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Researchers Discover "Magnetic Current"
fsouto writes "Researchers have discovered a magnetic equivalent to electricity. From the article, 'The phenomenon, dubbed "magnetricity," could be used in magnetic storage or in computing. Magnetic monopoles were first predicted to exist over a century ago, as a perfect analogue to electric charges. Although there are protons and electrons with net positive and negative electric charges, there were no particles in existence which carry magnetic charges. Rather, every magnet has a "north" and "south" pole.'"
The only thing new here is the current, not the "magnetic charge" from the monopole. And it's theoretical physics ridiculously far from being used in magnetic storage or computing.
The vaunted Maxwell equations are crying.
Veramocor
Mr Tesla, Were only 100 late
Magnet current? Like, in a transformer?
Shouldn't it be magneticity?
Abstract from the actual paper:
"Electrically charged particles, such as the electron, are ubiquitous. In contrast, no elementary particles with a net magnetic charge have ever been observed, despite intensive and prolonged searches (see ref. 1 for example). We pursue an alternative strategy, namely that of realizing them not as elementary but rather as emergent particles—that is, as manifestations of the correlations present in a strongly interacting many-body system. The most prominent examples of emergent quasiparticles are the ones with fractional electric charge e/3 in quantum Hall physics. Here we propose that magnetic monopoles emerge in a class of exotic magnets known collectively as spin ice: the dipole moment of the underlying electronic degrees of freedom fractionalises into monopoles. This would account for a mysterious phase transition observed experimentally in spin ice in a magnetic field, which is a liquid–gas transition of the magnetic monopoles. These monopoles can also be detected by other means, for example, in an experiment modelled after the Stanford magnetic monopole search."
Not just for RC planes any more!
Eat sleep die
If this is a discovery then why did I learn about this in my electromagnetics class I took a semester ago? And why did I have to work on problems with magnetic circuits if this phenomenom wasn't discovered yet?
Nope. Gauss's law (electricity) has some nice formula while the corresponding Gauss's law for magnetism has a big fat zero.
If magnetic monopoles were taken into account, the magnetism one will have a nontrivial div like the electricity one.
Thank you wikipedia. Now I know to ask for for christmas: A Student's Guide to Maxwell's Equations! The amazon reviews are good. Let's learn together, slashdot. div grad curl too, in case old Maxwell's a little heavy with the vector calc
div B = rho_b
I think so. It sounds more like "electron holes" in semiconductors. The spin ice contains tetrahedrons formed from ions. Because of this arrangement, adjacent ions must form a positive-negative pair, which then affects the way electrons spin and the resulting magnetic field. Bring in an external magnetic field and that runs the process in the opposite direction. That's where the storage idea comes from.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
Seriously? Magnetricity? That's the best name they could come up with? Really?
I hope if they can't do better figuring out what term to measure in it, they at least pander to the attention it would gather and call the unit "Colbert"
More buzzwords and concepts for Trek to abuse.
...that whizzing sound is my karma, flying out the window.
Isn't that how a hard drive operates?
The "Gauss' Law" for magnetism (in quotes because this isn't a universally accepted name) is commonly taken to be div(B) = 0, but that's not always the case. The law can be div(B) = rho_m (Gaussian units), where rho_m is the magnetic charge density, analogous to the rho_e electric charge density in Gauss' law. In this case there is also a non-zero J_m, magnetic current.
Basically, Maxwell's equations and the rest of EM theory accept a magnetic monopole freely, but as far as we have seen, none exist in nature. Paul Dirac has shown that the existence of magnetic monopoles would explain the quantization of electric charge.
Do you have to have smision to be able to detect it?
sic transit gloria mundi
...that whizzing sound is my karma, flying out the window.
You've discovered the karmic equivalent to electricity!
The phenomenon, dubbed "karmicity", could be used in meta-moderation or in troll suppression. There were previously no known particles in existence which carried karmic charges. A net-positive karmic particle is known as a karmon; a net-negative particle, a moron.
