I, for one, welcome our Romulan overlords.

October 20, 2006 3:03 PM

Cloaking Device Revealed.in a joint effort, US and British scientists succesfully make a copper cylinder invisble to microwaves at Duke University thanks to metamaterials. (Previous invisibility posts on the Blue.)
posted by luminous phenomena (28 comments total)

But there is a catch. While any cloaked object would be invisible, it would also be blind within the cloaked frequency range, since any light directed toward it would be rerouted around it.

So I can sneak into the girls' locker room but I can't see anything? The horror!
posted by brain_drain at 3:13 PM on October 20, 2006

I don't see it.
posted by Mister_A at 3:16 PM on October 20, 2006

Interesting, but how long until we fill the gap and match Romulan technology?
posted by Lucy2Times at 3:19 PM on October 20, 2006

"Metamaterials are engineered materials whose properties are determined by their physical structure rather than their chemistry"

Can someone please define what a metamaterial is better than this vaguery? As far as my primitive brain can determine, I could pick up a rock and call it a metamaterial simply because I desire something with the function of a rock and it is indeed rock-shaped and rock-like.

I'm vaguely grasping the definition from the description of the rods and fiberboard in the cloaking device, but I'm not entirely sure why it requires the metamaterial distinction.
posted by loquacious at 3:21 PM on October 20, 2006

Old news. And that was an effin' BOAT.
posted by linux at 3:25 PM on October 20, 2006

Well according to Wiki: meta material (or metamaterial) is an object that gains its (electromagnetic) material properties from its structure rather than inheriting them directly from the materials it is composed of.

So it's electromagnetically, it's sum is greater than it's parts.

I guess.
posted by quin at 3:26 PM on October 20, 2006

Well I suspected it. Now it's confirmed.

We ARE the Romulans. Look at Bush's haircut!
posted by tkchrist at 3:29 PM on October 20, 2006

Can someone please define what a metamaterial is better than this vaguery? As far as my primitive brain can determine, I could pick up a rock and call it a metamaterial simply because I desire something with the function of a rock and it is indeed rock-shaped and rock-like.

IANAMaterialsScientist but I think it means materials like graphite and diamond which are chemically identical but due to their different physical structure have very different properties.
posted by public at 3:30 PM on October 20, 2006

"Commander, it is my judgement we run from a reflection."

"Perhaps so... but MY judgement prevails!"
posted by zoogleplex at 3:39 PM on October 20, 2006

Jesus, doesn't America have any respect for the Treaty of Algeron?
posted by Citizen Premier at 4:14 PM on October 20, 2006 [1 favorite]

materials like graphite and diamond

Aren't they just isomers?
posted by matthewr at 4:16 PM on October 20, 2006

I thought the Romulans' little brothers from Remus made the cloaking technology and the Romulans stole it?

Uh oh.
posted by Cyclopsis Raptor at 4:16 PM on October 20, 2006

Aren't they just isomers?

I don't think Graphite and Diamond are isomers, and isomers do have different chemical properties, especially in biological systems. You could certainly tell the difference between L-MDMA and D-MDMA, for example.

I think what they mean are materials who 'micro structure' determines how it behaves. A good example would be different types of steel, or tempered vs. untempered glass.

Think of the difference between a cotton t-shirt and a cotton-sweater. Both are made of "cotton fabric" but the fabric behaves much differently because of the way it's woven.
posted by delmoi at 4:23 PM on October 20, 2006

Ah, allotrope is the word I ought to have used instead of isomer.
posted by matthewr at 4:33 PM on October 20, 2006

A metamaterial takes the impact of structure one step further (and more artificial) than something liked tempered glass. The standard thing that is done for this sort of research basically amounts to putting a bunch of small loops and lines of metal in a lattice. A picture of metamaterials, and lots more info, can be found at this research group's website.
posted by Schismatic at 4:40 PM on October 20, 2006

Finally. I've been trying to microwave coffee in my copper cylinder for years now. It's good to know that I won't have to put out those pesky fires anymore.
posted by koeselitz at 4:46 PM on October 20, 2006

metafilter: constructed from advanced "metamaterials"
posted by dminor at 4:50 PM on October 20, 2006

So, like, ColdFusion?
posted by crawl at 4:52 PM on October 20, 2006

To explain a bit further, even something like various alloys of steel is getting its properties from its chemical nature. The response to electromagnetic radiation is based from how electrons can run around inside of a material. To a very strong degree, we define the way that electrons can move inside a material to be its chemical properties, even though the physical organization of the components will certainly affect this, it is different than the impact of structure in a metamaterial. There, we can limit the motion of electrons using a large number of small, disjoint pieces of metal. Small rods and loops with a slit in them can, together, bend light in ways that a real material never could. Imagine sending light through a flat piece of glass and having it focus to a point on the other side. With metamaterials, we can do things like that. Unfortunately, the engineering means that they only can currently work for a narrow band of frequencies. You can choose the band, but it's always narrow. And even more unfortunately, engineering can physical limitations seem to make it somewhere between very hard and impossible to do something similar with visible light this way.
posted by Schismatic at 4:57 PM on October 20, 2006

