Talk:Magnetic monopole

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Comments:

From reading this article, I don't understand why protons and electrons do not count as magnetic monopoles. Could someone give a definition that clearly to a beginner does not include the charged particles we are familiar with?

An idea from a post further down: The protons and electrons would be electric, not magnetic, monopoles, and those are known to exist.  — Sverdrup (talk) 14:24, 18 Dec 2003 (UTC)
Ah, that's helping a little bit. The magnetic monopole article has a link to charge in the first sentence, referring to "magnetic charge", but there is only an article on "electric charge". I still don't quite know what the difference is between those two things.
IMO, this is abt the dipole article not being helpful enuf, and i am really hesitant to tackle that bcz of limited expertise; wish someone else would, and add some stuff in this article as well. But:
An electric monopole is simply a point charge, and a charged particle is a very good approximation to a point charge. I may never have heard the expression "magnetic charge" before, but let it stand; i suspect it could be just a metaphor based on analogy between
  • electric dipoles that sometimes are made up of two equal and opposite charges or electric monopoles, and
  • the hypothetical magnet (not based on motion of charges, but a dipole composed of two magnetic monopoles), that would act like the magnets we know, except that when "broken in half", the two equal and opposite magnetic charges, or magnetic monopoles, could be manipulated separately. --Jerzy 20:48, 2003 Dec 19 (UTC)

stray text from another page; anything not already on article needs to be merged in:


Magnets exert forces on one another; similarly to electric charges, like poles will repel each other and unlike poles will attract. There is one big difference between magnets and electric charges, though - magnetic poles always exist in north-south pairs! If you take a magnet and cut it in half, you don't wind up with just a north pole and just a south pole; you wind up with two smaller magnets, each with its own north and south poles. An isolated magnetic pole is called a magnetic monopole; it has been theorized that such things might exist in the form of tiny particles similar to electrons or protons, but no such particles have ever been found.

Merged looxix 18:32 Feb 21, 2003 (UTC)


From "Talk:Magnetic monopole (crackpot)":

Until now, no magnetic monopoles have ever been discovered. Nonetheless, if such monopoles could actually exist, they would cause an unprecedented revolution in electrical engineering. For instance, if one could replace the iron core of a transformer with an identical core that would be made of a substance containing free magnetic monopoles, in other words, of a 'magnetic conductor', this transformer could work as well on direct current as on alternating current, perhaps better on DC,judging from the latest theories claiming that magnetic monopoles are much heavier than electrically charged elementary particles.

Have included a reason for the Kuhne theory being mentioned. I'm not convinved that the theory is well enough accepted to deserve a mention, but seeing the whole area is speculative I think it may deserve a place. EddEdmondson 12:50 Dec 16, 2003.

Contents

[edit] Other thoughts

This article doesn't cover all the views on this. For example, Maxwell's equations tells us that no monopoles exist. Or is that irrelevant?  — Sverdrup (talk) 15:58, 17 Dec 2003 (UTC)

It may be worth mentioning this, but I think this is in Maxwell's Equations because no-one's ever seen a monopole rather than any more fundamental reason. EddEdmondson 12:50 Dec 16, 2003.

Now I don't know about the math of all this, I'm just posting so that better-knowing can answer my thinking. If it is stated in Maxwell's equation, then ain't it fundamental of the reason that commonly accepted fundamental theories are derived from the Maxwell equations?  — Sverdrup (talk) 14:01, 18 Dec 2003 (UTC)
Well, actually Maxwell's equations could easily be fixed to accomodate magnetic monopoles. Just like the first equation (\nabla \cdot \mathbf{D} = \rho) accounts for electric monopoles, the second equation could be rewritten \nabla \cdot \mathbf{H} ="magnetic charge density". In the absence of magnetic monopoles, this would of course predict the same behaviour as today. Rasmus Faber 14:19, 18 Dec 2003 (UTC)
Aha, I see. So the article is all about wheter Maxwell's postulate that they do not exist is true or not? Thanks.  — Sverdrup (talk) 14:24, 18 Dec 2003 (UTC)

I am moving the following 'graph out of the article Magnetic monopole for work:

However, there is a theory by Rainer W. Kühne from 1997 in which he predicts a second kind of photon, the "magnetic photon", which if found would provide indirect evidence for Dirac monopoles. This magnetic photon may have been observed by Kundt. New experiments to test Kühne's theory appear to confirm the magnetic photon rays.

It is so tenuous in the first sentence, and so vague in the second, as to merely confuse things.

IMO it could be the beginning of a longer 'graph or two that would enhance the article, but now its not yet ready for prime time. --Jerzy 19:41, 2003 Dec 18 (UTC)

Similarly, the sentence abt DC transformers resulting (which could itself badly use some explanation & references!) ended

perhaps better on DC, judging from the latest theories claiming that magnetic monopoles are much heavier than electrically charged elementary particles.

