Talk:Magnetic monopole/Archive 3

Archive 1

Archive 2

Archive 3

Hadjesfandiari's paper

Hadjesfandiari's paper (Character of the magnetic monopole field) finally got published. 128.205.24.69 (talk) 22:54, 17 April 2009 (UTC)

Covariant formulation

It would be nice to have covariant formulation of Maxwell's equations without and with magnetic monopoles. Without magnetic monopoles, equations are (according to Carroll, S. - Spacetime and Geometry, p. 30):

• $\partial _{\mu }F^{\nu \mu }=J^{\nu }$

File:Image name

Caption

— Preceding unsigned comment added by 84.42.225.153 (talk) 16:23, 2 June 2011 (UTC)

• $\partial _{\mu }F_{\nu \lambda }+\partial _{\nu }F_{\lambda \mu }+\partial _{\lambda }F_{\mu \nu }=0$

so it is reasonable to think that with magnetic monopoles they would be:

• $\partial _{\mu }F^{\nu \mu }=J^{\nu }$
• $\partial _{\mu }F_{\nu \lambda }+\partial _{\nu }F_{\lambda \mu }+\partial _{\lambda }F_{\mu \nu }=M_{\mu \nu \lambda }$

where $\ M_{\mu \nu \lambda }$ is an totally antisymmetric tensor describing magnetic charge and current density.

This should be added when the sources are found. --78.0.230.126 (talk) 23:48, 6 June 2009 (UTC)

Monopoles: an open problem

"Monopole detection is an open problem in experimental physics. Within theoretical physics, some modern approaches assume their existence."

Duh !? In physics or mathematics, if you assume that something exists, then it does exist. [Doesn't anyone know the difference between "to assume" and "to draw a conclusion"?] We conclude that protons exists, and electrons, and muons, and pions -- but we do not assume that they exist. The existences of those other particles have huge amounts of evidence to support them. 98.81.1.67 (talk) 17:59, 9 August 2010 (UTC) Monopole detection is an open problem only for those who do not understand electromagnetic phenomena. Those who do know that no magnetic monopoles exist.

Is this just a silly topic?

Magnetic field is just the name for an electric field seen from a different frame of reference (i.e. with relative velocity). Magnetic fields do not have "poles". Magnetic fields have a rotation-like effect and when the electric field moves in a very small circle then the magnetic field's rotation-like effect tends to reinforce giving rise to the appearance of "poles", or specifically an axis coincident with the axis of the circle, and the axis is directed since the rotation-like effect is directed. The axis is called a "pole" and one end is called "north" while the other is "south".

Note that when an isolated electric field travels in a straight line the perceived magnetic field (through time) is essentially columnar (or a helix) with no "pole" of any sort.

The prediction of magnetic monopoles should be considered a simple disproof of a theory.

The whole valorization of "Magnetism" as a separate study comes from the easy availability of masses of aligned rough-circle-traveling electrons (i.e. ferromagnets) and should not be taken to mean that it has some separate existence from "moving charged particles". Magnetism has the same relationship to electrics that music has to sound. 76.126.215.43 (talk) 20:16, 9 July 2009 (UTC) You are right, magnetic fields do not have any poles in the physical sens, we only use this word for describing magnetic phenomena coused by the motion of electric charges.

An "easy" way to produce magnetic monopoles is to slingshot two black holes past each other (i.e. pass close but eventually escape each other's influence) in such a way that each one traps different points in the same magnetic field lines. Then you have two matched monopoles (and magnetic charge is conserved). —Preceding unsigned comment added by 76.126.215.43 (talk) 20:21, 9 July 2009 (UTC)

It's technically untrue that a magnetic field is just an electric field seen from a different frame of reference: if there's a static nonzero magnetic field and no electric field in a region of space then the magnetic field can't be made zero by any Lorentz boost. People talk about "magnetic dipoles" because the far magnetic field of a current loop looks the same as the far electric field of a dipole. Surely you know all this. -- BenRG (talk) 21:04, 20 July 2009 (UTC)

"a static nonzero magnetic field and no electric field in a region of space" and Hows that even possible? —Preceding unsigned comment added by 86.175.122.183 (talk) 01:40, 8 February 2011 (UTC)

I don't believe that part about "technically untrue". Using the Special Theory of Relativity, all magnetic fields can be shown to be aspects of electic fields and moving charges. There is a close relationship between Maxwell's Equations of electomagnetism and the Special Theory of relativity. Also, I have never heard of such a thing as a "Loretz boost", and I don't think that such a thing exists.98.81.1.67 (talk) 18:11, 9 August 2010 (UTC)

I don't believe that 76.126.215.43 was suggesting that the magnetic field over a non-zero volume of space could be reduced to zero by a suitable choice of reference frame, merely that the contribution from each charge could be so reduced. Perhaps, like the very persistent User:JA.Davidson (whose comments are now removed to the archive), the questioner considers the magnetic field to be non-physical, a mathematical construction to reduce second-order differential equations to first-order ones. If so, then the answer is that maybe it's so - but we don't know that for sure. --catslash (talk) 22:44, 20 July 2009 (UTC)

86.175.122.183 asks: ""a static nonzero magnetic field and no electric field in a region of space" and Hows that even possible?". You're asking how it is possible to have a volume where E=0 and B≠0. One example is, the space near a bar magnet. Another example is, the space near a stationary wire that is carrying a current. :-) --Steve (talk) 03:01, 8 February 2011 (UTC)

daa, im so stupid, i was thinking 'no charges' not 'no field', of course the charges can be arranged, in a given reference frame, to produce no field.

although, now i think about it, since charges can't be at exactly the same point, wouldn't that mean its a practical impossibility to ever make an EXACTLY zero field? (obviously this wasn't my point before, or even what i was mistakenly thinking.)—Preceding unsigned comment added by 86.175.122.183 (talk) 12:27, 11 February 2011 (UTC)

Dirac's quantization

Are the recent edits on Dirac's quantization entirely accurate (e.g. Dirac showed that the existence of magnetic monopoles was consistent with Maxwell's equations only if electric charges are quantized, which is what we observe)? Surely the argument is (existence of both monopole and charge) + (quantization of spin) + (P = E × H) => (quantization of charge). But P = E × H is not a consequence of Maxwell's equations; you can add any divergenceless field to this and it's still consistent with Maxwell's equations. I'm only familiar with classical electromagnetism, so forgive me if I'm talking cobblers here. Also is it not clearer simply to say that the existence of monopoles would require the quantization of charge? --catslash (talk) 14:41, 16 August 2009 (UTC)

OK; I see you're way ahead of me. --catslash (talk) 14:45, 16 August 2009 (UTC)

Well, what I was trying to say is that monopoles only require Dirac strings if we insist on retaining Maxwell's equations. Do you agree? The stuff about charge quantisation is just a side consequence of that, and I probably expressed myself poorly.

