Take the tour ×  Why do we have an elementary charge $e$ in
physics but no elementary mass? Is an elementary mass ruled out
by experiment or is an elementary mass forbidden by some
theoretical reason?  share|improve this question Related:
physics.stackexchange.com/q/122/2451 –  Qmechanic Mar 9 '12 at
20:09 add comment  7 Answers  up vote 12 down vote accepted  Let
me add two references to points already mentioned in this
discussion:  Today, there is no reason known why the electric
charge has to be quantized. It is true that the quantization
follows from the existence of magnetic monopoles and the
consistency of the quantized electromagnetic field, which was
shown first by Dirac, you'll find a very nice exposition of this
in    • Gregory L. Naber: "Topology, geometry and gauge fields."
(2 books, of the top off my head I don't know if the relevant
part is in the first or the second one).  AFAIK there is no
reason to believe that magnetic monopoles do exist, there is no
experimental evidence and there is no com