Refractive materials gives us some limited control of light: we can fashion lenses, and construct waveguides, but complete control of light is beyond simple refracting materials. Ideally we might wish to channel and direct light as we please just as we might divert the flow of a fluid. Manipulation of Maxwell's equation shows that we can achieve just that provided we have access to some highly unusual material properties. Metamaterials open the door to this new design paradigm for optics and provide the properties required to give complete control of light. One potential application would be to steer light around a hidden region, returning it to its original path on the far side. Not only would observers be unaware of the contents of the hidden region, they would not even be aware that something was hidden. The object would have no shadow.
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