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"Overwhelming" Evidence For Magnetic Monopoles
Thorfinn.au sends along big physics news: magnetic monopoles have been detected at low temperatures in "Dirac strings" within a single crystal of Dysprosium Titanate. Two papers are being published today in the journal Science and two more on arXiv.org, as yet unpublished, provide further evidence. "Theoretical work had shown that monopoles probably exist, and they have been measured indirectly. But the Science papers are the first direct experiments to record the monopole's effects on the spin-ice material. The papers use neutrons to detect atoms in the crystal aligned into long daisy chains. These daisy chains tie each north and south monopole together. Known as 'Dirac strings,' the chains, as well as the existence of monopoles, were predicted in the 1930s by the British theoretical physicist Paul Dirac. Heat measurements in one paper also support the monopole argument. The two, as yet unpublished, papers on arXiv add to the evidence. The first provides additional observations, and the second uses a new technique to determine the magnetic charge of each monopole to be 4.6x10-13 joules per tesla metre. All together, the evidence for magnetic monopoles 'is now overwhelming,' says Steve Bramwell, a materials scientist at University College London and author on one of the Science papers and one of the arXiv papers."
I think this is at least one of the Science articles to which the post (almost) refers.
It's only against the law to use your monopole to extort the market.
Kwisatz Haderach
Sell the spice to CHOAM
This Mahdi took Shaddam's Throne
"...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
So, can haz magtube now plz?
Damn! Anonymous Coward has thought of something none of the scientists have even considered. Give this guy a research position ASAP.
Surely if they are two monopoles tied by a dirac string then they actually make a dipole. I was under the impression a monopole would create a dirac string (a discontinuity in the field) that extends to infinity. Interestingly by allowing the dirac string to extend first in one direction, then in the other and joining the two resultant fields gives a fully continuous description of the monopole without the need for a dirac string.
I think what the summary is refering too is similar to the creation of a electron and hole pair in a semiconductor rather than a fundamental monopole particle. So they are in fact creating both poles but that inside the spin glass they are not confined with respect to each other so each one appears as a monopole in the material.
is it possible to create pepetium mobiles now? ;)
most of the the 'free energy' designs are based around non-existing monopoles, and tricks to 'emulate' monopoles.
Isn't this just in time for the new season of the show Big Bang Theory, where Sheldon is on an expedition to find magnetic monopoles? :)
Yea like that electric charge nonsense, you can't have a particle with a single electric charge! that'd be crazy whatever it is will allways have another side with the oposite charge!
All my coins are shaped like mobius strips.
That tells me nothing. How many beard seconds is that?
A magnetic monopole is to a magnetic field what an electron is to an electric field.
This will, amongst other things, mean that Maxwell's equations become more symmetrical.
div D = rho; div B = 0
Will become
div D = rho_e; div B = rho_m
And there will be a magnetic current term for curl H.
It's long been known that if a magnetic monopole exists then charge must be quantized.
I've not looked at any of the papers but I'm interested to find out if they've got a mass estimate for them. Last I remember reading about this they were expected to be heavy (uranium nucleus sort of heavy) but I don't recall if that was an extrapolation from their non-detection or whether there was a more fundamental reason for them needing to be so massive.
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
Are there any applications for it within our understanding of physics?
The existence of monopoles is a possible "explanation" for the quantization of electric charge. Maxwell's Equations are only self-consistent if:
1. magnetic monopoles don't exist, and charge is not quantized;
OR
2. magnetic monopoles do exist (at least one, somewhere), and charge is quantized.
As charge is quantized, it has always been a strong argument for monopoles' existence. Of course, perhaps Maxwell's Equations aren't applicable at the quantum level, but so far they've done a damned good job of being consistent and predicting and explaining things.
I think the stupidity is yours. Magnets are not just atoms lined up, atoms themselves have magnetic poles. In fact, the components of atoms (such as electrons) have magnetic poles as well.
