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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Pupils need internet classes? Here are 41 lessons they should learn

Forget privacy and security, here's what to do when a black and blue dress looks white and gold. 

It is imperative that children are taught how to survive and thrive on the internet, claims a new House of Lords report. According to the Lords Communication Committee, pupils need to learn how to stay safe, avoid addictive games, and become “digitally literate”.

It’s hard to argue with the report, which is a great step forward in acknowledging that the internet now basically = life. Yet although it is crucial that children learn how to stay private and secure online, there are also some equally crucial and not-at-all-flippant pieces of information that the youth urgently need to know. Here are the first 41 lessons in that curriculum.

  1. To figure out how much to donate towards your mate’s charity half-marathon, half X OR double Y, where X is the amount paid by their mum and Y is the amount donated by your closest rival, Becky
  2. Don’t mention that it’s snowing
  3. If – for some reason – you talk about bombs in a Facebook message, follow this up with “Hi Theresa May” in case Theresa May is looking, and then Theresa May will think you are just joking
  4. If you are on a train and you are annoyed about the train, do not tweet @ the social media manager who runs the account for the train, because they are not, in fact, the train
  5. If a Facebook meme starts “Only 10 per cent of people can get this puzzle right” – know that lies are its captain
  6. It’s not pronounced me-me
  7. Never say me-me nor meem, for they should not be discussed out loud
  8. People can tell if you’ve watched their Instagram stories
  9. People can’t tell if you’ve waded back through their Zante 2008 album and viewed all 108 photos
  10. People can tell if you’ve waded back through their Zante 2008 album and viewed all 108 photos if you accidentally Like one – in this circumstance, burn yourself alive
  11. Jet fuel can melt steel beams
  12. If a dog-walking photo is taken in the woods and no one uploads it; did it even happen?
  13. Google it before you share it
  14. Know that Khloe Kardashian does not look that way because of a FitTea wrap
  15. Do not seek solace in #MondayMotivation – it is a desolate place
  16. Respect JK Rowling
  17. Please read an article before you comment about a point that the article specifically rebutted in great detail in order to prepare for such comments that alas, inevitably came
  18. Don’t be racist, ok?
  19. Never, under any circumstances, wade into the Facebook comment section under an article about Jeremy Corbyn
  20.  If a dress looks white and gold to some people and black and blue to some others, please just go outside
  21. Open 200 tabs until you are crippled with anxiety. Close none of the tabs
  22. Despite the fact it should make you cringe, “smol puppers” is the purest evolution of language. Respect that
  23. Take selfies, no matter what anyone says
  24. Watch Zoella ironically until the lines of irony blur and you realise that the 20 minutes you immerse yourself into her rose-gold life are the only minutes of peace in your agonising day but also, what’s wrong with her pug? I hope her pug is ok
  25. Nazi Furries are a thing. Avoid
  26. Use Facebook’s birthday reminder to remember that people exist and delete them from your Friends list
  27. When a person you deleted from your Friends list inexplicably comes up to you IRL and says “Why?” pretend that your little cousin Jeff got into your account
  28. Don’t let your little cousin Jeff into your account
  29. “Like” the fact your friend got engaged even if you don’t actually like the fact she is reminding you of the gradual ebbing away of your youth
  30. No one cares about your political opinion and if they act like they do then I regret to inform you, they want to have sex with you
  31. Please don’t leave a banterous comment on your local Nando’s Facebook page, for it is not 2009
  32. Accept that the viral Gods choose you, you do not choose them
  33. Joke about your mental health via a relatable meme that is actually an agonising scream into the void
  34. Share texts from your mum and mock them with internet strangers because even though she pushed you out of her vagina and gave up her entire life to help you thrive as a person, she can’t correctly use emojis
  35. Follow DJ Khaled
  36. Decide that “Best wishes” is too blah and “Sincerely” is too formal and instead sign off your important email with “Happy bonfire night”” even though that is not a thing people say
  37. If someone from primary school adds you as Friend in 15 years, accept them but never speak again
  38. The mute button is God’s greatest gift
  39. Do not tell me a clown will kill me after midnight if I don’t like your comment because that is not a promise you can keep
  40. Don’t steal photos of other people’s pets
  41. Accept that incorrect "your"s and "you’re"s are not going anywhere and save yourself the time 

Amelia Tait is a technology and digital culture writer at the New Statesman.