
#REDIRECT Magnetic monopole
In physics, magnetic monopole is a term describing a hypothetical particle that could be quickly clarified to a person familiar with magnets but not electromagnetism as "a magnet with only one magnetic pole". In more accurate terms, it would have net "magnetic charge". Interest in the concept stems from high-energy physics like Grand Unified Theory and superstring theory that predict either the existence or the possibility of magnetic monopoles. == Background == Magnets exert forces on one another; similar to electric charges, like poles will repel each other and unlike poles will attract. When a magnet, that is, an object conventionally described as having a north and a south pole, is cut in half across the axis joining those "poles", the resulting pieces are two normal (albeit smaller) magnets each with its own north pole and south pole, rather than two separate north-only and south-only pieces. Since all known forms of magnetic phenomena involve the motion of electrically charged particles, and since no theory suggests that "pole" is, in that context, a thing rather than a convenient fiction, it may well be that nothing that could be called a magnetic monopole exists or ever did or could. A hypothetical 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, forming from topological defects in a similar manner to cosmic strings, but no such particles have ever been found. Maxwell's equations of electromagnetism relate the electric and magnetic fields to the motions of electric charges. The equations are very nearly symmetric under interchange of electric and magnetic field; in fact symmetric equations could be written if one allowed for the possibility of "magnetic charges" exactly analogous to the observed electric charges. When no magnetic charges are present in a region, these symmetric equations reduce to the conventional equations of electromagnetism. So, classically, the question is "Why does the magnetic charge always seem to be zero?" This has been a curiosity for a long time, but it has become more of a problem in recent years, when new theories of physics seem to predict the existence of magnetic monopoles. == Attempts to find monopoles == A number of attempts have been made to detect magnetic monopoles, ranging from simple experiments with large coils of wire attempting to catch passing monopoles to experiments involving the analysis of collisions in particle accelerators. Although there have been tantalizing events recorded, none of these experiments have produced reproducible evidence for the existence of magnetic monopoles. There are a number of possible explanations for these results: * monopoles do not exist, or * that they are very rare, or * that they have some property that prevents them from being detected by our current experimental designs, or * that the experiments are flawed. == Theory == In particle theory, a magnetic monopole arises from a topological glitch in the vacuum configuration of gauge fields in a Grand Unified Theory or other gauge unification scenario. 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 tensor 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 creates a problem, because it predicts that the monopole density today should be about 1011 times the critical density of our Universe, according to the Big Bang model. But so far, physicists have been unable to find even one. Also, the Universe appears to be close to its critical density - for all matter combined. Non-inflationary Big Bang cosmology suggests that monopoles should be plentiful, and the failure to find magnetic monopoles is one of the main problems that led to the creation of cosmic inflation theory. In inflation, the visible universe was much smaller in the period before inflation, and despite the very short time before inflation, it would have been small enough for the whole visible universe to have been within the horizon, and thus not requiring many monopoles. At the moment, versions of inflation seem to be the most likely cosmological theories. The idea of magnetic monopoles existing is an appealing one, in light of the very natural and elegant way they would fit into a number of theories that physicists find promising. For example, Paul Dirac's conclusion (related to the Aharonov-Bohm effect) that the existence of magnetic monopoles implies that both electric and magnetic charge are quantum is unquestioned. == See also == * Soliton (topological) * Dirac monopole * Dyon * 't Hooft-Polyakov monopole * Felix Ehrenhaft * Eric Laithwaite == External links == * [http://arxiv.org/abs/hep-ex/0302011 Magnetic Monopole Searches (lecture notes)] * [http://pdg.lbl.gov/2004/listings/s028.pdf Particle Data Group summary of magnetic monopole search] * [http://moedal.web.cern.ch/moedal/evidence_for_monopoles.htm "Evidence for Monopoles (?)"] * [http://www.arxiv.org/PS_cache/physics/pdf/0405/0405050.pdf "A Regular Theory of Monopoles"] Magnetism Quantum field theory
