"Is the neutron stable inside an atom because the atom shooting out charge photons keeps positrons away."

I think this is a reasonable explanation. The emitted charge field of the greater atomic structure 'shields' the minimally emitting Neutron. on its own, the Neutron has little emission to knock any rogue particles from a collision course. To me, thise explains why free neutrons decay within about 15 min.

 

"If the neutron is unstable outside the atom because of positron collisions, shouldn't protons likewise be unstable because of electron collisions?"

It seems that stability is tied directly to the emitted charge field of the particle itself. The more charge it emits, the greater its ability to protect itself and thus remain stable.

 

"Might there be a process that could condense neutrons into neutronium, which is theorized to be the core of pulsars or neutron stars?"

It would have to be shown that such condensation could occur with a charge field through-put. As Miles explains it is the charge channels that determine the greater nuclear structure; but with minimal charge through a neutron, I'm not sure any condensation would be stable for any length of time. Its an interesting idea, I just never have bought into the 'neutron star' concept. Seems like to much fantasy to cover a hole in a gravity-only theory.

 

tharkun