LHC, eat my shorts.
...we're 0.00317% closer to flying cars!
Table-ized A.I.
So, what's the next breakthrough? According to the Alpha Centauri tech tree I'm reading, we can now research Unified Field Theory and Nanominiaturization now that we have Monopole Magnets!
Okay, I'm replying to myself as I thought I should immediately after posting the above.
Yes, Gauss's Law of Magnetism, one of Maxwell's Equations, says the magnetic field has zero divergence, meaning there is no net magnetic charge.
That is an assumption based on the lack of experimental evidence for a monopoles.
This does not mean Maxwell's Equations preclude the existence of monopoles, because they don't. What's the difference between precluding their existence, and presuming their non-existence? Well, let's look at something that is both assumed and precluded by theory: the speed of light being different for different inertial observers, and Special Relativity.
Special Relativity assumes c is constant for all inertial observers. It also precludes the possibility of that not being true, because the entire theory is based on that assumption, and falls apart if that assumption does not hold. All the equations of special relativity contradict observer-relative speed of light. If you ever discovered a case where this was not true, you would have to scrap Relativity and re-write the theory from scratch. That's precluding.
Maxwell's Equations assume net magnetic charge is zero, but if that assumption doesn't hold, then you simply have another term in the equations and you don't need to go back to the drawing board. Gauss' Law of Magnetism simply becomes a special case where net magnetic charge is zero (though this 'special' case is the most common case). You don't need to re-write the theory of electromagnetism. These researchers are not claiming to be re-writing the theory of electromagnetism, because the theory does not preclude magnetic monopoles.
The enemies of Democracy are
flying cars?
if a magnet is large enough to detect north and south, we can tell, but what if it isn't?
Well, in the interest of closing the loop, these aren't totally disjoint ideas ;^)
In the standard magnetic circuit with flux and field, the analogy between a magnetic circuit and an electrial circuit is
MMF = PATHINTEGRAL (H dot dl) vs EMF = PATHINTEGRAL(E dot dl)
Without any magnetic monopoles, this path integral that represents the magnetic circuit is merely analogous to a magnetic charge making a loop in the circuit creating a potential around the loop. Although this MMF is now taught as being generated by transformer/inductor coils wrapped around the magnetic circuit using the relationship MMF = N*i, but instead in a world with magnetic monopole current (i.e., magnetic current), in principle the same MMF relationships can be used.
Interestingly with magnetic monopoles this can also be extended like "electrical" circuit element.
R = dv/di, C = dq/dv, L = dF/di, M = dF/dq, i = dq/dt, and v = dF/dt
Historicall, only Resistance ~ Reluctance was the only one of the analogs that made sense w/o magnetic monopoles.
Now that we have magnetic monopoles, the other electrical circuit elements now have possible analogs in a magnetic circuit.
So this is actually a similar idea that shouldn't be dismissed out of hand.
The classic illustration of magnetic field lines is to put a big bar magnet on a table and sprinkle iron filings on and around it; they will end up tracing the magnetic field lines of the bar magnet.
So say they could construct the monopole equivalent of such a bar magnet, just one big lump of North or South. If we put that on a table and sprinkled iron filings on and around it, what (if any) lines would they end up tracing? Just rays away from the monopole?
-Forrest Cameranesi, Geek of all Trades
"I am Sam. Sam I am. I do not like trolls, flames, or spam."
just as soon as you can make coins with one side
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
In spin ice "monopoles" lines of "molecular bar magnets" line up head-to-tail to form a tetrahedral network of "pipes" along which a flux much less than h/e can be said to flow,
Usually, at each lattice point of the spin-ice pyrochlore structure two pipes have inward flowing flux, and two have outward flowing flux.
At a "monopole-like" defect, three flow in and one flows out (or vice versa) and the excess flux sprays out from the defect in all directions, looking like there
was a monopole there. This radial flux is not quantized and much less than the dirac monopole flux
The monopole looks like
SNSN*NSNSNS
.
