Invisibility cloak 'possible'
2006-05-29 09:52
Washington - The invisibility cloak worn by Harry Potter in a series of books by JK Rowling is theoretically possible, US and British researchers say.
Researchers at Duke University and Imperial College London said they had developed a blueprint for an invisibility cloak that could have a range of uses, from defence applications to wireless communications.
The research team reported its findings last week in Science Express, the online advance publication of the US journal Science.
Their work was partly funded by the Defence Advanced Research Projects Agency, an agency of the US Department of Defence.
'Metamaterials'
The cloak theoretically could be achieved by using exotic artificial composite materials called "metamaterials", they said.
But first they would have to make the metamaterials, which would deflect light and sound and other force waves.
"The cloak would act like you've opened up a hole in space," said David Smith, professor of electrical and computing engineering at Duke University, in the south-eastern US state of North Carolina.
Electromagnetic waves would flow around the metamaterial cloak like water in a river flows around a smooth rock, he said.
"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," he said.
Military uses
The cloaking could be used for military purposes, to conceal an unpleasant view or obstructions to wireless communications, they said.
Smith and his colleagues first had demonstrated in 2000 that the characteristics of metamaterials - composed of particles determined at a microscopic level - are determined by their form and not by their chemical composition.
Their characteristics could be modified so that electromagnetic waves coming into contact with the invisibility cloak would not reflect light or cast a shadow.
"It's theoretically possible to do all these Harry Potter things, but what's standing in the way is our engineering capabilities," John Pendry of Imperial College London, co-author of the study.
"Early versions that could mask microwaves and other electromagnetic radiations could be as close as 18 months away," he said.
The Duke researchers are working on producing the metamaterials suitable for cloaking, the university said.