Scientists Make Item Invisible to Microwaves

Vicissidude writes "A team of American and British researchers has made a cloak of invisibility. In their experiment the scientists used microwaves to try and detect a copper cylinder. Like light and radar waves, microwaves bounce off objects making them visible and creating a shadow, though it has to be detected with instruments. If you can hide something from microwaves, you can hide it from radar and visible light. In effect the device, made of metamaterials — engineered mixtures of metal and circuit board materials, which could include ceramic, Teflon or fiber composite materials — channels the microwaves around the object being hidden. When water flows around a rock, co-author David R. Smith explained, the water recombines after it passes the rock and people looking at the water downstream would never know it had passed a rock. The first working cloak was in only two dimensions and did cast a small shadow, Smith acknowledged. The next step is to go for three dimensions and to eliminate any shadow."

I know a recently-shampooed poodle

[by Anonymous Coward]

...that would love to be invisible to microwaves.

hmm,

[joe 155 (937621)]

I'm unsure about the water claim, although it is true that you can't tell the difference that doesn't mean that it's not different, the water has been moved all over the shop, but it looks like it hasn't been affected.

Other than that if they make something invisable from visable light then it wouldn't be able to see anything, so a person would be blind or a bot would be virtually impossible to navigate, because you couldn't see it or track it...

Still, very interesting idea.

Moo

[Chacham (981)]

FTA:

A team of American and British researchers has made a Cloak of Invisibility. Well, OK, it's not perfect. Yet. But it's a start, and it did a pretty good job of hiding a copper cylinder.

So, we'll just just change his name to Harry Copper.

This title is absurd. Invisibilty?

The research is very kewl though, and i hope it progresses. But why not lay off the stupid titles, and produce results based on kewlness or usefulness, instead of what can be termed with a popular buzzword. Information Technology is bad enough from its buzzword infusion. Must we destroy legitamte research/discoveries as well?

Re:Moo

[twostar (675002)]

someone using the term "kewl" is complaining about buzzwords?

*Ring* Hello?
Hi, this is the Pot calling. Is the Kettle in?

Yay for TV Dinners

[Odin_Tiger (585113)]

This will allow for more variety in TV Dinner desserts, because they can just shield it so only the stuff that needs to get nuked will get nuked. w00t!

You know you are a fat geek when...

[B5_geek (638928)]

You know you are a fat geek when...
    the first thing that came to your mind when reading this summary was:

"Oh cool, no more burnt and undercooked mini-pizzas!"

I really should go outside more often.

Bah!

[Clazzy (958719)]

They could've posted a pict...

Oh, wait. Never mind!

Re:Picture here!

[ichigo 2.0 (900288)]

The site seems to be cloaked from the HTTP spectrum.

meta-materials

[lgw (121541)]

If you can hide something from microwaves, you can hide it from radar and visible light.

I don't think this follows, at least when we're talking about metamaterials [wikipedia.org]. So far no one has invented metamaterials for optical wavelengths, as metamaterials rely on complex structure that's somewhat wavelength specific. It's easier to play "fool the photon" with microwaves (because of the longer wavelength) or X-rays (because of the higher energy) than it is with visible light. (Xiang Zhang's experiments in extending near-field effects of visible light are a very different mechanism, and are lumpedin with metamaterials simply for lack of a better term.)

Was Anyone Else Thinking...

[Banner (17158)]

Romulan Bird of Prey? (Or equally, the small Klingon ships also armed with the cloaking device?).

Sorry, grew up on waaaay too much startrek :-)

Re:Was Anyone Else Thinking...

[angelasmark (856143)]

You obviously didn't grow up on too much star trek. Any true trekkie would know that its a Romulan Warbird and a Klingon Bird of Prey...

Re:Was Anyone Else Thinking...

[OfficialReverendStev (988479)]

You obviously didn't either. Somebody bring me the learnin' stick. You're both technically right. The Romulan Bird-of-Prey (from TOS, small white-ish ship with the bird painted on the bottom) did have a cloaking device, as did the Klingon (and Romulan) D-7 Battlecruiser. In the TNG era the Romulan Warbird (big and green) and the contemporary Klingon ships (Bird-of-Prey and Vor'Cha). Now, go play. I have a phaser to polish.

Backpack of Invisibility?

[Doc Ruby (173196)]

I'll go out on a limb on a series of "ifs" (and maybe a bag of physics naivetes), but let's say we perfect this manner of imperceptibly "derefracting" light. And let's say we also complete the ambitious work identifying and manipulating gravitons, still hypothetical. Could we "cloak" spaces and matter from any interaction with our universe, not just electromagnetic? Maybe the Stong and Weak Forces would remain for interaction, but practically, outside the tiny diameter of a nucleus, could anyone notice?

Could a "gravity cloak" create subspaces operating as independent universes? Could we contain matter too highly interactive for current use safely? Like a tiny black hole conveniently near a device it's powering, or a pair coupled into a wormhole for "faster than light" travel through custom-folded space? Vast amounts of stuff crammed into pocketsized spaces.

Maybe the old playground philosphers choosing between "teleportation or invisibility superpowers" will finally have a lab to figure out which is really better.

Stealth Ship

[rlp (11898)]

Sounds like a better version of stealth. I recall reading that an early attempt at a stealth ship did TOO good of a job of dispersing microwaves (compared to background reflection of empty ocean) and showed up as a moving 'hole' on surface radar screens. Assuming that this technology could be applied to bending light around an object, it would need to do so without creating obvious distortions.

