Cloaking Device?
Like time travel (at least the going back in time part) and teleportation (as it applies to anything other than photons), invisibility has been one of those standard plots devices of casual science fiction -- that is, TV and movies -- with very little theoretical grounding. But that may be changing:
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."
The idea is to manipulate plasmons, which are waves of electron desnity. A plasmodic shield should reduce the scattering of light normally associated with an object, thus making it very hard if not impossible to see. Of course, there are limitations:
Pendry warns, however, that the concept as it stands is "no magic cloak", because it would have to be delicately tuned to suit each different object it hides. Perhaps even more of a drawback, he points out, is the fact that a particular shield only works for one specific wavelength of light.
An object might be made invisible in red light, say, but not in multiwavelength daylight.
And crucially, the effect only works when the wavelength of the light being scattered is roughly the same size as the object. So shielding from visible light would be possible only for microscopic objects; larger ones could be hidden only to long-wavelength radiation such as microwaves. This means that the technology could not be used to hide people or vehicles from human vision.
But that need not undermine other potential uses, Engheta says. For example, the effect could be useful for making antiglare materials.
And of course the shielding would work fine for concealing large objects such as spaceships from sensors or telescopes that used long-wavelength radiation instead of visible light.
I wonder whether plasmodic shields might become available for cars? They would no doubt be illegal, in the vein of radar detectors. But lots more dangerous.
via Kurzweil AI