  We demonstrate that to all large scale cosmological structures where
gravitation is the only overall relevant interaction assembling the system
(e.g. galaxies), there is associated a characteristic unit of action per
particle whose order of magnitude coincides with the Planck action constant
$h$. This result extends the class of physical systems for which quantum
coherence can act on macroscopic scales (as e.g. in superconductivity) and
agrees with the absence of screening mechanisms for the gravitational forces,
as predicted by some renormalizable quantum field theories of gravity. It also
seems to support those lines of thought invoking that large scale structures in
the Universe should be connected to quantum primordial perturbations as
requested by inflation, that the Newton constant should vary with time and
distance and, finally, that gravity should be considered as an effective
interaction induced by quantization.
