http://www.breitbart.com/news/2006/10/20/061020170453.em0doxnf.htmlScientists make Harry Potter-like 'cloak of invisibility'
Oct 20 1:04 PM US/Eastern
For fans of the fictional Harry Potter, US and British scientists have demonstrated a working "invisibility cloak" that could, in time, make wearers disappear.
Initial tests focused on making objects invisible to microwaves, but the scientists said the same principles could theoretically apply to visible frequencies, making a true invisibility cloak like storybook hero Potter's possible.
Scientists at Duke University in North Carolina sought to put into practice the design theory revealed earlier this year by Sir John Pendry of Imperial College London.
They made a five-inch cloak (12.7 centimeters) from a complex artificial composite, or metamaterial, of copper rings and wires patterned onto fiberglass composite sheets.
The material is designed to distort space so that microwaves are not reflected back, but are instead bent around the cloaked object, whatever its shape, and allowed to flow on as if it didn't exist.
The result is that the beams are deflected like water flowing around a rock in a river, without noticeably interrupting the main current.
"By incorporating complex material properties, our cloak allows a concealed volume, plus the cloak, to appear to have properties similar to free space when viewed externally," said Duke scientist David Smith.
"The cloak reduces both an object's reflection and its shadow, either of which would enable its detection."
The effect is different from, for instance, stealth technology which protects US Air Force bombers from radar. That technology simply deflects the radar in ways to disguise the jets, while not making them invisible.
The invisibility cloak has potential applications in wireless communications or radar -- preventing objects from blocking waves or being disturbed by them or, for instance in military use, hiding them from waves. Indeed, some of the funding for the research came from the US Defense Department's high-tech research unit, the Defense Advanced Research Projects Agency.
But the scientists said it's still a long leap to a real Harry Potter-like cloak which would allow someone to walk around unseen. It would take a much greater advance in engineering metamaterials that do to the whole spectrum of visible wavelengths what the existing cloak material now only does to microwaves.
"It's not yet clear that you're going to get the invisibility that everyone thinks about with Harry Potter's cloak," said Smith.