Put it back, IMO, when "the latest theories" have names and authors, and when "much heavier" is clear enough that, e.g., we know a magnetic monopole would still be light enough to be mobile in these "magnetic conductors". --Jerzy 21:44, 2003 Dec 19 (UTC)

"This creates a problem, because it predicts that the monopole density today should be about the times the critical density of our Universe, according to the Big Bang model."

(I have little idea about this subject, but that doesn't look right to me Motor 23:58, 15 Jan 2004 (UTC)

At first glance one would thing they meant "three", but according to [1] it's 1011. -- Tim Starling 00:04, Jan 16, 2004 (UTC)

I have just written Eric Laithwaite and was surprised to find a link in this article. Could somebody tie a bow round this please? I've also added Felix Ehrenhaft whose claims are better known (to me) Cutler 13:19, 11 Feb 2004 (UTC)

Plz clarify yr request. --Jerzy(t) 08:26, 2004 Mar 4 (UTC)
Ah, i see: no mention except in link. But the link was added in the edit described as
. 20:21, 2003 Dec 19 . . The Anome (* Eric Laithwaite)
at the page history; it may be worth consulting User:The Anome or inspecting their other edits that hour or the next day. --Jerzy(t) 08:41, 2004 Mar 4 (UTC)

The following reference from the article & section Magnetic monopole#External links may be of interest to specialists, but IMO is not worth the distraction it has been presenting to more typical readers:

--Jerzy(t) 08:26, 2004 Mar 4 (UTC)

[edit] vector magnetic monopole?

What about a source of vector magnetic potential, rather than magnetic field lines? That's technically different from a magnetic monopole, right?

Adding a function with no curl (but some divergence) to the vector potential has no physical effect. So a source of vector potential isn't a meaningful physical concept. This is explained in Griffiths 3rd ed. section 5.4, ISBN 0-13-919960-8 -- Tim Starling 01:44, Oct 12, 2004 (UTC)

[edit] Single magnetic monopole in the universe

Referring to [2]: it's not necessary for even a single magnetic monopole to be present in the universe, there only needs to be the potential for one to exist. The argument is that charge quantisation is required for renormalisation of the magnetic monopole wavefunction. -- Tim Starling 01:39, Nov 30, 2004 (UTC)

[edit] Magnetic monopole applications?

Can anyone perhaps give some examples of magnetic monopole applications (assuming magnetic monopoles would ever be discovered)?

There are two major ones that I know of.
  1. Conversion of matter into monopolium. If introduced into normal matter monopoles would effectively become the nucleus of the atoms, with nucleons orbiting them and electrons ejected into an external electron sea. Because orbital radius is proportional to mass, the resulting matter would be on the order of a million times denser than normal matter.
  2. Monopole-catalyzed total conversion plants. Massed monopoles in excited energy states catalyze nucleon decay, via the following reactions: \scriptstyle M + n \rarr M + \pi^{-} + e^{+}\,\! and \scriptstyle M + p \rarr M + \pi^{0} + e^{+}\,\!. Atomic nuclei are therefore converted into electrons and mesons, which will then decay further into more electrons and energy. Essentially matter is converted into energy with a very high efficiency.
67.86.75.109 23:56, 4 February 2006 (UTC)

[edit] How to make a monopole

My friend, lets call him Peter, wondered why you can't make a monopole by cutting a magnet in half and glue the positive ends together so that there will be two negetive ends? Please explain why this is impossible so I can tell him and my Physics teacher.

It is conventional to call one side of a magnet north and the other side south instead of positive and negative. The two poles which you glued together in the middle won't go away for no reason. Therefore there is no monopole created. --MarSch 09:56, 23 October 2005 (UTC)

[edit] Can someone explain this in English?

The length scale over which this special vacuum configuration exists is called the correlation length of the system. A correlation length cannot be larger than causality would allow, therefore the correlation length for making magnetic monopoles must be at least as big as the horizon size determined by the metric of the expanding Universe. According to that logic, there should be at least one magnetic monopole per horizon volume as it was when the symmetry breaking took place.

This statement consists primarily of self-referential gargon, and desperately needs to be re-written:

  1. What is the "correlation length", and why does it exist?
  2. Why can't it be "larger that causality would allow"? What does this even mean?
  3. What "horizon size determined by the metric of the expanding Universe"? Do you mean "the size of the universe"?
  4. Why should there be 1 monopole per volumn? And what volume, I thought we were talking about length?
  5. If there's 1 per such volume, why do we expect 10^11 of them today? Alternately this could be re-phrased as why is the volume 10^11 different than it was during the symmetry breaking? And when did this occur?
I can't explain all of it, but the questions you ask lead into other areas of physics, rather than magnetic monopoles. For 1, the correlation length is the distance over which quantum vacuum fluctuations influence (or correlate with) one another. So this leads to a volume of the area within that distance, which is where you get the volume you mention in 4. For 3, the horizon size is the size of the observable universe. See the wikipedia page on 'observable universe'. Notably, the early observable universe was much smaller than it is now, and at one point it would have been 10^-11 times the volume, which may go some way towards clarifying that. None of this is self referential, and in my opinion is written just fine. It's just using scientific terms you may be unfamiliar with. Perhaps it might be a good idea to link up some of the technical terms to their relevant wikipedia pages though. Also, a 'correlation length' article would be useful if anyone is skilled enough to write it.314159 00:59, 1 August 2006 (UTC)

[edit] Mass

From the article:

"The most recent such experiments suggest that monopoles with masses below 600 GeV/c² do not exist, while upper limits on their mass due to the existance of the universe (which would have collapsed by now if they were too heavy) is about 1026 eV."

