sure the example here is a type of Hopf fibration [8] [9]) but this is the essence of spin-orbit coupling. You can call the magnetic field that arrises from the orbit as "synthetic" or "artificial" compared to that of the intrinsic spin if you want, but it is still very much a magnetic field that arrises from a rotating charge. Both the spin and the orbit are intrinsic to the system and are adiabatic. If i put a compass inside this field, barring special case solutions, in general it would not settle into an equilibrium position because of the nonlinearity of the magnetic field present. The magnetic field in such an area is path dependant thus non-abelian.[10]

Now lets move on to cold atom systems being bombarded by lasers. The essence of these systems is to exploit and manipulate the degrees of freedom present in a magnetic field by engineering the exact nature of the spin-orbit coupling. Atoms are trapping and cooled, and two (or more) lasers are used to create a standing wave soliton that acts as an optical lattice, this process was the subject of the 1997 Nobel prize [11] Using such a system to create a many body state was the subject of the 2001 Nobel prize. [12] Such systems can be used to generalise Rashba effect where the spin-orbit coupling is prolate [13], spherical [14] or oblate [15] [16] [17] etc.

The original idea of using quantum adiabatic system to manipulate gauge structures came well before cold atom systems and was first put forward by Frank Wilczek and Anthony Zee [18] who enigmatically state "It is of course, potentially significant for models of elementary particles that gauge fields can arise "from nowhere" but we shall not attempt specific speculations along that line here". Wilczek later showed how this can be applied to the creation of magnetic monopoles [19]. It was realised that many bodied systems in cold atom give rise to an exact implementation of the situation described by Wilczek [20]. Not an analogy!

It is also interesting to note that time crystal's were made via a cold atom set up at Maryland Uni- none of the press or academic papers said that a time crystal was "simulated" on the contrary they said a real new state of matter had been made for the first time [21] [22] [23]. No different from the monopoles here...

There is no conceivable way anyone can claim that synthetic magnetic fields as implemented above does not arise from the adiabatics of charged particles - they are a "generalised magnetic field" [24] with higher levels of symmetry! Simple!--Sparkyscience (talk) 18:08, 26 February 2017 (UTC)

Thanks yourself!! I think I am getting a better idea of where you are coming from, though I could certainly be wrong! Let me try again! It's worth a shot!

You ask: "Is the B field defined inside the Meissner effect?" Yes. "B=0 inside a superconductor". "B=0 inside a superconductor". "B=0 inside a superconductor". "B=0 inside a superconductor". "the total magnetic field is very close to zero deep inside [a superconductor]". I can go on and on. I have never heard anyone suggest that B is undefined inside a superconductor. It is well-defined, and it is equal to zero. (Well, it is nonzero very close to the surface, and asymptotes to zero as you penetrate deeper into it.)

"I am sure you will agree there are plenty of electromagnetic phenomena which QED is not a good model including plasmas, nonlinear solitons, superconductors etc. ... QED is not compatible with general relativity or indeed QCD ... QED does not hold in the monopole field around Ray et al etc." I disagree with you more-or-less 100% here, and I think this is the most important reason that we are talking past each other and interpreting the same facts and descriptions in such different ways. So let's talk about it!

Do you understand the relation between fundamental laws and emergent phenomena the same way that I do? Let's talk about Conway's game of life. There is a one-sentence "fundamental law" of the game-of-life universe. It says which cells turn on and off each timestep, and therefore they allow you to simulate any arbitrary system. This law holds universally. It has no exceptions.

As it happens, there are a dizzying variety of large-scale emergent phenomena that can happen in this game-of-life "universe", for example "this configuration of cells is a glider; gliders always move at a speed of exactly 1/4" and "this large-scale configuration of cells here is a Turing machine" and so on. When describing and predicting such emergent phenomena, I admit that it is often not useful to refer to the "fundamental law". For example, take the Turing machine, a hugely complicated configuration of millions of cells. If you ask me to predict how the configuration will evolve over time, I would obviously analyze it at a high level, thinking of it as a Turing machine. I would not choose to hand-simulate the switching on and off of its millions of constituent cells! But—this is the key point—the fundamental law is still true. It's not always super-helpful, but it is absolutely always true!!

In most subfields of physics (condensed matter physics, fluid dynamics, nuclear physics, plasma physics, atomic physics etc.), we have a somewhat analogous situation: We know the fundamental laws! The fundamental laws are the Standard Model of Particle Physics (a combination of QED, QCD, and weak force theory) plus GR. (Contrary to what you say, these are beautifully compatible with each other except in weird situations like exploding black holes—situations which do not come up in the subfields of physics that I mentioned.) Starting from these fundamental laws, one can derive (through successive approximations) the normal laws of gravity and electromagnetism and nonrelativistic QM etc. And from that, we can derive the structure of the periodic table, and then we can work our way up to the laws governing hydrogen-bonding and surface tension and plasma instabilities and pretty much all the physics in all the textbooks for these subfields.

