Adam,

Thanks for the response.

But doesn't the electron and neutrino (e & v) mass have to come from somewhere. They can't just materialize out of nothing and remain.
You are right, the proton is "almost" the same mass as the neutron, but slightly less. The proton is enough smaller than the neutron that the difference in mass more than accounts for the mass of the electron and neutrino. However, since the neutron doesn't directly decay into a proton, electron, and neutrino, as Fermi originally hypothesized, and does require the W as an intermediary, it seems the mass of these, admittedly small, but still massive (in that they have some mass) particles (the electron & neutrino) must come from somewhere. Overall in the decay, energy, charge and spin are conserved; I am clear on that and on more or less why this is so. That is, I can see the balance between the beginning and the end, but I just cannot figure out where the mass of the final products arises from in relation to the W-, if at all. I know this all occurs in a fraction of a second, but it just seems to me that since the e & v are separated from the neutron or proton in space, the mass must come from somewhere else, namely the W particle that acts as the intermediary. I suppose what I'm thinking at the moment, and please somebody correct me if I have things confused, as I'm sure I do, is that the W, as an "intermediary", transfers mass from the neutron to the e & v, and since the W was, potentially, able to borrow some of it's mass from the neutron, that part of the W's mass would not have to re-dissipate into the universe (a la Heisenberg Uncertainty). Perhaps I am just thinking too much about a question that will have little influence on the way I relate to quantum physics.

Thanks,

Kevin