Hiding in plain sight

The Easter holiday rush is receding into distant memory. The only thing airport security personnel have to worry about is what happens when everyone starts arriving for the Olympics. That, and the helpful physicists who have worked out how to smuggle a gun through a metal detector.

It all started as a bit of harmless blue-sky thinking. In the late 1960s, a Russian physicist pointed out the fun you could have if you invented a material that bends light in the opposite direction to normal. You could use it as an invisibility cloak, he said: just as water diverts round a rock in a stream by going first to one side, then back to the other, light bent in two different directions as it passed an object would give a viewer the impression that the light had travelled in a straight line and that the object simply wasn’t there.

Oh, how everybody laughed. Then, in 2000, someone turned this ridiculous fantasy into reality. John Pendry of Imperial College London showed how to create “left-handed materials” that would bend microwave radiation the wrong way. The practicalities were a little cumbersome and it didn’t work with visible light. But still, it was surprising, impressive and fun, in a nerdy kind of way.

Over the past decade, the technology has matured. At first, left-handed materials were constructed from intricate arrays of copper rings and could only hide tiny objects from a microwave detector. Now, we have invisibility “carpets” made from cheap and widely available crystals of the mineral calcite. They are able to hide objects the size of your thumb – and they work in visible light.

That technology is not yet going to smuggle a gun through airport security, though. Even if the X-ray machine doesn’t make the outline obvious, the magnetic field from the steel triggers an alarm. But a paper recently published in the journal Science can get you round that obstacle.

As it turns out, you can cloak a metal’s magnetic field for less than £1,000. First, wrap your gun in a layer of superconducting tape. Magnetic fields cannot pass through a layer of superconductor, so the scanner wouldn’t see the gun’s field. The scanner would see the superconductor’s field, though. However, this can be countered by adding a layer of flexible magnetic strip, rather like that found on the back of a fridge magnet. The researchers showed that this combination of readily available materials does a reasonable job of cloaking a magnetic field.

Touching the void

OK, it’s still not quite a credible threat. The superconductor has to be kept at liquid-nitrogen temperatures and a cloud of nitrogen vapour coming out of your hand luggage might raise a few eyebrows. A simple thermal detector would certainly put paid to any gun-smuggling plans.

But the physicists aren’t beaten yet. While some have been content to bend light as it travels through space, Martin McCall of Imperial College London has played around with bending light as it travels though time.

The technique involves slowing down and speeding up light inside an optical fibre – something that physicists have learned to do with astonishing skill in the past few years. McCall now has a blueprint for a device that doesn’t just make things invisible; it makes it look like they never even happened. It only works on technologies with an optical fibre feed, such as a CCTV camera. Nevertheless, in principle, we now know how to create the illusion of a void in both space and time – a void that could plausibly be exploited to evade surveillance technologies. Of course, it’s ridiculous. But where these troublesome physicists are involved, nothing remains ridiculous for long.

Michael Brooks’s “Free Radicals: the Secret Anarchy of Science” is published by Profile Books (£12.99)

Michael Brooks holds a PhD in quantum physics. He writes a weekly science column for the New Statesman, and his most recent book is At the Edge of Uncertainty: 11 Discoveries Taking Science by Surprise.

This article first appeared in the 30 April 2012 issue of the New Statesman, The puppet master

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Three’s adblocking trial is terrible news for journalism

Against a backdrop of editorial redundancies, it's hard to feel celebratory about the rise of adblocking. 

In a decision which will delight phone users but strike fear into media companies' hearts, the mobile provider Three is running an adblocking trial across its network from mid-June.

The company says it's considering adblocking as a way to improve its customers' privacy and reduce data costs, which makes sense, up to a point. Ads, especially video ads, can eat up mobile users' data and battery life, and can render already-clunky mobile websites practically unusable.

However, the move comes in a week where both new and old news organisations, the Telegraph and Vice, have laid off staff in a bid to make cost savings. These organisations rely (to differing extents) on ad revenue. If readers aren't seeing ads, then whoever published and paid for that writing isn't making money, and probably won't be able to pay for that writing for much longer. 

The trial mirrors Apple's launch in September 2015 of an operating system which supported adblocker apps (which unsurprisingly shot up the Apple Store charts). At the time, I wrote about what this could mean for journalism:

Apple's move is just another which puts journalism at the mercy of giant tech companies. The consumption of media is already dictated by the whims of Google's algorithm, with publications forced to redesign sites and tweak content to ensure they rank highly and are indexed by the search engine.

Apple, notorious in the industry for its fanged response to attacks in the press, will now select its own news for readers via its news app. And media producers may now be forced to turn to social media sites like Facebook, where adblockers have less power, to market or even publish their content. 

Without ads, media companies will need to find other revenue streams, which could include subscription or paywall models - great if they work - or more sponsored posts by companies. 

Ads certainly need to become more user-friendly, and Three makes a good point when it argues that advertisers should pay for the data costs of their ads. But if you were saddened by the editorial redundancies across the media this week, take pause before you celebrate the rise of adblocking. 

Barbara Speed is a technology and digital culture writer at the New Statesman and a staff writer at CityMetric.