Talk:Magnetic monopole

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Archives
Archive 1 Feb 2003 - Jul 2007

1 SI
2 Price's non-monopole
3 Dirac quantization condition
4 SI again
5 properties, searches
6 Lorentz force in SI
7 Uses?
8 Point that could use clarification

[edit] SI

There are Maxwell's equations written in cgs system in the article. Can somebody include Maxwell's equations written in SI in the article? --78.1.23.137 (talk) 15:28, 12 January 2008 (UTC)

It's not cgs either (note the lack of c's), it's "nondimensionalized", as explained in the sentence immediately prior. My preference would be to take that one out, and put in both the cgs and the SI (I think the equations are sufficiently important in this article to warrant including two forms). The nondimensionalized can be generated easily enough from the cgs. Thoughts? --Steve (talk) 08:20, 14 January 2008 (UTC)

It would be a good idea to have both cgs and SI equations. --161.53.6.108 (talk) 16:28, 16 January 2008 (UTC)

[edit] Price's non-monopole

Regarding my recent revert, the source is quite aware of Price's "result":

"Since the revival of interest in monopoles in the 1970s, there have been two well-known announcements of their discovery: that of Price et al [163], who found an cosmic ray track etched in a plastic detector, and that of Cabrera [158], who reported a single event in a induction loop. The former interpretation was immediately refuted by Alvarez [164], while the latter has never been duplicated, so is presumed spurious."

I believe this represents the scientific consensus: Price found nothing. Melchoir (talk) 21:20, 17 January 2008 (UTC)

The section in the body should also be looked at for accuracy. Melchoir (talk) 21:20, 17 January 2008 (UTC)

The necessary reference is http://usparc.ihep.su/spires/find/hep/www?irn=93726 Melchoir (talk) 22:03, 17 January 2008 (UTC)

"Scientific consensus" is meaningless if the science community is unaware of the results. Price did not find "nothing". Price found the track of a highly anomalous cosmic ray that did not fit with any prior cosmic ray tracks he had been observing for more than a decade. Price was the acknowledged Dean of cosmic ray research at the time, with hundreds of published papers. That is a fact that is not in dispute. The finding was not only published in the scientific literature, it was also published in the lay press of the day [Time, August 25, 2005, full page story; front page headlines of numerous newspapers, including SF Chronicle]. The tracks themselves were subject to extreme criticism, but no plausible explanation [other than the monopole explanation] for them were put forward by anyone, including Alvarez. Alvarez used a twisted and contorted theory of a "doubly fractionating" normal nucleus, with wide variations on the error bars, to suggest a normal nucleus having traversed the particle detector, causing the 64+ tracks that were measured. One would have to wonder why the first such doubly-fractionating nucleus just happened to mimic a magnetic monopole, without any of the trillions of expected other tracks coming close to, but not mimicing, a magnetic monopole having been seen first. This article is not to "prove" the validity of the experiment. Rather, it is to direct the reader to the idea that anomalous cosmic rays are detected which suggest the validity of magnetic monopole theory. Please do not revert again. —Preceding unsigned comment added by Oldnoah (talk • contribs) 02:19, 21 January 2008

Okay, let's break this down:

Your edit replaces "never been observed" with "never been directly observed". This change strongly suggests that magnetic monopoles have been indirectly observed, a claim for which you do not provide a source. Per Wikipedia:Verifiability, this claim should be removed until a source is found.
Your edit also introduces the explanation "However, Milton's review neglects the substantial discovery of an anomalous cosmic ray particle found by Walter L. Wagner and P. Buford Price in 1975...". This is false. Milton's review does not neglect Price's event.
I'm not nearly familiar enough with Price's experimental technique or body of data to independently evaluate either. I also can't comment on the plausibility of Alvarez's or others' explanations. This is consistent with Wikipedia:No original research. However, I am perfectly comfortable citing reviews by modern authors who call Price's anouncement a mistake (and these include Price himself, a few years afterward).

