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Science

'Antimagnet' Cloak Hides Objects From Magnetic Fields 87

Posted by Soulskill
from the don't-let-ian-mckellan-get-his-hands-on-this dept.
ananyo writes "Researchers have made a cloak that can hide objects from static magnetic fields, realizing a theoretical prediction they made last year. This 'antimagnet' could have medical applications, but could also be used to subvert airport security. The cloak's interior is lined with turns of tape made from a high-temperature superconductor. Superconductors repel magnetic fields, so any magnetic field enclosed within a superconductor would be undetectable from outside. But the superconductor itself would still perturb an external magnetic field, so the researchers coated its external side with an ordinary ferromagnet. The superconductor tries to repel external field lines, whereas the ferromagnet tries to draw them in — together, the two layers cancel each other out (abstract)."
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'Antimagnet' Cloak Hides Objects From Magnetic Fields

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  • by hpa (7948) on Friday March 23, 2012 @10:02AM (#39451391) Homepage
    "Hey, mind if I take in this superconductor cooler through the checkpoint?"
    • Re: (Score:3, Insightful)

      by Brad1138 (590148)
      Don't assume airport security adheres to any sort of logic...
      • Do they make liquid nitrogen storage dewars of less than three ounces?

        If so, I don't think that there is anything about cryogens(so long as they aren't compressed, compressed gas cylinders not Specifically Approved have been on the list for at least a decade before the security theatre opened in earnest).

        If that dewar contains more than three ounces of liquid, though, you'd better touch your toes and think of Freedom while I get the exam glove.
        • by jo_ham (604554)

          I would not take a dewar of any cryogenic liquid onto an aircraft - I don't even ride in the lift with them. That said, a small volume wouldn't pose all that much of an asphyxiation hazard. I carry LN2 around in a cheap thermos bought at the grocery store and you can keep it liquid that way for hours.

        • by bryan1945 (301828)

          "If that dewar contains more than three ounces of liquid, though, you'd better touch your toes and think of Freedom while I get the exam glove."
          Why would I be touching my toes while you are getting rectally probed? Is this like a wrestling tag team match?

      • Re: (Score:3, Interesting)

        by Ihmhi (1206036)

        Besides, it's much easier to bypass airport security. Just be rich.

        What, poor people can't get in through the rich lines? Well, a Fortune 500 CEO flying on a private jet surely has assistants, security, and other personnel, and he'll be damned if some "airport security" will hold up his tee time in Cabo!

        I wonder how long it will take for someone to exploit this particular attack vector.

        • Not just the rich (Score:4, Interesting)

          by mcrbids (148650) on Friday March 23, 2012 @05:50PM (#39457173) Journal

          Anybody who has their own plane pretty much does whatever they want. I've landed my plane at large airports (EG: Oakland, CA) with extensive security lines for commercial flights, and driven my car out to the plane in order to load it. The only credentials I need are the keys to a plane and maybe a driver's license.

          I've landed my private plane at big airports in order to hook up with commercial flights, and it's truly absurd to land, walk in off the tarmac, be personally greeted at the private aviation side of the airport, and then take a shuttle to be treated like a potential criminal in a cattle stock yard. This affords me very little respect for the TSA.

          You don't need to be a Fortune 500 CEO to have a private plane, the actual cost to own (especially for a time share aka "flight club") can be similar in cost to owning a recent model car.

    • by tylerni7 (944579) on Friday March 23, 2012 @10:08AM (#39451479) Homepage
      No look, this is perfect. We convince DHS that the terrorists are trying to develop room temperature superconductors to subvert metal detectors and security checkpoints.

