L'universo di de Sitter, il gruppo di Fantappie e la cosmologia del Big-Bang.
The Poincaré group of relativistic physics can be perfected in a unique way by the Fantappié group. In this way we obtain a new group version of the Big-Bang Cosmology (Projective Cosmology), in which the velocity of light is not constant, and the expansion-collapse of the Universe is tied to a process of creation-anihilation of matter.