Quantification of electrical charges in Kaluza Klein theory without   strings of Dirac
  It is proposed a formalism of quantification of the electric charges in the Kaluza Klein theory of five dimensions and a explanation of the cause of the variation of the electromagnetic fine-structure constant in cosmological times.There is a formalism that eliminates the problem that impeached the KK theory to complete the unification of the electromagnetic and the gravitational fields. The complete unification of these two fields is obtained. The radius of compactation is determined as 70,238 lengths of Planck. 
Paulo da Costa Moreira