There have long been materials with properties artificially manipulated through micro-structure though.. In particular powder cores for transformers, but I'm also wondering about transistors (geometry is as important as material), fiber-optics (the geometry of total internal reflection), anti-reflection coatings..
posted by Chuckles at 5:36 PM on October 20, 2006

Accentuating capacitance by micro etching the conductive plates.
posted by Chuckles at 5:42 PM on October 20, 2006

I would say the key difference between situations where geometry is as important as material properties is that in those, you still have a material there (glass, GaAs, etc..) and the properties are of that material in a given geometry. Look at the picture of a metamaterial on the researcher's site I linked. It's just a bunch of oscillators connected by hand. The novel thing that's been done (and this is well before this invisiblity cloaking stuff) is to realize that if you lay down a particular group of oscillators in a particular way, they behave like a solid block of real material with strange properties (negative index of refraction, namely). There is no real macrostructure material, hence the name. Ultimately, of course, it's just nomenclature, and in this case I think the nomenclature gets in the way of understanding what is really going on.
posted by Schismatic at 10:14 PM on October 20, 2006

I don't see it.

Of course you don't, no one can see in microwaves. But if you could see it, it would be invisible! That's the miracle of this technology.

It puts to mind the old Zen koan, if a tree falls in the forest, but no one can see it fall in the microwave spectrum, did it actually fall?

And actually, since no one can see in microwaves, isn't everything invisible all the time anyway?

Now I can stage all of those Hubble Telescope practical jokes I've always wanted to (Stephen Hawking: OHMIGODOHMOGODOHMIGOD CLOSED COSMOS! awww... shucks.)
posted by XMLicious at 5:48 AM on October 21, 2006

OK, I am a Materials Scientist (and incidentally, an author on a metamaterials paper which was recently accepted into Nature), so I can try to further clarify the concept of a metamaterial, though I think Schismatic did a pretty nice job.

Conventionally, the properties of a thing are based strongly on the material itself, though geometry often plays an important role. For example, a piece of glass can reflect or transmit light based on the contrast between its index of refraction and the surrounding media (e.g. air/water/etc.)

In a metamaterial, one takes advantage of the strange ways in which electromagnetic waves (e.g. light, microwaves, etc.) interacts with structures with lengh scales similar to the wavelength of the light. Because these interactions are more a function of the artificially-created structures rather than the material itself, there are two main consequences: 1) the material itself only has a second-order effect on various proerties (e.g. a metal is a metal and the properties of the metamaterial have little/nothing to do with the metal properties), and 2) the properties obtained from the metamaterial can be vastly different from anything which would be seen in any conventional material.

The classic example is a material with a negative index of refraction. The wikipedia article on metamaterials^ gives a nice summary of the properties of materials with a negative index of refraction. It also gives the example of a person swimming in a pool of a liquid with a negative index of refraction; the swimmer would appear to be hovering above the pool to any observer.

All in all, the physics of metamaterials are fascinating and very non-intuitive. This is a dangerous combination, because the net result is invariably a confused public and massive hype (yay, invisibility cloaks for all! Except, not exactly because metamaterials are very wavelength-specfic and harder to do for visible light.) Of course, when the field fails to live up to the (artificially-induced) hype, public disillusion with science grows and no one wins. Incidentally, this is why I didn't make a FPP about metamaterials when I saw this article a few days ago; in one sense, popular articles about metamaterials are much ado about nothing.
posted by JMOZ at 10:53 AM on October 22, 2006

Is this correct?

Metamaterial: substance with an altered index of refraction due to features in it's physical structure.

in one sense, popular articles about metamaterials are much ado about nothing.

I think we all say "ugh" to popular science writing :P
posted by Chuckles at 11:51 AM on October 22, 2006

Chuckles: index of refraction is one of the myriad properties that can be modified through the use of resonant structures, but that's a pretty good first approximation.
posted by JMOZ at 12:34 PM on October 22, 2006

So on looking at that wikipedia article again, I guess it should really be something like this..

Metamaterial: A substance with altered permiability and/or permittivity due to features in it's physical structure.

A powder core has the permiability, μ, of the original material, but an altered permittivity, ε (I guess). That would make it a metamaterial..

But then you use the word resonant..
posted by Chuckles at 1:17 PM on October 22, 2006

Err..

I don't know why wikipedia is using the wrong epsilon, but I guess it would have been more clear if I had said:

A powder core has the permiability, μ, of the original material, but an altered complex permittivity, ϵ_c.

Specifically an altered conductivity, but whatever. That would still make it a metamaterial..
posted by Chuckles at 1:50 PM on October 22, 2006