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Physicists Devise Magnetic Shield
sciencehabit writes "The sneaky science of 'cloaking' just keeps getting richer. Physicists and engineers had already demonstrated rudimentary invisibility cloaks that can hide objects from light, sound, and water waves. Now, they've devised an 'antimagnet' cloak that can shield an object from a constant magnetic field without disturbing that field. If realized, such a cloak could have medical applications, researchers say."
Would this not cause a security nightmare?
n/t
Perhaps this is the justification for restricting liquids on airplanes: presumably a liquid is required to cool the conductor to make it a superconductor.
From reading the headline I was almost expecting a shield a la Star Trek. All we would have left would be to find a way to make the Alcubierre warp drive something more than a theoretical possibility and I'd be donning Vulcan ears. Oh, well, I guess the waiting is not almost over yet.
I like my dinosaurs feathery, and my pterosaurs hairy (or is it pycnofibery?)
Not as well as we thought, apparently.
Score one for ICP (sigh).
Now the problem with raising the magnetic field strength to get higher resolution is the the distortion of the field. Most of this distortion can be avoided just by shielding everything except what you are going to image in this magnetic shield.
Forget the actual medical applications. The applications for pseudo medicine are just as good. There are already a ton of people sleeping on magnetic mats. They would eat this up. Maybe even literally.
Can they make a gravity shielding device?
Imagine a clock face, even hours magnetically shielded, odd hours not. Now imagine a set of pistons arranged in a circle below and a set of permanent magnets above. Spin the clock face so the pistons rise towards the magnets, then fall with gravity as you shield them.
World's problems: solved.
There have been many interesting studies on the topic of electro-gravitism, Mr. Smith. The real question is -are humans ready to utilize it?
A better headline would be, Physicists Come up with Idea to Build Perfect Magnetic Shield. As the article states, the device itself is hypothetical no proof of concept has been built.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
It would have to be 100% efficient to even attempt that. Otherwise you'd lose energy in the conversion process and as a result end up with less energy than you had, rather than more.
...or am I the only one around who remembers that totally cheesy, yet elementary schoolkid riveting, post-apocalyptic edutainment show "Tomes and Talismans"
I suspect that one of these choices is incorrect. Correct.
Okaaaaaay. I hate to break it to you guys, but passive and active magnetic shielding has been around for a long time now. This is simply a new spin on old tech, adapting it and slightly enhancing it.
Shielding an object from external fields is not difficult provided you have money to spend. Hospitals do it all the time for their MRI suites. The shielding may be either passive (LOTS of steel plates in the floor, walls and ceiling), or actively by installing 3-axis helmholtz coils in the walls, floor and ceiling. The coils are then driven by a set of very large and fast amplifiers. The amplifiers are driven by correction signal from a computer that has at least one 3-axis magnetometer. Obviously, the active solution is better as it can correct for things like elevators, automobiles and other things that influence the local magnetic field. The passive shielding is only good is the external field does not change.
I remember one such shielding job in San Francisco that gave trouble because of the volume of *WATER* flow in the city water main running under the MRI suite. Yes, even water can affect magnetic fields. Passive shielding would not work, so the site had to switch to the more expensive active shielding.
I also have had trouble calibrating magnetic instrumentation because of cars in the car park moving around. I'd have to wait for a window where there was no activity outside the building. I'm talking about smallish cars more than 50' away, and large trucks could change the fields from more than 100' away...
Why is it that most of the people that I encounter seem to have been shat from the Sphincter of Mediocrity?
Two I can think of:
Carriers and other high-value ships are probably too big to use this. I'm not sure if their escorts would want this as much.
Any more?
Can someone link me that story? Must have missed it. How do you shield something from water waves?
I wonder if something like this could be used to shield a spacecraft. If an object can be made "invisible" to solar radiation (I realize this is just magnetic so far, but the technology seems to be advancing quickly) perhaps we can shield a ship well enough to make a trip to Mars feasible. At least it seems applicable to making a submarine invisible to magnetic sensors.
Also, you have to take into account the energy to make the shield.
magnets don't have sides.
What do you mean by "shield one side"?
If you physically cut the magnet in half, you just have two magnets. If you left the magnet intact you wouldn't be able to shield it from itself. Unless maybe you had an infinite length shielding device spanning the whole universe...
hmmm...
trolled weren't I now?
Nonsense. If the explanation as summarized is accurate you could use a permanent magnet. Let it attract an iron object on a string wound around a generator. As the object is attracted, the generator produces electricity. Normally, you have to EXPEND just as much energy to pry the object away from the magnet again. But if instead you introduce this "magic shield" between the magnet and the object just before they touch, you can pull the object away again for almost no energy expenditure. Rinse, lather, and repeat over and over again and you produce an infinite number of surges of electricity for next to no energy input. Even a generator of 5% efficiency would be plenty to provide perpetual motion plus energy coming out to run you TV (after being suitably converted, filtered and leveled).
Of course a real device would be much more sophisticated than the above mind exercise, but the above is enough to show that it breaks the law of conservation of energy.
So no, I do not think the summary as given is accurate, because I believe in the law of conservation of energy.
what does this have to do with sharks and lasers?
Yes, loss prevention officers at malls need to be on the lookout for shifty-looking people who are toting dewars of liquid nitrogen. Of course, we presume that type II superconductors will be adequate to handle those pesky anti-shoplifting tags. If not, then those bastards will no doubt resort to using the readily-available liquid helium.
"Don't mind this, it's my superconducting blanket with liquid nitrogen feed. I have a doctor's note. See?"
But you know, if the scanners suck and you can carry around a superconductor with you to the mall, you could make bank! Where do I sign up?
You forget one thing in your example: /. summary) a machine like the one you describe is no perpetuum mobile. The laws of energy conversion are still hold up.
the object you pull has to be placed back at its starting position. That costs exact the same amount of energy you have earnt before. So even with a magnetic shield device (I strongly suggest you read the article instead fo the
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
Forget about metal detectors. This can make submarines invisible.
The three laws of thermodynamics:(1) You can't win. (2) You can't break even. (3) You can't even quit.
According to the laws of thermodynamics, the power to create the shield would be the same or more than the power you could gain there. Makes sense, really.
Help I am stuck in a signature factory!
What a great material to wrap around my credit cards when they're in my eel-skin wallet.
The eel skin has its electric field left over from its life shocking the s*** out of the fish it eats, which of course translates after death into a magnetic field that wipes the magstripe info from my credit card.
With a layer of this between them, I wouldn't have to worry about that.
And for that matter, this kind of shielding would probably wreck havoc on communications to the RFID chips on the "smart pay cards" like SpeedPass, so that people couldn't steal my money by putting a reader under the subway seat.
Hmm, now where's my patent lawyer?
--Joe
Part way through the article I see the words "If realized"... Why get my hopes up of owning my own anti-Magneto suit, just to dash them by saying that this process/device is only hypothetical? I weep silently as I sit in my chair, cursing the day I got that adamantium skeleton installed in place of my bones. -Signed, Wolverine
I can't believe that all of you missed the one obvious military application: concealment of nuclear submarines.
Presently nuclear subs are detectable by planes (like the P3 etc.) via use of magnetometers.
A sub, being a very large metal object, interferes with the Earth magnetosphere (which is for the purpose of detection a constant magnetic field) and thus can be detected an "anomaly" in the magnetic field, far above their actual location deep underwater.
This is one major weakness of modern subs that makes them detectable.
This discovery is practically custom made as a solution to this problem: to hide an object that affects a constant magnetic field.