Many pixels have been devoted to exotic materials that could one day make "invisibility cloaks" a reality, thrilling science fiction fans who dream of, say, their own Tardis equipped with a "chameleon circuit." (Time travel, alas, is a thornier issue).

The latest research on this comes from the University of Michigan, where engineering professor L. Jay Guo has developed a "perfect black" type of cloth that can render a 3D object "invisible." Guo's work is described in a new paper in Applied Physics Letters.

It's basically a black carpet made out of carbon nanotubes (CNT), capable of absorbing 99.9 percent of the light that hits it. "It's not cloaking, as the object can still cast a shadow," Guo cautioned. "But if you put an object on a black background, then with this coating, it could really become invisible."

And there are implications for astronomy! Coating the inside of telescope tubes with this stuff could pretty much eliminate the problem of internal light scattering in those instruments.

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