(from an anonymous physicist who knows about the spin-ice/pyrochlore work)
if it's only working inside some material (spin ice), then it appears to me that the magnetic charge it is not truly a fundamental particle, but some macroscopic effect is at work...
anyone who can explain what is really going on? why can this magnetic effect only be shown inside spin ice?
Why not link directly to arXiv in all scientific posts? Maybe a divulgative link AND a link to the paper in the arXiv. I am crazy?
to build a stargate
Here is a better article http://www.physics.rutgers.edu/grad/681/mpoles_physicstoday.pdf
I would have gone for Magtricity. It has a better ring to it. That or Ultra Mago-Leetricity.
..found this circa 60 years ago. http://en.wikipedia.org/wiki/John_Searl
What is a magnetic field composed of? The article says that a small magnetic field is formed around the muons. Is a magnetic field composed of particles?
just as soon as you can make coins with one side
You mean, Moebius strip-shaped? Those would have one side and one egde!
A bit tricky to manufacture and store, and therefore impractical, but still possible.
WYSIWIG, but what you see might not be what you need
Turn it on and it creates a link to a black hole!
Shades of A. Bertram Chandler! How long before we get LodeJammers?
Viewed this way, there's no theoretical reason for ANYTHING to exist - the laws of physics don't REQUIRE there to be any matter. Particles are either allowed, or they aren't. And our experience has shown that particles that are allowed, exist. Except for magnetic monopoles. Which is kind of weird.
It should be noted that the "monopoles" discussed in TFA aren't "real" monopoles - they're quasiparticles that have the same properties as monopoles, but don't "really" exist. They're much the same as "holes" in electrically conductive materials - holes have the same electrical properties as positrons... but they aren't really positrons. The best evidence for now indicates that true magnetic monopoles don't exist, and we don't really know why.
Looks like someone finally Picked up Ed Leedskalnin pamphlet and actually read it.
Suppose a bar magnet is touched at its north end with a long iron wire. At the other end of that wire will be a "north attractive pull" of a now greatly extended bar magnet. Um, yes? So, imagining that wire to be 200,000 miles long, when we touch the bar magnet with the end of the wire, it will take one+ seconds before that "northness" is measurable at the other end of the wire. Therefore, is this not a "current of magnetism" that will behave in every way possible like an electrical current? If so, what passes along the wire that's akin to "electrons?" What would be the magnetic equivalents of ohms, amps and volts?
And it really does make your head hurt. From Newton (let's just leave Einstein out of this for now... please?): F=ma, and F = Gm1m2/r^2. Let's say that we're dealing with two bodies, one with mass m, and one with mass -m. So, substituting: the negative mass body feels -ma = Gm(-m)/r^2. The minus signs cancel, and the negative mass body is attracted to the positive mass body. But the positive mass body feels ma = Gm(-m)/^r2... so it's repelled by the negative mass body. In other words, set up these two bodies, and they'd chase each other across the universe at ever increasing speeds, forever. Which would appear to violate conservation of energy.
It gets even stranger when you consider that "mass" is not a completely well-defined term. You can talk about inertial mass, active gravitational mass (essentially, how much gravity a mass produces) and passive gravitational mass (how much force is produced when an object interacts with another object's gravity). For normal mass, it's been shown that these are all equivalent (at least, active and passive gravitational mass either have to be equivalent, or you have to give up conservation of momentum, and inertial and passive gravitational mass have to be equivalent, or general relativity doesn't work anymore). But it turns out that as long as you're speculating, you can go ahead and give these different kinds of mass different signs for the same body. Then you get even weirder results - for example, the negative mass might repel the positive mass, but still move toward it because such objects would accelerate in the opposite direction of forces applied!
I told you this stuff made your head hurt.
In what sense is "being in debt" different from "having negative dollars"? If I have a credit card balance of $1000, and no assets, and then I make $100 and send them in the direction of my credit card account, the credit card balance will annihilate the $100 and reduce itself to $900. I think "negative potential energy" is a perfectly valid concept.
