James Bond movie is famous for gadgets that people think are impossible to invent and it is just pure cinematic. One such gadget is the invisible car.
Soon, it will be a reality as scientists came up with the invisibility cloak.
Experts create invisibility cloak
By Paul Rincon
Science reporter, BBC News
A US-British team of scientists has successfully tested a cloak of invisibility in the laboratory.
The device mostly hid a small copper cylinder from microwaves in tests at Duke University, North Carolina.
It works by deflecting the microwaves around the object and restoring them on the other side, as if they had passed through empty space.
But making an object vanish before a person's eyes is still the stuff of science fiction - for now.
The cloak consists of 10 fibreglass rings covered with copper elements. This is classed as a "metamaterial" - an artificial composite that can be engineered to produce a desired change in the direction of electromagnetic waves.
The precise variations in the shape of copper elements patterned on to the ring surfaces determines their properties.
Like light waves, microwaves bounce off objects making them visible and creating a shadow, though at microwave frequencies the detection has to be made by instruments rather than the naked eye.
The metamaterial cloak channelled the microwaves around the object like water in a river flowing around a smooth rock.
Gone from view
When water flows around a rock, the water recombines on the opposite side. Someone looking at the water downstream would never guess it had passed by an obstacle.
In the experiment, the scientists first measured microwaves travelling across a plane of view with no obstacles. Then they placed a copper cylinder in the same plane and measured the disturbance, or scattering, in the microwaves.
Finally, the researchers placed the invisibility cloak over the copper cylinder. The cloak did not completely iron out the disturbance, but it greatly reduced the microwaves being blocked or deflected.
"This cloak guides electromagnetic waves around a central region so that any object at call can be placed in that region and will not disturb the electromagnetic fields," said co-author Dr David Schurig from Duke University.
In principle, the same theoretical blueprint could be used to cloak objects from visible light. But this would pose a challenge, as nano-scale engineering would be needed to make the cloak.
"As an application it's not clear that you're going to get the invisibility that everyone thinks about - as in Harry Potter's cloak, or the Star Trek cloaking device," said co-author David Smith of Duke.
"But it shows what can be done with artificial materials. It gives us some insight that we can design something that we wouldn't have been able to do with any existing material."
A key collaborator on the project was Professor John Pendry from Imperial College London.
The researchers say that if an object can be hidden from microwaves, it can be hidden from radar - a possibility that will fascinate the military.
Cloaking differs from stealth technology, which does not make an aircraft invisible but reduces the cross-section available to radar, making it hard to track.
Paul.Rincon-INTERNET@bbc.co.uk
Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6064620.stm
Published: 2006/10/19 15:30:00 GMT
© BBC MMVI
Thursday, October 19, 2006
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