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."

Re:Metal Detectors?

[icebike]

Well, it says constant magnetic field. That's pretty hard to generate, since lots of things cause magnetic fields to fluctuate (including body movement of a metal object).

TLDR version of TFA:

The hypothetical device would work as a magnetic cloak by creating a space that is protected from an external magnetic field while at the same time causing no telltale distortion of the field. Alternatively, it could also be used to conceal a magnetic object and prevent its magnetic field from extending out into space—

So, yeah, if made portable enough it would be a security problem. But don't hold your breath.

Better headline

[pz]

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.

This is news how?

[Cosgrach]

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...

Re:This is news how?

[robot256]

Everything you said is true, but all those methods of shielding an enclosed space can be detected from outside the space by the resulting warp in the fields around it. The researchers in this article propose a method of layering materials so that the warping of the field is contained within the shield itself, rendering its presence undetectable. This is a significant advance over conventional shielding, but it has yet to be proven feasible.