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Evidence of Magnetic Monopoles Found?

Posted by michael on from the speculation dept.

TheMatt writes "As reported on PhysicsWeb and published in Science (subscription required), researchers at AIST and co-workers believe they have found evidence of magnetic monopoles. They observed an anomalous Hall effect in a ferromagnetic crystal that they say can only be explained via magnetic monopoles. To refresh your memory, magnetic monopoles are the magnetic analogue of electrons and other charged particles--a "north" or "south" pole only. Dirac in 1931 showed that the existence of a magnetic monopole naturally leads to the quantization of electric and magnetic charge. Thus, showing the existence of just one magnetic monopole would be quite profound for physics, but their mass (> 10^16 GeV) has made searches for them difficult."

66 comments

  1. There's monopolies on everything else... by Black+Parrot · · Score: 3, Funny

    ...so why not magnets too?

    --
    Sheesh, evil *and* a jerk. -- Jade
    1. Re:There's monopolies on everything else... by YU+Nicks+NE+Way · · Score: 1

      Aren't self-sustaining network effects evidence of magnetic monopolies?

    2. Re:There's monopolies on everything else... by pmz · · Score: 1

      Sadly, it costs a lot of money to exercise free speech in America.

      The incremental costs of posting to Slashdot are nil. The same is true for writing an editorial for the local newspaper.

      It isn't money that prevents free speech, it's fear of imprisonment for conducting cutting-edge research or for finding flaws in government policies. One of the worst aspects of things like the PATRIOT Act or the DMCA aren't the laws themselves but the resulting chilling effect they cause. They are an example of the direct effect that regulation has on stifling innovation an progress.

      --
      Healthcare article at Kuro5hin
  2. For non-physics geeks... by rjh · · Score: 4, Informative

    This is really fundamental and amazing stuff, if it turns out to be true. (Every decade or so someone discovers monopoles, then six months later, oops!, guess we didn't.) The reason why it's fundamental and amazing is the conflict between relativity and quantum mechanics.

    Relativity and quantum mechanics currently give physicists nightmares. As near as we can tell, both are fantastically accurate descriptions of the world, and both are fundamentally at odds with each other. If we could find a flaw in one or the other, that would potentially open the door to a new and better theory, one which might allow us to reconcile these differences without resorting to theology [*].

    Now, when Einstein devised relativity, he based it very heavily on Maxwell's Laws. The Laws are a set of four equations which describe pretty much all electromagnetic phenomena out there. It was the world's first Grand Unified Theory (GUT), in that it unified electricity and magnetism into one package. And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST. NO OPEN MAGNETIC FIELD LINES EXIST.

    So if Maxwell's Laws are wrong and relativity is built heavily on Maxwell's Laws, then there's a tantalizing chance relativity is wrong.

    Or if Maxwell's Laws are right and monopoles are conclusively proven not to exist, then there's a tantalizing chance quantum mechanics is wrong.

    Either way, physics wins: no matter what happens, we get to see a flaw in our current theories. And seeing that flaw is the first step to coming up with better, more accurate theories.

    What's the worst-case scenario? The worst-case scenario is these guys are wrong, just like every other monopole researcher before, and the "do magnetic monopoles exist?" question remains unresolved for the next few hundred years.

    Warning: I'm not a professional physics geek. In fact, I may be stark barking mad wrong here. :)

    [*] Theology, aka string theory. Sorry, but any theory which literally cannot be experimentally tested at any realistic energy level isn't a theory at all. It's an article of faith.

    1. Re:For non-physics geeks... by PurpleBob · · Score: 3, Interesting

      It's my impression that Maxwell's equations can account for the existence of magnetic monopoles; in fact, there are some interesting physics problems you can do (using Maxwell's equations) if you assume the existence of magnetic monopoles.

      The equation can be stated "the divergence of the magnetic field equals the density of magnetic monopoles", but of course, in most situations, it's easier to say "zero" than "the density of magnetic monopoles", since there aren't any magnetic monopoles around.

      --
      Win dain a lotica, en vai tu ri silota
    2. Re:For non-physics geeks... by Aardpig · · Score: 1

      NO OPEN MAGNETIC FIELD LINES EXIST.

      You are wrong here; it is perfectly easy to get open field lines, using a current distribution.

      --
      Tubal-Cain smokes the white owl.
    3. Re:For non-physics geeks... by Bootsy+Collins · · Score: 4, Informative

      And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST. NO OPEN MAGNETIC FIELD LINES EXIST.

      So if Maxwell's Laws are wrong and relativity is built heavily on Maxwell's Laws, then there's a tantalizing chance relativity is wrong.

      Or if Maxwell's Laws are right and monopoles are conclusively proven not to exist, then there's a tantalizing chance quantum mechanics is wrong.


      You have to be careful here. Your first paragraph is a correct statement of what's implied by one of the four Maxwell Equations. It's a bit misleading, though, to say that "relativity is built heavily on Maxwell's Laws." That seems to imply that relativity somehow depends upon Maxwell's Equations being true. That isn't correct. A better way of putting it is that Maxwell's Equations can be shown to incorporate special relativity within them, in the sense that the laws of electromagnetism stay the same ("Lorentz covariance") after changing relativistic reference frames (through a Lorentz transformation).