      Then, clearly the solution is for DHS to start giving obscene amounts of money to physicists in the USA to develop the technology first! It's pretty much a win-win-win situation.
      • Alternatively, they may just put all of the related researchers under surveillance, which seems like the more natural thing to do for them. The physicists aren't their friends, after all; they're just ordinary citizens.
      • Here here. I like this thinking:O)

        I hear terrorists are working on fusion, hangover free beer and hoverboards too...
      • by Grave (8234)

        Sorry, but you're thinking with a level head here--that's now how these decisions get made. DHS does not exist to solve a problem via positive improvements. It exists to solve a problem via control, invasive action, and denial of freedom. That's much easier to do than to be inclusive, pro-active, and innovative. Unfortunately, it's also not nearly as effective, either. In the long run, it's a losing battle. DHS/TSA function the same way as the RIAA/MPAA - fighting the battle in the wrong way, wasting

    • by Anonymous Coward on Friday March 23, 2012 @10:09AM (#39451497)
      Amazing isn't it? Rea searchers make a breakthrough in practical physics, and all anyone can think about is terrorists!

      Be afraid people! There could be one under your bed right now!
      • Re: (Score:2, Funny)

        by Anonymous Coward

        There's a red under every bed.

      • same think happened with nuclear tech.

      • by Botia (855350)

        It's not the terrorists that scare me. It's the security checkpoints at the airports. They do any and all things to you and have the backing of the government.

    • by Malties (1942112)
      "Oh that cloud of smoke coming from under my trenchcoat? That's nothing"
    • by fluffy99 (870997)

      "Hey, mind if I take in this superconductor cooler through the checkpoint?"

      Meanwhile the guy with the ceramic knife in his pocket and the plastic explosives in his underwear walk through without garnering any attention at all.

    • by izomiac (815208)
      You could likely cool your high temperature superconductor to nearly absolute zero (thus over a hundred kelvin of leeway), then encase it in aerogel or some similarly powerful insulator (vacuum?). This setup should last long enough for mobile applications of this technology.

      Of course, if you have the resources and knowledge to implement this, just build a death ray and shoot down the plane. I don't have any idea why people keep thinking of ridiculous ways around TSA agents and security theater checkpoi
  • MRI (Score:4, Interesting)

    by nschubach (922175) on Friday March 23, 2012 @10:02AM (#39451395) Journal

    If I understand correctly, they should be able to envelope something like an MRI so that you don't have to worry about metal bits carried into the room?

    • Well, yes but no.

      You only need half of the equation (the superconductor) to do that. You don't care about "cloaking" anything when trying to dissipate the MRI field, you just get rid of it.

      As far as I know (and admittedly, when it comes to MRI machines that isn't a great deal) there isn't any real technical hurdle regarding removing it's magnetic field. It would be annoying (keeping even a high temperature super conductor cool), expensive, and a lot harder than just telling everyone to empty their pockets.

    • Re: (Score:3, Informative)

      by Anonymous Coward

      It renders the object invisible to static magnetic fields. MRI utilizes rapidly changing magnetic fields to encode position. This is still a problem.

      • What you are talking about are called gradients in MRI. There is also an RF magnetic field used for MR excitation. The gradients and the RF are not the reason you have to empty your pockets, it is the static field, which is orders of magnitude larger, and has the potential to dangerously accelerate metal objects towards the magent. In the absense of the static field, it would be no problem for bystanders / people around the magnet to have metal. Patients should make known any metal they have on their body,
  • by TheLink (130905) on Friday March 23, 2012 @10:04AM (#39451413) Journal
    You could use a zillion things to subvert airport security.

    Or use a private plane. Those stars don't seem to have trouble loading up private planes with all sorts of stuff.
    • by Anonymous Coward

      Or pay ("bribe") TSA $100 and you can walk on buy.... very cheap for drug smuggling...

  • by marcosdumay (620877) <marcosdumay AT gmail DOT com> on Friday March 23, 2012 @10:07AM (#39451469) Homepage Journal

    Since metal detectors use electromagnetic waves (call those non-static magnetic fields if you want), instead of magnetic fields, that cloak wouldn't be a problem at all. Well, ok, it would cloak its interior, like any piece of conductor would. It would also trigger the alarm itself, like any piece of conductor.

    But now, why are people so concerned about airport security anyway? The invention has no relation to it.

    • by jdgeorge (18767) on Friday March 23, 2012 @10:27AM (#39451719)

      But now, why are people so concerned about airport security anyway? The invention has no relation to it.

      They're not really concerned with airport security. Slashdotters desperately crave upward moderation. Posting a clever remark related to a popular meme is the easiest way to satisfy that desire.