It's perfectly conceivable to think of a point source of just North or South where the field lines radiate outwards in all directions. They would arc toward the nearest magnetic pole of opposite polarity. The diagrams are simple to draw and have been accepted by just giants in the field as Dirac for eighty years. The only question is: do they actually occur?
Magnetic charges fired in a customised photon torpedo were used in Voyager S96E10 to defeat the dudes with forehead that looked like vulva.
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
I know what magnetism is, I also know what a magnetic monopole is, hell I even know what a dirac string is and what a spin glass is. Honestly your argument about coins made no sense at all.
I was attempting to point out that electric charge also has field lines but that they do not have two sides like a coin, the entire point of the discovery of a magnetic monopole is that it doesn't have two sides in the way that all the other magnetic dipoles we are used to have.
I'm sorry, but you're going to have to provide your credentials if you want me to accept that you know more about magnetism than four separate physics research teams, two with articles in Science and two more with draft articles on arXiv.org, all of which show evidence of the existence of magnetic monopoles.
Christ, not to mention Paul fucking Dirac.
circletimessquare, you have one again exceeded yourself at demonstrating your truly incredible arrogance and stupidity.
Now I've scanned one of the papers I see that they're not detecting the sort of magnetic monopole I was thinking of (i.e. a new sub-atomic particle)
Instead they've detected the equivalent of a charged molecule.
They give an analogy of the disassociation of water into H3O+ and OH-. They claim to have done the same thing with magnets - ending up with a disassociated north and south pole.
So their work doesn't appear to give any clue to the mass of a magnetic monopole particle. But AFAICT they have still created a type of magnetic monopole, exactly the same way as a proton is an electric monopole even though it has an internal structure.
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
(Disclosure: I'm a physicist)
You could just as well ask: "how can an electric field line just stop somewhere?", and thereby conclude that there can be no such thing as an "electric monopole" (a positively- or negatively-charged particle). As long as the universe has no net electric or magnetic charge, all lines will terminate somewhere. If the universe did have a net charge the point is subtle, but that's irrelevant: the paper talks above pairs of opposite-pole monopoles created together, like a particle and its antiparticle. So this argument doesn't hold water.
Monopoles aren't impossible in principle (it would just be an extra term in Maxwell's equations) and are predicted in some theories, but fundamental-particle monopoles have never been observed. The summaries of this paper are confusing a lot of people: the authors are describing a crystal system with excitations that look like monopoles. They are NOT describing discovery of a new fundamental particle, but rather a new kind of solid-state phenomenon.
Sorry son, it is you who have been defeated by your own ignorance and closed-mindedness. You threw out one (dumb, totally invalid and irrelevant) analogy, somebody came back with a very proper analogy to something actually *related* to magnetism, and you shrugged it off as him not understanding magnetism. In fact, your narrow understanding of magnetism with your little coin analogy has been a convenient way to understand the concept for many years...until today. That's the point. Scientists have been researching monopoles for a long time, quite simply because the coin analogy never quite added up - there was no good reason why they *always* came as dipoles, besides that monopoles had never been observed. Now they have been, everything you know about magnets will probably be wrong once more data is gathered, and you will either have to take the scientists' word for it, or you will have continue using inaccurate mental models to make sense out of it for yourself.
The whole crowd of people selling devices that use Zero Point Energy and magnetic suspension perpetual motion machines and people who write hundred page manuscripts in purple ink arguing why the Second Law of Thermodynamics must be repealed are going to come out of the wood work now.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Having read at least one of the arxiv articles, it is clear to me that the authors have NOT detected magnetic monopoles, and don't actually claim that they have. They claim that a certain type of ordering in a very specific crystal at very low temperatures BEHAVES AS IF it was a magnetic monopole - it's an analogy at best. The energy required to trigger the effect is minute, so they can "see" lots of MMAs (magnetic monopole analogs [my terminology]), and hence study what would happen if lots of REAL MMs existed in some other situation. They confirm that setting up Maxwell's equations to include a monopole shows the same sorts of behavior as what they see. But a real, isolated magnetic monopole? Not this time......
