for National Geographic News
Researchers announced today that they've built the world's first invisibility cloak, although the fine print may disappoint science-fiction fans.
The device works only in two dimensions and only on microwaves.
Still, the experiment proves that a theoretical blueprint for building invisibility cloaks unveiled by the same team just five months ago works.
(Read "Invisibility Cloaks Possible, Study Says" [May 25, 2006].)
"The concept that you can cloak something and make something invisible can now be demonstrated by this method," said Duke University physicist David R. Smith.
"This is the first time where we show that you can actually take electromagnetic waves and wrap them around some region that you want to conceal and restore them on the other side."
An uncloaked object would cause an interruption in the waves, creating a "shadow" behind the object. But the cloak succeeded in making the waves reconnect on the other side.
The team describes its experiment in tomorrow's issue of Science Express, the online early edition of the journal Science.
The electromagnetic sleight-of-hand is enabled by novel, human-made substances called metamaterials.
Developed just seven years ago, the materials use a matrix of exceptionally tiny, sometimes nanoscale, metal wires and loops to control electromagnetic radiation in ways natural substances can't.
(See a National Geographic magazine feature about nanotechnology.)
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