I reverted because I started to realise that it seems the Dirac string has a non-zero energy/length, so shouldn't it be observable? Just wondering. --Michael C. Price ^talk 16:01, 16 August 2009 (UTC)

Sorry, I can't really comment, since my understanding of electromagnetism is rudimentary; I only ever consider E and H, never A. Also I may have carelessly understated the role of Maxwell's equations in determining where the momentum is - it's just that the result is not unique. Sticking to the most basic concepts in (B and D fields rather than Dirac strings) would help keep the article accessible to the likes of me. --catslash (talk) 18:23, 16 August 2009 (UTC)

Seems like unnecessary confusion to me. Has anyone formulated a variant of Maxwell's equations which allows magnetic monopoles and non-quantized charge and is consistent with everything we know about electromagnetism and quantum mechanics? Probably not. In your phrasing, it seems like if there's a magnetic monopole, you can either modify Maxwell's equations or have quantized charge. But really only the latter is an option, since Maxwell's equations are established experimentally. So why even bring up the possibility? By the way, you could equally well say "Assuming quantum mechanics is correct, monopoles imply quantization of charge." You shouldn't say that either, for the same reason. --Steve (talk) 00:06, 17 August 2009 (UTC)

Okay, let me think about it. --Michael C. Price ^talk 06:56, 17 August 2009 (UTC)

Has anyone formulated a variant of Maxwell's equations which allows magnetic monopoles and non-quantized charge and is consistent with everything we know about electromagnetism and quantum mechanics? Isn't the doubling of source and fields to incorporate magnetic charges (mentioned above in conversation with Likebox) such an example? It allows magnetic charges/monopoles, but does away with Dirac strings since the magnetic charge is inserted at a fundamental level. Is consistent with current electromagnetism which is valid whereever the 2nd field is zero. Since it does away with Dirac string there is no requirement for charge quantization (since this only follows from the requirement that the D-string be unobserable). Therefore the incorporation of monopoles by extending of Maxwell's equations by doubling fields and sources removes the needs for charge quantisation. --Michael C. Price ^talk 09:23, 17 August 2009 (UTC)

I don't think that's right, I think you're misunderstanding what Likebox was talking about, and also where the Dirac string comes from. Can you write down a "Maxwell's equations with monopoles" that's different from the standard one in the article? Because the standard one in the article (which does have two types of charges and two types of currents) is the one that's the basis for Dirac strings and quantized charge. --Steve (talk) 13:24, 17 August 2009 (UTC)

(deindent) Kaku in QFT (page 539) says

"Before we discuss the properties of the gauge monopole, let us review the the properties of the Dirac magnetic monopole found in ordinary electrodynamics." (My italics)

I interpret this and subsequent passages as implying the that Dirac monopole is modelled using 19C Mawell's equations with no magnetic sources. The function of the Dirac string is to carry away the magnetic flux so that $\nabla \cdot \mathbf {B} =0$ can be maintained. Also Kaku goes on to use the conventional $B=\nabla \times \mathbf {A}$ when modelling the Dirac string, which would not be valid in the two-source formulation. Is this correct?--Michael C. Price ^talk 14:06, 17 August 2009 (UTC)

Need for charge quantization can be removed by doubling the potentials, and this would not change the Maxwell's equations. Without monopoles, electric field and magnetic field are (in cgs):

$\mathbf {E} =-\nabla \phi -{\frac {1}{c}}{\frac {\partial \mathbf {A} }{\partial t}}$

$\mathbf {B} =\nabla \times \mathbf {A}$

while with magnetic monopoles, using additional potentials, they would be:

$\mathbf {E} =\nabla \times \mathbf {G} -\nabla \phi -{\frac {1}{c}}{\frac {\partial \mathbf {A} }{\partial t}}$

$\mathbf {B} =\nabla \times \mathbf {A} +\nabla \psi +{\frac {1}{c}}{\frac {\partial \mathbf {G} }{\partial t}}$

where G is additional vector potential and $\psi$ is additional scalar potential (actually, they are pseudovector and pseudoscalar) and together they can form additional four-potential. For more information, see: [1]. --antiXt (talk) 10:47, 28 August 2009 (UTC)

Yes, that was what I meant by "two-source formulation", although I was probably using a misleading label. I suspect the double potential route can't be quantised and gauged, but I don't know for sure.--Michael C. Price ^talk 10:55, 28 August 2009 (UTC)

Pseudo-magnetic charge?

I'm out of my area of expertise. Still let me pose a question. Since the magnetic field is a pseudo-vector it's direction is dependant on the whether the coordinate frame is right handed or left handed. If there where magnetic monopoles their charge would have to be a pseudo-charge, that is a positive or negative magnetic monopole is referance frame dependant, otherwise the force would be a pseudo-vector which is unphysical, the direction of the force is not referance dependant. So my question are all the magnetic monopoles claimed to have pseudo-charge? Does this mean there aren't positive and negative magnetic charges? If they are not pseudo-charges doesn't the fact that the magnetic field is a pseudo-vector prohibit the exsistence of magnetic monopoles? Please correct me if I'm talking nonsesne, since I know close to nothing about field theory and string theoryEranus (talk) 12:03, 29 August 2009 (UTC)

I guess magnetic charges would not be called positive or negative, but rather "north" and "south". Indeed they would be pseudo-scalars and "north" or "south" would depend on whether you are using left or right coordinate system. There is nothing wrong with pseudo-scalars as indeed there exist pseudo-scalar particles -- pions are pseudo-scalars if I remember correctly. Bakken (talk) 13:40, 29 August 2009 (UTC)

Magnetic charge is indeed an pseudoscalar quantity. There are other pseudoscalar quantities in physics, such as magnetic flux, and there is nothing wrong with it.

