A cloaking device that really works–underwater

The last of the "Harry Potter" movies have come and gone--but the real-world search for an invisibility cloak lives. Researchers at the University of Texas at Dallas announced a ground-breaking cloaking device that can make things disappear. But there's one important hitch: The things in question have to be underwater.

According to the university's press release, this cool experiment "not only takes advantage of one of nature's most bizarre phenomena, but also boasts unique features; it has an 'on and off' switch and is best used underwater."

The best part: There's a video that shows the disappearing act happening in real time. In the demonstration, a researcher flicks a switch off camera, as an object in an underwater tank disappears and reappears, as if by magic.

And despite what jaded cynics may think, the researcher the isn't merely playing with a light switch. The new technology basically creates the conditions of a mirage underwater. And yes, the most common mirage really is imagining you see a pool of water where none exists--as anyone who has been parched and stranded in a desert will quickly confirm. Your mind plays a trick when the ground is hotter than the air, causing light rays to bend upward toward your eye, rather than bounce off the surface.

And here's the basic hardware behind the magic trick: As announced in the Nanotechnology journal, the design makes use of sheets of carbon nanotubes, which the press release explains, "have the density of air but the strength of steel." By conducting heat and transferring it to surrounding areas, the nanotubes are able to mimic a mirage. And presto: an underwater disappearing act.