Mathematical Model Supports Concept of Invisibility Cloak

May 10, 2007

A computer model designed by a mathematician suggests that it's possible to make large objects, such as airplanes and submarines, appear invisible at close range.

University of Liverpool mathematician Sébastien Guenneau and colleagues Frédéric Zolla and André Nicolet, both from the University of Marseille, report that their computer-based mathematical model lends credence to the idea of an invisibility cloak. The research findings were published in the May Optics Letters.

"The shape and structure of [airplanes] make them ideal objects for cloaking, as they have a fixed structure and movement pattern," Guenneau noted in a University of Liverpool news release. "Human beings and animals are more difficult as their movement is very flexible, so the cloak — as it is designed at the moment — would easily be seen when the person or animal made any sudden movement."

"Using this new computer model," Guenneau added, "we can prove that light can bend around an object under a cloak and is not diffracted by the object."

But, for their cloaking device to work, Guenneau said, the light must "separate into two or more waves resulting in a new wave pattern." Within the pattern would be both light and dark regions, which are needed for an object to disappear from view.

This reportedly happens because the metamaterial — a material that gains its properties from its structure rather than directly from its composition — that makes up the cloak "stretches the metrics of space." It's akin to what planets and stars do for the metrics of space-time, according to Einstein's general theory of relativity.

Applications are obvious: fighter planes, submarines, military equipment.

The invisible man and Harry Potter's invisibility cloak remain artifacts of fiction and Hollywood . . . but an invisible Klingon bird of prey?

Source: University of Liverpool via Eurekalert
F. Zolla, S. Guenneau, A. Nicolet, and J. B. Pendry. 2007. "Electromagnetic analysis of cylindrical invisibility cloaks and the mirage effect," Optics Letters 32:1069-1071. Abstract.