If you just want to draw attention to the monopole candidates, that's fine: the lead of the article should cover its contents. But innuendo isn't going to get the job done. Start by finding some reliable sources to reference. Melchoir (talk) 04:41, 21 January 2008 (UTC)

OK, now that you've acknowledged your lack of exxpertise in the field, then perhaps we can reach a compromise, and at least include Price's event as a leading magnetic monopole candidate event that is as of yet unproven. While Price did subsequently "retract" his claim, he did not say that the event was not recorded. Rather, he suggested that it might not have been a magnetic monopole, as it would have had to have been exceptionally massive [and theory at the time did not lend credence to exceptionally massive monopoles, though they do nowadays]. Likewise, Milton's review neglects the importance of the event, even if making casual mention. Please note that the event was recorded some 64 different times [top and bottom of each sheet of plastic], and there is no question that a cosmic ray of exceptionally high ionization potential traversed the particle detector.

All efforts to identify the tracks as having been caused by a known particle [e.g. doubly fractionating heavy nucleus] have the difficulty of being exceptionally implausible. One would have expected to have seen Billions of such doubly fractionating nuclei coming close to, but not exactly, mimicing a magnetic monopole track before having the first one ever detected exactly mimic a magnetic monopole. Price himself acknowledged this, and his "retraction" did not attempt to identify the culprit that caused the tracks. Rather, he was under intense pressure from Alvarez and others to "retract" his claim, and without proof of a "live" magnetic monopole, he left it inconclusive.

I happened to have worked with the Price group at that time, and personally saw the tracks, and they indeed were quite anomalous compared to all other cosmic ray tracks [in the millions] observed. I am quite familiar with the track-etch technique, which has been used successfully by many other groups since Price et al. pioneered the technique in the late 1960s when he worked at GE.

Since Milton does make some mention, I will correct that part. Oldnoah (talk) 21:31, 21 January 2008 (UTC)Oldnoah

Well yes, clearly Price's event is a leading magnetic monopole candidate. In fact, I rather envy you for having seen the tracks! But the edits you keep restoring are more sensational and simplistic than your explanations here. Rather than force you to defend them again, I'll try something else. The current lead is, after all pretty short... Melchoir (talk) 04:14, 22 January 2008 (UTC)

Oldnoah, the crux of the issue is that we have a verifiable source (Alvarez's paper) that refutes Price's analysis, but we do not have a verifiable source that refutes Alvarez's refutation. What we have is your own refutation of Alvarez's refutation, but your comments on the discussion page of a Wikipeda article do not constitute a verifiable source. It seems to me, based on the verifiable sources we have available so far, that the physics community has long since given up on interpreting this event as a monopole. If that's incorrect, please point us to a verifiable source that says otherwise.--76.93.42.50 (talk) 03:05, 9 March 2008 (UTC)

[edit] Dirac quantization condition

In the text, it is mentioned that Dirac stated that the product of the electric charge and the magnetic pole units is an integer number, and therefore that these two entities have reciprocal units.

Can you set a reference and an explanation for that? I have the original work by Dirac in 1931 (Proc. Roy. Soc. A133, 60) and the later one from 1948 (Phys. Rev. 74, 817) right now on my table, which I read in the last day, and the quantization condition Dirac showed is quite different:

$\hbar c / e\mu_0 = 2$ ,

with the symbols being respectively Planck's constant, velocity of light, electrical charge and magnetic pole (he uses the symbol $g$ , still used now, in the later work). In this picture, $e$ and $μ 0 (g)$ should actually have the same units, since:

$e^2 = (1/137) \hbar c$ .

