Gli universi ipersferici, il gruppo conforme ed il campo gravitazionale di Newton

The theory of the Hyperspherical Universes $S_n$, based on the rotations group $R_{n+1}$, for $n=4$ gives the "Special Projective Relativity" and the equations of magnetohydrodynamics. Instead, for $n=5$ we obtain a generalization of the "Conformal Relativity" and an unified theory of matter and electricity based on group theory.