Erasing the past is now easier thanks to the latest time cloak, which conceals events instead of objects. The device can't cloak large-scale events such as a bank robbery but it can hide data flowing through an optical fibre, which could allow secret messages to be sent without a trace. Time cloaks work by slowing down light in an optical fibre, creating a gap in the beam. Any outside light that enters the hole becomes cloaked when the original beam is sped up. It's as if the original beam has been stitched back together like a spliced movie, hiding any record that the extra scene ever happened