Hiding objects inside a cloak that channels light around them to make it look as if they aren't there may soon be possible thanks to a breakthrough idea by materials scientists. It raises the prospect of invisibility shields that could hide objects sitting right under your nose.
© New Scientist
Objects are visible simply because light scatters off their surfaces and into your eyes. So in theory, a cloaking device could work by steering light around an object so that you see only the light from behind it, and not the object itself. Now John Pendry, a theoretical physicist at Imperial College London, and his colleagues have worked out how this could be done with a spherical cloak that channels light around an object hidden at its centre (see Diagram).
The stuff that makes this plausible is a new generation of "metamaterials", which can be tailored to have exotic electrical and magnetic properties not found in nature. The metamaterials developed so far consist of complex arrays of metal washer-like shapes and wires. The metal shapes are smaller than the wavelength of light and so interact with it, explains Pendry. "On these scales, it is not the chemical properties of the metal that determine how it interacts with light, it's the metal's structure."
The new idea is to build a sphere of metamaterial whose components are arranged in such a way that they bend radiation around the central cavity before sending it on its way, like a ring road diverting traffic around a town.
