Controlling and bending light around an object so it appears
invisible to the naked eye is the theory behind fictional invisibility cloaks.
It may seem easy in Hollywood movies, but is hard to create
in real life because no material in nature has the properties necessary to bend
light in such a way. Scientists have managed to create artificial
nanostructures that can do the job, called metamaterials. But the challenge has
been making enough of the material to turn science fiction into a practical
reality.