These two figures should be converted to the same notation for clarity. I'd do it myself but I'd have to bust my brains to remember how, and then I'd probably screw it up. Also, I don't understand why the first figure has the "/c²"; it's a constant, so do the math for the poor reader. KarlBunker 17:37, 26 January 2006 (UTC)

You remember E=mc²? Well, eV and GeV are units of energy. So, if we take Einstein's famous equation, and divide by c² on both sides, we get E/c²=m. Thus, we can measure mass in units of energy divided by the square of the speed of light. Properly, we should use eV/c² or GeV/c² in both cases, but physicists are lazy, and it is a sufficiently strong and widespread convention that the c² is frequently left off in practice. If we "[did] the math for the poor reader" by actually dividing by c², we'd have to choose some non-standard and/or less informative units for mass. 600 GeV is the rest mass energy of a particle massing 600 GeV/c², to explain why the chosen units are particularly informative. See Electronvolt#Using electronvolts to measure mass for somebody else's wording of what I just said. Jon Wilson 24.162.120.52 03:46, 29 August 2006 (UTC)

This has been fixed - it should be eV/c^2.

[edit] Magnetic force

The article says: "The magnetic force is actually due to the finite speed of a disturbance of the electric field, the speed of light, which gives rise to forces that appear to be acting along a line at right angles to the charges. In effect, the magnetic force is the portion of the electric force directed to where the charge used to be."

I find this to be bull. This would predict no magnetic force from an electrically neutral current carrying wire (because there was never an electric force). I don't know if the author of this part was trying to explain the Lorentz transformation of the EM field but I think the way it is written is very misleading.Achoo5000 04:49, 28 March 2006 (UTC)

[edit] Apr 06 removal

The following was just added:

Although Maxwell equation do not support monopoles J. Garcia suggested that if the radial part of the Magnetic field :B = a / (r − d)2 where d is somehow a distance from the origin to a point (a,b,c) on R^{3} for r=d the magnetic field goes to inifnite, if we take the equation

:\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}} {\partial t}

and integrate over a surface :T = S + S(ε) where epsilon is the surface of a sphere with center in (a,b,c) the volume enclosed by this surface avoids the singularity at r=d so the volume of integration would be :V − V(ε) we have that B comes from a rotational (curl) so div(rot(E))=0 but we had that:

\iint_{S}dsRot(E)-\iint_{S(\epsilon)}Rot(E)ds= 0 (divergence theorem),the Rot(E)=-dB/dt and the integral over the sphere making epsilon tends to 0 is equal to :4πB(d,t) so we can associate a "magnetic charge" to the point where singularity for B occurs in the form:
divB=Q_{m}=-4\pi{\int_{a}^{t}{duB(d,u)}}

to make this valid the radial part of the magnetid field should depend only on the variable r and t but not on the angles :Ω, every time there is a singularity of the magnetic field, there is also a magnetic charge associated to this, if we are integrating over the surface of an sphere, its normal vector is n(r) and the integral is equal to :\int_{0}^{R}f(r+d)4\pi{r^{2}}dr so the quadratic singularity cancels, making the radius tend to 0 we get the value f(d) being d the distance from the origin to the center of the sphere.

I've removed it as original research. Melchoir 18:31, 27 April 2006 (UTC)

[edit] Merge Dirac monopole into this article

The two articles discuss aspects of the same general idea, so I'd suggest merging them. Yevgeny Kats 03:06, 2 August 2006 (UTC)

Done. Yevgeny Kats 16:48, 9 August 2006 (UTC)

[edit] General observations

Would it be better to write Maxwell's Equations in such a way that does not assume the medium is free space? For example, writing Gauss' Law of Electric Charge as Div(D) = Pe rather than Div(E) = Pe/epsilon? This would allow any medium (including anisotropic and non-linear mediums) to be represented. Also, what are the units of the magnetic charge density variable? When I do the calculations, I am getting Coulombs per cubic meter. Shouldn't the magnetic charge density be in units of webers per cubic meter? Can someone please give a second opinion on this? Nlalic 09:47, 15 October 2006 (UTC)

I haven't heard any response, so I've made the changes outlined above Nlalic 08:09, 31 October 2006 (UTC)
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