They're making this WAAAAAAAAY too complicated.

[frogstar_robot (926792)]

Just paint the copper cylinder pink and turn on a cheap and simple Somebody Else's Problem Field.......

Quite some time.

[AltGrendel (175092)]

This was already addressed to some degree in the SciFi book "The Last Mortal Man". The reasoning for making them illegal was that the criminal element used them to evade law enforcement. I'm sure the DHS would have alot to say about this.

Re:Quite some time.

[Rei (128717)]

And the biggest beneficiary of infantry invisibility suits? Guerilla fighters.

Sure, they won't get them right away. But you better believe that they'll try to capture them, and any state sponsors that they have immediately try and produce or otherwise acquire them. Big armies, trying to cloak things like tanks driving down the stret, will have a much harder job at it than fighters simply hiding themselves and their RPG, already in the shadows or buildings. Not to mention things like pressure or vibration-triggered mines/IEDs won't be affected, which also benefits guerilla fighters on their own turf.

Re:Quite some time.

[c6gunner (950153)]

It just means that organized combat would evolve to take advantage of them also. Ever since WW2 we've been moving to smaller and smaller units working as independent organizations, then re-combining to carry out more complex tasks. With the introduction of cloaking technology you'd see the extreme end of that. 4-8 man squads operating independently on foot and light vehicles, hunting down guerrillas the same way the currently hunt us. Biggest obstacle to us doing that NOW is that we're so easy to identify. If we could have small units operating all over a city, totally invisible to anyone...well, good luck trying to plant IED's, or even gathering at your buddy Ahmed's house to discuss tomorrow's plan of attack.

Re:Quite some time.

[Rei (128717)]

That's silly. The teller can hear you.

Even if there was no "on-off" button on this, it would be trivially easy to "make" one. Paint water colors on all or part of the object that you can wash off. Tape on visible objects. Put a cover over it. Etc. This assumes that the cloak *itself* isn't flexible, allowing you to take that on or off.

Also, I doubt it'll be perfect invisibility. Even if, to the naked eye it appears perfect, I doubt it would to custom goggles analyzing the scene. Surely there are some wavelengths that it won't work on (from the sound of it, you need to customize a layer of this for a *specific* wavelength). Or the polarity could be thrown off. Or all sorts of other things.

Re:Quite some time.

[XenoRyet (824514)]

The real issue, and the major downside to a cloak of this nature, is how do you see where you're going while you are wearing it?

If it's diverting all the light around you, there's no light to get in and hit your eye so you can see.

The solution would be much more complex than the basic cloak. You'd have to let some light in, but make sure it didn't get back out again. I can see that being problimatic.

Re:Quite some time.

[borawjm (747876)]

The real issue, and the major downside to a cloak of this nature, is how do you see where you're going while you are wearing it?

Use your feelings, you must

Re:Why should Harry Potter have all the fun?

[thermopile (571680)]

I was on a selection committee for DARPA to look into this stuff a few years ago.

Negative Index of refraction Materials (NIMs), metamaterials, or whatever you want to call them, are relatively easy to make in the microwave region, since the wavelengths are on the order of centimeters. Thus, using a special arrangement of rings, loops, and wires, you can craft a lattice-like material that exhibits negative refraction. Technically, it has a negative magnetic permeability (mu) and negative permittivity (epsilon).

This has all kinds of weird implications. The group velocity is still in the forward direction, but the phase velocity goes in reverse. Evanescent waves propogate, not die off. Perfect lenses can be made. Measurements LESS than the wavelength of light can be taken. There was a list of implications in the August issue of Scientific American, I believe.

Anyhow, this works great at the ~cm scale. Visible light is hard as hell: the scale there is on the order of nanometers. And the copper or silver or tungsten wires used to make the metamaterials have MISERABLE magnetic losses at these small scales, so mu is no longer negative. The energy no longer propagates in the medium. As of three years ago, there were no promising candidates for solving this problem. There was an outside hack at using carbon nanotubes -- which may or may not maintain their permeability down to small scales -- but it was a long shot at best. Arranging the little guys would have been devilishly difficult.

Glad to see that Pendry, who's been in this field almost as long as Veselago, is still making good strides. Even if they can't get to the visible wavelength, NIM's have spectacular applications for microwave antennae.

Re:bad analogy

[zippthorne (748122)]

fluids follow the path of least resistance. Light follows the path of least time.

Fermat's principle

[by Anonymous Coward]

To expand: light following the path of least time is known as Fermat's principle [wikipedia.org]. Fermat's principle can in turn be derived from Feynman's path integral formulation of quantum mechanics [wikipedia.org]; it is related to [wikipedia.org] the principle of least action [wikipedia.org]. Feynman's book QED: The Strange Theory of Light and Matter has a lay derivation of Fermat's principle from path integrals (due to constructive superposition of quantum phase differences).

Re:Actual invisibility is useless

[DrKyle (818035)]

There's this thing called a pinhole camera, it's a relatively new advance. By allowing this pinhole of light in with the proper equipment just enough light could be absorbed to allow the user to navigate. Of course there would be a visible pinhole floating in space, but could you reliably pick it out at a distance of more than a few feet?