Thursday, May 25, 2006
D.A.R.P.A.'s Cloak of Invisibility? 
by Lenka Reznicek [permalink] 
A U.S.-U.K. research team funded by DARPA has announced a milestone in developing a "Cloak of Invisibility" that guides electromagnetic radiation (like light) around an object instead of reflecting it.
[AP] ...Researchers in England and the United States think they know how to do that. They are laying out the blueprint and calling for help in developing the exotic materials needed to build a cloak.

The keys are special manmade materials, unlike any in nature or the Hogwarts School of Witchcraft and Wizardry. These materials are intended to steer light and other forms of electromagnetic radiation around an object, rendering it as invisible as something tucked into a hole in space.
A cloak made of those materials, with a structure designed down to the submicroscopic scale, would neither reflect light nor cast a shadow. Instead, like a river streaming around a smooth boulder, light and all other forms of electromagnetic radiation would strike the cloak and simply flow around it, continuing on as if it never bumped up against an obstacle. That would give an onlooker the apparent ability to peer right through the cloak, with everything tucked inside concealed from view.

...The Pentagon's Defense Advanced Research Projects Agency supported the research, given the obvious military applications of such stealthy technology. [read full article]
Note that this technology is different from the "transparent cloak" developed in 2004 that uses a video camera and special display-screen fabric to capture and replay images in real time to give the illusion of "invisibility." What's interesting is that the proposed "cloak"'s characteristic of guiding electromagnetic radiation around the object would make the cloak-ee "invisible" to many forms of detection besides visible light. I'm curious whether any detectable infrared would "leak" out of the cloak?

UPDATE: More links to the relevant scientific papers available here in this BoingBoing post.