Now, like the game-of-life example above, it is rarely if ever useful to apply the standard model and GR directly to, say, a fluid dynamics problem. (You need a supercomputer just to simulate a single proton directly from the standard model! Forget about an airplane wing!) But the fundamental laws are still true. Indeed, there are even situations where emergent behavior is kinda independent of the fundamental laws. For example, the 2nd law of thermodynamics would be true even if the fundamental laws were very different. But the fundamental laws are still true.

Let's look at superconductivity, a fine example. Early on, people constructed a phenomenological theory of superconductivity, Ginzburg–Landau theory, a simple model which correctly predict all kinds of properties of superconductors. You might be satisfied at this point—we have a model that works—but physicists were not satisfied. Something big was missing, and BCS theory added it. The missing ingredient was a derivation of Ginzburg–Landau theory from the fundamental laws. (Also called a "microscopic theory" of superconductivity.) Again, BCS theory starts with normal QM and electromagnetism and so on (which in turn have previously been derived from the fundamental laws) and ends with a proof that Ginzburg–Landau theory can emerge as an approximate description of certain materials under such-and-such conditions.

Similarly, high-temperature superconductivity is universally regarded as one of the most important unsolved problems in condensed-matter physics. What exactly is unsolved about it? After all, we can model these materials perfectly fine with Ginzburg–Landau theory. Well, what is unsolved is the derivation from the fundamental laws. Nobody doubts for a second that the fundamental laws are true inside a high-temperature superconductor, and that therefore this microscopic derivation exists, if only we can find it.

Again, when we see a funny phenomenon in a condensed-matter physics (or plasma physics or fluid dynamics etc.) apparatus, and describe it with some funky model, the normal fundamental laws of physics are also true at the same time in the same place. This is considered so obvious that I don't even know what physics textbook would bother to state it! (Maybe a freshman intro textbook? I can look...) Well, look at any of the theoretical condensed-matter or atomic-physics papers you've cited. All those equations and analyses are exactly the process of starting from the usual fundamental laws of physics and deriving some emergent behavioral model from that starting point. Look at condensed-matter textbooks and AMO textbooks and plasma physics textbooks. They have long background chapters on microscopic physics. Why? Because they know that the normal fundamental laws of microscopic physics are consistent with (and indeed often necessary for explaining) the fascinating emergent behavior which makes up the rest of the textbook!

Please let me know where you agree or disagree here!! This is critical to my belief—which I believe is unanimous in mainstream physics but which you seem to disagree with—that the laws of QED are just as true inside a funky laser-illuminated atomic cloud as they in a precision QED test apparatus or anywhere else on Earth. :-D

PS: I think the term "synthetic magnetic field" is "extremely and maybe even deliberately misleading" precisely because "the fields under discussion are not magnetic". I'm not sure why you are accusing me of "cognitive dissonance" in reference to these two statements. I think you must have misunderstood something I said... --Steve (talk) 05:19, 28 February 2017 (UTC)

Lots of fun things to talk about here - I will get back to this thoroughly I'm just a little busy this week! :-) --Sparkyscience (talk) 15:11, 2 March 2017 (UTC)