      In fact, we already know that the Maxwell Equations are wrong. We know that they're wrong because they fail to explain behavior on the quantum scale. For that, we turn to quantum electrodynamics (QED), which, again, incorporates special relativity. Maxwell's Equations are thus seen as an excellent approximation on macroscopic scales. The failure of such an approximation to allow for magnetic monopoles doesn't seem like much of a failure.

      That said, I've forgotten enough of my field theory that I don't remember how monopoles fit into QED. But I do know lots of field theorists, and most of them believe that monopoles are around (they'd be produced by the breaking of certain fundamental symmetries that many theorists expect to have been present in the early universe; although any inflationary epoch in the history of the Universe would be expected to make monopoles very very rare); and they don't seem to be stressing about the implications of monopoles for QED. So my suspicion is that QED is OK.

      Oh, and just as a brief defense of string theorists . . .I don't much like string theory myself, and I echo your reluctance to take it seriously on the basis of the difficulty in making comparison to experiment. But I think most string theorists would take exception to your statement that string theories "literally cannot be experimentally tested at any realistic energy level." To we who are not string theorists, that's what it looks like, yes; but a string theorist would simply reply that string theorists haven't yet been clever enough to figure out how to extract observable predictions. In other words, I don't think many string theorists would disagree with the principle that for a theory to be interesting, it must be testable. In fact, they would claim that that's their goal with string theory -- to figure out how to make realistically testable predictions -- and they just haven't yet been successful. The Planck scale is a long way from observable energy scales, to be sure. But people explore ideas that allow the examination of classes of models, e.g. the "one large dimension" stuff from a few years ago that would have had observable consequences.

    4. Re:For non-physics geeks... by jaakkeli · · Score: 5, Informative
      Relativity and quantum mechanics currently give physicists nightmares. As near as we can tell, both are fantastically accurate descriptions of the world, and both are fundamentally at odds with each other.

      From the later parts of your post it's obvious that you're now talking about *special relativity*. It is not in any way at odds with quantum mechanics; in fact, the fusion of relativity and quantum mechanics (something called "quantum field theory") is *the most succesful theory of physics ever developed* (at least when success is measured by how well the theory fits with experiment).

      What we don't have is a quantum theory of gravity. We have a very well working *classical* theory of gravity, called "general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.

      Now, when Einstein devised relativity, he based it very heavily on Maxwell's Laws. The Laws are a set of four equations which describe pretty much all electromagnetic phenomena out there. It was the world's first Grand Unified Theory (GUT), in that it unified electricity and magnetism into one package.

      That would not be a _GUT_.

      And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST.

      This is certainly true, but it is trivial to fix this law to handle magnetic monopoles. Remember, you have one Maxwell equation basically stating that

      div E = electric charge density

      and another, the one that states that no magnetic monopoles exist,

      div B = 0

      (for the completely unprepared reader: here E and B are the electric and magnetic fields and "div" is a certain sort of an operator that acts on vectors) If you compare these two equations, you'll see *why* the divergence of B is zero: by analogy, div B should just equal the "magnetic charge density", but since there are no magnetic monopoles, the magnetic "charge" density is always zero and div B = 0. In other words, there is no *theoretical* reason why you couldn't write

      div B = magnetic charge density

      but since the *experiments* tell us that this is always zero, we don't usually bother talking about magnetic charges at all and just set this to zero. If the experiments ever tell us that magnetic monopoles exist, then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well.

      So if Maxwell's Laws are wrong and relativity is built heavily on Maxwell's Laws, then there's a tantalizing chance relativity is wrong.

      No, there isn't. First of all, including magnetic monopoles the way I outlined above won't make Maxwells theory of electromagnetism in any way incompatible with special relativity. This would be a very minor modification of electodynamics. Second of all, special relativity isn't *based* on electrodynamics at all - ED was an inspiration for Einstein (basically, Maxwells ED is at odds with Newtonian mechanics; Einstein saw this and decided to seek an alternative theory of mechanics that wouldn't be in conflict with it - and found one). If electodynamics ever turned out to be wrong, it wouldn't yet say anything at all about the validity of special relativity.

      Warning: I'm not a professional physics geek.

      Well, I am. Trust me, I know what I'm doing. :-)

    5. Re:For non-physics geeks... by Froze · · Score: 2, Informative

      Don't forget that you also need to include the magnetic monopole current term, analogous to
      curl(B)-(1/c)(partial E/Partial t) = (4pi/c)J_e to get
      curl(E)+(1/c)(partial B/partial t) = (4pi/c)J_b rather than 0.

      --
      -- The morphemes of your disquisition are ascertainable, but they have eschewed an ambit of transpicuous exposition.
    6. Re:For non-physics geeks... by bcrowell · · Score: 1

      You are wrong here; it is perfectly easy to get open field lines, using a current distribution.
      Nope, that creates closed field lines.

