Invisibility Cloak... Need We Say More?
Real-world invisibility cloaks are not only theoretically possible -- they may be coming faster than anyone might have guessed, a few years back.
Harry_head The cloaks would rely on so-called "metamaterials": composites structured to let electromagnetic waves flow them, rather than reflect those waves back. (That's a called "negative refractive index" in science-speak.) In theory, it should work with any wavelength -- ultraviolet, microwave, visible, you name it. But, in practice, "invisibility in the optical spectrum will be challenging because metamaterials will need to be constructed on a scale corresponding to the wavelengths of visible light, which is just a few hundred nanometers," DANGER ROOM's David Hambling noted. "That technology will not be around for at least five years."
I don't know how this would allow the viewer to see whatever is behind the invisibility device, though: if you were wearing an inviso-suit in the middle of a field, would we see the trees twenty meters behind you, or would you look like a greenish-brownish blur? There are military applications for this, sure, but I was thinking more of PUNK'D.