Inferences from the dark sky: Olbers' paradox revisited
  The classical formulation of "Olbers' Paradox" consists in looking for an explanation of the fact that the sky at night is dark. We use the experimental datum of the nocturnal darkness in order to put constraints on a Newtonian cosmological model. We infer then that the Universe, in such a model, should have had an origin at a finite time in the past. 
Mauro Arpino (Planetario "U.Hoepli", Milano, Italy), Fabio Scardigli   (ITP, University of Bern, Bern, Switzerland)