      --
      Find free books.
    7. Re:For non-physics geeks... by bcrowell · · Score: 2, Informative
      The existence or nonexistence of magnetic monopoles has nothing to do with the validity of relativity. Relativity has been thoroughly tested. It's not speculative at all. Here is a book with some information on tests of special relativity (chapter 1). General relativity is also starting to be a well tested theory; the GPS system incorporates general relativistic effects, for instance.

      Although people often state the principles of relativity using the word "light," e.g., describing c as the speed of light, actually relativity is about space and time, not electromagnetic radiation. The factor c is better understood as a kind of space-to-time conversion factor. Even if light didn't exist, special relativity would be the same theory; you could then describe c as the speed of X, where X is any massless particle other than the photon.

      Theology, aka string theory. Sorry, but any theory which literally cannot be experimentally tested at any realistic energy level isn't a theory at all. It's an article of faith.
      I agree that string theory has been oversold, and that it's in danger of becoming theological. However, quantum gravity doesn't have to be entirely voodoo. For one thing, there was this big experiment called the Big Bang, which probed the right conditions to test theories of quantum gravity such as string theory. A really cool book is Three Roads to Quantum Gravity by Lee Smolin; I like it because it focuses on the basic principles that are relatively independent of which approach you use.

      --
      Find free books.
    8. Re:For non-physics geeks... by Cujo · · Score: 1

      Not really. The del dot B = 0 equation can easily be amended to del dot B = rho, where rho is the magnetic monpole density, and that makes it beautifully balanced with the del dot E equation, and there are no problems for relativity.

      --

      Helium balloons want to be free.

    9. Re:For non-physics geeks... by You're+All+Wrong · · Score: 1

      You said:
      """
      talking about *special relativity*. It is not in any way at odds with quantum mechanics;
      """
      and:
      """
      "general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.
      """

      So special relativity, being non-quantum, is also as much at odds with quantum mechanics as any classical theory too?

      So it's not in any way at odds with quantum mechanics, and yet it's at odds with quantum mechanics.

      Woh, deep!

      """
      Trust me, I know what I'm doing
      """

      Maybe, but your explanations aren't the clearest.

      Care to disambiguate what you wrote, olkaa hyvaa?

      YAW.

      --
      Your head of state is a corrupt weasel, I hope you're happy.
    10. Re:For non-physics geeks... by Aardpig · · Score: 1

      No, you can get open field lines from infinite current sheets. I've encountered these in MHD simulations of winds from luminous, magnetic stars.

      --
      Tubal-Cain smokes the white owl.
    11. Re:For non-physics geeks... by bcrowell · · Score: 1

      That's an unphysical artifact of unrealistic boundary conditions. A monopole would make open field lines that terminated at the monopole, not at infinity.

      --
      Find free books.
    12. Re:For non-physics geeks... by Aardpig · · Score: 2, Interesting

      You misunderstand; I have open field lines which terminate at the stellar surface (where the field is generated). Without the wind, the field is a dipole; however, the wind rips the field lines open and creates unterminated lines. In what way is this unrealistic? Stars have been observed which appear to be doing this.

      --
      Tubal-Cain smokes the white owl.
    13. Re:For non-physics geeks... by mburns · · Score: 1

      It is my understanding that it is not trivial to modify EM to allow for monopoles. Doing so would destroy EM's status as a pure tensor, a geometric object. Allowing the EM potential, A, as a tensor (rank 1 and covariant) yields the Maxwell equations plus conservation of charge as theorems; they become Bianchi identities. In other words, the nonexistence of magnetic monopoles is a mathematical truth if general relativity is more than just another system of epicycles.

      Quantum field theory is very successful experimentally (as successful as epicycles would be with the use of an unlimited hierarchy), but it is notably unsuccessful philosophically; there is no unity of substance in the theory. Therefore, as Spinoza commented, relations between the different substances, charges, matter, fields and space, become magical in nature, not providing a philosophically satisfying account of the physics.

      I think that radical empiricism, in its opposition to such philosophical satisfaction, is actually an anti-intellectual movement. And, I see a danger in trusting empiricism as an implied and unexamined metaphysics for academic physics.

      --
      Mike Burns

      --
      Michael J. Burns
    14. Re:For non-physics geeks... by jaakkeli · · Score: 1
      Doing so would destroy EM's status as a pure tensor, a geometric object. Allowing the EM potential, A, as a tensor (rank 1 and covariant) yields the Maxwell equations plus conservation of charge as theorems; they become Bianchi identities. In other words, the nonexistence of magnetic monopoles is a mathematical truth if general relativity is more than just another system of epicycles.

      If I read you correctly, you'd want to assume that electromagnetism can be built on a single vector potential and then conclude (from the theory that you get this way) that magnetic monopoles don't exist. Sorry, but this is utter nonsense. If you had taken a basic course on electromagnetism, you'd know that the ability to describe electromagnetism with a single vector potential depends on the fact that the divergence of the magnetic field vanishes and it - just like I said in my previous post - only vanishes if magnetic monopoles don't exist.

