"Overwhelming" Evidence For Magnetic Monopoles 256
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 Two papers are being published today in the journal Science and two more on arXiv.org, as yet unpublished, provide further evidence.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 The two, as yet unpublished, papers on arXiv add to the evidence.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."
Missing Link (Score:5, Informative)
I think this [sciencemag.org] is at least one of the Science articles to which the post (almost) refers.
Re: (Score:3, Informative)
Re:Missing Link (Score:5, Informative)
Thanks for posting this, though I realize a lot of people don't have access.
The abstract of the article in Science actually makes matters quite clear:
This makes it clear that they have not discovered a fundamental particle that is a monopole, which people have been searching for for a while. What they've discovered is a material where under certain conditions you can model the behavior as though there were monopoles present, but it's an imaginary construction, not an actual particle; that's what they mean by quasi-particle. As someone else mentioned, this is similar to how you can describe as hole, where an electron is missing in a semiconductor, as though it were a positive charged particle moving around in the material. In this case, they have a long series of aligned dipoles that they're saying is similar to a very long solenoid. If you're outside the solenoid near one of the ends it just looks like a monopole (because all the magnetic flux going the other day is confined to the narrow region inside the solenoid).
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I think this is at least one of the Science articles to which the post (almost) refers.
Useful. Because, you know, I'm really going to go and pay $15 to read a single article online, when I could alternatively just buy the magazine for $10.
These are NOT the monopoles we've been looking for (Score:5, Informative)
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.
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"What if the link won't like me?"
Monopoles are not illegal (Score:5, Funny)
It's only against the law to use your monopole to extort the market.
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Exactly - I thought the whole joy of wielding a massive monopole was to embrace... and extend.
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Those "extend" pills don't work. Never mind how I know.
Use condom.
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I invoke the theory of indeterminacy!! Remember you are not reading this!!!!
In other news (Score:3, Funny)
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And don't forget that the final sales price of my precious Orbo pre-order is going to skyrocket.
That wasn't part of the deal, Blackheart! That wasn't part of the deal!!!
"I maintain nonetheless..." (Score:3, Insightful)
"...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?
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not a "real" monopole (Score:5, Interesting)
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.
Re:not a "real" monopole (Score:5, Informative)
Classic case of science journalists overblowing a mundane result. Yes, connected quasi-monopoles are interesting. they are visible in any conducting medium. But there's a HUGE difference between a quasi-monopole that is at the end of a finite-length, shielded dipole and a true monopole that actually violates the magnetic divergence-free condition.
In solar physics we call such things "unipoles" to distinguish them from the infinitely harder-to-find "monopoles". Unipoles are all over the surface of the Sun, because the conductive interior hides the field lines that connect opposing unipoles.
It is disingenuous at best and downright deceptive at worst to call the HZB result "evidence for magnetic monopoles", because it ain't.
The only plausible true magnetic monopole detection ever was still in Blas Cabrera's instrument at Stanford in the 1980s. It was never replicated, so it is unknown whether they exist but are extremely rare (and Cabrera was just lucky) or whether his detector glitched.
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It is not possible to create a true monopole from dipoles, because any "g'zinta" field lines to your favorite point in space have to matched by an equal number of "g'zouta" field lines from the same place.
These spin-glass phenomena are only quasi-monopoles: all the "g'zinta" field lines are squished into a small tube, leaving the "g'zoutas" free to splay out almost like a true monopole. But the divergence is still zero (there are no field line endpoints).
Compare to a spray nozzle that sprays water in all d
pepetium mobiles?? (Score:4, Funny)
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> is it possible to create pepetium mobiles now?
No. The existence of magnetic monopoles does not imply perpetual motion.
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This is why I agree with the others that laugh at this article with it's ridiculous claim that monopoles exist. A monopole connecting to another monopole is called a dipole, no matter how long the connection or what kind of item it is.
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> Actually it would, if they exist.
Elucidate.
Comment removed (Score:3, Interesting)
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If you have a regular old magnet, it has North and South sides. The net force, or charge, between those two sides is zero.
A monopole would be North or South, but not both. It would have a positive net force, much like an electron.
