Klingon spaceships used an invisibility cloak to hide their ship in the Star Trek series. A similar technology will be tested in as soon as 18 months.

John Pendry and colleagues at Imperial College London, UK, have calculated that materials engineered to have abnormal optical properties, known as metamaterials, could make light pass around an object so it appears as if it were not there at all.

Pendry's team has drawn up plans for a spherical metamaterial structure that would render an enclosed object invisible. Electromagnetic waves (Radar, light), instead of reflecting off the structure, would flow around it like water around a rock in a stream.

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National Geographic News
abstract of paper in Science
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