Hi there, I have a short thought that I want to share with all of you and see if there has been something written about it and, if not, why not?: A free particle spin is something that can take a discrete range of values, as it happens with electromagnetic or colour charge. However the other important observable, impulse, can take a continum range of values. This seems suspicious to me since nature seems to be formed by a finite (inmense, but finite) number of mathematical objects. Isnt out there any model or research where it is supposed that impulse is also a discrete observable? perhaps lattice quantum mechanics or something like that? Thanks!