The world just took a step closer to people being able to wear cloaks of invisibility. And that’s the real world, not World of Warcraft.

Scientists at Berkeley’s University of California say they’ve finally been able to surround three-dimensional objects with artificial materials which redirect light around the objects. Previously that had only been possible with objects so ultra-thin they were as good as two-dimensional.

The research is partly funded by both the US Army and the National Science Foundation. That’s likely because such invisibility could have extremely useful military applications. It’s worth nothing that this technique is different to existing stealth planes which are visible to the human eye but more difficult to track with radar.

There are actually two different teams working on the project: they’ve used different materials to produce the same ends. One used layers of silver and non-conducting metal (with holes punched through it) to produce a structure similar to a fishnet. The other used extremely thin wires of silver grown inside an aluminium oxide.

Both substances are known as metamaterials because they have properties which don’t occur naturally. In this situation, the key property is refraction. That’s a measure of how light bends when it passes through a surface: normal materials have varying degrees of positive refraction which is why, for example, a stick standing in water appears to bend away from you.

These metamaterials have negative refraction, making it possible to completely surround an object such that light bends right around it, making it impossible to see,

Right now, the wavelengths in which it’s possible to reverse light’s natural behaviour are pretty limited, so there’s no immediate prospect of making people or even buildings invisible. But the short-term uses could include greatly-increased capability in microscopes, possibly to the point of being able to view a living virus.

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Entry was posted on Monday, August 11th, 2008 at 3:12 pm under Science and technology.

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