A new principle is proposed for constructing a theory of dynamic coupled electromagnetomechanical processes in dielectrics and piezoelectrics. It is based on the purely mechanical two-continuum description of the deformation of dielectrics as a mixture of neutral molecules each formed of bound positive and negative charges. Based on the definition of a polarization vector and associated electric field, the mechanics equations are transformed into coupled equations for the displacements of neutral molecules and electric-field strength. These equations, invariant under the Galilean transformation, describe longitudinal electric and transverse electromagnetic dispersed waves in moving dielectrics as well as coupled acoustic and electromagnetic waves in dielectrics and piezoelectrics. From these equations Maxwell's equations and the acoustic approximation in electroelasticity for piezoelectrics follow as particular cases. Under this theory, the ether is modeled as a dielectric that is a nearly perfect fluid in which heavenly bodies freely move and transverse electromagnetic waves propagate as mutual displacements of the positive and negative charges of neutral particles that form the ether. Such a model makes it possible to uniquely explain, within the framework of classical physics, the fundamental experiments due to Fizeau, Michelson, Miller, and Galaev, stellar aberration, and the rotational experiments, which point to the fact that the ether exists Introduction. Coupled mechanical and electromagnetic processes have intensively been studied in modern continuum mechanics. The mathematical basis of such studies is the balance equations of continuum mechanics incorporating ponderomotive forces, Maxwell's equations, and the simultaneous equations of state for mechanical and electromagnetic parameters [5,8,9,28,29]. The noninvariance of Maxwell's equations under the Galilean transformations and Michelson's null result (failure to detect the ether wind [11]) resulted in Einstein's special relativity theory, which requires that the mechanical and electromagnetic equations should generally be formulated in relativistic form.Due to the increasing use of piezoelectric materials in technology, static and dynamic problems of electroelasticity have become especially important in solid mechanics [3,4,6,13,19,22,23,29,30]. The original electroelastic equations [3,6] include the static or dynamic equations for an elastic body, the electrostatic equation (acoustic approximation), the equations of state relating the stress tensor and the electric-displacement vector with the strain tensor and electric-field vector, and the Cauchy relations. The equations of state are derived on the assumption that the internal energy is a function of the strains and electric displacement.The major drawback of the acoustic approximation in dynamic problems of electroelasticity is neglecting the dynamic components of Maxwell's equations, though the electric-displacement vector and electric-field strength depend on time explicitly. In this case, the f...