Washington: It will be good news for robbers. Scientists have described a new type of invisibility cloak that does not just hide objects – but events.
Using the ultimate bank heist as an example, Martin McCall and Paul Kinsler of Imperial College London, explained how a thief could, in principle, use an “event cloak” to steal money from a safe, without even the CCTV surveillance cameras being aware.
The burglar would somehow need to split all the light approaching the safe into two parts: “before” and “after”, with the “before” part sped up and the “after” part slowed down.
This would create a brief period of darkness during which the burglar could enter the scene and steal the money, being careful to close the safe door before they leave.
With the safe-cracker gone, the process of speeding up and slowing down the light would then be reversed, leading to an apparently untouched scene once again.
As McCall and Kinsler explained, a more likely application of a full-size event cloak would be to control the flow of signals in an optical routing system, where one may need to process simultaneous uninterrupted signals at the same time.
The consensus seems to be that a set of parallel, artificially structured “metamaterial” layers would be needed, each containing an array of tiny metallic elements that can be controlled to dynamically adjust the speed of light passing through.
Although no one has yet tried to build a space–time cloak in the lab, McCall and Kinsler argue that “there is no obvious reason why such a cloak could not be achieved quite soon, perhaps even within a few years”.
The study was published in this month’s special issue of Physics World.