SDRAWKCAB sevaworcim! Physicists have recorded microwaves in enough detail to replay them backwards for the first time, a feat that has never been achieved with electromagnetic waves before. The trick is based on a technique pioneered for acoustic waves more than a decade ago.
The idea of time-reversed signals is simple. A detector analyses the signal and rebroadcasts it in reverse order – so the last signal to arrive is the first to return. The result is that time-reversed waves converge on the original source. “It’s like playing a movie backwards – if a fountain is shooting out water, the…