(btw. pion (which is a pseudoscalar meson) is not an pedagogical example (it is particle, not an quantity), and as such is not very useful in such explanations)

Interestingly though, one can consider electric field as pseudovector instead of vector and electric charge as pseudoscalar instead of scalar, and then magnetic field and charge would be pseudovector and pseudoscalar respectively. Such symmetry is only possible because there are three spatial dimensions, otherwise in general case of n spatial dimensions, vector field would have n components, while n-dimensional analogue of the pseudovector field would have n(n-1)/2 components. Also, an analogue of pseudoscalar charge would have n(n-1)(n-2)/6 components instead of one. It is an interesting coincidence that n and n(n-1)/2 are equal for n=3, the number of observable spatial dimensions of the space we live in. --antiXt (talk) 00:28, 30 August 2009 (UTC)

Magnetic charges, pseudoscalars and pseudovectors are significant problems. They are contrary to the Bianchi identity or the demands of the Principle of General covariance. Eranus made exactly an argument from general covariance - that quantities which vary with subjective systems of coordinates can not be objective physics. This is a signal not to be ignored; it should trigger a search for the forms that do not vary with coordinate system mischief. Very few physical entities are actually scalars or vectors. The forced imposition of these ideas make for a system of compensating errors that resembles epicycles in its fragility. But adherence to general covariance yields geometric representations of physical entities that are not deformed by mischief with coordinates.

The invariant form of electromagnetism is based on the 1-form potential A. Think of this 1-form as a sequence of (oriented) plates in spacetime. The Bianchi Identity is then a theorem which requires that the current density of magnetic monopoles be zero, d²A = 0 . The geometric content of this is that, when you draw (oriented) tubes around the edges of a sequence of (oriented) plates, and then draw (oriented) boxes around open ends of the tubes, there are no boxes as the result (no monopoles). In general, "The boundary of a boundary is zero.", just as recited in the book GRAVITATION.

--99.18.99.23 (talk) 23:53, 21 September 2010 (UTC)

I like you're reasoning on this, but can you tell me...Can the use of 1-form in electromagnetic theory be extended to fiber bundles? If so, how, because if not I don't think using the 1-form is appropriate for describing magnetic monopoles. — Preceding unsigned comment added by Brockhad (talk • contribs) 19:44, 15 April 2011 (UTC)

Found?

Any one check the veracity of this please, maybe worth inclusion? ^Khukri 09:48, 4 September 2009 (UTC)

Now in nature, I'll have a look and start putting a draft together this afternoon, unless someone beats me to it. ^Khukri 10:14, 4 September 2009 (UTC)

It looks like interesting research, but the "monopoles" are dipoles connected by observable flux tubes. They've created a condensed matter environment where it's energetically favorable for long thin solenoids to form spontaneously, which is neat, but it's not magnetic monopoles. -- BenRG (talk) 13:34, 4 September 2009 (UTC)

On looking at the article I see that there's already a section on this, citing older papers: Magnetic monopole#"Monopoles" in condensed-matter systems. -- BenRG (talk) 17:38, 4 September 2009 (UTC)

recent monopole 'discovery'

Magnetic monopoles detected in a real magnet for the first time by the Researchers from the Helmholtz-Zentrum Berlin für Materialien und Energie have, in cooperation with colleagues from Dresden, St. Andrews, La Plata and Oxford, for the first time observed magnetic monopoles and how they emerge in a real material. They publish this result in the journal Science within the Science Express web site on Sept. 3. http://www.eurekalert.org/pub_releases/2009-09/haog-mmd090209.php 115.129.6.163 (talk) 21:43, 3 September 2009 (UTC)

Article by science daily. What should we make of this. We need a specialist! Goldencako 14:02, 4 September 2009 (UTC)

I moved this thread (which I hadn't previously noticed) down to the bottom to join the other thread on the same topic. -- BenRG (talk) 14:12, 4 September 2009 (UTC)

Whoever wrote this should be ashamed of themselves. It's virtually impossible to read that and correctly understand what the experiment did and didn't show, and what the prior art is in this field. Scientific press releases are the worst things in the world...it's propaganda presented in a way such that people will take it at face value. --Steve (talk) 00:59, 5 September 2009 (UTC)

Definitely. It can also fool some readers that those are real magnetic monopoles. --antiXt (talk) 11:41, 5 September 2009 (UTC)

Care to explain how these aren't real monopoles? 216.96.141.71 (talk) 15:49, 6 September 2009 (UTC)

Yes, it's awful, but it's also business as usual. What I don't understand is how the same propaganda ended up at nature.com ([2]). I thought they were better than that. -- BenRG (talk) 15:46, 5 September 2009 (UTC)

It's being published in Science. 216.96.141.71 (talk) 15:47, 6 September 2009 (UTC)

The actual research is fine. But their "monopoles" come in matched pairs connected by flux tubes, an arrangement better known as a "dipole". Even if you accept this use of the word "monopole", these aren't the magnetic monopoles that physicists have been searching for for decades—the free particles that are predicted by big bang cosmology. Most science articles in the popular press are based on deliberately deceptive press releases like this. The goal is not to accurately represent the research but to make the funding institution look good so that it can attract more donors. Most news sources quote the press releases unquestioningly because they don't have anyone on staff who can evaluate them for accuracy. I expected Nature to do better. -- BenRG (talk) 16:25, 6 September 2009 (UTC)

LOL, I think I'll trust the real scientists in the peer reviewed journals rather than the armchair "physicists" on wikipedia 72.155.20.79 (talk) 03:18, 8 September 2009 (UTC)

If you wish to refute what BenRG has stated, please find any sources that state explicitly that this isn't the case that there are no flux tubes or strings, instead of resorting to insults. Even the abstract itself states resembling monopoles and looks like a magnetic monopole no actualities. Also you may want to have a look around try here Oleg Tchernyshyov at Johns Hopkins University in the US said that the findings of both teams are in agreement with a theory (see "'Spin ice' could contain magnetic monopoles") that was unveiled last year by several of Morris's colleagues. However, he cautions that the theory and experiments are specific to spin ices, and are not likely to shed light on magnetic monopoles as predicted by Dirac. Regards ^Khukri 07:13, 8 September 2009 (UTC)

The information discussed here is relevant to the article, especially with the "magnetic electricity" article being #1 on BBC today. A lot of readers are going to wonder why the page isn't updated yet and not look at the talk page. -Craig Pemberton (talk) 03:14, 15 October 2009 (UTC)

Well, it's in the article, but not in the lead. You're right, it should be. I'll add something. --Steve (talk) 05:10, 15 October 2009 (UTC)

Done. --Steve (talk) 05:34, 15 October 2009 (UTC)

You're right. I saw that later. Me (and a lot of people) aren't going to know to look under "spin ice" for clarification unless they carefully compare the news article and the TOC. Thanks for the update! -Craig Pemberton (talk) 05:55, 15 October 2009 (UTC)

Question!

