  Questioning the experimental basis of continuous descriptions of fundamental
interactions we discuss classical gravity as an effective continuous
first-order approximation of a discrete interaction. The sub-dominant
contributions produce a residual interaction that may be repulsive and whose
physical meaning is of a correction of the excess contained in the continuous
approximation. These residual interactions become important (or even dominate)
at asymptotical conditions of very large distances from where there are data
(rotation curves of galaxies, inflation, accelerated expansion, etc) and
cosmological theoretical motivations that suggest new physics (new forms of
interactions) or new forms (dark) of matter and energy. We show that a discrete
picture of the world (of matter and of its interactions) produce, as an
approximation, the standard continuous picture and more. The flat rotation
curve of galaxies, for example, may have a simple and natural explanation.
