  In agreement with Michelson-Morley experiments performed in vacuum, we show
that, assuming the existence of a fundamental aether frame and of a length
contraction affecting the material bodies in the direction of the Earth
absolute velocity, the light signals, travelling along the arms of the
interferometer arrive in phase whatever their orientation, a result which
responds to an objection opposed to the non-entrained aether theory. This
result constitutes a strong argument in support of length contraction and of
the existence of a model of aether non-entrained by the motion of celestial
bodies.
