Wednesday, March 02, 2005

Your Invisibility Cloak Is Ready

I know it's here somewhere. Just give me a minute to find it. Dang! Now where did that thing go?

Maybe someday, according to Nature (hat tip: AmyG): "Engineers devise invisibility shield - Philip Ball
Electron effects could stop objects from scattering light.
The idea of a cloak of invisibility that hides objects from view has long been confined to the more improbable reaches of science fiction. But electronic engineers have now come up with a way to make one.

Andrea Alù and Nader Engheta of the University of Pennsylvania in Philadelphia say that a 'plasmonic cover' could render objects 'nearly invisible to an observer'. Their idea remains just a proposal at this stage, but it doesn't obviously violate any laws of physics.

'The concept is an interesting one, with several important potential applications,' says John Pendry, a physicist at Imperial College in London, UK. 'It could find uses in stealth technology and camouflage.'

Cloak of many colours
Types of invisibility shielding have been developed before, but these mostly use the chameleon principle: a screen is coloured to match its background, so that the screened object is camouflaged.

For example, inventor Ray Alden in North Carolina has proposed a system of light detectors and emitters that project a replica of the scene appearing behind an object from its front surface. Researchers at the University of Tokyo are working on a camouflage fabric that uses a similar principle, in which the background scene is projected on to light-reflecting beads in the material.

But the invisibility shield proposed by Alù and Engheta in a preprint on arXiv1 is more ambitious than this. It is a self-contained structure that would reduce visibility from all viewing angles. In that sense it would be more like the shielding used by the Romulans in the Star Trek episode 'Balance of Terror' in 1966, which hid their spaceships at the push of a button."
There are a few "catches" apart from the hypothetical aspect. The effect is wavelength dependent, so the object would still be visible with other light wavelengths. Also the size of the object must be similar to the wavelength of the light, so better start working on your shrink ray if you want to escape detection with visible light. :-D

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