The study, by researchers from Imperial College London, involves a new class of materials called metamaterials, which can be artificially engineered to distort light or sound waves. With conventional materials, light typically travels along a straight line, but with metamaterials, scientists can exploit a wealth of additional flexibility to create undetectable blind spots. By deflecting certain parts of the electromagnetic spectrum, an image can be altered or made to look like it has disappeared.
Previously, a team led by Professor Sir John Pendry at Imperial College London showed that metamaterials could be used to make an optical invisibility cloak. Now, a team led by Professor Martin McCall has mathematically extended the idea of a cloak that conceals objects to one that conceals events.
"Light normally slows down as it enters a material, but it is theoretically possible to manipulate the light rays so that some parts speed up and others slow down," says McCall, from the Department of Physics at Imperial College London. When light is 'opened up' in this way, rather than being curved in space, the leading half of the light speeds up and arrives before an event, whilst the trailing half is made to lag behind and arrives too late. The result is that for a brief period the event is not illuminated, and escapes detection. Once the concealed passage has been used, the cloak can then be 'closed' seamlessly.
Such a space-time cloak would open up a temporary corridor through which energy, information and matter could be manipulated or transported undetected. "If you had someone moving along the corridor, it would appear to a distant observer as if they had relocated instantaneously, creating the illusion of a Star-Trek transporter," says McCall. "So, theoretically, this person might be able to do something and you wouldn't notice!"
While using the spacetime cloak to make people move undetected is still science fiction, there a
|Contact: Katherine Barnes|
Imperial College London