      • I see what you did there
        • by jdgeorge (18767)

          Sigh. Yes, I got upwardly moderated, perhaps demonstrating my point. I guess in this case, the implied meme was "Slashdotters are desperate" for something.

          My point was that I think people aren't REALLY as thoughtless as a lot of the tinfoil hat responses seem to indicate; they're just milking the anti-airport-security-theater thing.

    • by Anonymous Coward
      We aren't - but since some **** put it in the summary (may be the submitter, probably an editor), it makes it fair game to talk about. I'm sure we all cringed when reading the summary and had a bunch of pointed disparagements towards the submitter / editor run through our heads. I know I did.
      • FTFA:

        This 'antimagnet' could have medical applications, but might also subvert airport security.

        First paragraph, at least read that far dude.

  • by Anonymous Coward on Friday March 23, 2012 @10:08AM (#39451483)

    Finally, a tinfoil hat replacement. Everyone knows that some aliens use magnets and not EM waves.

    • by Anonymous Coward

      It it really a tin foil hat replacement?

      The reason I ask is that some have been misled to believe that aluminum foil works just as well. But those of us who use actual tin foil hats know that aluminum foil doesn't work.

      "They" can penetrate aluminum foil with their mind control rays so "they" worked to drive down the price of aluminum foil while making real tin foil more expensive. This was done in conjunction with a "grass roots" whisper campaign selling the virtues of aluminum foil as blocking their mind c

  • by Anonymous Coward

    will not be pleased.

  • by mark-t (151149) <markt@ l y n x.bc.ca> on Friday March 23, 2012 @10:14AM (#39451551) Journal

    Because it's not "high temperature" in any sense that would be understood by the term.

    It's called high temperature because it's significantly hotter than temperatures where superconductivity occurs in ordinary metals (around 30K). But even the highest temperature at which superconductivity has ever been observed is still freakin' cold... over a hundred degrees below 0

    Until room temperature superconductivity is discovered (an enormous breakthrough in physics that would have countless applications), nothing's getting by airport security with this mechanism.

    • by theshowmecanuck (703852) on Friday March 23, 2012 @10:48AM (#39452039) Journal
      That was my first thought. But this might end up being a good prod to get true high temperature superconductor research a super boost. One of the main methods used to detect submarines in the military are magnetic anomaly detectors usually attached to a plane or helicopter. The aircraft don't even need to dip them in the water, just fly over and look for magnetic anomalies (granted the sub needs to be fairly close... but I'm not sure if the military tells anyone what counts as really close). So the crux is that if this will help hide their subs, DARPA and the military might be inclined to shovel piles of money into high temperature superconductors. Although I'm sure they have financed this in the past, this direct applications of stealth for submarines could help with an improved cash flow (or maybe this project is financed this way already.... ?). mmmmm blah blah blah ... profit! Or something like that.
      • Don't worry, the military is already lots interested in superconductors that work at room temperature.

        More money would help, more money is more eyes on the problem. But frankly the superconductor field is kind of waiting for it's Einstein if you will. We fundamentally lack understanding about some key things and more than likely it's only going to be solved when somebody has the eureka moment.

      • by martas (1439879)
        Here's hoping. I would also imagine that the military are already funding superconductor research for other applications, e.g. railguns (superconductors would help there, right?)
  • by Monoman (8745)

    "lined with turns of tape" makes the network geek in me picture this as STP.

  • by danaris (525051) <danaris @ m ac.com> on Friday March 23, 2012 @10:22AM (#39451669) Homepage

    So...is this something that could someday be used to protect magnetic storage media from accidental (or even deliberate) exposure to magnetic fields?

    Dan Aris

    • Well it could, but it's overkill. The big deal about this thing is that it doesn't distort any magnetic field it's in, making it effectively "invisible" from the magnetic field

      If you just want to protect something from a magnetic field and you don't care who knows it, just contain it in something like mu-metal [wikipedia.org]

    • it's where you put your precious...my precious....

    • by Zadaz (950521)

      What magnetic storage media are you talking about? The strongest magnets in your house are inside of your hard drives.

      Are you talking about floppies, Zip disks, audio tape, or VHS? Because if you haven't noticed those things don't really exist any more.