      In other words, assuming that one vector potential is enough is equivalent to assuming that magnetic monopoles don't exist. Your argument really says nothing else than "if you assume that magnetic monopoles don't exist, then magnetic monopoles don't exist".

      Quantum field theory is very successful experimentally (as successful as epicycles would be with the use of an unlimited hierarchy), but it is notably unsuccessful philosophically; there is no unity of substance in the theory.

      Oh dear. Please check your cracpot index before further explicating your personal philosophy.

    15. Re:For non-physics geeks... by jaakkeli · · Score: 1
      Don't forget that you also need to include the magnetic monopole current term

      I didn't forget. Did you notice that part where I said that "...then we'll just have to include these magnetic charge/current terms (which are normally set to zero) in Maxwells equations as well."

      :-)

    16. Re:For non-physics geeks... by jaakkeli · · Score: 1
      "general relativity", which is obviously as much at odds with quantum mechanics as any classical theory is.

      So special relativity, being non-quantum, is also as much at odds with quantum mechanics as any classical theory too?

      No.

      Woh, deep!

      Not really; this is just an issue with terminology. What's a classical theory and what's a quantum theory? Well, I don't want go into that much detail on a web forum, so lets just grab some simple example, like the point particle.

      The classical (Newtonian or relativistic) theory of a point particle is just the "physics" they tought you in high school. The basic objects in this theory have some property called "position" and another one called "velocity", the speed at which the "position" changes; to completely describe one such object you need to specify its "position" with three numbers (assuming we're doing 3D physics) and its "velocity" with another three numbers. That's how you describe a system of classical point particles. Then, when you want to include some actual physics, you introduce "forces" between the particles and apply Newtons laws to see how their velocities change due to these forces.

      The quantum theory of point particles still consists of these same properties, "position" and "velocity", but in a very different way. Briefly put, a quantum particle doesn't have a specific position or velocity, but can be in a "superposition" of different positions - you can have a particle sitting here with 36 % probability and there with 24 % probability and so on (and then you'll also have to think of something called the "phase" to completely describe the system, but lets not go into that now).

      So, in QM, position and velocity are no longer the basic quantities that you'd directly solve from the laws of physics. Instead, the basic law, "the Scrodinger equation" (for point particle nonrelativistic QM), only gives a "wave function", a mathematical object from which you can calculate the probabilities of observing the particle in different positions and with different velocities. (Then, if you wanted to include some actual physics in the picture, you'd insert something representing interactions in the Schrodinger equation and solve the wave functions.)

      That's how it works for the point particle. But it works the same way for any sort of a system. For example, we might have objects called "fields", which are things that have some value (which might a single number, a vector or something else) at every point in spacetime. To handle this classically, you need an infinite number of numbers (much more than the 2*3 you need with point particles!), but otherwise it works similarly. Again, the quantum version of is different, in the expected way (although in the actual study of quantum fields you'd run into many unexpected things).

      The point is, you have a bunch of numbers (called "degrees of freedom") that describe some sort of a system; once you have decided in this way what kind of a system you have, you can do either classical mechanics or quantum mechanics with it. (Of course, it really isn't this simple, but I just want to bring out a certain point, so maybe a little simplification can be allowed.)

      Now, is special relativity a classical or a quantum theory? You can sort of argue that it's neither: it's just a statement about the (fixed) geometry of spacetime. There are no numbers, "degrees of freedom", that go along naturally with it. It doesn't concern any sort of a system; it just tells you a fixed thing, a symmetry that you need to include in your equations if you want them to comply with this "special relativity". In this sense you can talk of "special relativistic QM" or "special relativistic mechanics" (or "special relativistic anything") and mean the same thing - that you're doing physics in a "special relativistic" ("Minkowskian") spacetime.

      What's general relativity, then? Well, it's just the same as SR, but this time the geometry of spacetime is dynamical i

    17. Re:For non-physics geeks... by Froze · · Score: 1

      oops, sorry. I read right past that part :-/

      --
      -- The morphemes of your disquisition are ascertainable, but they have eschewed an ambit of transpicuous exposition.
    18. Re:For non-physics geeks... by IWannaBeAnAC · · Score: 1
      It is unrealistic because it violates the continuity equations. If the magnetic field is divergence-less then there should be no terminating field lines, end of story. Of course, in a simulation with finite-precision arithmetic, it is not possible to rigorously enforce div B = 0 so some extreme field configurations might produce this (how 'extreme' must ultimately depend on the precision).

      Check the data again, it is quite possible that field lines can appear to terminate, but on closer inspection they do not. Frankly, I do not believe your claim that there is experimental evidence of such an effect in some stars. This would, of course, be experimental evidence for monopoles. Not out of the question, but unlikely (and big enough news that the astronomers whom I just asked about this would probably have heard about it before). Any citation links around?

    19. Re:For non-physics geeks... by Aardpig · · Score: 1

      Whoops, there I go again. What I meant to say was that, deep within the star, the field lines are those of a dipole. However, above the stellar surface, the wind pulls the lines into an open configuration. So, the field lines do not terminate at the stellar surface; they pass through the surface and assume a dipole form at small radii.