We know that magnetic force appeare only in some frame of references. So the magnetic field is a part of electro-magnetic field. If there is one field, there is one charge(electric). How can exist magnetic charge? Gvozdet (talk) 06:28, 7 September 2009 (UTC)

Permanent magnets are so-called "magnetic dipoles"; they can be thought of as a pair of opposite magnetic charges brought close together; their fields interacting. The thought is that there exist free particles that have a magnetic charge; these were predicted by particle physicists (mostly Dirac) in the 20th century and have yet to materialize. 160.36.28.155 (talk) 18:29, 22 September 2009 (UTC)

New Nature paper?

Does anyone care to find the paper this BBC story mentions? Pcap ping 01:33, 26 November 2009 (UTC)

Found it. If anyone that has the knowledge and patience to read it, please update the wiki article. Pcap ping 01:58, 26 November 2009 (UTC)

I think the elementary unit of magnetic charge measured in this paper should at least be mentioned... Pcap ping 02:06, 26 November 2009 (UTC)

That Nature article has recently been questioned (see here [3]). Perhaps the reference to the Nature article (currently Ref 27) should be removed until resolved? Physicsguy2 (talk) 19:04, 22 November 2011 (UTC)

This might be of interest

Scientists at Imperial College created a magnetic monopole (magnetic substance with only north or south polarity, not both), by assembling a metallic nanostructure in the shape of a honeycomb. Article —Preceding unsigned comment added by Alainbryden (talk • contribs) 13:04, 15 April 2010 (UTC)

I don't think what they did is the same thing as creating a magnetic monopole. John (talk) 05:31, 18 April 2010 (UTC)

What is the fate of a magnetic monopole?

I would like to see a section that explains the expected fate of a magnetic monopole as it travels towards the Earth. I assume that it would have some interaction with the Earth's magnetic field. What happens once it strikes an atom? Would it join the atom and stay around forever, get annihilated, or just fly through Earth with little interaction? Dstahlke (talk) 19:15, 17 April 2010 (UTC)

Monopole problem

Why does monopole problem redirect here? —Preceding unsigned comment added by 70.250.199.143 (talk) 17:59, 23 July 2010 (UTC)

After this article was created, someone created an article on the same subject but with a different name. When that was discovered, the newer article was turned into a redirect to this one. Dougweller (talk) 18:34, 23 July 2010 (UTC)

If "monopole problem" is a term in actual usage, and it redirects here, then I find it odd that there's not a section for it. Especially since I find one here: Inflation_(cosmology)#Magnetic_monopole_problem. Isn't it more appropriate in an article about monopoles? 70.250.199.143 (talk) 23:13, 23 July 2010 (UTC)

I've changed the redirect to go to the section that you noted above in the short term, though I agree it maybe better noted here. Cheers ^Khukri 16:39, 12 April 2011 (UTC)

The delta function

Aha, the expression delta function was somewhat ambiguous, because that link takes one to a disambiguaution page. What we needed was the Dirac delta function and not the Kronecker delta function. Oddly, both of these appear in Fourier analysis, but the Dirac delta function is used in continuous-time Fourier analysis (like Joseph Fourier invented), whereasthe Kroniker delta function is used in the discrete Fourier transform.
Also, continuous-time Fourier analysis can be used to derive Heisenberg's uncertainty principle, so Fourier analysis is more important in physics than you might imagine. We communications systems engineers use Fourier analysis all the time. 98.81.1.67 (talk) 23:59, 9 August 2010 (UTC)

By the way we can make so called monopole magnets by the way we wire them, but really they have 3 poles for example: + - +. it can be made to act like a monopole magnet. —Preceding unsigned comment added by 174.27.42.58 (talk) 16:13, 12 April 2011 (UTC)

A PhysOrg article worthy of examination?

Since I lack the math background necessary for understanding the subject beyond layman's terms, I'll refrain from making any comments and let the other readers discuss the article's veracity.

Scientists capture first direct images of theoretically predicted magnetic monopoles —Preceding unsigned comment added by 69.134.195.42 (talk) 18:30, 8 November 2010 (UTC)

It would go in the section Magnetic monopole#"Monopoles" in condensed-matter systems. The section could use expansion, but only by someone with a good understanding of the whole field to provide balance and perspective. The first paragraph is good, but the current second paragraph is disproportionate emphasis on just one study of many, and seems based just on a press release. Anyway, I don't know enough. --Steve (talk) 19:31, 8 November 2010 (UTC)

Long term semi-protection

It appears that the person repeatedly inserting the OR recently has actually been doing it since 2007. Since they IP-hop, I've semi-protected the article for a year. I'm not familiar with the culture of physics articles; if constructive editing is frequent from IP's and new accounts, and a 1-year semi-protection was too drastic, please let an admin know (I probably won't be around) and they can knock it down. If it is infrequent, then apologies to the constructive IP and new editors, but please use the {{edit semi-protected}} template. --Floquenbeam (talk) 18:25, 9 February 2011 (UTC)

If it wasn't you who was going to semi protect it, after yesterday I was going to anyway. I agree with the protection and don't worry I have this page watch listed so anyone can just leave a message here if the protection gets in their way and I'll sort it out. Cheers ^Khukri 07:50, 10 February 2011 (UTC)

Monopole has been made

Though they are made artificially, the monopole has been achieved: http://www.physorg.com/news/2010-10-scientists-capture-images-theoretically-magnetic.html

