Spacetime cloak 'may hide history'
A concept straight out of science fiction could one day make it possible to "hide" history by editing out passages of time.
The "spacetime cloak" would speed up and slow down light to give the illusion that events have not happened.
A "cloaked" individual could, for instance, travel from one place to another while appearing to vanish and rematerialise instantaneously in a new location.
To an outside observer it would look as if the person had been "beamed" across space by a Star Trek-style matter transporter. Such a device would also make a mockery of CCTV, disproving the adage that the camera never lies.
A scientifically-savvy thief with access to the technology could open a safe, empty its contents, and make his escape right under the watchful eye a surveillance camera.
The video footage would show that the safe door was closed all the time. In effect, events in history could be "edited out" so that they never appear to have happened.
It sounds like the stuff of fantasy, but scientists at Imperial College London have proved it could work in theory by adapting standard fibreoptic technology.
The research is outlined in the Institute of Physics publication Journal of Optics.
Lead scientist Professor Martin McCall said: "We have shown that by manipulating the way the light illuminating an event reaches the viewer, it is possible to hide the passage of time. 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. So, theoretically, this person might be able to do something and you wouldn't notice."
Graduate student Alberto Favaro, who also worked on the project, used the analogy of a stream of cars travelling down a road to illustrate the theory: "You want to have a pedestrian crossing without interrupting the traffic, so you slow down the cars that haven't reached the crossing, while the cars that are at or beyond the crossing get sped up, which creates a gap in the middle for the pedestrian to cross. Meanwhile, an observer down the road would only see a steady stream of traffic."