Cylon raider? A new Tron vehicle that we’ll see in an upcoming director’s cut? Definitive proof that we are not alone? Actually, it’s none of those things, but the dead silence it produces is amazing anyway.
The object is representative of a metamaterial, the strange, almost magical substance that has the uncanny ability to bend electromagnetic waves in near-incomprehensible ways. It’s the stuff that invisibility cloaks will be made of, some day, although what we see above is grounded in acoustics, not sight.
Such a material (an “acoustic cloak”) would be right at home in the water, covering a submarine, which would become effectively invisible to sonar waves should the vessel be draped in the sound cloak Duke University researchers have perfected (on a small scale) in their labs:
To manipulate sound waves in air, (electric engineer Steven) Cummer’s team designed and built a cloak that sits atop an object like a piece of draped carpet. By layering simple metamaterial building blocks – ordinary strips of perforated plastic – the researchers hid a triangular wooden block a couple of inches high and more than a foot long at its base.
Sound waves over a range of high but audible frequencies slowed and changed direction cleanly after striking the holey plastic. Most reemerged appearing to have traveled all the way down to the flat surface beneath the block.
Caveat: The design only works on a 2D plane, but Cummer’s optimistic that a working 3D model is only a matter of time. Isn’t that how these types of stories always go down? [Science News via Boing Boing]