Invisibility might be in use already. Only, if carried out successfully we are not able to see it.

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http://dukenews.duke.edu/2006/05/cloaking.htmlTheoretical Blueprint for Invisibility Cloak Reported
Durham, N.C. -- Using a new design theory, researchers at Duke University's Pratt School of Engineering and Imperial College London have developed the blueprint for an invisibility cloak. Once devised, the cloak could have numerous uses, from defense applications to wireless communications, the researchers said.
Such a cloak could hide any object so well that observers would be totally unaware of its presence, according to the researchers. In principle, their invisibility cloak could be realized with exotic artificial composite materials called "metamaterials," they said.
"The cloak would act like you've opened up a hole in space," said David R. Smith, Augustine Scholar and professor of electrical and computer engineering at Duke's Pratt School. "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."
Electromagnetic waves would flow around an object hidden inside the metamaterial cloak just as water in a river flows virtually undisturbed around a smooth rock, Smith said.
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http://www.dukenews.duke.edu/2006/10/cloakdemo.htmlFirst Demonstration of a Working Invisibility Cloak
Durham, NC -- A team led by scientists at Duke University's Pratt School of Engineering has demonstrated the first working "invisibility cloak." The cloak deflects microwave beams so they flow around a "hidden" object inside with little distortion, making it appear almost as if nothing were there at all.
Cloaks that render objects essentially invisible to microwaves could have a variety of wireless communications or radar applications, according to the researchers.
The team reported its findings on Thursday, Oct. 19, in Science Express, the advance online publication of the journal Science. The research was funded by the Intelligence Community Postdoctoral Fellowship Program.
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Much more on this topic here:
http://droneacademy.conforums.com/index.cgi?board=NAN&action=display&num=1218547055And here:
http://droneacademy.conforums.com/index.cgi?board=SC&action=display&num=1213262595EVS