On Fri, Mar 1, 2013 at 7:27 PM, Jones Beene <[email protected]> wrote:
Quark mass does not have a value which can be agreed on, so how can > protons? > If I were a betting man, I would bet that the mass of a proton can change, as well as that of a neutron. The reasoning goes like this. An atomic nucleus is composed of protons and neutrons. Add a nucleon to a light nucleus through proton or neutron capture, and sometimes you will get an energy release through mass deficit. The mass-energy has to come from somewhere in the vicinity nucleus. It can come from the protons or the neutrons or from a magical source of mass apart from the nucleons. Setting aside magic and mystery and dark matter and superstrings for the moment, that leaves us with protons and neutrons. Does the mass deficit come only from the protons or only from the neutrons? Here we would have to delve into quantum chromodynamics to get much further. But from a 10,000 foot view, it seems reasonable to assume it comes from both. The difference in mass between a neutron and a proton is 1.29 MeV, and if my memory serves me, it is common for a neutron or proton capture event in a larger nucleus to produce an exothermic energy release well beyond this energy, including in cases where there is no change in the overall ratio of protons to neutrons (I should vet this assumption). So the mass deficit is not coming only from something related to the electron involved in an inverse beta decay. All of this is suggestive that the masses of the component neutrons and/or protons have each dropped a little to adjust to the new atomic mass. Assuming neutrons and/or protons can have different masses, a follow-on question is whether this is a property that is specific to the nuclear context or whether this can also occur outside of a nucleus. Eric