Can I make a section on this? --Synethos (talk) 17:52, 21 February 2011 (UTC)

As I understand it, it is already in the article in this section and all they have produced is very long Dirac strings. Though I'm sure others more knowledgeable than I will confirm. Cheers ^Khukri 18:58, 21 February 2011 (UTC)

Yes, this is one of many papers in the same field of research which is discussed in the last paragraph of the lead section, and in that section that Khu linked to. :-) --Steve (talk) 19:01, 21 February 2011 (UTC)

Magnetic di- or mono-poles? Nothing but words

Looking for magnetic monopoles, trying to prove their existence, is nothing but lost of time, due to misunderstanding caused by application of inaccurate and confusing term "magnetic dipole" for the description of magnetic phenomena, inducing false supposition that the magnetic field is "produced" by some particle-like "poles", south and north. Nothing like that is true. The magnetic field, hence all magnetic phenomena are results of motions of electrical charges, in practice most often electrons. Evidently the motion of electrical charge can not be divided into any particle-like "poles" (which is evidently logical nonsense). If we accept the fact that magnetic phenomena are always bound to moving electrical charges, the senselessness of searching for "magnetic dipoles" is evident. The non-existence of "magnetic poles" follows of course also from Maxwell theory of electromagnetism. Easy to understand are two basic equations, called Coulomb equation for the force between two electrical stationery charges, and Lorentz equation for the force between moving electrical charges. Gauss's law for magnetism states that there are no "magnetic charges" (also called magnetic monopoles). Magnetic fields can be generated in only two ways: by electrical current (this was the original "Ampère's law") and by changing electric fields (this was "Maxwell's correction"). To change the electric field some electric charge must be moved. Hence, any magnetic phenomenon is bound to moving electrical charges, never by hypothetical "magnetic charges" Any serious discussion of "magnetic di- or mono-poles" should not be in conflict with above mentioned indisputable physical facts. —Preceding unsigned comment added by 84.42.225.153 (talk) 11:12, 21 May 2011 (UTC)

No one believes that, for example, an iron bar magnet contains magnetic monopoles. No one has believed that since the 19th century. Anything made of protons and neutrons and electrons (including everything in the periodic table) does not contain magnetic monopoles, because protons and neutrons and electrons (not to mention neutrinos and all other known particles) have zero magnetic charge. If a magnetic monopole particle is found it would be an entirely new particle so far unknown to science. Physicists who use the word "magnetic dipole" are not implying or thinking that there are two individual poles. For example, the electron magnetic dipole moment does not mean that the electron has one lobe with a positive magnetic charge and another lobe with a negative magnetic charge. "Dipole" has a specific mathematical meaning familiar to physicists (see multipole expansion) and it does not require or imply that there are two separable pole-particles. All these things are well understood by every physicist in the world, as far as I know, certainly including the physicists who study the theory of magnetic monopoles. They are not remotely controversial. I'm glad you agree too!

Of course, Maxwell's equations, as they are usually written (particularly div B = 0), imply that there are no magnetic monopoles. If magnetic monopoles are ever discovered, it would require us to modify Maxwell's equations. See the section, Magnetic monopole#Maxwell's equations.

I will modify the introduction to make it even clearer that magnetic monopoles have nothing whatsoever to do with bar magnets or electromagnets or any other magnetic phenomenon ever measured so far.

Hope that helps!! :-) --Steve (talk) 00:37, 22 May 2011 (UTC)

Magnetic monopoles detected - mistake or mystification?

I am one of those who know that nothing like "particle-like magnetic monopoles" exist. That means that I can not consider reports like e.g.<Magnetic Monopoles Detected In A Real Magnet For The First Time> otherwise than a mistake or mystification. The deliberate misinformation is less probable, but could not be totally excluded. I think that for the sake of real image of the magnetic phenomena also information about MAGNETIC MONOPOLES in WikipediA should be revised and rewritten, keeping in mind the fact, that no magnetic monopoles (or "magnetic charges") exist. In the present form it does not disprove the existence of magnetic monopole, even though in the first sentence it is presented as hypothetical. I am amazed at announcement like: "In Search of the Magnetic Monopole: Large Hadron Collider Experiment Could Rewrite Laws of Physics (Mar. 28, 2010". I can not believe that somebody in Cern could agree with such an expensive absurd experiment, searching for "magnetic monopoles"! Somebody should also write what he (she) thinks about "Monopole has been made", or other articles admitting existence of magnetic monopoles.

This topic is discussed in the last paragraph of the introduction, and in the section Magnetic monopole#"Monopoles" in condensed-matter systems. --Steve (talk) 18:25, 22 May 2011 (UTC)

Facts about "magnetic monopoles"

 @ bluehigh: 

A magnetic pole is NOT a REAL object like an electric charge: It is a bunching of flux lines owing to the geometry of the whole magnetic field. The poles are caused by the field being there: The field is not caused by the poles being there. The divergence through a pole stays zero. To have a monopole all the flux lines must either end within the pole or originate within the pole. This means that the pole must define a conservative field which it no can do. Furthermore, it also means that a North and a South pole must cancel each other when they overlap. This is also not possible: For example, when a magnetic field is generated by a current flowing around a single ring, the North and South poles overlap, but one still has flux lines moving through the centre of the ring. So please let's do physics and forget about Dirac's "beautiful mathematics"; which is just plain wrong!

When it comes to monopoles their possible existence has been derived by violating the rules of mathematics. This is why I am asking for physics to determine the issue: And why I want to know how the magnetic field lines form around a "monopole". This is a simple physics problem which do not require mathematics. I am thus waiting with bated breath!

For a more technical explanation of why magnetic monopoles DON'T EXIST, see the University of Texas online course on classical electrodynamics:

farside.ph.utexas.edu/teaching/em/lectures/node35.html

"...all steady magnetic fields in the Universe are generated by circulating electric currents of some description. Such fields are solenoidal: that is, they never begin or end, and satisfy the field equation (nabla * B = 0).

This, incidentally, is the second of Maxwell's equations. Essentially, it says that there is no such thing as a magnetic monopole."

