It sounds like something out of a comic book, or Lord of the Rings, I know. But there’s a chance that invisibility – real-life, honest-to-God invisibility – may actually be possible, some day.
The technology doesn’t come from some dubious unknown inventor, but from Professor Sir John Pendry, the legendary theoretical physicist, I write in this month’s BBC Focus magazine – “the world’s best science and technology monthly.” Pendry has developed the concept of metamaterials, which have properties determined by their structure rather than their composition. This can give them ‘impossible’ properties, such as a negative refractive index. Initially, there was some debate about whether this could ever be achieved. But the proof came last year with the demonstration of a superlens capable of beating any lens made of normal material. 
By utilizing metamaterials, it should be possible, in theory, to create what Pendry calls an invisibility cloak — although invisibility shell might be more accurate as it will need to be rigid. Such a cloak would divert any incident light around its surface and release it on the same path on the other side: to any observer the wearer is invisible.
Interestingly, Pendry’s work on metamaterials started when he was working for Marconi. He was looking at the application of carbon fiber for a stealth coating when he realized that its interaction with radar was determined by the length of the fibers – it was effectively acting as an array of tiny aerials – and that the same effect could have many other applications.
Invisibility in the optical spectrum will be challenging because metamaterials will need to be constructed on a scale corresponding to the wavelengths of visible light, which is just a few hundred nanometres. That technology will not be around for at least five years.
But radar invisibility is much easier because radar wavelengths are in the centimeter range. Pendry’s colleague, Dr. David R. Smith at Duke University, is already working on a microwave metamaterial. Results are expected within eighteen months.
Unlike existing stealth techniques, a metamaterial should in principle be able to make an aircraft (or missile) literally invisible to any radar from any aspect.
There are likely to be other metamaterials along later. As Pendry explained, they can have all sorts of mechanical or acoustic properties as well as affecting light or other radiation. But for the mean time, we are likely to have out hands full just thinking of applications for invisibility.
The biggest question is likely to be the width of spectrum that any given material can handle. According to Pendry, a sufficiently deep metamaterial should be able to cope with a very wide spectrum. This might include all visible wavelengths plus a chunk of infra-red and UV. However, it’s clear that even very limited invisibility could be a major military asset.
“he realized that its interaction with radar was determined by the length of the fibers – it was effectively acting as an array of tiny aerials”
I’m not certain, but do you mean the spacing of the fibers, not their lengths?
One issue worth mentioning – if you bend all EM radiation over a certain spectrum around yourself you can’t see in that spectrum, either, because no radiation reaches you to be detected. So if you’re invisible, you’re also blind. Not saying it’s no good, but it’s not quite a sci-fi cloaking shield.
William Gibson does it again. This sounds like the Polycarbon suits worn by the Panther Moderns in Neuromancer – written in 1984.
Eric hit on one of the two complications associated with EM refraction: 1) refracting light around you effectively makes you blind and 2) the cloaking lense would have to take the shape of a dome or large lense.
Provided that a cloaking lens only refracted visible light, one could get around the blindness problem with an infrared scope. Even if the lens wasn’t useful for maneuvering troops, you could probably use it to hide CPs, bases, or vehicle laagers from high altitude photography.
I thought superlens article made a more compelling case for the development of hyper-sensitive detection equipment. A negative refractive index on a spy satellite could break down resolution barriers for all types of snooping cameras.
I suspect that the ‘invisible infantryman’ is a way of putting the idea across and has all sorts of practical issues (how much of your job can you do inside a fiant egg?).
For vehicles it becomes a lot more practical; for sensors all you need are some pinhole-sized apertures which are going to be minimally visible.
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“you mean the spacing of the fibers, not their lengths”
No, I believe he said lengths.
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Another semi-obvious application: coat a missile in metamaterial invisible to the range of wavelengths used by the opponent’s anti-missile laser, rendering it useless.
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The superlens could also have applications as suggested in terms of sensing, and also for focusing lasers for various applications.
Bad-ASS!!!
A few quick comments:
1) No one said it had to be egg-shaped, just rigid. So you could still have an invisible infantryman.
2) It’s possible to use this for partial concealment, so you could still see. Leave the eyes uncovered. While you wouldn’t be 100% invisible, you’ve still got a whole lot more concealment than you would have otherwise. It’s much harder to spot a pair of eyes than a whole body.
3) If radar-avoiding materials are capable of being tested within 18 months, it’s just in time for the new B-3 bomber.
About using the material as an anti-laser device – I suspect this won’t work any better than mirroring the thing.
Both run into the issue that a high energy pulse may not be completly absorbed, but if enough is the mirror/invisible material loses its special properties and the follow-up pulses burn through.
This brings up another issue – how durable is this stuff? If the radar-invisible material is carbon fiber, that’s pretty nice. But could you coat a missile or aircraft with all the stuff, or would the stuff that handles, say, visible light burn off a missile nose cone?
ok…that’s just creepy…the idea of a pair of eyes being there without a body accompanying it just freaks me out for some reason…lol.
Far more practical methods will probably be fabrics embedded with nano circuits activating color changing dyes, or nano OLED’s where small cameras view the environment cause a view of the surroundings to be displayed.
Even today, you could put something like a color e-ink material on a vehicle or aircraft and use a simple magnetic wand type mechanism (somewhat like a printer’s print head) to change the camo on it immediately. Such an approach might be good for armored vehicles and the underside of UAV’s.
Neither of these two cammo’s won’t be perfect, but are both near term and could provide considerably improved capabilities over today’s “static” systems.
David…a broadband microwave version has already been fielded in ’special applications’.
This stuff has been called by various names over the past 15 years, it’s a bit confusing to most as to where and how to find info on it.
‘Metamaterial’ is the proper name but for a long while we’ve been calling them ‘left-handed magnetic materials’. If you poke around for it under that nomenclature you’ll find a bunch of info on the zero-to-negative permeability metamaterials. The entire metamaterial effect is sort of groupable under plasmonic engineering – the intentional modification of the behaviors of electron clouds around atoms.
A left-handed magnetic coating can do quite a bit of the things you discussed in your article, although now they can also achieve negative or radically enhanced permittivities, which is a totally different kettle of fish.
Left-handed coatings can do a lot of freaky things, amongst which are inverse or static Dopplers. That is, the return from the craft exhibits no Doppler effect or even more unintuitively return a LOWER frequency as they increase in velocity relative to the radar.
There are many an application for these. Some of them you haven’t mentioned yet.
Oh, btw, Phantomworks was the first to field.
So does this mean that an “invisible” infantryman would have to have a rigid suit, like a knight in invisible armor?