On 7/8/09, Mike Stay <metaweta@gmail.com> wrote:
No, all bosons of a particular kind are indistinguishable, as are all fermions of a particular kind. You can distinguish a boson from a fermion by looking at its spin (fermions have half-integer spin, bosons have integer spin). You can distinguish an electron from a proton by looking at either its charge or mass, even though both are fermions. ... [and lots more intriguing details]
In this sort of discussion about fundamental physics, it becomes particularly obvious that the question of the "existence" or otherwise of atoms, electrons etc. is simply an irrelevance: all that matters is the theory connecting them, and there's no question about whether that theory exists, nor (assuming Mike's account is reliable) whether it is experimentally verifiable (it "works"). As soon as we move away from direct sensory perception, we are brought up against a sort of extended Erlangenprogramm --- existence resides in the relations between (putative) objects, and it is meaningless to enquire whether or not the latter "exist" in isolation. [If I understood category theory, I might at this point have to admit that this is the point Jim was attempting to make initially --- but since I don't, I can't!] Fred Lunnon