Metamaterials and Cloaking?

[BISMARCK]

These scientists seem to have made it work with microwaves.

I remember reading about this months ago when they first were talking about it.

My question is, what exactly are "metamaterials", and is it possible for anything like that to be naturally occuring? If it is possible, it seems like it would be a dark matter candidate.

[01101001]

My question is, what exactly are "metamaterials", and is it possible for anything like that to be naturally occuring? If it is possible, it seems like it would be a dark matter candidate.

Wikipedia: Metamaterial

In electromagnetism (covering areas like optics and photonics), a 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. This term is particularly used when the resulting material has properties not found in naturally-formed substances. Metamaterials are promising for a diversity of optical/microwave applications, such as new types of beam steerers, modulators, band-pass filters, superlenses, microwave couplers, and antenna radomes.

[BISMARCK]

Thanks. I wonder what use something like that would have beyond espionage or military?

Would it work as a kind of radiation shield, if it could just redirect radiation around a sensitive object?

[01101001]

I wonder what use something like that would have beyond espionage or military?

Miss this part?

Metamaterials are promising for a diversity of optical/microwave applications, such as new types of beam steerers, modulators, band-pass filters, superlenses, microwave couplers, and antenna radomes.

They appear to be very useful in broad and diverse applications, some of which, as usual, have military use.

Would it work as a kind of radiation shield, if it could just redirect radiation around a sensitive object?

I have no idea.

[BISMARCK]

Hmm. Well, the stuff sounds very interesting. I imagine this stuff could make for some unique wardrobe choices.

[Romanus]

I read a fascinating article about this in a recent issue of "Discover", IIRC. The article however, pretty much dashes any hopes for this being a viable visible cloaking device, for two reasons:

1.) The metamaterials' components must be similar in size to the wavelength diverted. The current metamaterials have a structure similar in size to microwaves, which is why they work with those wavelengths. Visible light rays are much smaller, and making metamaterials that size is well beyond current capabilities.

2.) As everyone probably already knows, visible light is made up of photons of all different wavelengths; it would be very difficult to say, make a metamaterial that would divert blue and red light equally well.

Re using these for radiation blockage:
Not only would the problems with visual light be even worse at shorter wavelengths, but the higher energies of the photons might render the metamaterials useless. Also don't know how it would work with charged and uncharged particles, as opposed to photons.

[NEOWatcher]

Hmm. Well, the stuff sounds very interesting. I imagine this stuff could make for some unique wardrobe choices.

And if you want more, there are a whole lot of threads talking about Harry Potter. (er, I mean invisibility cloaks)

Besides, I beat you to this article by about a half hour.

[Swift]

I read a fascinating article about this in a recent issue of "Discover", IIRC. The article however, pretty much dashes any hopes for this being a viable visible cloaking device, for two reasons:

1.) The metamaterials' components must be similar in size to the wavelength diverted. The current metamaterials have a structure similar in size to microwaves, which is why they work with those wavelengths. Visible light rays are much smaller, and making metamaterials that size is well beyond current capabilities.

2.) As everyone probably already knows, visible light is made up of photons of all different wavelengths; it would be very difficult to say, make a metamaterial that would divert blue and red light equally well.

Re using these for radiation blockage:
Not only would the problems with visual light be even worse at shorter wavelengths, but the higher energies of the photons might render the metamaterials useless. Also don't know how it would work with charged and uncharged particles, as opposed to photons.

I would not say that making metamaterials for visible light are "well beyond" current capabilities, though it may be semantics. I just attended a conference where there were a lot of papers on nanomaterials, and a lot of this stuff gets close to the feature sizes of visible light (for example, see this article). I suspect we will get there within a five year time frame or so.

The multiple wavelength problem may be more of a problem. You would have to make the stuff "sloppy" enough to handle a range of wavelengths.

But it is one thing doing this on an optical bench, I see it as orders of magnitude more difficult to do it for a tank, ship, person, or other macrosized thing.

[Fortis]

But it is one thing doing this on an optical bench, I see it as orders of magnitude more difficult to do it for a tank, ship, person, or other macrosized thing.

You just have to make the tank, ship, or person a lot smaller.

(The Russians, during the WW II did something a little like this with their tanks. IIRC, people were sized to fit the smaller tanks, rather than the tanks being designed to fit the usual range of people sizes.)

[Swift]

You just have to make the tank, ship, or person a lot smaller.

(The Russians, during the WW II did something a little like this with their tanks. IIRC, people were sized to fit the smaller tanks, rather than the tanks being designed to fit the usual range of people sizes.)

It is not particularly just size, though making enough material to put around a tank or ship is much more challenging than making enough for a bench test or even in some piece of microwave electronics. I was thinking of allignment issues.

[Fortis]

It is not particularly just size, though making enough material to put around a tank or ship is much more challenging than making enough for a bench test or even in some piece of microwave electronics. I was thinking of allignment issues.

That's true enough. The cylinder that they used in the experiment has a pretty straightforward geometry.