Friday, October 20, 2006

Invisibility shed

If, for whatever reason, you've ever wanted to make your shed invisible, then you don't have long to wait. According to an article in The Guardian today, scientists claim they can now make objects effectively disappear using what they describe as an "invisibility shed". Key excerpts below:

'The device works on the principle that an object vanishes from sight if light rays striking it are not reflected as usual, but forced to flow around it and carry on, as if it was not there. To make cloaks, scientists developed "metamaterials", meticulously patterned thin metal sheets that can bend light in precisely the right way. In the demonstration, scientists showed that a small object surrounded by rings of metamaterials in effect disappeared.

'The test involved firing a beam of microwaves at the object, the same radiation used for radar. Normally the beam would penetrate and bounce off the rings, but measurements showed the waves split and flowed around the centre. "The wave's movement is similar to river water flowing around a smooth rock," said David Schurig, a scientist at Duke University who helped conduct the experiments.

'Sir John Pendry, the theoretical physicist at Imperial College London, who developed the idea, said cloaking devices to hide vehicles from radar were only a matter of years away. "It's already been quite an achievement designing this cloak, but next we want to develop a thin skin that can cloak a plane without interfering with the aerodynamics. If you wanted to cloak something big and clunky like a tank, that's feasible in the medium term," he said.

'A cloaking device that makes objects invisible to the eye is a tougher prospect. Radar waves are about 3cm long and to cloak objects from them, metamaterials need to be designed with features a few millimetres across. Visible light waves are far shorter - less than one thousandth of a millimetre - meaning a cloaking device would need metamaterials with much finer features to bend light properly.

'"It's not yet clear that you're going to get the invisibility that everyone thinks about with Harry Potter's cloak or the Star Trek cloaking device," said David Smith, who led the experiments at Duke University. While scientists have high hopes for invisibility devices, they are less optimistic they will ever be able to challenge Harry Potter's stealth garment. "Our device is more an invisibility shed than an invisibility cloak," said Prof Pendry.'

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