      The point I am making, however, is that the field lines above the surface are ripped open by the wind. This is a counterexample of the assertion "magnetic monopoles are required for open field lines". Look here for a suitable citation (note: I am not one of the authors on this paper).

      --
      Tubal-Cain smokes the white owl.
    20. Re:For non-physics geeks... by IWannaBeAnAC · · Score: 1

      Ok, I had a quick glance at the paper. There is a misunderstanding; By "open field lines" they mean a radial arrangement where the field lines extend well beyond the stellar surface, it doesn't mean that the field lines actually terminate (which would imply monopoles). They are simply making an assumption that, within the vicinity of the star (meaning 6 x radii - see section 2.3) the field lines can be assumed to be radial. In a more detailed calculation, the field lines would meet at a distance much larger than 6 radii away.

    21. Re:For non-physics geeks... by Aardpig · · Score: 1

      No, they aren't making such an assumption (I know this for a fact, since I work with one of them); 6 stellar radii is just the outer boundary of their computational domain. More detailed calculations indicate that the field lines extend out to inifinity without meeting. Such behaviour is perfectly compatible with the fact that div B = 0; why are you insisting that it isn't?

      --
      Tubal-Cain smokes the white owl.
    22. Re:For non-physics geeks... by IWannaBeAnAC · · Score: 1

      Well, I would consider that the lines DO meet at infinity. But this is just a matter of how exactly you define the boundary, it is not physical anyway. The important point is that it is much larger than 6 radii away and div B = 0 everywhere in the physical domain. Hence no terminating field lines anywhere in the physical domain and no monopoles.

    23. Re:For non-physics geeks... by Aardpig · · Score: 1

      You can consider what you want, but that won't make it true.

      If you look back through my posts, you will see that I never set out to claim that I had terminating field lines (in your sense) without monopoles. I claimed that I had open field lines without monopoles, from a physically-realistic model. This contradicts what the original poster wrote: that open field lines are only realizable with magnetic monopoles. Please explain to me how I am wrong.

      --
      Tubal-Cain smokes the white owl.
    24. Re:For non-physics geeks... by IWannaBeAnAC · · Score: 1

      Except that the existence (or not) of magnetic monopoles radically changes the symmetry of the fields. In particular, a U(1) vector potential is no longer enough.

    25. Re:For non-physics geeks... by IWannaBeAnAC · · Score: 1
      Hmm. The original post to which I replied stated:

      You misunderstand; I have open field lines which terminate at the stellar surface (where the field is generated).

      This certainly is a (later corrected) claim that you had terminating field lines in a circumstance which ought to be a magnetic monopole.

      Field lines that 'terminate' at infinity do not produce a monopole because, of course, they do not actually 'terminate'. div B = 0 everywhere.

      This is completely consistent with bcrowell's earlier comment: That's an unphysical artifact of unrealistic boundary conditions. A monopole would make open field lines that terminated at the monopole, not at infinity. I would not go as far as saying 'unphysical', but unless the universe is actually infinite then it is indeed an unrealistic boundary condition. If you have a bounded domain, then open field lines cannot exist. This is completely ignoring general (or even special) relativity, at which point it no longer makes sense to consider a static configuration of field lines independent of how they got there. It is irrelevant anyway, because this is way outside the domain of the computational simulation you cite.

      I never said that open field lines imply monopoles. All I said was that terminating field lines imply monopoles. In fact I cannot find anywhere in this entire thread where anyone claimed that open field lines imply monopoles. Way back, someone erroneously claimed that open field lines do not exist (they do, but only on an unbounded domain), but there was no link to monopoles at that time. I don't know what you are arguing about. None of the work you have cited has any connection (no matter how loose) to monopoles.

    26. Re:For non-physics geeks... by Aardpig · · Score: 1

      In fact I cannot find anywhere in this entire thread where anyone claimed that open field lines imply monopoles

      I quote diretly from a post by rjh, which began this thread: And one of Maxwell's Laws ("the divergence of the magnetic field equals zero") has, as a direct consequence, an absolute law: NO MAGNETIC MONOPOLES EXIST. NO OPEN MAGNETIC FIELD LINES EXIST. This is, at least a link between magnetic monopoles and open field lines.

      My response to rjh's post was (I quote): You are wrong here; it is perfectly easy to get open field lines, using a current distribution. Note that I haven't said anything about monopoles.

      bcrowell then piled in to claim: Nope, that creates closed field lines.. The work I cited was to demonstrate how he was demonstrably wrong in his assertion. After this point, I rather muddied the issue by claiming that the field lines terminated at the stellar surface, when indeed they do not -- and I think that's where monopoles became involved. However, I remained correct in my original assertion that open field lines can be produced in situations where the div B = 0 law remains valid.

      I don't know what you are arguing about. None of the work you have cited has any connection (no matter how loose) to monopoles.

      ...and I have never claimed that it does; as I indicate above the work I cited was to demonstrate that open field lines can exist in a situation where div B = 0. You need to go back and read the whole thread, not pick it up halfway through as you appear to have done...