I'm glad you provided the episode number, because the description didn't narrow it down much.
If you were blocking sigs, you wouldn't have to read this.
Dirac's argument (and all the field-theoretic) arguments in favor of the existence of magnetic monopoles have had to do with an elementary particle exhibiting those characteristics. Sometimes this is phrased in the terms of a 0-dimensional topological defect, something that would be produced by certain kinds of symmetry breaking; and indeed one of the arguments in favor of cosmological inflation theories was the fact that we don't see fundamental-particle monopoles, and would expect to. Finding one of these guys would be amazing news.
What these experiements seem to have done, however, is detected the effect of what condensed matter physicists like to refer to as a quasi-particle, akin to the phonon, which is a different thing entirely.
Or am I missing something?
If they were real, physical, isolable monopoles, they might turn out to have some minor applications in energy production. (Yeah, I linked the same article upthread; it's interesting enough to repeat.) The claim is that they would make protons (and neutrons) decay promptly. Of course, if these folks were seeing that kind of monopole, they would have noticed side effects, starting with a sudden inability to keep their samples below 1 K.
This mentality is a good example of what Joel Spolsky calls fire and motion. You just keep moving, keep publishing, keep innovating, and your opponent is so busy trying to catch up or deal with your earlier work that you gain huge momentum. Sometimes unstoppable momentum. People just can't deal with the information overload.
For 30 years, physicists have believed that the universe is made up of tiny vibrating dimensional strings which only they are clever enough to understand. A fine idea, except it turns out not even they are clever enough after all. Nevertheless, they persist in this belief because the mathematics is beautiful. Likewise, many physicists persist in their belief in magnetic monopoles because the concept is beautiful, or some other such rubbish. Look! It even makes Maxwell's equations symmetric. So what? What's so important about having symmetric equations. Unsymmetrical ones are so much more interesting!
There's only one arbiter in physics, and science in general. It isn't a "flurry of papers". It isn't "beauty" or "symmetry" or "elegance" or "coolness". It isn't how many people agree with your viewpoint. It isn't how many journalists you can get to print words like "overwhealming evidence" in headlines. It isn't how much "supporting (online) material" you can find to back you.
The one, only, and final arbiter is the experiment. An honest to gods experiment. It finds things. It separates truth from fiction. You can try to twist the meaning of the result this way and that, throw back the grenade and carry on with your fire and motion, but in the end the results of all those experiments will finally weigh down your dishonesty and halt your advance.
There are no magnetic monopoles. You can try to separate north and south pole. You can even construct models of "magnetic charge" and dipoles if you like. But in the end, you can't get a north pole without having a corresponding south pole, very, very close by.
Modern science, and worst of all physics, is in a deplorable state. Cargo cult scientists,frauds, charlatans, fakes, and deluded true believers(Yes I'm serious about that last link) have saturated certainly the media circuit, but I fear many physics departments as well. Sensationalism and media attention are now as never before, deciding what the "consensus"* in science should be. It's disheartening to see the world lose its faith in the method of observation, hypothesis, experiment and above all skepticism that has served it so well for so many centuries.
P.S.
*Before the cranks jump in; No, I do not in fact, doubt the reality of anthropogenic climate change.
May the Maths Be with you!
IAAP and I did do my PhD on this stuff, but it is a while ago now...
The Dirac string is not real, but is really just a failure of the coordinate system. Coordinate systems are always failing: just stand at the North Pole and ask which direction is South. All directions are, and the coordinate system is broken at that point. That's fine, it works everywhere else and we jsut remember to be careful in the rare cases where we are asking for directions at the North Pole. There is no fundamental breakdown of space and/or time going on, it's just because we chose to impose a silly coordinate system onto the physical world. The fact the it breaks down at the North and South poles is also a red herring - we just chose to make the polar axis the same as the axis of rotation of the earth.