Also the wiki explanation on how Dirac gets to his conclusion is not consistent with what written here in the original work. Maybe this is another way to get to the same results (which is actually not the same in this case), but the corresponding reference should be cited as the main source of the paragraph. As it is right now, it looks like Dirac made such statements, which is not true. —Preceding unsigned comment added by 213.100.42.209 (talk) 00:05, 8 February 2008 (UTC)

[edit] SI again

Will anybody add Maxwell's equations in SI units to the article? --83.131.70.167 (talk) 20:05, 9 February 2008 (UTC)

Done. I copied the SI straight out of a textbook (see the footnote I put in), but for the cgs, I just guessed that magnetic and electric charges would have the same units, and that the previous version on this page was correct in nondimensionalized form. It would be best if someone could check it against a reliable source, and cite it. Anyone?--Steve (talk) 06:28, 10 February 2008 (UTC)

Good jod! I did some fixings. You forgot to square the c's; I used such units for magnetic charge such that in static situation (no currents) it would be $\nabla \cdot \mathbf{H}=\rho_{m_{free}}$ , just like units 99%+ times used for electric charge are such that $\nabla \cdot \mathbf{D}=\rho_{e_{free}}$ . I did so because magnetic $\ \mathbf{H}$ analogous to electric $\ \mathbf{D}$ (both don't need

ε 0

s and/or

μ 0

s when being calculated). Because such units probably weren't used by Jackson, I've commented out your reference. --161.53.6.108 (talk) 10:04, 11 February 2008 (UTC)

Hello! I like the bold vectors. I'm not sure about the other changes though:

CGS: I don't think the c's should be squared in the cgs version of Faraday's and Ampere's. See for example [1] or the article Maxwell's equations (section 5). (It should agree with the standard versions when rho_m and J_m are zero, of course.) Also, why did you put 1/c^2 in the cgs Gauss's law of magnetism? If E and B have the same units in cgs, wouldn't it be most likely that rho and rho_m have the same units too? Is there a source for this?

SI: I see how it's nice and symmetrical with a mu_0 multiplying the magnetic charge, but the article should have the equations in the most common and conventional way, not the best way. It's not our place to choose the units for magnetic charge; this is an encyclopedia, not a standards-committee. Now, Jackson purports to have the extended Maxwell's equations in SI units, and there's no mu_0. Do you have a comparably reliable source that has it with a mu_0? If so, great, we should put in a citation, and add a note that other unit conventions are also sometimes used. If not, I'm afraid we'll have to take the mu_0 back out. --Steve (talk) 17:57, 11 February 2008 (UTC)

I've now reverted these changes, but added a "citation needed" template to cgs to emphasize that we should have a reliable source on it. (More reliable than my educated guess.) --Steve (talk) 00:11, 12 February 2008 (UTC)

[edit] Emphasis here is to the symmetry!

This article is about monopoles, not about Maxwell's equations (and Extended and unit variants!).

It is important here emphasis in the symmetry, then simplified by nondimensionalization highlight the symmetry!

Please, REVERT TO http://en.wikipedia.org/w/index.php?title=Magnetic_monopole&oldid=190222242 —Preceding unsigned comment added by 143.107.230.53 (talk) 20:31, 11 February 2008 (UTC)

Well, the above anon asked me to comment here on my talk page. I don't hold a strong opinion on which presentation is best for the reader. If it's a big deal, one possible solution would be to expand on all possible forms in a new article, Symmetrized Maxwell equations, and leave just enough here to have something to refer back to. Melchoir (talk) 20:53, 11 February 2008 (UTC)

The cgs version displays the symmetry just as clearly as the nondimensionalized. The SI version does not, but is a widely-used, standard system of units, the inclusion of which was repeatedly requested. So we put in both. Seems like a perfect solution. Anyone interested in the nondimensionalized version will have no trouble reconstructing it from the cgs. We could even say explicitly, "for nondimensionalized, take out the c's from the cgs", but I don't see the need.

That said, if someone wants to make a separate article on symmetrized Maxwell equations, there are some other things to say about it, such as the extra transformations under which they're invariant (see Jackson, for example). But without the addition of new content, I don't think it would be appropriate to make a separate article just for three tables and two paragraphs of text. --Steve (talk) 22:12, 11 February 2008 (UTC)

Makes sense to me. In general, I tend to favor the creation of stubs in topics that have room to grow, but this one would really start out slim. Melchoir (talk) 22:32, 11 February 2008 (UTC)

I added a sentence immediately above the tables, saying that cgs displays the symmetry more clearly than SI. Does that help make the point? If not, other ideas? --Steve (talk) 00:08, 12 February 2008 (UTC)

About "The cgs version displays the symmetry just as clearly as the nondimensionalized" (from Steve 22:12), NO. It is not a kind of "personal taste", please compare objectively: nondimensionalized have

Where you see the largest tables?
Where you see more metric-dependent constants (4pi is universal mathematic)
Where reader can "see fast" the equations and symmetry?