If Maxwell's Wonderful Equations are true, and a century of experiments seem to uphold them so far, magnetic monopoles (ACTUAL magnetic monopoles, not all these so-called "defect-monopoles") DO NOT EXIST.

I am fairly confident that REAL monopoles just cannot exist since there is no such a thing as magnetic charge. I feel sorry for Blas Cabrera who is wasting his valuable time looking for monopoles — Preceding unsigned comment added by 84.42.225.153 (talk) 14:34, 28 May 2011 (UTC)

(copied from above)

No one believes that, for example, an iron bar magnet contains magnetic monopoles. No one has believed that since the 19th century. Anything made of protons and neutrons and electrons (including everything in the periodic table) does not contain magnetic monopoles, because protons and neutrons and electrons (not to mention neutrinos and all other known particles) have zero magnetic charge. If a magnetic monopole particle is found it would be an entirely new particle so far unknown to science. All these things are well understood by every physicist in the world, as far as I know, certainly including the physicists who study the theory of magnetic monopoles. They are not remotely controversial. I'm glad you agree too!

Of course, Maxwell's equations, as they are usually written (particularly div B = 0), imply that there are no magnetic monopoles. If magnetic monopoles are ever discovered, it would require us to modify Maxwell's equations. See the section, Magnetic monopole#Maxwell's equations. --Steve (talk) 16:45, 28 May 2011 (UTC)

This last contribution arises some questions:

You first write that "...everything in the periodic table does not contain magnetic monopoles... All these things are well understood by every physicist in the world, certainly including the physicists who study the theory of magnetic monopoles."

(Where could be found anything about "...the theory of magnetic monopoles"?)

How did you find out that I agree that "They are not remotely controversial"? I do not agree!

Maxwell's equations will never be required to be "modified",in particular not due to the existence of magnetic monopoles, the existence of which is excluded just by this theory. There is no doubt that this theory is obeyed in the whole universe.

For this reason the hunting for "magnetic monopoles" should eventually be stopped. LZobac — Preceding unsigned comment added by 84.42.225.153 (talk) 19:10, 28 May 2011 (UTC)

Sorry to be unclear. When I said "I'm glad you agree", I meant "I'm glad you agree that a current loops and bar magnets do not have magnetic monopoles inside them". Indeed, you are in good company, because this fact is explained in detail in every textbook on introductory electromagnetism. You'll notice that this fact is stated in the first paragraph of the article.

You say "Maxwell's equations will never be required to be modified" and are "obeyed in the whole universe", but I have bad news for you: Maxwell's equations were modified a long time ago by quantum electrodynamics (QED), and they are not exactly valid anywhere in the universe, much less everywhere. In fact, there are many cases where Maxwell's equations predict one thing, but QED predicts something different. When people measure it experimentally, QED is always correct and Maxwell's equations are always wrong. So Maxwell's equations have been proven "wrong" a long time ago. We only continue to use Maxwell's equations because Maxwell's equations are often (not always but often) a good approximation to QED.

So QED (more precisely, its expansion into the standard model of particle physics) is the true theory of electromagnetism in our universe, and Maxwell's equations are approximations that are accurate only to the extent that they agree with QED. So if QED predicts that magnetic monopoles may exist somewhere in the universe, then we should take the prediction seriously! (Even if we have never seen them here on earth.) We should not dismiss this prediction because of Maxwell's equations. Again, QED supersedes Maxwell's equations.

The "theory of magnetic monopoles" that I mentioned comes from the standard model of particle physics and its plausible extensions. It is discussed at great length in this article, and includes such topics as the 't Hooft–Polyakov monopole. Fuller explanations can be found in quantum field theory textbooks, and also specialized books like this one. :-) --Steve (talk) 20:24, 28 May 2011 (UTC)

I added an image to the top of the article to illustrate the point that you made originally (that there are no magnetic monopoles inside bar magnets or current loops etc.). It is indeed important to explain that there are no magnetic monopoles inside bar magnets, and I think the diagram should also help show that the field of magnetic monopoles is not a field that sprung out of someone's misconception that there are magnetic monopoles inside bar magnets. :-) --Steve (talk) 03:46, 29 May 2011 (UTC)

Thanks for another explanation of your point of view. You have added a new "argument", the QED, with assertion That "...Maxwell's equations have been proven "wrong", but without any real example. Can you give us some? LZobac

When QED was formulated and experimentally confirmed in the mid-20th century, it replaced Maxwell's equations as the most accurate theory of electromagnetism. QED has been tested more stringently than any theory of physics ever, see precision tests of QED. Every experimental test of QED is simultaneously a disproof of Maxwell's equations, although people don't usually say it that way because it goes without saying. I am unaware of anyone who thinks that QED is fundamentally wrong and Maxwell's equations were correct all along. I'll give some examples:

Maxwell's equations does not include photons!! More specifically, Maxwell's equations predict that charges in motion should generally create a smoothly-varying radiation field. But in fact we don't see a smooth field when the charge motion is weak, we see one photon here and there and nothing at all everywhere else. The existence of photons is already compelling evidence that Maxwell's equations are not the complete and correct theory of electromagnetism in the universe.

The Lamb shift involves quantum fluctuations of the electromagnetic field (virtual photons); if Maxwell's equations were true instead of QED, the Lamb shift would be zero.

Spontaneous emission is similar: It occurs because of quantum fluctuations, and calculations confirm that it does not occur if you assume Maxwell's equations.

The electron anomalous magnetic moment was famously predicted by QED, and the measurement agreed with the prediction to one part in 100,000,000! This QED prediction involves a lot of virtual photons that appear and disappear from the vacuum, something that doesn't happen in Maxwell's equations. I think Maxwell's equations predict that the anomalous magnetic moment is zero, which is wrong.

Here is a more elementary example: Maxwell's equations require that the electric field and magnetic field be classical vector fields. If that were true, you could not have quantum entanglement of distant photons, which means photons could not violate the Bell inequality. But quantum entanglement of distant photons violating the Bell inequality have been observed in many experiments; see Bell test experiments.