The coordinate system used to simultaneously describe electric and magnetic charges is also broken, and the Dirac string is really just a way of fixing up this breakage. We imagine that one unit of magnetic flux arrived through a very narrow tube at the monopole and then spewed out in all directions (think toddlers or teenagers at this point). The tube is not real, it is just a way of patching up the failure of the coordinate system. In the same way that the Poles as points of failure is our choice, the direction that the tube arrives at the monopole is also an artifact of how we set up the coordinate system.
We can change the direction that the tube arrives at the monopole from transparently using what is technically known as a gauge transformation, but let's not worry about that here.
The tube is not real, so we must not be able to detect it. This leads to the concept of quantisation of electric charge. Normally, if you take a tube carrying g units of magnetic flux and then take an electrically charged particle round it in a circle, the wavefunction of the charged particle will change by a complex phase exp(i.theta) where theta is proportional to the product of q (its electric charge) and g. You can detect this phase using a quantum-mechanical interference experiment, if you feel the urge. If the Dirac string is to remain physically unobservable, no interference effects must be seen so the phase rotation must be a multiple of 2.pi, because exp(i.2.pi)=1.
So, we know if there is one magnetic monopole anywhere in the universe then q.g = 2.pi.n (where n is some integer) so that the Dirac string (a mathematical fix for a choice of broken coordinate systems) remains just a theoretical trick and not observable physics. We must then have that the electric charge of every particle in the universe is some integer multiple of e = 2.pi/g, where g is the magnetic charge of that monopole.
Whether you consider the smallest unit of electric charge to be the charge on the electron or the charge on a free quark (one third of this) doesn't matter. We do observe that electric charge is quantised (i.e. integer multiples of some base amount) and magnetic monopoles as fundamental particles provide a relatively elegant solution as to why this is true.
so i must be insane, or the whole lot of you are ignorant of what a magnetic field is
I'd like you to consider the possibility that it's neither of the above. I recognize your signature and remember you making many good posts in the past. I don't think you're crazy. I just think you don't understand the theory of electricity and magnetism very well.
Electric fields also begin and end at particles. And there are electric dipoles, just like there are magnetic dipoles. Why should magnetism only have dipoles and not monopoles like electricity?
Just as electric dipoles are made from positive and negative electric monopoles (charges), there is no reason magnetic dipoles can't be made from opposing magnetic monopoles. Electric monopoles are definitely MUCH easier to observe in nature, but that doesn't mean there are no magnetic dipoles.
Did you know that observers in different reference frames will disagree about the strength of electric and magnetic fields? Electric and magnetic fields vary (in a coordinated way) under Lorentz transforms. That is, what looks like a pure electric field to one observer might look like a combination of electric and magnetic fields to an observer in a different reference frame. Putting it differently, eletricity and magnetism are two aspects of a single force called, creatively enough, the electromagnetic force. That's a reason to believe that magnetic monopoles might exist.
Additionally, electric charge is observed to be quantized in nature. All free particles observed so far have charges that are integer multiples of the electron charge. Quarks are believed to have charges that are +/- 1/3 or 2/3 of the electron charge, but free quarks have not been directly observed, and in any case, even if the basic unit of charge quantization is 1/3 of the electron charge, charge is still quantized. And in the theory, the existence of magnetic monopoles automatically leads to charge quantization. That's a big reason many very smart folks with Ph.D.s in physics have been looking for magnetic monopoles for some time.
I remember a magnetic monopole detector that was sitting in a garage-like bay at HEP, the High Energy Physics group's building, at the University of Chicago in the late 1980s. I believe it was something Henry Frisch had set up really cheaply, so the risk was low, and the potential return enormous. Think of it as a low-budget HEP nerd experiment in Chicago. If you look at Professor Frisch's CV, you'll see that he's written a bunch of papers about magnetic mnopoles and their detection.
