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back to article Spanish boffins unwrap anti-magnetic cloak

No, I don’t mean “non-magnetic”: if you wrap a magnet in cotton, you can still detect the magnet outside. “Anti-magnetic” means you can put a magnet inside and not detect it from the outside, and similarly, from the inside, you can’t detect outside magnetic fields. That is what a group of scientists working in Spain claim they …

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Gimp

I have just seen an Apple employee heading for the patent office and waving a copy of the El Reg, do you think.....?

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I think he's probably going to patent the flexible e-paper that his "copy of El Reg" is printed on.

Quite unusual for Apple to be patenting something genuinely new, though.

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Coat

In other news, warp engines are possible...

... all we need is a source of dilithium crystals and a "Cochrane Motor" a.k.a Gravimetric Field Displacement Manifold.

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Key difference:

"Our device is feasible and needs only two kinds of AVAILABLE materials."

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Right!

Bring me the Unobtainium!

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Silver badge

Magnetically shielded speakers

Maybe they could try ripping a few duff CRT monitors and tellies apart?

And do I really need to use the joke icon?

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Boffin

Silly...

Look up "mu metal" sometime. It's a magnetic conductor, field lines want to go through it rather than what's beyond. It's used in hard disk drives all the time. The problem is that being able to detect the magnetic field from the other side isn't at all the same as having a mine attracted to the outside. The mine will still get reeled in, I would think. This said with the caveat that it's late, and it may appear different in the morning.

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Pirate

But if the material is placed outside the metal layer then it would stop the field being generated, would it not? Therefore the mine would sit where it was because there is no field to pull it in.

This was my understanding of it. Though my armchair science moments tend to get a bit fanciful sometimes.

Skull and Cross err Swords (where are the bones) for the pirates.

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Bronze badge

Magnetic mines don't work like that.

The magnetic mines that we are worried about work by detecting the bias that the metal hull and machinery of the ship places on the Earth's magnetic field. So, if you could make a device to wrap round the hull that hides the metal hull from that field, yes, it would protect the ship from magnetic mines.

However, and this is a big but, it is far cheaper to simply degauss the ship's hull every six to eight weeks. This was known during the Second World War, and once it was discovered, Allied ships, both civilian and military, routinely had electric cables wiped over their exteriors to cancel the bias. It's not as effective as a full-on shielding device, but mine countermeasures only need to be effective enough to allow ships to go through unharmed.

(Yes, yes, I know that modern magnetic mines are more sensitive and better at detecting decoys etc., but the fact remains that exotica like cryogenic superconductors placed outside the hull are definitively overkill, both in terms of absolute effectiveness and also in terms of operating cost.)

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Boffin

Don't shoot me all at once, but perpetual motion?

If you can shield one side of the magnet, and make a large loop of magnets running on the outside of piping, each leaning on the next with one pole angled towards the tube, the other away, then place a magnet inside the tube, with NS the other way round, only one set of the opposite poles will do any pushing?

I guess blocking one of the poles of the magnet in the tube would have the same effect?

It's early, I'm tired, and I'm more excited about faster than light travel, but what's wrong with these thoughts? I'm sure there's something.

Boffinry image not for my post, but in hope for the following ones.

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Gold badge

Briefly, there's no such thing as "one side of a magnet".

A magnet is not two monopoles at either end of the bar, it is a dipole all the way through. If you take a long bar and shield one end, you are left with a shorter unshielded magnet.

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My design for a perpetual motion machine relies on being able to shield the magnetism briefly (as in the stolen design described above!!) ... you let the static N pull the S on the circle, once it starts moving your magnetic shield moves in, momentum carries the circle magnets past, and the shield moves out of the way in time for next S to get attracted, and the passing N to be pushed away...

Now need to figure out how other people are stealing ideas out of my head... was really annoyed when Google launched Circles!

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FAIL

Sigh

And where will all the energy for moving and powering the shield come from, eh ?

You can't build a perpetual motion machine. The specifics of the design don't matter to the laws of thermodynamics.

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Coat

Just cilinder?

So it would be more practical to wrap the mines instead of the ships?

eehr, ill just go

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Fine in theory ....

Not sure what they mean by "superconductors" but we've spent several years trying to get HTS to work in an industrial context; and it is not easy.

So wrapping your average pacemaker in several layers of exotic materials then hanging a cryogenic chamber off them does not seem to me to be a goer.

Same is nearly true for minesweepers.

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Silver badge

Brrrrr!

My submarine is full of .....liquid nitrogen :(

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JDX
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@Raggs

I had the same idea some years ago so you're not alone in your stupidity :)

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Thumb Up

So to sum it all up...

.... they have a THEORY? Yawn. Wake me up up when they break the good china. Cause the war barrier is a ways away.

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Facepalm

Have you considered a career as a Government SpAd? You seem to have the right outlook for it.

It would be nice if people could do a few numbers in the morning and come up with a device ready for production by tea time. Sadly it doesn't work like that.

These guys are not really trying to build a device (not yet anyways). Rather, they are addressing the more fundamental problem of whether or not the laws of nature allow for it to be built. (Which is by no means obvious)

It doesn't matter how convoluted or impractical the arrangement may be. The point is that the problem, they claim, has, at least, one solution.

Engineering that into a commercially viable product is an entirely different kettle of fish and, I'm guessing, not necessarily what these guys do. (It is also impossible to do unless someone works out the physics first. -- And hence, the argument that funding "applied" science at the expense of "theoretical" science is shortsighted and, ultimately, pointless)

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They found the USS Eldridge then did they.

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Pirate

I'd just like to take the time...

... to salute Jordi Prat-Camps, who IMHO has the name of the decade.

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Anonymous Coward

Re: I'd just like to take the time...

In Catalan, Prat (one 't' only) means "meadow" and is a rather common surname. Same with Camps (lit. "fields"). They are nearly homonyms with the English nouns you are thinking of, save for the shorter 'a' in English 'prat', and the different pronunciation of the 'r' sound (whether rolled or unrolled).

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Go

Check me on this one...

Is blocking magnatism similar to blocking charged particles? if so, screw water-ship hulls. we need to plaster ths on anything going past LEO. Then all we need is a decen propulsion system for Mars.

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WTF?

An-isotropic?

"... and isotropic magnetic materials.

The latter describes materials whose magnetic properties are directionally-dependent."

No,sir. Isotropic means equal in all directions. Directionally-dependent would be anisotropic.

Has there been an error of dictation, listening, and writing down?

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Anonymous Coward

Re: An-isotropic?

Well spotted. Option four: the bloody spell checker decided to "correct" a term it didn't know.

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Anonymous Coward

No no no no no...

"anti-magnets could [...] conceal metals from [...] airport scanners."

For the love of God, don't let the politicians find out about this. Shoe-less DNA destroying naked-pic full body scans are quite enough thank you.

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Uh, sure

I'd have a ham sandwich - if I had any ham.

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Joke

anti-magnetic cloak....

I guess it depends on the magnet. My fridge magnet gets defeated by 2 take out menus, perhaps I should patent them?

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Pint

Yawn...

Who cares ? Come up with something genuinely useful, like an anti-gravity cloak, or a light- bending invisibility cloak.

Hell, I'd even settle for a cloak of pint refrigeration, designed to keep your pint of ale at just above freezing during the game.

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