Scientists develop Harry Potter style invisibility 'cloak'

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Magic: Wizard Harry Potter is famed for his invisibility cloak

It sounds straight from the pages of Harry Potter - but researchers have developed an "invisibility cloak" that will allow people, planes, tanks and even ships to disappear.

But sadly the cloak, developed by a British and American team, cannot grab light waves and make objects invisible to us - it can only make them disappear from radar screens.

Set to be produced in just five years time, the cloak "grabs" waves that head towards it and makes them flow smoothly around it, making the object "invisible," according to a report in Science Express.

Researchers compare the process, which uses specially-designed metamaterials, to the way that water in a river flows around a stick.

Radars, which use microwaves to detect objects, are easier to hide from because they have a wavelength 30,000 times longer than light waves.

Although the technology to make items appear invisible to the naked eye would be the same, we might never have advanced enough equipment to make it reality, scientists said.

The US military, keen to develop vehicles that are undetectable to enemy radar, has funded the project at Duke University in America and Imperial College London.

The team have tested a small prototype cloak they built, less than five inches across, proving the waves flowed round it as predicted.

They say it will be relatively cheap and easy to build huge cloaks, even onto warships.

It could also be used to protect mobile phone users from radiation given off by their phones.

Professor Sir John Pendry, a theoretical physicist at Imperial College, said the cloak worked first by ensuring no waves were reflected and then releasing them to make it appear that nothing had got in their way.

He said: "The cloak has go to do two things - one is to deflect any waves away from the object, because if it reflects, it can be seen."

"The second is to get rid of the shadow. It is a challenge because the waves have got to be released so it appears they have been going in the same direction and have not been deflected by any object."

"It can be compared to a black ball which does not reflect light, you can still see it when it is thrown up in the air because you can see where the light has been deflected - like a hole in the air."

"It is very much harder to make it invisible to the naked eye."

"The cloak we have developed can deflect radar waves, which have a wavelength of 3cm, but light has a wavelength of one micron."

"This would require nano-scale engineering which is certainly not possible at the moment, and may not even be possible in the future."

The professor said the cloak should be cheap to produce and could easily be made big enough to cloak a ship because it was simply made from copper and the innovation was in the way it was produced.

He added: "It is just made of copper wire deposited on a circuit board, so when it takes off in a big way it will not be a problem to make a bigger cloak and should not be expensive."

"In the first instance it will be a speciality product and the military will probably be the first users."

"It could easily be used to cloak a ship - the bigger you make the cloak the easier it actually is."

"It could cloak people from radar, but it would appear less like a cloak and more like a shed."

"To cloak something like an aeroplane would cost hundreds of thousands of pounds, but that is in the context of an aeroplane costing millions of pounds."

"The American military have provided the funds and there has been a lot of interest, although I don't want to go into too much detail."

The current model is only able to grab waves approaching horizontally and research will now focus on a three dimensional cloak that can hide from waves coming from any direction, which is set to be demonstrated by 2010.

 

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