Invisible Carpet Idea Close to Actual Invisibility
Eric Bland, Discovery News

July 17, 2008 -- Invisibility cloaks are cool, but an invisibility carpet is more practical.

That's according to scientists from Imperial College London, who recently published a paper detailing the creation of a material that would be the first to hide objects in visible light, something no cloaking device has ever achieved.

"We've given a prescription for how to cloak something in visible light," said John Pendry, who, along with Jensen Li, wrote the paper that appeared recently on ArXiv.org. "It will be difficult to make but it is also practical."

Cloaking an object requires structures, often referred to as metamaterials, that channel light in a specific way.

The only way to channel light in that fashion is by using structures smaller than the wavelength of light being used to detect an object. In 2006, Duke University scientists cloaked an object from light centimeters long by creating a metamaterial with structures millimeters in size.

To cloak an object in visible light, which has a much smaller wavelength, around half a micron, scientists would have to create structures nanometers in size, which, according to Pendry, "requires some clever nanotechnology."

That nanotechnology would come from combining special layers of common silica and silicon, each of which reflects light differently.

"It's a lot like a mirage," said Pendry. "The sun heats the air above the desert and creates a temperature gradient, so when light from the sky comes down the graded refraction bends the light and it enters your eye and you see a mirage the looks like water."

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