      [ Reply to This ]
      --
      Tubal-Cain smokes the white owl.
    27. Re:For non-physics geeks... by mburns · · Score: 1

      Radical empiricism also counts as a very dubious "personal" philosophy. Spinoza is not a crackpot.

      Proceeding from the existence of the EM potential, A, is not begging the question; it is merely organizing the theory on a parsimonious basis, since writing the wave function of a test charge inherently requires the existence of A.

      The existence of A also ties into unification with general relativity. Kaluza pointed out long ago that A becomes the addition to the metric tensor - the potential of gravity - when an extra dimension is added to space. The conventional string theory adopts Kaluza's suggestion as a premise.

      --
      Mike Burns

      --
      Michael J. Burns
    28. Re:For non-physics geeks... by You're+All+Wrong · · Score: 1

      Kiitos.

      --
      Your head of state is a corrupt weasel, I hope you're happy.
  3. Well I feel dumb by NanoGator · · Score: 3, Funny

    Many moons ago when Star Control II came out, one of the resources you could collect was 'Magnetic Monopoles'. I remember thinking I was all smart by drilling it into a friend of mine's head that it was impossible to have one of those.

    Man I hope he doesn't find my email address.

    --
    "Derp de derp."
    1. Re:Well I feel dumb by WolfWithoutAClause · · Score: 2, Funny
      I remember thinking I was all smart by drilling it into a friend of mine's head

      You trepanned your friend?

      that it was impossible to have one of those.

      Yeah you find it impossible to have friends, what a surprise.

      Man I hope he doesn't find my email address.

      Well I for one am giving it to him if he asks, and I'm mailing Cowboy Neal to get him to release full details on you, you psychopath. Mind you, after drilling into his brain like that, he probably doesn't even know what day it is.

      --

      -WolfWithoutAClause

      "Gravity is only a theory, not a fact!"
    2. Re:Well I feel dumb by Pav · · Score: 2, Informative

      StarControl II? Classic game! ...now open sourced and available at sc2.sourceforge.net . Binaries for Linux and Win32...

    3. Re:Well I feel dumb by NanoGator · · Score: 1

      "Yeah you find it impossible to have friends, what a surprise. "

      Burn!!

      Good one! :)

      --
      "Derp de derp."
    4. Re:Well I feel dumb by Anonymous Coward · · Score: 0

      Well, actually, I'm pretty sure you'd have two of those (or more generally, an even number), so you'd still be right. Otherwise, there'd be a magnetic imbalance in the universe.

  4. not front page? by Anonymous Coward · · Score: 0

    why is this not front page news? why are there only 4 posts so far? If this is true, it will change the face of modern physics. If the article even has a bit of credibility, it deserves to be on the front page. If everyone understood a little more E&M theory, the world would be a better place anyway.

    1. Re:not front page? by Anonymous Coward · · Score: 0

      You must be mistaken. Slashdot is a place for paranoids and communists. It ceased being news for nerds a couple years ago.

    2. Re:not front page? by Lars+T. · · Score: 1

      Just wait for the dupe ;-)

      --

      Lars T.

      To the guy who modded me down from perfect to terrible Karma - Apple haters still suck

  5. I guess by Trikenstein · · Score: 3, Funny

    We can look forward to visits from Pak Protectors soon.

    1. Re:I guess by praedictus · · Score: 2, Funny

      And in 517 years we can finally build the engine of the new Yamato, before the earth gets blown up!

      --
      Watashi wa chikyubutsurigakusha desu.
    2. Re:I guess by PakProtector · · Score: 1

      I'm already here.

      Where is the one you call Jack Brennan?

      --

      Edward@Tomato - /home/Edward/ man woman
      man: no entry for woman in the manual.
      "Qua!?"

  6. Can "only" be explained? by kevinatilusa · · Score: 1

    That's a pretty strong statement to be making. Why do they think its a magnetic monopole and not one of a myriad other unknown or poorly understood effects?

    1. Re:Can "only" be explained? by Anonymous Coward · · Score: 1, Funny

      Got me, but it worked for the "dark matter" guys the other day too. I smell something funny in my house. It's not anything I recognize. Must be space aliens.

    2. Re:Can "only" be explained? by You're+All+Wrong · · Score: 2, Funny

      Exactly. That was the first thing that jumped out at me too.

      Do you reckon there's cold fusion going on in those crystals instead, perhaps?

      YAW.

      --
      Your head of state is a corrupt weasel, I hope you're happy.
  7. I doubt it by Omega037 · · Score: 0, Insightful

    I took calc based physics II over the summer and remember specifically that monopoles either don't exist, or are so small that it wouldn't matter either way. I somewhat doubt that monopoles do exist, merely at such a small size it appears to have only one pole.

    Magnitism, much like gravity, is one of those invisible forces that we don't truly understand why they exist. We understand the properties and interactions of these forces, and can apply both when beign used to solve a problem. But our understanding of why masses attract each other or why magnetic particles attract each other is still unknown.

