Some aspects of infrared (large distances) modification of gravity are discussed. Various ideas ranging from Fierz-Pauli ‘s proposal of massive gravity to extra dimensional models are discussed. It appears that it is very difficult to build up an effective theory of gravity, modified in the IR, which is free of patologies and perturbative, in agreement with experimental tests, like the bending of light from the sun. As result, the hope of explaining some quirkish properties of our universe with a modification of Newton’s law is rather elusive.

Padoue