About a lot of big metric-polluted tables and non-relevant information: it is visual pollution, the SI+CGI tables not add encyclopedic information. Wikipedia text must be simple, didactic, exact, etc. not polluted and so difficult to read (and to download!).

[edit] More than 1 year ago!

The "enhancing notation for show symmetries" edit, is from 03:33, 28 January 2007. For DELETE User:Sbyrnes321 MUST FIRST TALK HERE. See comparison bellow.

[edit] Nondimensionalized, SI, and CGI comparison

About visual pollution, please compare and vote (justify) for decide if change or not the article text. Important sugestion: only ONE table at the article.

About "visual pollution":

Where you see the largest table?
Where you see more metric-dependent constants?
Where reader can "see fast" the equations and symmetry?

Nondimensionalized

Name	Without Magnetic Monopoles	With Magnetic Monopoles
Gauss's law:	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$
Gauss' law for magnetism:	$\nabla \cdot \mathbf{B} = 0$	$\nabla \cdot \mathbf{B} = 4 \pi \rho_m$
Faraday's law of induction:	$-\nabla \times \mathbf{E} = \frac{\partial \mathbf{B}} {\partial t}$	$-\nabla \times \mathbf{E} = \frac{\partial \mathbf{B}}{\partial t} + 4 \pi\mathbf{J}_m$
Ampère's law (with Maxwell's extension):	$\nabla \times \mathbf{B} = \frac{\partial \mathbf{E}} {\partial t} + 4 \pi \mathbf{J}_e$	$\nabla \times \mathbf{B} = \frac{\partial \mathbf{E}} {\partial t} + 4 \pi \mathbf{J}_e$

Name	Without Magnetic Monopoles	With Magnetic Monopoles
Gauss's law:	$\nabla \cdot \mathbf{E} = \rho_e / \epsilon_0$	$\nabla \cdot \mathbf{E} = \rho_e / \epsilon_0$
Gauss's law:	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$
Gauss' law for magnetism:	$\nabla \cdot \mathbf{B} = 0$	$\nabla \cdot \mathbf{B} = 4 \pi \rho_m$
Faraday's law of induction:	$-\nabla \times \mathbf{E} = \frac{\partial \mathbf{B}} {\partial t}$	$-\nabla \times \mathbf{E} = \frac{\partial \mathbf{B}}{\partial t} + 4 \pi\mathbf{J}_m$
Ampère's law (with Maxwell's extension):	$\nabla \times \mathbf{B} = \frac{\partial \mathbf{E}} {\partial t} + 4 \pi \mathbf{J}_e$	$\nabla \times \mathbf{B} = \frac{\partial \mathbf{E}} {\partial t} + 4 \pi \mathbf{J}_e$

CGS

Name	Without Magnetic Monopoles	With Magnetic Monopoles
Gauss's law:	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$	$\nabla \cdot \mathbf{E} = 4 \pi \rho_e$
Gauss' law for magnetism:	$\nabla \cdot \mathbf{B} = 0$	$\nabla \cdot \mathbf{B} = 4 \pi \rho_m$
Faraday's law of induction:	$-\nabla \times \mathbf{E} = \frac{1}{c}\frac{\partial \mathbf{B}} {\partial t}$	$-\nabla \times \mathbf{E} = \frac{1}{c}\frac{\partial \mathbf{B}} {\partial t} + \frac{4 \pi}{c}\mathbf{J}_m$
Ampère's law (with Maxwell's extension):	$\nabla \times \mathbf{B} = \frac{1}{c}\frac{\partial \mathbf{E}} {\partial t} + \frac{4 \pi}{c} \mathbf{J}_e$	$\nabla \times \mathbf{B} = \frac{1}{c}\frac{\partial \mathbf{E}} {\partial t} + \frac{4 \pi}{c} \mathbf{J}_e$