Also: I don't think he really failed physics.
Although you don't run into it in any real-world situation, negative energy is useful in modeling the vacuum.
GP poster, I think you can consider yourself smacked down.
... the summary is just copypasta of the first paragraph ...
I just _LOVE_ pasta!
A "field" in math is an object that assigns a value to every point in space. A "magnetic field" assigns a vector that has to do with the amount of force experienced on an electrically charged particle moving with a certain velocity at that point. So it's not really "composed of" anything, any more than the earth's gravitational field is composed of anything. It's just a property.
THIS is the year of absolute-zero-chilled, neutron-and-muon-bombarded memory on the desktop!
Populus vult decipi, ergo decipiatur...
"Force shits upon Reason's back." - Poor Richard's Almanac
Are these objects actually monopoles? Well, yes and no. They fall into an interesting gray area:
No, they are not the fundamental monopoles that Dirac proposed. They are not fundamental particles, but only quasiparticles arising from the dynamics of some substrate. In this case, the substrate is quite exotic: a spin ice, which is a kind of material (dysprosium titanate) with polar atoms arranged into tetrahedra.
OK, so they're not fundamental, but they're still quasiparticle magnetic monopoles, right? Sort of. These quasiparticles still have to obey the standard laws of electromagnetism, and those laws still forbid the existence of magnetic monopoles. Every magnetic monopole is actually a member of a monopole-antimonopole pair connected by a Dirac string. To quote the paper:
So this is the key innovation here. A normal magnetic dipole like a bar magnet can be thought of as being like a stick: it has two ends; if you break it, both pieces have two ends; when you wave the stick around, both ends wave around. But this system is like a rope: it still has two ends; if you break it, the pieces still have two ends; but when you wave one end of the rope around, the other end can remain fixed. So the end of a rope can act like an object independent of the other end.
This makes it a great model system for playing with monopoles, as long as you close your eyes and pretend the rope doesn't exist. But it does exist, Maxwell's equations are obeyed and all is well in the universe.
when i point out that monopoles are an impossibility?
it's like saying you want to feel the wind in your face, to turn around, and then feel no wind at all on your back. as if a magnetic field flows out, but not in, or in, but not out. you understand why you can't have a coin with one side, right? if you understand that you understand conceptually why monopoles don't exist: there is no such thing as a magnetic field that goes out, but never returns. logically, belief in a monopole is the same as belief in a perpetual motion machine
and, interestingly enough, monopoles are frequently featured in perpetual motion machine schemes. perhaps because that, indeed, if monopoles existed, you really could have a perpetual motion machine. a monopole, under the influence of a magnetic field, would begin moving and never stop. you understand that right? doesn't that tell you something about what a monopole really is in terms of reality/ not reality?
but for the sake of argument, let's say i'm wrong. ok, show me a monopole. i'm waiting
it's not like i'm a flat earth advocate arguing against the existence of the globe, or a creationist arguing against the existence of evolution. i'm simply pointing out that a monopole is a conceptual impossibility, and i get treated like i'm the electric universe troll
whatever
i just don't understand where this weird fervent certainty of monopoles comes in to the point where i have to be modbombed every time i point out that they don't exist and can't exist. its like i'm questioning the existence of god to a bunch of religious fundamentalists. this site is apparently overwhelmed with excitable physics freshman
i don't understand this bizarre certainty of belief in monopoles
there AREN'T ANY folks. pfffffft
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
What I find funny is all the people insisting divB=0 is "just" a reflection of the experimental inability to find a magnetic monopole. All of those equations are "just" reflections of the experiments they summarize. I think any experimental result that contradicts the thousands that preceded it deserves a fair amount of skepticism.
"The ability to delude yourself may be an important survival tool" - Jane Wagner -
So the whole issue is a misinterpreted electrostatic polarization then.
Michael J. Burns