Invisibility, intangibility and invulnerability

wise words

I’ve been following the development of meta-materials for a few years now, basically a meta-material is a compound material which has a negative refractive index. You can read a LOT more about them here Meta-material wiki. In summary that means, and I quote “Negative refractive index materials appear to permit the creation of super-lenses which can have a spatial resolution below that of the wavelength”. In summary-summary for those less blessed with a deep understanding of optical or wave physics it means that waves are refracted at an interface in the reverse sense to that normally expected. i.e. instead of bending one way they bend the other way. If you could build lenses out of a meta-material, convex lenses would scatter and concave lenses would focus.

here's a simulated super lens, notice the spooky refraction thing

As per usual I hear a loud “so what fatso?” and “are you doing any real work?” chorus but this seemingly pointless fact set does have some deeply fascinating implications and possibilities. In short meta-materials can permit a form of invisibility for certain classes of wave. This isn’t to say that the thing would be become see through, an object covered by a meta-material “cloak” would be invisible due to the way the waves would flow around it without reflecting back to any source or range of sources. The object would simply disappear from the point of view of any observer using that range of waves.

This is stupendous. The object becomes immune from any effect of that wave, it simply doesn’t impinge upon the object at all. Current stealth technologies absorb and reflect away radar, current low observability solutions rely on scattering reflected light and altering it’s frequency. In both scenarios the object is still effected by the wave, radio or light, and thus second-order impacts like thermal loading or deformation can be generated, which means the stealth model can fail or even the object can be damaged. A cloak made of meta-materials is immune from these effects. A cloak which worked in visible light would make an object vanish to the naked eye but would also protect it if you shone a gigawatt green laser at it. The laser light would simply pass around it. You couldn’t see it, there would be no shudder in the air to detect it and your laser is as pointless as your torch.

Impressive I hear you mutter, but still of limited import no? A fascinating little diversion into the world of stealth and security but not much impact on the wider world. But you’re missing a vital point. All energy is transmitted in waves. Imagine meta-material structures used as sea defences, as heat shielding, as foundations for buildings in earthquake zones. They wouldn’t buffer the thing they are protecting stuff from, from the point of view of a wave, infra-red heat or an earthquake pulse, the protected object simply isn’t there and the wave would pass by without effect. This really is awesome stuff and would smack of science fiction if it weren’t for the serious efforts being made to explore the concept, excerpts from the published paper at the Royal Society can be found here.

Now there will be obvious limitations to this, if the wave deforms the cloak enough to disrupt the meta material basis then it will fail, but there may be ways to design against that and then another huge threat to life, limb and property will have been significantly mitigated. 

Now if could find a meta material cloak to shield me from the green house like conditions here at the coal face today I’d be much happier.