References

• Brumfiel, Geoff (2009). "'Overwhelming' evidence for monopoles". Nature. doi:10.1038/news.2009.881. ISSN 0028-0836.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Castellani, Elena (2016). "Duality and 'particle' democracy" (PDF). Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics. doi:10.1016/j.shpsb.2016.03.002. ISSN 1355-2198. {{cite journal}}: Invalid |ref=harv (help)
• Castelnovo, C.; Moessner, R.; Sondhi, S. L. (2008). "Magnetic monopoles in spin ice" (PDF). Nature. 451 (7174): 42–45. Bibcode:2008Natur.451...42C. doi:10.1038/nature06433. ISSN 0028-0836.
• Carnap, R. (1931). "Überwindung der Metaphysik durch logische Analyse der Sprache". Erkenntnis. 2: 219–241. JSTOR 20011640.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Chan, Hong-Mo; Tsou, Sheung Tsun (1993). Some Elementary Gauge Theory Concepts. Singapore: World Scientific. ISBN 978-981-02-1080-9. {{cite book}}: Invalid |ref=harv (help)
• Dalibard, J.; Gerbier, F.; Juzeliūnas, G.; Öhberg, P. (2011). "Colloquium: Artificial gauge potentials for neutral atoms". Reviews of Modern Physics. 83 (4): 1523–1543. arXiv:1008.5378v2. Bibcode:2011RvMP...83.1523D. doi:10.1103/RevModPhys.83.1523. ISSN 0034-6861.
• Gleick, James (1987). Chaos: Making a New Science. Viking Books. ISBN 0-7493-8606-1. {{cite book}}: Invalid |ref=harv (help)
• Ho, T.-L.; Shenoy, V. B. (1996). "Local Spin-Gauge Symmetry of the Bose-Einstein Condensates in Atomic Gases" (PDF). Physical Review Letters. 77 (13): 2595–2599. arXiv:cond-mat/9603077v2. Bibcode:1996PhRvL..77.2595H. doi:10.1103/PhysRevLett.77.2595. ISSN 0031-9007. {{cite journal}}: Invalid |ref=harv (help)
• Lin, Y.-J.; Compton, R. L.; Jiménez-García, K.; Porto, J. V.; Spielman, I. B. (2009). "Synthetic magnetic fields for ultracold neutral atoms" (PDF). Nature. 462 (7273): 628–632. arXiv:1007.0294v1. Bibcode:2009Natur.462..628L. doi:10.1038/nature08609. ISSN 0028-0836.
• Nikolić, Predrag (2014). "Vortices and vortex states in Rashba spin-orbit-coupled condensates". Physical Review A. 90 (2). arXiv:1406.1198v1. Bibcode:2014PhRvA..90b3623N. doi:10.1103/PhysRevA.90.023623. ISSN 1050-2947. {{cite journal}}: Invalid |ref=harv (help)
• Ray, M. W.; Ruokokoski, E.; Kandel, S.; Möttönen, M.; Hall, D. S. (2014). "Observation of Dirac monopoles in a synthetic magnetic field" (PDF). Nature. 505 (7485): 657–660. arXiv:1408.3133v1. Bibcode:2014Natur.505..657R. doi:10.1038/nature12954. ISSN 0028-0836.
• Ray, M. W.; Ruokokoski, E.; Tiurev, K.; Mottonen, M.; Hall, D. S. (2015). "Observation of isolated monopoles in a quantum field" (PDF). Science. 348 (6234): 544–547. Bibcode:2015Sci...348..544R. doi:10.1126/science.1258289. ISSN 0036-8075.
• Rehn, J.; Moessner, R. (2016). "Maxwell electromagnetism as an emergent phenomenon in condensed matter" (PDF). Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 374 (2075): 20160093. arXiv:1605.05874v1. Bibcode:2016RSPTA.37460093R. doi:10.1098/rsta.2016.0093. ISSN 1364-503X.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Sapolsky, Robert (2010a). "Chaos and Reductionism". youtube.com. Stanford. {{cite web}}: Invalid |ref=harv (help)
• Sapolsky, Robert (2010b). "Emergence and Complexity". youtube.com. Stanford. {{cite web}}: Invalid |ref=harv (help)
• Seiberg, N.; Witten, E. (1994). "Electric-magnetic duality, monopole condensation, and confinement in N=2 supersymmetric Yang-Mills theory". Nuclear Physics B. 426 (1): 19–52. arXiv:hep-th/9407087. Bibcode:1994NuPhB.426...19S. doi:10.1016/0550-3213(94)90124-4. ISSN 0550-3213.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Seiberg, N. (1995). "Electric-magnetic duality in supersymmetric non-Abelian gauge theories" (PDF). Nuclear Physics B. 435 (1–2): 129–146. arXiv:hep-th/9411149. Bibcode:1995NuPhB.435..129S. doi:10.1016/0550-3213(94)00023-8. ISSN 0550-3213.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Qi, X.-L.; Li, R.; Zang, J.; Zhang, S.-C. (2009). "Inducing a Magnetic Monopole with Topological Surface States" (PDF). Science. 323 (5918): 1184–1187. arXiv:0811.1303v1. Bibcode:2009Sci...323.1184Q. doi:10.1126/science.1167747. ISSN 0036-8075.
• Qi, X.-L.; Zhang, S.-C. (2010). "The quantum spin Hall effect and topological insulators" (PDF). Physics Today. 63 (1): 33–38. doi:10.1063/1.3293411. ISSN 0031-9228.{{cite journal}}: CS1 maint: ref duplicates default (link)
• Witten, E. (1979). "Dyons of charge eθ/2π" (PDF). Physics Letters B. 86 (3–4): 283–287. Bibcode:1979PhLB...86..283W. doi:10.1016/0370-2693(79)90838-4. ISSN 0370-2693. {{cite journal}}: Invalid |ref=harv (help)

What on Earth?

What on Earth has happened to the discussion of the monopole problem on Wikipedia? I seem to recall there actually being a decent article on this topic. But now monopole problem redirects to a page about inflation? And only a handful of poorly explanatory material at that? Seriously? Isn't that a bit POV? Wouldn't this page be a more appropriate place for an NPOV discussion? There is already text referring to the issues here, although it's not a coherent thread. I could have sworn it already had a reasonable page. It certainly merits one, as it could support a number of other articles, such as this one, articles about Grand Unified Theory, unresolved problems in physics, and yes, even inflationary theory. Don't know what's happened, but something definitely seems awry here. 75.139.254.117 (talk) 06:09, 3 April 2017 (UTC)