Does the idea of invisibility interest you? Would a cloak like the one the Romulans had in the Star Trek series be useful in hiding that big TV tower from the neighbors? If so, you may be interested to know that researchers at Duke University and Imperial College in London have actually demonstrated cloaking!
The cloak used in the demonstration was, of course, somewhat limited. This cloak, which consisted of a series of concentric two-dimensional rings, only works at specific microwave frequencies. The rings themselves are not easy to make. Precise variations in the shape of the copper elements on the rings allow interaction with electromagnetic waves in a very specific way. Microwave energy hitting the rings is diverted around the object being cloaked and comes out the other side showing little indication there was anything in the way. Imperial College said in a statement "the cloak is thought to be one of the most complex metamaterial structures ever made, as it has a unique circular geometry and it's (sic) electromagnetic properties vary across its surface."
On the Web page The Science Fact and Fiction of Invisibility, Duke University researchers examine the possibility of science fact meeting science fiction. As it turns out, the most realistic portrayal of invisibility is one in which the person or object is only partially transparent, such as the alien in the movie "Predator." The research group said, "...cloaked, the predator is mostly transparent, but there is a noticeable distortion of the transmitted light that just vaguely outlines the shape of the predator. As depicted in the movie, it is difficult to perceive the presence of the alien unless you know it's there and it's in motion. Otherwise, the imperfect cloaking does a pretty good job of keeping the alien well hidden. Although the underlying fictional technology is not described in the movie, the cloaking effect appears to be related to the alien's armor, which would make it more akin to the material cloak that we think might be possible."
The amazing thing is researchers have been able to design metamaterials that provide some cloaking. The cloaking works only in certain microwave bands and is very complex, but as we've seen with modern computers and digital receivers, what was previously thought impossible can now be achieved at reasonable cost. Will the same thing happen in the world of metamaterials?
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