On the problem of the correct interpretation of phason elasticity in   quasicrystals
  Recently Francoual et al. claimed to have observed the dynamics of long-wavelength phason fluctuations in i-AlPdMn quasicrystals. We will show that the data reported call for a more detailed development of the elasticity theory of Jaric and Nelsson in order to determine the nature of small phonon-like atomic displacements with a symmetry that follows the phason elastic constants. 
G. Coddens (Laboratoire des Solides Irradies)