Interpreting the Dark Side of the Universe as Curvature Effects

Astrophysical observations are pointing out huge amounts of "dark matter" and "dark energy" needed to explain the observed large scale structures and cosmic accelerating expansion. Up to now, no final experimental evidence has been found, at fundamental level, to explain such mysterious components. The problem could be completely reversed considering dark matter and dark energy as "shortcomings" of General Relativity at infrared limit. Alternative theories of gravity, in particular f(. R) gravity, could explain, in principle, the accelerated expansion of the Universe and the clustering of structures without adding unknown matter ingredients but extending General Relativity by using more general functions of the curvature invariants. However, no final extended theory is capable, up to now, of fitting all the observations at any scales. In any case, this alternative "geometric" paradigm deserves a lot of attention since, in the near future, could give rise to a new self-consistent picture of the dark side of the Universe