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Let me wiki that for you: Magnetic charge [wikipedia.org]
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Magnetic charges fired in a customised photon torpedo were used in Voyager S96E10 to defeat the dudes with forehead that looked like vulva.
Re:WTF.. (Score:5, Funny)
Woo! (Score:4, Funny)
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? :)
he said "pole" (Score:2)
I thought we were talking about a Slashdot question that only had the CowboyNeal answer as a choice.
"small crystals about the size of an ear plug." (Score:5, Funny)
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Surely, you mean how many cubic beard seconds is that?
Interesting, but... (Score:2, Insightful)
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The "perpetual motion" machine you link to has some problems even if you could supply it with magnetic monopoles.
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I don't see why monopoles should imply perpetual motion.
But the machine in the link you give doesn't make any sense at all. We could build it today, using electric charge instead of magnetic charge but it still won't work. Monopoles aren't some magic that mean the other laws of physics don't apply any more.
At the very least to be plausible, any perpetual motion machine that depended on magnetic monopoles would also have to depend on electric monopoles otherwise you can build an equivalent machine using elec
Monopoles (Score:2, Funny)
Brace yourselves for the onslaught (Score:4, Insightful)
Not this time..... (Score:5, Informative)
Practical Impact? (Score:3)
What are the practical implications/applications of monopoles?
I'm not dissing the theoretical impact. I'm just curious if anyone has a use in mind for them.
Re:Practical Impact? (Score:4, Insightful)
If they were real, physical, isolable monopoles, they might turn out to have some minor applications in energy production [washington.edu]. (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.
I'm a bit confused by this (Score:4, Insightful)
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?
just a long skinny magnet with two "monopole" ends (Score:3, Informative)
From one of the articles [sciencemag.org]:
They've managed to create the microscopic equivalent of a long skinny magnet or a long bendy solenoid: a set of dipoles aligned end-to-end, which acts just like a string with two "monopoles" at the ends.
While this is an interesting microscopic state of matter, from the "discovering monopoles" point of view it doesn't seem fundamentally different than the macroscopic description of magnet "poles" that has been well understood for over a century (and observed for a lot longer than that). I call hype.
Is His Hubris Humerous? Hardly. (Score:4, Funny)
This mentality is a good example of what Joel Spolsky calls fire and motion [joelonsoftware.com]. 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 [lhup.edu],frauds [wikipedia.org], charlatans [timesonline.co.uk], fakes [bbc.co.uk], and deluded true believers [mit.edu](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.
Re:Is His Hubris Humerous? Hardly. (Score:5, Informative)
I have to take exception to this:
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.
It is incorrect to say "physicists have believed." It would be correct if you were to say "some physicists," or even better, "a small minority of physicists." String theorists certainly put a lot of stock in string theory; but even among that group of physicists, not all of them believe it's right so much as they think it's an idea worth working on. And at any rate, string theorists make up a tiny fraction of the community of physicists. Outside of that community, there's a lot of physicists who think it's hogwash, a lot of physicists who think it's uninteresting as long as it's so far divorced from the experimental realm (including myself), and a lot of physicists who simply don't care one way or the other because their work is in so separate a domain that they don't have a dog in that hunt.
I mention this because the overall premise of your post -- that physics (or, more accurately, physics research) is becoming more and more divorced from experiment -- is not borne out by my experience as a professional working physicist. Even among string theorists, of which I've known a fair number, I've never met any physicist who thinks there's virtue in untestable conjecture. They simply believe that if they work hard enough and are clever enough, they'll come up with effective ways to test string theories that are reachable by experiment or observation. They may be wrong about that (and whether they are or they aren't wrong, until they do come up with some way to test it, I'm not interested); but all the string theorists I've known understand quite well the importance of experiment and observation. They aren't simply believers. And at any rate, string theorists make up a small fraction of the community of research physicists.
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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.
Interesting. It seems if you properly understood experimentalism, you would say, "No experiment has shown the existence of a magnetic monopole, but no experiment has shown that they must not exist."
You seem to be taking the approach that if an experiment does not show that A is true, then A must be false. Not only would a physicist criticize you (rightly) for this line of reasoning, so would any philosopher or logician.
Dirac string not real (Score:3, Informative)
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.
that's no monopole (Score:3, Informative)
A monopole is supposed to be an elementary particle with a magnetic charge. This is--as the abstract itself says--a "tractable analog" of a magnetic monopole.