Oh here's another thing: See nonclassical light. Things like "squeezed states" have been experimentally observed. These cannot be described by a classical electromagnetic wave obeying Maxwell's equations. :-) --Steve (talk) 21:16, 29 May 2011 (UTC)

Hi Steve, thanks for your last contribution, albeit it presents more new questions than answers. I do not understand how "...Every experimental test of QED is simultaneously a disproof of Maxwell's equations". Should I understand that these equations are wrong as you write? Perhaps I could agree that "...The existence of photons is already compelling evidence that Maxwell's equations are not the complete theory of electromagnetism in the universe...", but I do not agree that they are not correct. If there is something like "...nonclassical light" and "Things like "squeezed states" which "... cannot be described by a classical electromagnetic wave obeying Maxwell's equations ..." , it is not a prove, that Maxwell´s equations are wrong (which should eliminate the best argument confirming the assertion that there are no "magnetic monopoles"). 84.42.225.153 (talk) 14:01, 30 May 2011 (UTC)

Again, if QED is exactly correct, then Maxwell's equations are not. The equations are quite different. Their predictions are quite different. I gave all those examples above: Like, if Maxwell's equations are true, then photons definitely cannot be quantum-entangled, but experimentally they can.

I guess you want to believe that Maxwell's equations are correct but not complete. You want a theory called "Maxwell's equations plus photons included". Of course, that was the first thing that physicists tried in the early 20th century, but they found that it didn't work. (They could explain some things that way, but got the wrong answer for lots of other things.) The problem is, Maxwell's equations describe classical fields but photons are quantum particles. That's why they developed QED! I guess in a sense, QED is "Maxwell's equations plus photons included", but actually QED modified Maxwell's equations beyond recognition!

Maxwell's equations are "wrong" as a fundamental law, but they are very useful as an approximation to QED. Just like Newton's law of gravity is "wrong" as a fundamental law, but useful as an approximation to general relativity (GR). Newton's law of gravity is a very good approximation to GR in some situations (the gravity between me and Earth), and a very bad approximation to GR in other situations (black holes). Likewise, Maxwell's equations are a very good approximation to QED in some situations but not others. Physicists still use Maxwell's equations in situations where Maxwell's equations more-or-less agree with QED. Maxwell's equations are still taught in school, and should be, even though we have all known for 50 years that they're not exactly correct. The equations are still definitely worth putting in the article! :-) --Steve (talk) 17:41, 30 May 2011 (UTC)

Thanks for the new contribution to our discussion. It seems to me that our viewpoints concerning QED and Maxwell's equations are (almost) identical. You no more say that: "...Every experimental test of QED is simultaneously a disproof of Maxwell's equations, although people don't usually say it that way because it goes without saying. I am unaware of anyone who thinks that QED is fundamentally wrong and Maxwell's equations were correct all along." I would fully agree with you if you in the sentence "...Maxwell's equations are "wrong" as a fundamental law..." would replace the word ..."wrong"... by the word ...insufficient...!

Nevertheless, let us not forget what this discussion has been started with: The question: "may magnetic monopoles as particles exist anywhere in our universe?" Does QED presented any prove of their possible existence, which the "imperfect" Maxwell's equations exclude? 84.42.225.153 (talk) 07:22, 31 May 2011 (UTC)

There is a big difference between "insufficient" and "wrong". "Insufficient" means "it is correct but other things are also correct". "Wrong" means "it makes predictions that experiments can prove to be false". I gave all those examples above to argue that Maxwell's equations are "wrong" not just "insufficient". Again, this is just like how Newton's law of gravity is "wrong" because Newton's law predicts that the anomalous Perihelion precession of Mercury is zero, when in fact it is not zero, as explained by general relativity.

QED was expanded into the standard model of particle physics. There are some arguments (but no "proof") that the standard model should be expanded into a grand unified theory of some sort. If that's true, then for well-understood theoretical reasons, we can be sure that some 't Hooft–Polyakov monopoles were definitely created during the Big Bang.

Also, string theory predicts that there are magnetic monopole particles, although I don't know the details. I also have heard that it's a "generic" prediction of quantum gravity, just based inevitably on well-understood properties of quantum field theory and black holes, not any details of string theory. Here's one paper from this field, but I really don't know much about this.

A few gung-ho particle physicists (including wikipedia editor "Likebox", see my discussions with him/her) say that we already have theoretical "proof" that there must be magnetic monopole particles, based on the particle physics we already know (QED and everything that QED has led to), including the two examples above and other arguments I'm even less familiar with. But I think the much more common view among particle physicists is magnetic monopoles are very likely but not yet "proven" in our current state of knowledge. --Steve (talk) 09:40, 31 May 2011 (UTC)

Thank you for your last contribution to our discussion. I hope that I do now better understand your arguments, though I am not much familiar with quantum mechanics or particle physics (being an engineer working in electron microscopy and electron beam welding). I have looked into the article "Hooft–Polyakov monopole" and found this information there: The "monopole problem" refers to the cosmological implications of Grand unification theories (GUT). Since monopoles are generically produced in GUT during the cooling of the universe, and since they are expected to be quite massive, their existence threatens to overclose it. This is considered a "problem" within the standard Big Bang theory. Cosmic inflation remedies the situation by diluting any primordial abundance of magnetic monopoles." (down to zero, LZ) This does not change my view of the question. Nevertheless, as I see it, we have reached the point in which we can (or should) make some conclusion to the debate: The mine is this: No real prove of the existence of magnetic monopoles has been found so far. I am convinced that it will remain so in the foreseeable future.84.42.225.153 (talk) 13:44, 31 May 2011 (UTC)

Great, we agree about everything. Indeed, we do not have a proof that there are magnetic monopoles in our universe, and we do not have a proof that there are no magnetic monopoles in our universe. That's what the article says too. :-) --Steve (talk) 03:20, 1 June 2011 (UTC)

Grate, we agree that "...we do not have a proof that there are magnetic monopoles in our universe...". You write that "...we do not have a proof that there are no magnetic monopoles in our universe."

