In his final battle against evil on the big screen, Harry Potter could have used a newfound type of cloak: one that hides not objects in space, but events in time.
Like filmmakers cutting together a movie, physicists have found a way to temporarily tear a hole in a beam of light. Events that occur during a brief period of time remain unseen, as does the hole itself.
Moti Fridman and colleagues at Cornell University report the first experimental demonstration of such “temporal cloaking” online July 11 at arXiv.org.
While this trick won't be hiding bank robbers from security cameras anytime soon, it could find its way into optical and electronic devices.
Previous invisibility cloaks hid objects from view by bending light. Just as water flows around a rock in the middle of a river, light waves curve around a cloak and rejoin perfectly on the other side, leaving no trace of their detour.
A time cloak conceals an event by changing light's speed, not its direction. With the speed of light capped at 299,792,458 meters per second, this trick works only when light travels slower than it would in a vacuum — such as through fiber-optic cables.
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