If you could pull off the ultimate bank heist without getting caught, would you try it? The perfect crime is possible – in principle – according to scientists at Imperial College London, who have described a new type of invisibility cloak that hides not just objects, but events as well. The researchers explained their theory by describing how a thief could use an “event cloak” to steal money from a bank safe without surveillance cameras catching it. To do so, the burglar would have to somehow 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 in which the burglar could enter the safe, steal the money, retreat and leave the safe door closed before exiting with the loot. Once the thief was safely outside, the process of speeding up and slowing down the light would be reversed, so the scene would appear to have been untouched. To bring this new cloak to fruition, suitable materials would have to be developed to manipulate the light – to speed it up or slow it down – the researchers said. They added that a set of parallel, artificially structured metamaterial layers would be required, each containing an array of tiny metallic elements that could be controlled to dynamically adjust the speed of light passing through it. Although a high-performance, macroscopic-size, fully functional space-time cloak has not yet been developed, one could be within the next few years, the scientists concluded. They also noted that a more likely application for the new 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.