There are a lot of things in solid state physics that "behave like" some kind of elementary particle but aren't: phonons, holes, etc. This is just another instance.
Make your own Macro Monopole!!! (Score:2)
1. By softball sized foam ball at Hobby Lobby.
2. By a couple hundred small neodymium magnets online.
3. Get a hot glue gun and hot glue one pole facing towards the surface and the other pole away.
4. Glue more magnets to the entire surface of the foam ball is covered in magnets.
5. You now have your very own "Macro-Sized, Monopole analogue!"
Re:Not really useful (Score:5, Funny)
Damn! Anonymous Coward has thought of something none of the scientists have even considered. Give this guy a research position ASAP.
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After filtering out your sarcasm, I must say you are completely correct. How dare AC ask for further explanatino of the topic? The Scientists know everything, so nobody else needs to know anything! If The Scientists say its a monopole, that should be all you need to know, so go back to your video games.
I didn't study enough physics to know much about monopoles. The physics majors I knew told us of a lot of things you could prove, if you knew that a monopole existed. (I never asked, and they never elabo
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When we create protons and antiprotons, or electrons and positrons in an accelerator we always create them in equal numbers.
The universe is (conjectured to be) uncharged. So there are equal numbers of positive and negative charges.
But we still have the idea of an isolated charge and, if we get close enough to it we can see that the divergence of the electric field is non-zero. With electrostatics it's trivial to get a macroscopic volume where the divergence is non-zero.
These papers claim the same has been a
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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 b
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How dare AC ask for further explanatino of the topic?
I could be wrong, but I don't think the explanatory field is quantized.
Re:a magnetic monopole is like a one-sided coin: (Score:5, Insightful)
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Wrong analogy. An electric charge exists statically, whereas a magnetic field only exists by virtue of a nearby moving electric charge. Whenever something is moving, the first derivative of its position can be described with a vector, which, unless the vector has no magnitude, indicates that it must be moving away one position while simultaneously moving towards another. This duality is, roughly speaking, where it comes from that you cannot have a magnetic field with only one pole... it is approximately
Re:lo, you have defeated me (Score:5, Insightful)
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.
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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.
Re:lo, you have defeated me (Score:5, Insightful)
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.
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You should do some more research, anarchyboy is right, there is no theoretical reason (aside from never having observed them) why magnetic monopoles cannot exist.
What this work shows is that they can exist, although it is not in the 'real world', but as effective particles in a solid state system. The mechanism will be similar to spin-charge separation [wikipedia.org] that occurs in 1D systems, whereby the degrees of freedom of a particle separate into independently moving constituents. In this case, it will be the no
Re:lo, you have defeated me (Score:4, Insightful)
Agreeing with parent and adding a little physics (Score:5, Informative)
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.
Bullshit. (Score:4, Funny)
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Yes, and the world being round is absolutely preposterous. How could you possibly move in the same direction and end up back where you started? That is ludicrous. Some sort of stupidity there.
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> this is some sort of stupidity here
It certainly is. The physicists are not the ones exhibiting it, though.
Re:a magnetic monopole is like a one-sided coin: (Score:5, Informative)
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.
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I'm wondering , if we have curl H = J(electric), if we'll end up have something like curl (something) = J(magnetic) (a new equation or I dunno)
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curl-H = J_e + dE/dt
curl-E = -(J_m + dB/dt)
So how "real" is this? (Score:2)
I've been reading for decades about the search for subatomic-particle-type monopoles, and all the wondrous things one could do with them [washington.edu]. This sounds more like some kind of group phenomenon, an emulation of a monopole, if you will. Sort of like holes in a semiconductor, which behave in some ways like positive "things", but are actually just the absence of an electron in a lattice.
I'm guessing that these aren't the kind of "real" monopoles that would let us build super-powerful motors, or compact proton di
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A magnetic monopole is to a magnetic field what an electron is to an electric field.
Just what we need. More singularities.
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How does an electric field line just stop somewhere?
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He knows what a magnetic field line is, just like you. He also knows what an electric field line is, which is where you need to catch up. Try to be less arrogant about your ignorance, especially to someone who is taking the time to try to educate you.