Second table is wrong since there should not be 4pi in SI equations. --193.198.16.211 (talk) 19:50, 17 February 2008 (UTC)

Yes, these tables have been edited since being posted on the talk page, and are now incorrect. Do not use them. The versions in the article should be watched more carefully, but I believe that they're correct at the moment. --Steve (talk) 06:04, 18 February 2008 (UTC)

[edit] Reply

Hello! I fully agree that the nondimensionalized version is the best single way to make the symmetry of the equations clear, with the smallest table and fewest metric-dependent constants.

Ok!

However, I strongly disagree that the SI and cgs, with their metric-dependent constants, are "non-relevant information" and do "not add encyclopedic information". Displaying the symmetry in Maxwell's extended equations is not, in my view, the only reason that the equations are in the article: The other important reason is so that people who want to do an electromagnetic calculation using monopoles can have a place where they can look up the equations they need. SI is the most common system of units in electromagnetism, used universally by engineers and often by physicists. So putting the equations in SI units is very relevent to many readers---and I think it's telling that there have been at least two independent requests on the talk page for the SI equations to be put in. It's certainly encyclopedic information.

Ok, SI vote. About "... other important reason is so that people who want to do an electromagnetic calculation using monopoles can have a place where they can look up the equations they need...", yes, I agree, but people have (here on Wikipedia) the Maxwell's equations (or complementar sections or articles if you prefer) for it (show "for utility" copy/paste not for simple, didactic, and exact explanation).

Perhaps a compromise would be to display the nondimensionalized version at the top of the section (where both charts are now),

Can you do this, I not well-come here, they delete may edits...

adding a note that this is equivalent to the cgs version, but with the factors of c removed. Then, at the end of the section, after all the text, say "The equations take on a different, less-obviously symmetric form in SI:" and put in the SI units. That way, someone reading the article from start to finish would get the pedagogical presentation of the nondimensionalized version, while the people trying to look up cgs or SI would be able to find it. I don't think two five-row charts overwhelms the section, so I don't see why it's necessary to just choose one. What do other people think? --Steve (talk) 17:08, 12 February 2008 (UTC)

It is better to use SI (and cgs) units because more people are familiar with those units than with non-dimensionalized ones.

Ok, SI vote.

And bold vectors used in SI and cgs tables are better than those used in non-dimensionalized ones.

OK, se here (up) the non-dimensionalized in bold face (exchanged \vec to \mathbf).

The anon who is against SI and cgs, and is for use of non-dimensionalized units seems to be the opposite of some editors who had complained that this article is pro-monopole biased. Perhaps this anon wants that article would be biased in such way as much as possible, but better to AFG first before jumping to conclusions.

The anon, am I? Sorry! No I not want bias this article.

However, there is no need for as hard as possible emphasis on symmetry, as this anon would probably like. I am going to revert to SI/cgs version now. --193.198.16.211 (talk) 00:08, 13 February 2008 (UTC)

Ops, ok, but the VOTE is to SI, then, we need revert ONLY SI.

Hi again! Thanks for contributing, and you certainly are welcome here :-) One note on style is: In the future, could you please reply in a single block of text, after all the previous text of that discussion? Inserting line-by-line comments, and editing your own text, works well in some places (like usenet, where readers can easily access the previous posts), but makes talk-pages very hard to read on Wikipedia. See WP:TALK.

Maxwell's equations with monopoles are not on any other Wikipedia page in SI or cgs units. So it's not a matter of "copy/paste for utility", it's making them available when they wouldn't be otherwise. Also, why are you so insistent on having only one form of the equations? If you look at other articles, for example Maxwell's equations, you'll find the equations written in 10 forms (by my count). "Magnetic monopole" is not an especially long article (see WP:SIZE), and I think it has plenty of room for two forms of these very important equations.