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. User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. --User: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 User: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. User:EddEdmondson 12:50 Dec 16, 2003. == 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? User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. User: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? User:Sverdrup— User:Sverdrup User talk:Sverdrup 14:01, 18 Dec 2003 (UTC) :: Well, actually Maxwell's equations could easily be fixed to accomodate magnetic monopoles. Just like the first equation () accounts for electric monopoles, the second equation could be rewritten "magnetic charge density". In the absence of magnetic monopoles, this would of course predict the same behaviour as today. User: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. User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. --User: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". --User: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 User:Motor 23:58, 15 Jan 2004 (UTC) :At first glance one would thing they meant "three", but according to [http://superstringtheory.com/cosmo/cosmo4a.html] it's 1011. -- User: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) User:Cutler 13:19, 11 Feb 2004 (UTC) : Plz clarify yr request. --User:JerzyUser talk:Jerzy 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 [http://en.wikipedia.org/w/wiki.phtml?title=Magnetic_monopole&action=history the page history]; it may be worth consulting User:The Anome or inspecting their other edits that hour or the next day. --User:JerzyUser talk:Jerzy 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: * [http://pdg.lbl.gov/2003/s028.pdf A review of monopole search experiments] (presented as a table in Adobe pdf format) --User:JerzyUser talk:Jerzy 08:26, 2004 Mar 4 (UTC) ---- == 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 -- User:Tim Starling 01:44, Oct 12, 2004 (UTC) ==Single magnetic monopole in the universe== Referring to [http://en.wikipedia.org/w/wiki.phtml?title=Magnetic_monopole&diff=6097857&oldid=6097851]: 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. -- User:Tim Starling 01:39, Nov 30, 2004 (UTC)
See other meanings of words starting from letter:
Words begining with Magnetic_monopole:
Magnetic_Monopole
Magnetic_monopole
Magnetic_monopole
Magnetic_monopoles
Magnetic_monopole_(crackpot)
Magnetic Monopole
#REDIRECT Magnetic monopole
Magnetic monopole
In physics, magnetic monopole is a term describing a hypothetical particle that could be quickly clarified to a person familiar with magnets but not electromagnetism as "a magnet with only one magnetic pole". In more accurate terms, it would have net "magnetic charge". Interest in the concept stems from high-energy physics like Grand Unified Theory and superstring theory that predict either the existence or the possibility of magnetic monopoles. == Background == Magnets exert forces on one another; similar to electric charges, like poles will repel each other and unlike poles will attract. When a magnet, that is, an object conventionally described as having a north and a south pole, is cut in half across the axis joining those "poles", the resulting pieces are two normal (albeit smaller) magnets each with its own north pole and south pole, rather than two separate north-only and south-only pieces. Since all known forms of magnetic phenomena involve the motion of electrically charged particles, and since no theory suggests that "pole" is, in that context, a thing rather than a convenient fiction, it may well be that nothing that could be called a magnetic monopole exists or ever did or could. A hypothetical 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, forming from topological defects in a similar manner to cosmic strings, but no such particles have ever been found. Maxwell's equations of electromagnetism relate the electric and magnetic fields to the motions of electric charges. The equations are very nearly symmetric under interchange of electric and magnetic field; in fact symmetric equations could be written if one allowed for the possibility of "magnetic charges" exactly analogous to the observed electric charges. When no magnetic charges are present in a region, these symmetric equations reduce to the conventional equations of electromagnetism. So, classically, the question is "Why does the magnetic charge always seem to be zero?" This has been a curiosity for a long time, but it has become more of a problem in recent years, when new theories of physics seem to predict the existence of magnetic monopoles. == Attempts to find monopoles == A number of attempts have been made to detect magnetic monopoles, ranging from simple experiments with large coils of wire attempting to catch passing monopoles to experiments involving the analysis of collisions in particle accelerators. Although there have been tantalizing events recorded, none of these experiments have produced reproducible evidence for the existence of magnetic monopoles. There are a number of possible explanations for these results: * monopoles do not exist, or * that they are very rare, or * that they have some property that prevents them from being detected by our current experimental designs, or * that the experiments are flawed. == Theory == In particle theory, a magnetic monopole arises from a topological glitch in the vacuum configuration of gauge fields in a Grand Unified Theory or other gauge unification scenario. 