Material With Negative Refractive Index Created

holy_calamity writes "The race to build a material with a negative index of refraction for visible light has been won by researchers in Germany. The advance could lead to super-lenses able to see details finer then the wavelength of visible light, or the previously predicted invisibility cloak for visible light." From the article: "[The researcher] determined the refractive index of the material by measuring the 'phase velocity' of light as it passed through. His measurements show the structure has a negative refractive index of -0.6 for light with a wavelength of 780 nm [the far red end of the visible light spectrum]. This value drops to zero at 760 nm and 800 nm, and becomes positive at longer and shorter wavelengths."

Invisibility cloak?

[namityadav]

I can understand how this material can make an item stealthy from radars and all. This material can be used to bend / deflect the rays so that they never return to the radar. But the same concept does not an invisibility cloak make. If a cloak deflects light, then the human eye will see a missing spot (Because, unlike the radar, an eye would see everything else around the cloak).

So, for a cloak to be invisible, we need it to pass light from the other end of the cloak. For this, the cloak would need to know the geometrical shape that it has currently, absorb light coming from one end, and forward it to a light emitting object on the other end of the cloak. The problem then will be that the cloak would need to know where the "eye" is to be able to map back and front ends correctly.

Am I talking non-sense here?

What we need now: SEP fields

[gardyloo]

These metamaterials have a long and interesting history (many posts here on slashdot and elsewhere) -- long because they were predicted a while ago by Veselago, and interesting because of the recent interest due to Pendry's production of workable devices in electromagnetic fields. There are even meta-materials being produced for acoustics problems, too.
      However, what I'm really looking forward to is a Somebody Else's Problem device -- this will make all of the other foophraw unnecessary.

Re:Negative or less than one?

[FooAtWFU]

So light goes backwards in this doodad?

Nope. Neither does light does not move faster than the speed of light, just phase groups. These crests and troughs of the light are features of the wave, but not any sort of signal or material in and of themselves. It's just an abstraction. Think of it this way: if you had two people a light-year apart, and they both raised their hands into the air at the same time to do The Wave, would you say that they sent a signal faster than the speed of light? If you had a one-light-year-long string of lights, and you rigged them all so they turned on at the exact same moment (presumably using some sort of countdown), would you say they've sent a signal faster than the speed of light? (Have you, in fact, sent a signal with infinite speed?) No, you haven't. You've gotten an abstraction to move faster than the speed of light, but that's not really very interesting for physics.

Re:Negative OK, but why |-1| ?

[Born2bwire]

Another way to describe the refractive index is in terms of the square root of the relative permeabilities and permittivities. In a negative refractive index, epsilon and mu are both negative. However, the refractive index is the square root of the product of these two. So they probably just retain the sign on the refractive index to show this important characteristic.

Basically all it means is that light is going to bend opposite of what we would normally expect. Instead of bending towards the interface, light will bend away from the interface. There's no fancy u-turns or anything like that. The negative sign is purely a consequence of the convention by which we choose our cross products when it comes to the vector form of Maxwell's Equations. Normally we use a right-hand convention, but a metamaterial behaves using the left-hand convention. This negative sign is one way of achieving the same effects using the right-hand vector convention.

Re:Why do Germans seem ...

[Fordiman]

It'll never happen. Respectable intellectuals hate to hear things that aren't politically correct, and as such tend not to test them.

Re:Why do Germans seem ...

[instarx]

It'll never happen. Respectable intellectuals hate to hear things that aren't politically correct, and as such tend not to test them.
Three points...
1. Not only won't it happen, it CAN'T happen. IQ tests are culturally biased. Comparing different cultures by measuring IQs has to many uncontrolled variables to provide meaningful results.

2. IQ test don't measure anyting other than ability to take IQ tests.

3. Don't make the mistake of thinking that just because something is politically incorrect it isn't also morally or ethically incorrect, or just plain vile and wrong.