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Ghostly “timescanned” images of New York’s streets
Okay, the war over “invisibility cloaks” has officially begun. A team of Chinese scientists have just announced that they’ve figured out how to defeat invisibility technology — and render “invisible” objects visible.
You may remember the famous experiment in 2006 in which Duke University scientists created an “invisibility cloak” — a wave-morphing shield that allowed them to render an object mostly invisible to microwave beams. (Check out a video of their original demonstration here; it’s pretty cool.) This generated endless news stories that breathlessly invoked Harry Potter; more hilariously yet, it set off a mini-boom in researchers frantically working on their own invisibility cloaks.
Now the counterattack has begun! Next week, a team of Chinese researchers will publish a paper called “The Anti-Cloak” in the journal Optics Express (PDF copy here). In essence, they did some calculations and figured out that if you coated an object with the right anisotrophic materials — stuff that reflects light in different ways depending on the direction the light comes at it, kind of like velvet — then the invisibility cloak wouldn’t work. (To be precise, you’d need “anisotropic negative refractive index material that is impedance matched to the positive refractive index of the invisibility cloak.”) Presto: The invisible becomes visible!
As they put it in their press release:
While an invisibility cloak would bend light around an object, any region that came into contact with the anti-cloak would guide some light back so that it became visible. This would allow an invisible observer to see the outside by pressing a layer of anti-cloak material in contact with an invisibility cloak.
I have to say, I laughed out loud with delight when I heard about this paper. This is the sort of perfectly demented, cackling scientific duel you normally only encounter in golden-age comic books. Freeze ray vs. anti-freeze ray! Antigravity vs. supergravity! At this rate we’ll wake up to find CNN footage of rival teams of scientists in 80-storey-tall mechas, duking it out with tachyon-particle cannons over the desolate ruins of Tokyo, and arguing about who’s got more citations.
I'm Clive Thompson, the author of Smarter Than You Think: How Technology is Changing Our Minds for the Better (Penguin Press). You can order the book now at Amazon, Barnes and Noble, Powells, Indiebound, or through your local bookstore! I'm also a contributing writer for the New York Times Magazine and a columnist for Wired magazine. Email is here or ping me via the antiquated form of AOL IM (pomeranian99).
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