If no one objects, I'll implement the "compromise" I suggested above, with cgs first (for didactic reasons) and SI at the end of the section. Does anyone have comments, pro or con? --Steve (talk) 19:13, 17 February 2008 (UTC)

Ok, Thanks for your "third opinion", and sorry about WP:TALK. About "complete set of Maxwell's equations variants", yes, the place is there, not need all copies here... but your solution was good. --anon (talk) 12:01, 19 February 2008 (UTC)

I find myself liking this idea. Looking at the current state of the article, it seems strange to have the SI version presented alone or even first. I don't have statistics, but it seems like very few authors make that choice when discussing monopoles.

We could even try a meta-compromise where the SI table contains only the symmetrized equations (since the point of comparison has already been made) and is condensed into a 2x2 format instead of 1x4. This way they take up less space, and the visual effect of redundancy is reduced. Melchoir (talk) 19:24, 17 February 2008 (UTC)

I tried to edit accordingly. Thoughts? --Steve (talk) 06:06, 18 February 2008 (UTC)

Looks good to me! Melchoir (talk) 08:24, 18 February 2008 (UTC)

Final comment about SI vs cgi: SI is the international standard, not cgi... "didactic cgs", is "didactic for USA". At en.Wikipedia people adopting SI. --anon (talk) 12:01, 19 February 2008 (UTC)

PS: it was, for discuss this little point ("how to display equations"), a lot of "discuss work" (!), but it result in a final consensus. I it was very good! --anon (talk) 12:01, 19 February 2008 (UTC)

[edit] units of the quantum of magnetic monopole charge?

The "Dirac's quantization" section ends up by saying that q_e q_m is an integer. However, it's not at all clear to me what units this would be in. In SI, the product of q_e and q_m has units of (C)(T.m2)=(J.s), i.e., angular momentum. In cgs, E and B have the same units, q_e and q_m have the same units, and therefore the product q_e q_m is not dimensionless. I can see two possible interpretations of the article as it stands:

The article states Maxwell's equations in cgs and SI, but then states the quantization condition in some other, unspecified system of units in which charges are dimensionless.
The article states Maxwell's equations in cgs and SI, and the statement of the quantization condition incorrectly omits some constants.

Anyway, I think the article should state what the quantum of magnetic charge comes out to be in both cgs units (statcoulombs) and SI (T.m2). In SI, I think it should equal a*hbar/e=(a)(4.1*10^-15 T.m2), where a is some unitless constant.--76.93.42.50 (talk) 21:02, 8 March 2008 (UTC)

I fixed the quantization condition, using SI from a textbook. Your unit calculation was correct, by the way, you divide by hbar times unitless constants. I don't have a reference for what the condition is in cgs.

If you want to calculate the quantized unit of magnetic charge, that's fine with me, but will you use the electron quantum of charge e, or the quark quantum e/3? I don't know which is right, so unless you have a good argument or a reliable source for one or the other, you should be careful about your wording, and may want to just not include that bit of trivia. --Steve (talk) 17:48, 9 March 2008 (UTC)

Thanks, I think that's a big improvement! I think the current statement of the quantization condition, with an explicit statement of the system of units as SI, is sufficient -- nothing would really be added by giving a number for the quantum of magnetic charge. I do think, however, that the question of whether it should be based on e or e/3 is an important one (it occurred to me, too), and should be discussed in the article. My personal opinion would be that it should be e, not e/3 (since I don't think the quantization argument succeeds with e/3 unless there is a free quark somewhere in the universe), but that would be original research; we need a source, and it may be that there are subtleties involved that I don't understand.--76.93.42.50 (talk) 05:41, 14 March 2008 (UTC)

I think it would also be helpful if the article presented the equation for the force exerted by a magnetic field on a monopole, in cgi and SI. I believe in SI, in a system where q_m is defined by the form of Maxwell's equations given in the article, it should be F=(c^2/k)q_mB, where k is the Coulomb constant. (The c^2/k can also be expressed as 4pi/mu0.)--76.93.42.50 (talk) 18:49, 15 March 2008 (UTC)

