  Gravitation might make a preferred frame appear, and with it a clear
space/time separation--the latter being, a priori, needed by quantum mechanics
(QM) in curved space-time. Several models of gravitation with an ether are
discussed: they assume metrical effects in an heterogeneous ether and/or a
Lorentz-symmetry breaking. One scalar model, starting from a semi-heuristic
view of gravity as a pressure force, is detailed. It has been developed to a
complete theory including continuum dynamics, cosmology, and links with
electromagnetism and QM. To test the theory, an asymptotic scheme of
post-Newtonian approximation has been built. That version of the theory which
is discussed here predicts an internal-structure effect, even at the
point-particle limit. The same might happen also in general relativity (GR) in
some gauges, if one would use a similar scheme. Adjusting the equations of
planetary motion on an ephemeris leaves a residual difference with it; one
should adjust the equations using primary observations. The same effects on
light rays are predicted as with GR, and a similar energy loss applies to
binary pulsars.
