PhysOrg gets non-linear with their look at “time reversal” and how we might soon use it:
Imagine a cell phone charger that recharges your phone remotely without even knowing where it is; a device that targets and destroys tumors, wherever they are in the body; or a security field that can disable electronics, even a listening device hiding in a prosthetic toe, without knowing where it is.
While these applications remain only dreams, researchers at the University of Maryland have come up with a sci-fi seeming technology that one day could make them real. Using a time-reversal technique, the team has discovered how to transmit power, sound or images to a nonlinear object without knowing the object’s exact location and without affecting objects around it. Their work, “Nonlinear Time Reversal in a Wave Chaotic System,” was published in the Feb. 7 issue of the Physical Review Letters journal.
When a signal travels through the air, its waveforms scatter before an antenna picks it up. Recording the received signal and transmitting it backwards reverses the scatter and sends it back as a focused beam in space and time.
Ah – so it’s more recreating waves than winding back the clock.