Since the development of ‘metamaterials’ that can bend electromagnetic waves – such as light – around an object, the hottest item for geeks and pranksters has been the invisibility cloak, which hides the wearer in plain sight.

But use of such devices to invade other people’s privacy has always been taboo. Now efforts are being made to tighten up control of invisibility cloaks, making them as restricted as firearms, and essentially illegal except for licensed government agencies.

Naturally the military uses for metamaterials are legion, and bring new meaning to the word ‘stealth’, which is why the US military research agency DARPA funded most of the research that went into the development of invisibility cloaks.

But it is in business where the advantages of invisibility change our everyday lives. As the cost of metamaterials declines, we can expect to see billboards that hover in mid-air and high-rise buildings that seem to be only one floor tall, leaving the view un-obscured, and raising property values.

It will also be easy to hide your ugly garden shed from view – if you can get permission from the government, that is!

ANALYSIS >> SYNTHESIS: How this scenario came to be

Metamaterials

The development of new materials could see items such as invisibility cloaks, a key weapon in the trickery of Harry Potter and countless science fiction plots, become a reality within five years.
Two research groups have published technical blueprints for making “metamaterials” which can change how light and other forms of radiation bend around an object, in a way similar to water flowing around a rock.

An observer would see whatever was behind the object as if it were not there, said Professor Ulf Leonhardt of St Andrews University, whose research was published in the latest edition of the journal Science.

David Smith from Duke University in the US, who has been independently pioneering the development of metamaterials with John Pendry of Imperial College London said the cloak would act “like you’ve opened up a hole in space”.

“All light or other electromagnetic waves are swept around the area, guided by the metamaterial to emerge on the other side as if they had passed through an empty volume of space,” Prof Smith told the Financial Times.

(from the Guardian)

Nano-technology

Of course nanotech lies at the heart of metamaterials. Carbon nanotubes are microscopic hollow tubes made of an assembly of carbon atoms, literally piled on top of each other in a cylindrical fashion. These ‘artificial molecules’ exhibit strange characteristics not normally associated with the natural forms of the element or compound. For example, nanotubes can be built so narrow that they separate the atoms of larger molecules that are forced though them, a kind of molecular filter.

But carbon is also a conductor of electromagnetic waves. At the nano scale, the wavelengths of carbon nanotube ‘antennae’ are so short that they can absorb and transmit visible light. Which means that you can build a surface as thin as paint that projects light or an image, if you can ‘wire’ it up correctly. In the same way, photo cells could be sprayed or painted onto a surface such as the roof of a building, turning it into a giant solar panel, or a glowing beacon.

Some technological challenges remain, but once they are solved we could see new types of light recording and emitting materials and objects, and those that are smart enough to do both at the same time will appear invisible.

Now where is my invisibility cloak? I’m sure I hung it up here somewhere…