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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Age verification rules won't just affect porn sites – they'll harm our ability to discuss sex

Relying on censorship to avoid talking about sex lets children down.

The British have a long history of censoring sex. In 1580, politician William Lambarde drafted the first bill to ban "licentious" and "hurtful... books, pamphlets, ditties, songs, and other works that promote the art of lascivious ungodly love". Last week, the UK government decided to have another crack at censorship, formally announcing that age verification for all online pornographic content will be mandatory from April 2018.

It is unclear at this point what this mandatory check will entail, but it's expected that you will need to submit your credit card details to a site before being allowed to access adult content (credit cards can’t be issued to under-18s).

The appointed regulator will almost certainly be the British Board of Film Classification who will have the authority to levy fines of up to £250,000 or shut down sites that do not comply. These measures are being directly linked to research conducted by the NSPCC, the Children’s Commissioner and the University of Middlesex in 2016, which surveyed more than 1,000 11 to 16-year-olds about viewing online pornography and found over half had accessed it. 

Digital minister Matt Hancock said age verification "means that while we can enjoy the freedom of the web, the UK will have the most robust internet child protection measures of any country in the world". And who can argue with that? No sane adult would think that it’s a good idea for children to watch hardcore pornography. And because we all agree kids should be watching Peppa Pig rather than The Poonies, the act has been waved through virtually unchallenged.

So, let’s put the issue of hardcore pornography to one side, because surely we are all in agreement. I’m asking you to look at the bigger picture. It’s not just children who will be censored and it’s not just Pornhub and Redtube which will be forced to age check UK viewers. This act will potentially censor any UK site that carries adult content, which is broadly defined by the BBFC as "that it was produced solely or principally for the purposes of sexual arousal".

I am a UK academic and research the history of sexuality. I curate the online research project www.thewhoresofyore.com, where academics, activists, artists and sex workers contribute articles on all aspects of sexuality in the hope of joining up conversations around sex that affect everyone. The site also archives many historical images; from the erotic brothel frescoes of Pompeii to early Victorian daguerreotypes of couples having sex. And yet, I do not consider myself to be a porn baron. These are fascinating and important historical documents that can teach us a great deal about our own attitudes to sex and beauty.

The site clearly signposts the content and asks viewers to click to confirm they are over 18, but under the Digital Economy Act this will not be enough. Although the site is not for profit and educational in purpose, some of the historical artefacts fit the definition of  "pornographic’" and are thereby liable to fall foul of the new laws.

And I’m not the only one; erotic artists, photographers, nude models, writers, sex shops, sex education sites, burlesque sites, BDSM sites, archivists of vintage erotica, and (of course) anyone in the adult industry who markets their business with a website, can all be termed pornographic and forced to buy expensive software to screen their users or risk being shut down or fined. I have contacted the BBFC to ask if my research will be criminalised and blocked, but was told "work in this area has not yet begun and so we are not in a position to advice [sic] you on your website". No one is able to tell me what software will need to be purchased if I am to collect viewers' credit card details, how I would keep them safe, or how much this would all cost. The BBFC suggested I contact my MP for further details. But, she doesn’t know either.

Before we even get into the ethical issues around adults having to enter their credit card details into a government database in order to look at legal content, we need to ask: will this work? Will blocking research projects like mine make children any safer? Well, no. The laws will have no power over social media sites such as Twitter, Snapchat and Periscope which allow users to share pornographic images. Messenger apps will still allow users to sext, as well as stream, send and receiving pornographic images and videos. Any tech savvy teenager knows that Virtual Private Network (VPN) software will circumvent UK age verification restrictions, and the less tech savvy can always steal their parents' credit card details.

The proposed censorship is unworkable and many sites containing nudity will be caught in the crossfire. If we want to keep our children "safe" from online pornography, we need to do something we British aren’t very good at doing; we need to talk openly and honestly about sex and porn. This is a conversation I hope projects like mine can help facilitate. Last year, Pornhub (the biggest porn site in the world) revealed ten years of user data. In 2016, Brits visited Pornhub over 111 million times and 20 per cent of those UK viewers are women. We are watching porn and we need to be open about this. We need to talk to each other and we need to talk to our kids. If you’re relying on government censorship to get you out of that tricky conversation, you are letting your children down.

The NSPCC report into children watching online pornography directly asked the participants about the effectiveness of age verification, and said the children "pointed out its limitations". When asked what intervention would most benefit them, this was the overwhelming response: "Whether provided in the classroom, or digitally, young people wanted to be able to find out about sex and relationships and about pornography in ways that were safe, private and credible." I suggest we listen to the very people we are trying to protect and educate, rather than eliminate. 

Dr Kate Lister researches the history of sexuality at Leeds Trinity University