    Without this fundamental understanding of these forces, we can never truly understand their nature. It is entirely possible that what we think of as magnitism is completely wrong. Much like how centrifugal forces appear to exist but don't, magnetism could actually just be a trick created by another phenomenon.

    Besides, monopoles sound too much like monopolies.

  8. burp! by orthogonal · · Score: 2, Funny

    I detected this large supply of monopoles, but it turned out to be a Pak Protector's ship.

    They I ate all these yams, and damn do I have a hangover.

    --
    Opinions on the Twiddler2 hand-held keyboard?
    1. Re:burp! by WhiteDragon · · Score: 1

      ROFL... The protectors one oaref Larry Niven's coolest ideas. Of course, for another interesting story about a monopole hunter, check out The Borderland of Sol (a Bey Schaffer (sp?) story).

      --
      Did you mount a military-grade, variable-focus MASER on an unlicensed artificial intelligence?
    2. Re:burp! by PakProtector · · Score: 1

      Tell me where you live, so you may be killed to prevent the human race from learning of my ship, off in the direction of the Constellation you beings call Saggitarius.

      --

      Edward@Tomato - /home/Edward/ man woman
      man: no entry for woman in the manual.
      "Qua!?"

  9. This is the end... by neglige · · Score: 1

    ...of magnetic storage devices as we know them :)

    --
    My cats ate my karma. They also wrote this comment.
  10. Relativity not based on Maxwell's theories by metamatic · · Score: 4, Informative
    Second of all, special relativity isn't *based* on electrodynamics at all

    Right. Just as a reminder to anyone reading this thread, the three axioms from which special relativity can be derived are:

    1. The laws of physics are the same for all non-accelerating observers.
    2. The speed of light in vacuum is a constant.
    3. Causality always applies.

    The third is often not stated, as it's implicit in most of physics anyway. I wish I could remember the entire proof, but it's been a few years. It's not especially arcane or incomprehensible, though, and you don't need a degree in physics to understand it.

    The fact that special relativity has so few dependencies, and is relatively simple, is part of its brilliance. It's also why theories that special relativity is flawed tend to be treated with extreme skepticism--it's hard to think of a theory that's more solid.

    Maxwell's theory of electrodynamics supports the idea that the speed of light in a vacuum is a constant, but it's not the only evidence; there's the Michelson-Morley experiment, for starters. So Maxwell's theory falling over would not prove that the speed of light wasn't constant, and would not knock down special relativity.

    If you want to knock down special relativity in favor of your own masterpiece, though, axiom #2 is certainly the one to go for... Throwing out either of the others tends to be a bit self-defeating. That's why most aether-theory crackpots claim that the Michelson-Morley experiment is flawed in some bizarre way.

    --
    GCHQ Quantum Insert installed. If only our tongues were made of glass, how much more careful we would be when we speak
  11. their mass; not in "real space"?? by bcrowell · · Score: 3, Informative
    Thus, showing the existence of just one magnetic monopole would be quite profound for physics, but their mass (> 10^16 GeV) has made searches for them difficult.
    This is an inaccurate representation of the article. The article says:
    • Magnetic monopoles are also predicted by some theories that seek to unify the electroweak and strong interactions. However, the monopole masses that are predicted by these so-called grand unified theories are much too large - about 10^16 giga-electronvolts - to be detected in experiments.
    They probably don't exist at all. Even if they do exist, it's only within the context of certain theoretical frameworks that this mass estimate could apply. If the mass is in the 10^16 GeV range, then there's no hope of creating them artificially with any forseeable technology; the only way to search for them would be to look for ones that occurred naturally soon after the big bang, and happen to cruise through your detector on a certain day.

    Instead of searching for magnetic monopoles in real space, Yoshinori Tokura of the National Institute of Advanced Industrial Science and Technology (AIST) in Tsukuba and co-workers turned to momentum space - the mathematical space in which condensed matter physicists construct Fermi surfaces, Brillouin zones and so on. The team was motivated by recent theoretical work which suggested that the behaviour of magnetic monopoles in momentum space is closely related to the anomalous Hall effect.
    I'm not a condensed matter specialist, so I don't really understand what they're saying here, but it sounds like they may be saying they found something mathematically analogous to a magnetic monopole, not a real magnetic monopole. Unfortunately they don't seem to have posted preprints anywhere, but they certainly aren't creating 10^16 GeV particles in a condensed matter lab, nor does it sound like they claim to have captured natural ones.

    --
    Find free books.
    1. Re:their mass; not in "real space"?? by Alsee · · Score: 2, Interesting

      I agree, it doesn't sound like they are talking about real monopole particles. It sounds like they have something that mimics the presense of a monopole, much like an electron hole in a semiconductor mimics a positron. The electron hole behaves like a positive charge and it moves around just like a particle. When it comes in contact with a free electron they even "anihilate each other" with a release of energy.

      An electron hole is merely a pattern that mimics an anti-matter electron.

      I think the crystal they describe is just aligning its internal feilds in the same sort of pattern you would get if there were a monopole present in an ordinary region. That pattern then moves around like a particle would and has the same sort of effects a monopole would have.