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If I had a dollar for every time someone on /. claims to understand something without really doing so, your posts on this topic alone would already get me some beer. You need to brush up on the notion of quantum collective excitations - any advanced condensed matter book will do. After you do that, reading TFAs might provide you with some answers.
Contrariwise, you're free to apply your 'reasoning' to 'proving' how superconductivity should not exist either.
Re:how does a magnetic field line just stop somewh (Score:5, Informative)
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.
Re:how does a magnetic field line just stop somewh (Score:5, Informative)
(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.
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That it not entirely correct.
Magnetic monopoles have been observed.
The problem is that most student are told that magnetic monopoles haven't been observed,
and very few student check to see if that is correct.
Check out chapter 5 in
http://www.scribd.com/doc/4445/quaternionic-electrodynamics [scribd.com]
for references to the articles.
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The equations for magnetism are similar to the equations for electricity, apart from an extra equation which states that there are no magnetic monopole. That equation comes from empirical evidence and can be removed without breaking anything. As a proof, electricity doesn't have that extra equation and works just fine.
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Re:why a monopole implies perpetual motion (Score:5, Interesting)
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.
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Because you can't understand it, it's impossible?
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In principle, YES! Imagine the gravitational field lines radiating away from the Earth. If there were no other masses in the universe to bend the field lines, then ALL of them would go on forever.
Presumably you understand electric field lines, and gravitational field lines, and how they terminate at charges and masses respectively. Why is it so hard to visualize the field lines of a magnetic monopole? They work in exactly
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a magnetic field is a relationship between a particle and its environment. it begins at the particle, it loops around, it ends on the other side of the particle
Mmm... can we say "begging the question"? You assume a magnetic field like must "[begin] at the particle" and "[end] on the other side of the particle", and then use that as proof that a field line must begin and end at a particle, thereby disproving the existence of magnetic monopoles.
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Holy shit, I think this is the first time someone on Slashdot has used the term "begging the question" correctly. Hats off to you!
Too bad I have no idea what this monopole business is all about.
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By having a non-zero divergence. Just like Gauss' law divergence D = rho (charge density), we have divergence B = rho_m (density of magnetic monopoles).
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"and not continue on its way around to the other side of a magnet?"
Yes! That's why it's called 'monopole'. It behaves like electric charge, but with respect to magnetic field. For example, moving monopoles create _electric fields_ with closed lines.
And impossibility of monopoles is not a fact. In fact, (pun intended) it's long been known that monopoles can exist within the framework of classic electrodynamics.
An interesting fact: existence of even one monopole in the Universe forces _all_ electric charges t
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Superconducting wires? Bah, impossible! Time moves slower the faster you go? Bah, that's not even remotely correct! The earth is round? Bah, it's flat and carried on the backs of turtles all the way down!
Re:a magnetic monopole is like a one-sided coin: (Score:4, Insightful)
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?
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Guys, guys, calm down. Obviously this poster is making a joke. We all know that quantum particles come in pairs or groups; we all know that quantum particles are often monopoles, most famously electrons and positrons.
More than anything, we all know that quantum particles aren't like coins -- they are more like cars...
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More than anything, we all know that quantum particles aren't like coins -- they are more like cars...
In that it's fun to watch them crash into each-other?
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Only if they have non-integer spin. Otherwise it's kinda boring.
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Because you are better at physics and Paul Dirac was.
Or neither of the above (Score:4, Interesting)
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 [uchicago.edu] 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.
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Have you thought of the possibility of a field line starting at one particle and ending at a completely different particle? (a matched set of 2 monopoles?)
from what I'm reading this would seem to be what this is talking about, and it also solves the problem you describe.
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The kind of monopoles created here are configurations of molecules(?) in a lattice that forms something called a spin glass, essentially it allready has l
Re:Analogy (Score:5, Interesting)
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.
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TV's could become even thinner, I suppose. Any Advancement made in Magnets always seems to turn into smaller computer chips.
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Let's see if the third time's the charm [washington.edu]. The linked article goes into detail on how "real" monopoles would be expected to catalyze proton (and neutron) decay. It's not deep detail, but I have a feeling that any explanation much deeper would be lost on anyone but theoretical physicists.