Only tangentially related: it has been 20 years, so I shouldn't have been surprised, but seeing Frisch's hair that white was a bit of a shock. Probably because of what it implies about my own age.
"It is nice to know that the computer understands the problem. But I would like to understand it too." --Eugene Wigner
As I have stated in response to circletimessquare elsewhere in this discussion, there are a few good reasons to believe magnetic monopoles might exist. I remember circletimessquare's sig, and remember him or her making good posts in the past, but it's clear that he or she does not understand electricity and magnetism very well.
Classical electric and magnetic fields vary in a coordinated way between different Lorentzian reference frames. So where one observer might only observe an electric field with no magnetic field, an observer in a different reference frame moving at a constant velocity with respect to the first observer's frame might see a combination of electric and magnetic fields. Electricity and magnetism are different aspects of a single force, believed to be one of the four "fundamental" forces. It is called, shockingly enough, the electromagnetic force. That's one reason to believe that since electric "monopoles" (charges) exist, magnetic monopoles might too.
There are electric dipoles, which are made of opposing electric "monopoles" (charges). Why couldn't magnetic dipoles also be made of opposing magnetic monopoles? That's another reason to believe magnetic monopoles might exist.
Dirac didn't just think magnetic monopoles might exist for no reason. He discovered in his calculations that the existence of magnetic monopoles would automatically lead to the quantization of electric charge. Since all electric charge observed in nature is quantized (in integer multiples of the electron charge for free particles and, we believe, in integer multiples of 1/3 of the electron charge if we include particles that are not observed "free"), we have yet another reason to believe there might be magnetic monopoles.
Very smart folks with Ph.D.s in physics have been looking for magnetic monopoles in creative ways for a very long time. In another post in this discussion, I mentioned Professor Henry Frisch of the University of Chicago. These people aren't just looking for magnetic monopoles to do something crazy. They're doing it because their deep understanding of the theory and the experimental data leads them to believe magnetic monopoles might exist.
"It is nice to know that the computer understands the problem. But I would like to understand it too." --Eugene Wigner
Unending magnetic field lines and a particle with a net magnetic charge does not result in "perpetual motion", where that term always means "perpetual motion in the face of friction or other counteracting forces", because minus that "perpetual motion" is just Newton's 1st Law and completely uninteresting.
In the case of a magnetic monopole, it's actually little different than electricity (I know you think otherwise but you're wrong, look at the force equation), and in the case of electric fields, a charged particle in that field has a certain amount of potential energy, and that potential energy may be converted into kinetic, and that kinetic energy may be enough to reach escape velocity for the universe, but it isn't perpetual motion.
I know it's pointless explaining this to the deliberately dumb troll, since even if you wanted to understand it'd require you knowing some of the actual theory and math behind the physics you only understand through inaccurate analogy, but it's entertaining anyway.
P.S. Yes you're insane and yes you're stupid.
The enemies of Democracy are
These are simply sets of atoms that, together, act like monopoles. What has been discovered is not a single particle with one pole. It is a place inside a material that acts like a monopole. Real 'Dirac strings' connecting real monopoles are not long chains of molecules, these long chains of molecules simply act like Dirac strings. Please. This is the most misleading title and summary I've ever read here, and that is saying A LOT.
- None can love freedom heartily, but good men; the rest love not freedom, but license. -- John Milton
In a box approximately 1nm on a side there is a north pole with no matching south pole. So there are magnetic field lines flowing out of the box with no matching field lines flowing in. Of course "over there" there is a south pole which has field lines flowing in without field lines flowing out.
Except, from my reading above, it seems that the matching "monopoles" are connected by a long series of aligned dipoles resembling solenoidal tubes, so there is mag field in the dipoles flowing into the box. Sure the "in" field occupies a very small area, but in/out still balances. Is this incorrect? If not, I don't see how this is evidence of the existence of monopoles.
And, as an aside, given the parallel you draw with conservation of charge, is there any corresponding persistent and unique connection between (e.g.) an electron and positron pair after they are created?