Harry Potter Invisibility Cloak — '10 Years Away'

That's the prediction of physicist David Schurig, quoted by Guy Gugliotta in a May 29 Washington Post story about the work of his group at Duke University, recently reported in the journal Science.

Long story short: the scientists have succeeded in engineering metal films to bend almost any kind of electromagnetic energy.

This year they expect to be able to control and deflect microwaves but they predict that visible light man management — creating an actual "invisibility cloak" — is perhaps a decade out.

Wrote Gugliotta, "Schurig said the first invisibility devices would probably be rigid 'shells' rather than supple cloaks, 'but, in principle, cloaks would be possible.'"

Here's the Post story.

Revenge of the Muggles?

Harry Potter and his pals Ron and Hermione have been scooting undetected around Hogwarts for years beneath the invisibility cloak Harry got from his murdered father, but now an international team of theoretical physicists suggests that muggles, or non-wizards, might someday make a cloak of their own.

Reporting last week in the journal Science, physicists J.B. Pendry of Imperial College London and David R. Smith and David Schurig of Duke University described a way to make high-tech "metamaterials" that can funnel light around an object and make it invisible.

Metamaterials, assemblages of small artificial bits of patterned metal films, can be engineered to bend almost any kind of electromagnetic energy. Schurig said that "probably this year," scientists will produce a metamaterial that can shield equipment from microwave radiation but that protecting objects from visible light -- creating an invisibility cloak -- is "further out," he said in a telephone interview -- "maybe 10 years."

Smith compared the process to a stream flowing around a stone -- essentially creating a "hole" in the water, where anything can be hidden and remain unnoticed from the outside: "We have shown it can be done for almost any frequency," he said in a telephone interview. "Being able to build it is another story."

Schurig said the first invisibility devices would probably be rigid "shells" rather than supple cloaks, "but, in principle, cloaks would be possible."

Harry and his friends will still have the advantage, though, because while metamaterials would make you invisible, they would also isolate you from the outside world. You wouldn't be able to spy on anyone. Like a Romulan Bird of Prey (at least until "Star Trek: Nemesis"), you'll have to decloak before attacking.

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Here's the abstract of the Science magazine report.

Controlling Electromagnetic Fields

J. B. Pendry, D. Schurig, D. R. Smith

Using the freedom of design that metamaterials provide, we show how electromagnetic fields can be redirected at will and propose a design strategy. The conserved fields--electric displacement field D, magnetic induction field B, and Poynting vector S--are all displaced in a consistent manner. A simple illustration is given of the cloaking of a proscribed volume of space to exclude completely all electromagnetic fields. Our work has relevance to exotic lens design and to the cloaking of objects from electromagnetic fields.

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The same issue of Science magazine contained a related article about the theoretical underpinnings of invisibility, by Ulf Leonhardt of the University of St. Andrews in Scotland; the abstract follows.

Optical Conformal Mapping

Ulf Leonhardt

An invisibility device should guide light around an object as if nothing were there, regardless of where the light comes from. Ideal invisibility devices are impossible due to the wave nature of light. This paper develops a general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics. The imperfections of invisibility can be made arbitrarily small to hide objects that are much larger than the wavelength. Using modern metamaterials, practical demonstrations of such devices may be possible. The method developed here can be also applied to escape detection by other electromagnetic waves or sound.

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Prediction: it won't be anywhere near as long as ten years from now.

Witness Professor Susumu Tachi of Tokyo University's invisibility cloak (below),

which he demonstrated back in 2003.