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Invisibility Devices Proposed

Might Harry Potter's Invisibility cloak be able to be produced by physics rather than magic? The prestigious journal "Science" today carries two articles by theoretical physicists on invisibility devices, and that way in which they might be made to work. One of the two papers is by our Prof Ulf Leonhardt.

Ulf says " I am working on ideas of designing invisibility devices based on modern metamaterials, inspired by Fermat's principle, conformal mapping, analogies between mechanics and optics, the optics of illusions, Arabia (and the imagination of my children)."

Bending of light through specially modified refractive index materials - Ulf Leonhardt

Rather than trying to make light go through an object, Ulf's ideas see light being guided around a region in space and ending up propagating in exactly the same way as if this curious region in space did not exist. This is seen above with the red lines indicating light rays coming in from the left, then bending around this curious region and carrying on again. If the object we wished to hide was in the apple-shaped region, no light would interact with it. Ulf's work has looked at this and related situations where materials of specially crafted refractive index properties can do potentially interesting things to the way that light propagates.

In a review of the two papers in Science, George Eleftheriade, an electrical engineer at the University of Toronto, is quoted as saying "The papers are "visionary". It's pioneering work that sets the stage for future research." In the same review Greg Gbur, a theoretical physicist at the University of North Carolina, Charlotte, is quoted as noting that others have studied invisibility but says that the new papers describe more precisely how to achieve it. "Each gives specific examples of how you might design an invisibility device," he says.

Update:- Ulf was later names as one of the world's top current 50 scientists by Scientific American, with the work summarised here being a major factor.

Posted BDS 26.5.06
Updated 30.5.06
Updated 3.7.07