Jeudi 27 mars 1997
The spin echo seems to represent a spontaneous fluctuation out of equilibrium, thus raising questions about reversibility and thermodynamics.
This is specially true of the "magic" echo which is evoked from a many - body system of interacting spins in a solid, in a manner to be described. How must the laws of macroscopic thermodynamics be stated in order to avoid a violation of the second law ?