      If anyone has a link or explanation that they are talking about a REAL monopole please jump in, but I'm pretty sure this is just a pattern that mimics a particle, not a real particle.

      -

      --
      - - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
    2. Re:their mass; not in "real space"?? by Mister+Attack · · Score: 1

      I've read the paper 3 or 4 times, and I honestly have no idea what they're claiming. The paper itself is pretty opaque, and it's not at all clear whether they're talking about a real monopole or some sort of k-space mathematical artifact that just smells like one.

      For those who don't have access to the article, these guys are making measurements on the anomalous Hall effect in a strontium ruthenate crystal. As far as I can tell, they are claiming that the fact that the transverse magnetoresistance is nonmonotonic with temperature implies an anomaly in the Berry phase of the electrons, hence a singularity in the vector potential and a magnetic monopole.

      All this is in the first page. The actual discussion is thoroughly convoluted, and none of the CM faculty here seem to have a clue as to what the paper actually says. My guess is that they're just talking about something that looks like a monopole, but it's hard to say just from reading the paper.

    3. Re:their mass; not in "real space"?? by OldFart58 · · Score: 2, Funny

      For those who don't have access to the article, these guys are making measurements on the anomalous Hall effect in a strontium ruthenate crystal. As far as I can tell, they are claiming that the fact that the transverse magnetoresistance is nonmonotonic with temperature implies an anomaly in the Berry phase of the electrons, hence a singularity in the vector potential and a magnetic monopole.

      Dude!

      I just had a STNG/Jordy flashback moment there...

      (whoa...)

      OldFart 8-)

    4. Re:their mass; not in "real space"?? by Anonymous Coward · · Score: 0

      Even if it just acts like a monopole, that could still have some rather interesting practical applications. Just like an electron hole still acts like a positron-sized positive electric charge, with all the properties that we could want, a crystal configuration with entities having the properties of magnetic monopoles could still be useful. I suppose it might be the beginnings of something like magnetic semiconductors or something.

    5. Re:their mass; not in "real space"?? by lethe1001 · · Score: 1

      working in momentum space instead of real space is just a convenient choice of coordinates. it does not make the results any less real.

  12. Patents by yerricde · · Score: 1
    yup. monopolies.

    Should this discovery check out, I wonder who will get the patents on inventions that arise from this discovery.

    --
    Will I retire or break 10K?
  13. Re:OK we need to discover... by logophage · · Score: 1

    R: I'll pay you $6
    D: I'll pay you $10, but I need $5 of that in taxes
    Who helps the poor?-- CodeGod@fark

    okay, so i have to take exception to this ;-). to be more accurate, it would be:

    R: i'll pay you $6 but you owe me $5 with interest.
    D: i'll pay you $10 but i need $5 back in taxes.

  14. I have a question... by annisette · · Score: 1, Interesting

    Take a magnet 6"x2"x1/2" and carve a sphere out the middle. What would be the characteristics of this sphere, what would happen if it was rolled across a flat steel plane?

    --
    I eat my grapes at room temperature, cuz the cold ones hurt my teeth
  15. ObSMAC by Repton · · Score: 0, Offtopic

    I maintain nonetheless that yin-yang dualism can be overcome.
    With sufficient enlightenment we can give substance to any
    distinction: mind without body, north without south, pleasure
    without pain. Remember, enlightenment is a function of willpower,
    not of physical strength.

    -- Chairman Sheng-ji Yang,
    "Essays on Mind and Matter"

    --
    Repton.
    They say that only an experienced wizard can do the tengu shuffle.
  16. Monopoles by Muhammar · · Score: 2, Funny

    they should be investigated and stopped
    from doimg their anti-competetive magnetic practices.

    --
    I doubt that we will ever figure out - and I suspect that even if we did figure out we couldn't do much about it
  17. I dont understand any of this by Anonymous Coward · · Score: 0

    wat

  18. Ramblings by Orne · · Score: 2, Interesting

    The other day, ther was a Slashdot article that supposed that reality (as we know it) is a 3-dimensional surface lying on a larger multidimensional surface, of 6+ dimensions. All of this was to bring the relative force of Gravity in line with the strengths of other microscopic forces.

    In the case of "magnetic monopoles"... putting aside everything I've ever learned in my years as an electrical engineer... lets suppose that these actually exist.

    The first pattern we see in nature is that matter exists in pairs... particles appear out of vacuum as matter and antimatter, we have electrostatic charge from protons and electrons, so I would think that you'd still have to have a "sink and source" arrangement when dealing with magnetic monopoles. Another law that we hate to break is the conservation of energy. Over a closed space, all exchange of energy nets to zero. So, I would think that for a field emitter to exist, there must be a field receiver... the only question is where does the energy go.

    Tieing these two theories together, what's to say that a "monopole" in 3-space isn't really still a dipole in multidimensional space? In 3-space, we'd see a discontinuity, but over the whole space, we'd still have the continuity that Maxwell's classic equations require.... There really are "returning" field lines, they're just not directly observable because they don't interact with our form of matter; like dark matter in gravitic space, who's to say that similar objects can't exist in electromagnetic fields?