      The only magnetic storage that is still in use that is vulnerable to magnetic fields is your credit card stripe, and even those are obsolete in most of the world.

    • by The Raven (30575)

      We can already do this, by surrounding something with a superconducting cage. This has been known (and done) for decades. The newsworthy portion of this item is that their bubble is also undetectable.

  • Honestly, I don't doubt that this will turn out to have 'security' uses, it just seems like dicking around with aircraft isn't going to be one of them...

    Magnetometers of substantial sophistication have been in use since at least WWII for naval detection and fuzing applications. Surely somebody is already writing up the proposal for a submarine and/or torpedo with a superconductor layer that can be cooled on demand to provide full magnetic field stealth...
  • Didn;t we use Mu-Metal to do this in the old days? just shape it like a laptop battery and apoligize for the stupid design.

    • by 50000BTU_barbecue (588132) on Friday March 23, 2012 @11:45AM (#39452889) Homepage Journal
      I was about to mention mumetal, but its claim to fame is very high permeability. It doesn't repel magnetic fields, it Shamwows them. I suppose if the mumetal is saturated from the inside, then it doesn't hide the object from an external field. Although it takes a lot to saturate properly treated mumetal.

      Old man story time. My Tektronix 547 CRT oscilloscope has its CRT encased in a mumetal shield. I got a powerful magnet and put it on the side of the case, the trace didn't budge at all. Great stuff. Of course, mumetal loses its properites if it's dinged, deformed or otherwise mechanically abused.

      • by rickb928 (945187)

        Since real oscilloscopes have wheels on the carts, shielding is crucial. Turning your scope sideways would move the trace.

  • by Anonymous Coward

    Great work, slashdot! Way to add controversy to what would otherwise be a completely ordinary, scientific article. Oh noes! Quick, the government is going to ban super conductors!!!

  • Why is it that we have come to a point where the first thing we think of for a cool new technology application like this is "could be used to subvert airport security"??

    I am sick and disgusted of where we have arrived.

    I want off.

    • Why is it that we have come to a point where the first thing we think of for a cool new technology application like this is "could be used to subvert airport security"??

      Deep down we are all enemies of the state. Even France realizes it.

  • Should have studied more in physics ...
  • Submarines (Score:4, Interesting)

    by tsotha (720379) on Friday March 23, 2012 @11:20AM (#39452537)
    This could be a big deal in submarine warfare if they can get the temperature up. With the advent of AIP, navies are having to rely on second-string technologies like Magnetic Anomaly Detectors.
  • Currently, high temperature superconductors work up to around 100K- which is about -170C. So currently you would need a liquid nitrogen cylinder to contain the cloak and keep it cold enough. Then you would need to hide that in some other way. somehow I don't think that is likely. Room temperature superconductors are some way off- they know how low temperature (few kelvin) superconductors work, but are not sure how the high temperature conductors work- so researchers are not sure how to improve on the curre
  • If a child swallows two buckyballs they have gotten stuck against different parts of the intestinal tract.
    this causes problems...

    a single passes no problem. could you use this (or some other magnetic field I suppose) to negate the attraction between two or more magnets long enough to let them pass as well?

  • Terrorist Jim: Bob, we will have you wear the antimagnet cloaking suit. All we have to do is have you walk into a restroom right before you go through the scanner, open this forty gallon Thermos container and pour the liquid nitrogen all over yourself.

    You'll walk to airport security and pass through the security check with no problems.

    Day of the terrorist strike.

    Bob enters the airport dragging a heavy carry-on suitcase. His suit is disproportionately large compared to his body, and seems quite stiff. He

  • I was going to say what about DC fields then I remembered - there's no such thing as DC, it's just very slow AC.

  • A friend and I were discussing the ramifications of superconducting racetracks [youtube.com] for low-friction transportation. One of the problems he brought up was how to deal with intersections. Quantum levitation locks your maglev car into a certain orientation relative to a magnetic field. But at an intersection the magnetic field changes. Either you stop levitating, or your car comes to a screeching halt as if it had hit a brick wall.

    Something which can shield from static magnetic fields would allow two magnet

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