Ten sci-fi devices that could soon be in your hands

In New Scientist:

2 Disappearing act

Few dreams have flipped from science fiction to fact as quickly as “invisibility cloaks”. The first, which worked only for microwaves, was unveiled in 2006. Since then the field has been inundated with attempts to make cloaks to rival Harry Potter's.

Cloaking makes an object disappear by steering electromagnetic waves around it – as if the waves had simply passed through. So far, the only way to do this is with “metamaterials”, which are made of electronic components designed to interact with light and direct it in a controllable fashion. The goal is to create a cloak that works for a broad spectrum of visible frequencies. Making these components isn't easy. They have to be tiny – smaller than the wavelength of light they are designed to interact with.

Last year, a group at the University of California, Berkeley, constructed a material that was able to bend – rather than reflect – visible light backwards for the first time. Ulf Leonhardt at the University of St Andrews, UK, has shown how metamaterials could work over a range of frequencies.

Even more mind-boggling, a team from The Hong Kong University of Science and Technology in China has worked out how to cloak objects at a distance. They suggest using “complementary materials” which have optical properties that cancel each other out. A wave polarised on a single plane passing through one material will become distorted, but this distortion is cancelled out as the wave passes through the complementary material, making it look as if neither material is there.