hearing and reversal of time

In search of sound (2)

(Invited conference to the symposium « feeling the sound », 23-25 April 2004)

Dr.Bernard M.Auriol

translated in english by Béatrice Bonzom-Gourc

We force sound even to come back to its origins. It is the great work of Mathias Fink which invite us, not only for the curiosity of the spirit, but also in order to test aircrafts or to destroy renal calculus (Rf. below drawing).
Real experiences of reversal of time can be implemented in the acoustic field using matrix of piezoelectric transducers. The « mirrors with temporal reversal » set up by Mathias Fink and his team within the laboratory « Waves and acoustics » (LOA, CNRS-ESPCI(1)- University Paris 7) sample and register an incident acoustic field, then send it out again in a reversed chronology.

Such plans allow to focus an acoustic wave through a very heterogeneous environment, in order to restore the different steps of the anterior life of this wave and so, to make it covering the reversed way during its spreading. The potential applications of this technique are numerous. The most advanced refers to the setting up of a very outstanding and non-destructive plan of control for titan parts of engine aircrafts. In the same way, a system of « lithotritie » that enables to follow a renal calculus in its movements and to destroy it, has been realized at the laboratory « Waves and acoustics ».

The irreversibility of the time is a question that has always concerned a great number of physicians. Although the equations of the classical and quantum mechanics are reversible at the microscopic scales, the macroscopic phenomena show mainly an irreversible behaviour linked to the exceptional increased number of the particles brought into play. Regarding physics of waves, the quantity of information needed are relatively weak in order to describe in a comprehensive way an undulatory field. Then, it is conceivable to realize experiences of reversal of time on an undulatory field for which it exists a technology of linear and irreversible captors networks able to be operated in receiver as well as in transmitter mode.

Psychosonique

11 Novembre 2004


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