Illusion Cloak Makes One Object Look Like Another 219
KentuckyFC writes "Metamaterials are synthetic substances that can steer light in any way imaginable. Their most famous incarnation is in invisibility cloaks which work by steering light around a region of space making any object inside that region invisible. But invisibility is just the start. A team of physicists in Hong Kong (the same guys who recently worked out how to cloak objects at a distance) have worked out how to create a cloak that makes one object look like another. Instead of steering light to make a region of space look empty, the illusion cloak manipulates light in a way that makes a region of space look as if it contains a specific object. So any object within that region of space, a mouse say, takes on the appearance of an elephant."
vaporware (Score:5, Informative)
The summary is bad enough, talking about invisibility cloaks as if they actually exist. This and the prior work by the team are nothing more than computer models. I'm not discounting the importance of the research, just the way in which it's framed. We don't have such cloaks yet and likely won't for a long time.
Re:ugg (Score:5, Informative)
That is because the people writing these articles have no idea what they are talking about. You can't make a mouse look like an elephant, unless you are dealing with waves much longer than an elephant, in which case that would be like making a baseball look like an elephant sized baseball, and you wouldn't be able to tell the difference between the balls or mice or elephants. Only the size of the shadow would have relevance.
Metamaterials can only cloak objects smaller than the wavelength of light you are dealing with. Once you start getting to half wavelength objects the cloaking turns to crap, and only works for a very very thin bandwidth. That wouldn't be very helpful for visible cloaking, because we see a wide range of wavelengths.
What metamaterials MAY be useful is radar cloaking. There are also applications useful for scientific instruments such as NSOM (Near-field Scanning Optical Microscope), in which you can cloak the probe so that you do not interfere with the light you are trying to measure.
Metamaterials are very interesting, but not for the layman. Move along.
Re:Doesnt sound like much? (Score:3, Informative)
If I remember correctly the invisibility cloak that exists (how strange to write that) is for the infrared spectrum. Visible light may be harder because the range is broader, or I could be way off base. It's a gamble!
Re:Doesnt sound like much? (Score:1, Informative)
It'd be great as a car alarm / defense system, one click of a button and the car changes from a Ferrari into a Robin Reliant (let's face it no-one's going to steal one of those)
Its actually Reliant Robin not Robin Reliant. http://en.wikipedia.org/wiki/Reliant_Robin [wikipedia.org]
Re:That's some sweet stuff (Score:4, Informative)
I don't have a wife, you insensitive clod!
Re:Doesnt sound like much? (Score:5, Informative)
There is good reason for this. If you hit a tank with something that just explodes and rains shrapnel, the hit will just bounce off, maybe destroying the optics but that is about it. You have to pierce the armor, which you do by hitting it with something very heavy and slender (such as a rod of depleted uranium) traveling at high speed that focuses a bunch of energy on one point. The heat from the collision and spalling from the armor itself then destroys whatever is behind the armor.
This does not work for a truck. If you hit it with a KE round, the round will just sail right through it. If there is nothing vital (the driver, engine, fuel lines, etc) where the KE round happens to pass, then the truck will just keep rolling. That is why you hit it with HE or MG fire. The many small bits of metal from an exploding HE round have a much higher chance of hitting something vital than the single big chunk from a KE round.
As far as a tank is concerned, you usually only get one or two shots at it before it or its buddies start returning fire. If you hit it with the wrong ammunition, he is going to kill you.
It should be noted that the inverse is also true. Making vehicles such as a truck look highly armored increases their survivability in certain situations because AT rounds are rarer than lighter ammunition and an infantry squad with a machine gun is not going attack a tank.