Yea, that would be part of the "Lorentz Force equation with and without monopoles", which would be a nice inclusion, paralleling the Maxwell's equations. Sadly, it's not given in Jackson. The cgs version is given in a semi-reliable source here (see eqn (38)). For SI, I'm willing to believe that your rendition is correct, but it would be even better if there was a source for it, and I can't find any. You could put it in and flag it with "citation needed" maybe, like I did for the cgs Maxwell's equations? Or just put it in.... Or only put in the cgs, I dunno. The above-linked paper surprised me, in that it's as recent as 2001, and yet claims to be original. It could be that the symmetrized Lorentz force just isn't well-established in the physics literature yet, and maybe no one's even written down the SI version yet. --Steve (talk) 23:29, 15 March 2008 (UTC)

I added the cgi version of the Lorentz force. I'm not confident enough that I have the SI version right to put it in. I think there's some material in the back of Jackson on how to convert cgi equations into SI...?--76.93.42.50 (talk) 03:56, 19 March 2008 (UTC)

Hehe, I think you mean "cgs" not "cgi". Jackson's appendix doesn't appear to discuss the units for monopoles. I think just having it in cgs is fine. :-) --Steve (talk) 14:29, 20 March 2008 (UTC)

UPDATE: The Lorentz force for monopoles (in SI) was in Jackson after all, as an exercise. I also found another publication with the cgs version, and cited it. That publication cites a book from 1952 as another place the law is discussed. It's funny that the recent arxiv paper seemingly didn't bother to find and cite the prior derivations of the law, given such a long history of it. It's nice, though, that everyone agrees on the end result. --Steve (talk) 16:55, 15 April 2008 (UTC)

[edit] properties, searches

IMO the article could use a more thorough and systematic discussion of the experimental and theoretical work that has been done on monopoles. The review paper by Milton has quite a bit of information.--76.93.42.50 (talk) 05:50, 14 March 2008 (UTC)

[edit] Lorentz force in SI

Can anybody put generalized Lorentz force equation in SI units in terms of E and B? This would be required because everything else in this article is expressed in terms of E and B as it should be. --193.198.16.211 (talk) 12:09, 15 April 2008 (UTC)

Done. Doesn't look quite as pretty, but I suppose there's something to be said for being consistent. --Steve (talk) 16:47, 15 April 2008 (UTC)

[edit] Uses?

Can we put in a new section that would detail the possible applications of a monopole? Right now I don't see the point in one. ScienceApe (talk) 03:53, 7 June 2008 (UTC)

I find it hard to imagine that there will ever be technological uses for magnetic monopoles, mainly because they're either nonexistent or extremely rare. Technological applications are certainly not why physicists are interested in them. Physicists are also interested in neutron stars and lots of things that don't likely having technological applications.

That said, if anything notable has been said about technological applications of monopoles (other than by kooks and science-fiction writers), I'm all for it. :-) --Steve (talk) 04:46, 7 June 2008 (UTC)

Magnetic monopoles would catalyze proton decay (if they exist and proton decay actually happens [like in SU(5)]). This could then be used to convert ordinary matter into an energy just like in case with annihilation of matter and antimatter, only that antimatter is not needed, which would make some things easier. However, can anybody find any sources about that? --193.198.16.211 (talk) 05:25, 10 June 2008 (UTC)

[edit] Point that could use clarification

The article says:

"Some current models suggest that while magnetic monopoles could exist, they are so massive that they may never be observed in practice."

Could anyone knowledgeable please clarify this? It's not clear to me why this implication (massive implies unobservable) should make sense, and certainly wouldn't be clear to a non-physicist. Does massive imply (1) Hard to create? (2) Hard to detect? (3) Rare? (4) Unstable? I can't imagine (2) is true, since it should have a clear electromagnetic signal. (1) is true but doesn't rule out observational studies with big underground detectors, or something like that. Whatever the answer is, this could be a lot clearer. --Steve (talk) 06:15, 10 June 2008 (UTC)