I have a question: how can be proved that something DO NOT exist? How could you prove that you have not done what you are accused of? LZ

— Preceding unsigned comment added by 84.42.225.153 (talk) 07:13, 1 June 2011 (UTC) 

In physics, we usually "prove that something does not exist" by trying to understand and the laws of physics that govern the universe, and then arguing that the thing is inconsistent with those laws of physics and forbidden by the laws of physics. For example, we completely understand that Earth has a gravity field and what its effects are, and based on this we can "prove" that flying reindeer do not exist. For example, we understand the first law of thermodynamics very well (not just as an empirical law but as an inevitable consequence of Noether's theorem) and from that basis we can "prove" that there are no perpetual motion machines (of the first kind). In any case, if magnetic monopoles were fundamentally inconsistent with the standard model of particle physics and extensions thereof, that might constitute a "proof" that there are no magnetic monopoles. But actually magnetic monopoles fit very naturally into the standard model of particle physics and its extensions. Nothing we know about particle physics gives any evidence of the impossibility of monopoles, analogous to how the theory of gravity gives evidence of the impossibility of flying reindeer. Therefore "there is no proof that there are no magnetic monopoles in our universe".

Of course, no "proof" in physics is absolute (it's not math), but you can come pretty close. :-) --Steve (talk) 16:58, 1 June 2011 (UTC)

Well, many thanks for the new explanation of your viewpoint. I can not argue with particle physics arguments as I am quite unknowing in this field, but I feel competent to argue with the Maxwell's laws of electromagnetic fields in the way you recommend: "...the prove that something does not exist" by trying to understand and the laws of physics that govern the universe, and then arguing that the thing is inconsistent with those laws of physics..." The existence of "magnetic particles" has no place in electromagnetic fields, nowhere in the universe. Hence, the proof is here.

Knowledge of this fact is for me satisfactory reason not to search for "magnetic monopoles". When some contemplations in any theory suggests possibility of their existence, I would rather look for some error in those considerations than for "magnetic monopoles". I would compare them to the flying reindeer. 84.42.225.153 (talk) 15:23, 2 June 2011 (UTC)

You started your paragraph by stating "I can not argue with particle physics arguments as I am quite unknowing in this field". I suggest you take your own word for it and stop making statements about whether magnetic monopoles can or cannot exist since, by your own words, you are quite unknowing in the field. Dauto (talk) 16:51, 7 June 2011 (UTC)

Dear Dauto, you suggest me to "...stop making statements about whether magnetic monopoles can or cannot exist..." because I am "... quite unknowing in the field." It seems to me that you did not read my statement carefully enough or ignore the fact that I did not "...argue with particle physics arguments...", but "I feel competent to argue with the Maxwell's laws of electromagnetic fields" , which I am familiar with.

I repeat: The "magnetic monopoles", or "magnetic charges" etc, are inconsistent with electromagnetic fields. That is for me sufficient argument that they DO NOT exist.Caboz (talk) 06:33, 8 June 2011 (UTC)

Knowledge of Maxwell's equations just isn't enough. Maxwell's equations DO NOT give a complete picture of the nature of electromagnetism. Magnetic monopoles, if they exist, are topological defects that are not covered by Maxwell's equations. Dauto (talk) 15:49, 8 June 2011 (UTC)

Mathematical proof of MAGNETIC MONOPOLES NON-EXISTENCE:

TOPOLOGY AND THE NON-EXISTENCE OF MAGNETIC MONOPOLES Daniel Henry Gottlieb Department of Mathematics Purdue University West Lafayette, Indiana 47906 Abstract Most of the work being done to unify General Relativity and Quantum Mechanics tries to represent General Relativity in the Quantum Mechanics language. We propose here an approach to represent Quantum Mechanics in the language of Relativity. In order to introduce discretness into the language of Relativity we consider the classical invarients of homotopy theory, in particular the index of a vector eld. We insist that these invariants be treated as physical quantities, independent of choices of observers and conventions. Following this prescription we found an argument that pseudo-vectorelds should have zero index. Hence magnetic monopoles should not exist. We give extended philosophical arguments that the index should play an important role in Mathematics, and hence Physics, based on a novel denition of Mathematics and the meaning of the underlying unity of Mathematics.

6. The Nonexistence of Magnetic Monopoles

We have the following picture immerging out of the previous sections. A vector �eld has a set of connected components of defects. Now under a homotopy these components move around and collide with one another. There is a conservation law which says that ........ Caboz (talk) 16:03, 5 June 2011 (UTC)

That smells like crackpot to me. Dauto (talk) 16:51, 7 June 2011 (UTC)

Please, do explain why.Caboz (talk) 06:33, 8 June 2011 (UTC) ">— Preceding unsigned comment added by Caboz (talk • contribs) 18:12, 7 June 2011 (UTC)

The phrase "We give extended philosophical arguments that the index should play an important role in Mathematics, and hence Physics, based on a novel definition of Mathematics and the meaning of the underlying unity of Mathematics." smells suspect in my opinion. Dauto (talk) 15:49, 8 June 2011 (UTC)

Thank you for making yourself clear.Caboz (talk) 16:04, 8 June 2011 (UTC)

Searches for magnetic monopoles

(This was moved to the bottom of the discussion on a moderator's recommendation.)

I suspect that the searches that are described here are looking in the wrong place. They are searching for a monopole that is just floating around alone in the middle of a lab. I would think that most monopoles would be cozily resting in a strongly magnetic material like iron ore. It would make a lot of sense to put a large superconducting loop where the railroad cars full of raw iron ore are arriving at a steel mill. That may be difficult, but I think it would find a monopole a lot faster than leaving a loop sitting on the corner of a lab table for 5 years. — Preceding unsigned comment added by 97.65.82.66 (talk) 17:32, 18 July 2011 (UTC)

Clarification regarding condensed-matter monopoles

I understand that there has been some controversy over the description of magnetic monopoles in condensed-matter systems, so I hope my modifications to this section aren't too unpopular. This is close enough to my area of research that I feel that I can make an informed contribution, if not necessarily an unbiased one.

Perhaps pointing out the distinction between monopoles in B and H is enough to satisfy those who insist that these are not "true" monopoles. Since the name "magnetic field" is just as commonly applied to H as to B, I think the name "magnetic monopole" (or "magnetic charge") is perfectly valid for these objects. In any case, this is the nomenclature that is used in the published sources (academic journals as well as the popular press), so I think it's entirely appropriate that Wikipedia uses it too. Stevvers (talk) 23:25, 22 December 2011 (UTC)

Your description sounds fine to me. :-) --Steve (talk) 00:04, 23 December 2011 (UTC)