Can a wave be living its past life again? This issue has been widely tackled at ESPCI Paris, especially for acoustic and electromagnetic waves. The process called ‘time reversal mirror’ implies a lot of sensors and heavy electronics. Yet, teams from the Langevin Institute (ESPCI Paris/CNRS) and the PMMH Laboratory (ESPCI Paris/CNRS/UPMC/Université Paris Diderot) have just genuinely revisited this phenomenon by using space and time symmetries while avoiding any electronics.
The concept -named ‘Instantaneous time mirror’- has been tested with water waves, and the associated works have been published online in Nature Physics on 11th July 2016.
article in Physics Today
V. Bacot et al., Time reversal and holography with spacetime transformations, Nat. Phys., 2016, doi: 10.1038/nphys3810