Can this magnetic invisibility cloak hide weapons?

Some day, people with implants — and guns — might be able to pass through this kind of security by using magnetic invisibility.
Some day, people with implants — and guns — might be able to pass through this kind of security by using magnetic invisibility.Getty Images
/ Source: Discovery Channel

A team of Spanish researchers say they can build a magnetic cloaking device that would help pacemaker patients pass through MRI machines without harm — but it could also be used by criminals to smuggle bombs or guns through metal detectors.

Physicists from the Universidat Autonoma de Barcelona published their work today in the New Journal of Physics.

"This is theoretical, but we have tried to get some recipes on how this could be made with available materials," said Alvar Sanchez, the study's lead author. "Imagine a shell with some kind of metallic layers. This shell in the shape of a cylinder could surround a magnet and make it disappear."

Sanchez said the device would allow people to pass through metal detectors with concealed weapons.

"A magnetic field interacts with gun and the machine detects the reflection," Sanchez said. "One can reduce the reflection because you don't disturb the magnetic field."

Sanchez said before he got to that point, he would consult with authorities on ways to defeat his own theoretical device.

This so-called "anti-magnet" consists of several layers. First would be a layer of superconducting material to stop the magnetic field of an object from leaking outside. That would be covered by outer layers of "metamaterials" which would correct distortions from an outside magnetic field, and thereby make the object appear invisible.

Sanchez said he did this using computer simulations of a cylindrical device cloaking a small magnet.

But not everyone is convinced.

MIT professor of materials science Caroline Ross says there are two big problems. First, nobody has been able to make superconducting materials at room temperature. The best right now is 77 degrees Kelvin (or minus 200 C).

"It's quite likely this thing works in a computer, but it's a question of whether it works in real life," Ross said.

Ross said that getting superconductivity at room temperature has been "the Holy Grail of physics for the past few decades."

She also pointed out that superconductors don't function in the presence of powerful magnetic fields, the kinds given off by MRI devices.

John Waugh, MIT professor emeritus of chemistry who is a pioneer in nuclear magnetic resonance imaging, also doubts cloaking a pacemaker would work.

"I'm very suspicious of it," Waugh said. "I don't think you could do that. The minute you put the patient in an MRI machine and start pulsing it, all kinds of hell will start happening."

Despite the engineering and scientific hurdles, Sanchez says his paper is a proof of concept design for others to continue.