A Spacetime Cloak, or a History Editor

Allan Boardman Photonics and Nonlinear Science Group, Joule Laboratory, Department of Physics, University of Salford, Salford M5 4WT, United Kingdom. (Dated: Wednesday 12 December, 2012) Abstract We introduce a recipe for producing a new type of electromagnetic cloak, the electromagnetic spacetime cloak, which conceals events rather than mere objects. Non-emitting events occurring during a restricted period are never suspected by a distant observer. The cloak works by locally manipulating the speed of light of an initially uniform light distribution, whilst the light rays themselves always follow straight paths. Any ‘perfect’ spacetime cloak would necessarily rely upon the technology of electromagnetic metamaterials, which has already been shown to be capable of deforming light in ways hitherto unforseen – to produce for example an electromagnetic object cloak. Nevertheless, we show how it is possible to use intensity dependent refractive indices to construct an approximate STC, an implementation that would enable the distinct signature of successful event cloaking to be observed. Potential demonstrations include systems that apparently violate quantum statistics, ‘interrupt-without-interrupt’ computation on convergent data channels, and the illusion of a Star-Trek transporter.