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 tensor 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 creates a problem, because it predicts that the monopole density today should be about 1011 times the critical density of our Universe, according to the Big Bang model. But so far, physicists have been unable to find even one. Also, the Universe appears to be close to its critical density - for all matter combined. Non-inflationary Big Bang cosmology suggests that monopoles should be plentiful, and the failure to find magnetic monopoles is one of the main problems that led to the creation of cosmic inflation theory. In inflation, the visible universe was much smaller in the period before inflation, and despite the very short time before inflation, it would have been small enough for the whole visible universe to have been within the horizon, and thus not requiring many monopoles. At the moment, versions of inflation seem to be the most likely cosmological theories. The idea of magnetic monopoles existing is an appealing one, in light of the very natural and elegant way they would fit into a number of theories that physicists find promising. For example, Paul Dirac's conclusion (related to the Aharonov-Bohm effect) that the existence of magnetic monopoles implies that both electric and magnetic charge are quantum is unquestioned. == See also == * Soliton (topological) * Dirac monopole * Dyon * 't Hooft-Polyakov monopole * Felix Ehrenhaft * Eric Laithwaite == External links == * [http://arxiv.org/abs/hep-ex/0302011 Magnetic Monopole Searches (lecture notes)] * [http://pdg.lbl.gov/2004/listings/s028.pdf Particle Data Group summary of magnetic monopole search] * [http://moedal.web.cern.ch/moedal/evidence_for_monopoles.htm "Evidence for Monopoles (?)"] * [http://www.arxiv.org/PS_cache/physics/pdf/0405/0405050.pdf "A Regular Theory of Monopoles"] Magnetism Quantum field theory
Magnetic monopole
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. User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. --User: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 User: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. User:EddEdmondson 12:50 Dec 16, 2003. == 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? User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. User: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? User:Sverdrup— User:Sverdrup User talk:Sverdrup 14:01, 18 Dec 2003 (UTC) :: Well, actually Maxwell's equations could easily be fixed to accomodate magnetic monopoles. Just like the first equation () accounts for electric monopoles, the second equation could be rewritten "magnetic charge density". In the absence of magnetic monopoles, this would of course predict the same behaviour as today. User: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. User:Sverdrup— User:Sverdrup User talk:Sverdrup 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. --User: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". --User: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 User:Motor 23:58, 15 Jan 2004 (UTC) :At first glance one would thing they meant "three", but according to [http://superstringtheory.com/cosmo/cosmo4a.html] it's 1011. -- User: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) User:Cutler 13:19, 11 Feb 2004 (UTC) : Plz clarify yr request. --User:JerzyUser talk:Jerzy 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 [http://en.wikipedia.org/w/wiki.phtml?title=Magnetic_monopole&action=history the page history]; it may be worth consulting User:The Anome or inspecting their other edits that hour or the next day. --User:JerzyUser talk:Jerzy 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: * [http://pdg.lbl.gov/2003/s028.pdf A review of monopole search experiments] (presented as a table in Adobe pdf format) --User:JerzyUser talk:Jerzy 08:26, 2004 Mar 4 (UTC) ---- == 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 -- User:Tim Starling 01:44, Oct 12, 2004 (UTC) ==Single magnetic monopole in the universe== Referring to [http://en.wikipedia.org/w/wiki.phtml?title=Magnetic_monopole&diff=6097857&oldid=6097851]: 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. -- User:Tim Starling 01:39, Nov 30, 2004 (UTC)
See other meanings of words starting from letter:
M
MA | MB | MC | MD | ME | MF | MG | MH | MI | MJ | MK | ML | MN | MO | MP | MR | MS | MT | MU | MW | MX | MY | MZ |Words begining with Magnetic_monopole:
Magnetic_Monopole
Magnetic_monopole
Magnetic_monopole
Magnetic_monopoles
Magnetic_monopole_(crackpot)
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