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Attention Muggles – Harry Potter’s Invisibility Cloak Is a Nanopillar Away


From the diplomatic halls of the Federation to the locker of the clumsy geek eager to sneak into the girl’s locker room, invisibility is a technology everyone’s longed for. The problems of true optical invisibility are immense, but scifi has thrown every possible solution possible at it: Sue Storm of the Harry Potter gets his from a magic, hand-me-down cloak; Dr. Griffin, The Invisible Man himself, was granted his unique transparency by a chemical formula that changed his refractive index, while Star Trek only ever answered the problem through Romulan technobabble.

But after 80 years of invisibility in science fiction cinema, we’re finally close to the possibility of a real-life cloaking device, if two separate but concurrent discoveries by physicists are anything to go by.

The two teams, lead by Michal Lipson at Cornell University and Xiang Zhang of UC Berkley, have both built optical cloaks that allow for visible light to “flow” around a hidden object like water. The cloaks are reflective, but comprised of surface patterns of tiny silicon nanopillars that sheath not only the object, but its bulge as well. Imagine a person hiding under a blanket: The man might be “invisible” in that he can’t be seen, but the three-dimensional space he occupies is wildly conspicuous. This new type of cloaking device would actually obscure even the bulge of the hidden man. If you listen closely, you can almost hear Harry Potter giggle with glee.

This kind of invisibility differs from stage magic’s traditional methods — say, an assistant who has “disappeared” from a magic box — which requires a number of mirrors to be very specifically aligned, with the effect only working from the audience’s perspective. This new technique works from all angles, thanks to the intricacies of its advanced nanopillar surface texture. It’s a mirror that doesn’t simply reflect the visible spectrum, but wraps it around an object, totally hiding it from view. An observer from any angle would only see the view behind the “invisible” object.

While a prototype of this technology was demonstrated by a group at Duke University in 2006, it only worked in two-dimensions. This new cloak is the first to work in the real-world… albeit, only at a scope of about the size of a pin head — so you better not ready your Klingon Bird of Prey for battle quite yet. Nevertheless, it has possibilities. Tomas Tyc, a theoretical physicist at Masaryk Univerzity in the Czech Republic, thinks this is the first step towards a true invisibility cloak.

“There is no doubt that the experiments are important and present very good achievements,” says Tyc. “But we are still are far from real full cloaking where a three-dimensional object looks like a zero-dimensional point, so it is invisible from any direction of view.”

So we’re not quite there yet. But if this technology can ever be blown up to the macro-level, and if the cloak can ever be made to hide itself as well as its wearer, we could all have a Harry Potter-style invisibility cloak folded and tucked up at the bottom of our clothes trunk soon enough. The girl’s locker room will never be the same.

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