The answer is really quite easy and clear. So that the Maxwell equations strives to have electrons be like that of photons-- perfect motion of particles. Perfect in the speed of light and symmetry of
E- M+ M- E+
So that the Hund's Rule wants the Minimum Principle-- shortest path is taken in EM, and that means the electrons occupy orbitals singularly before they pair because in singularity they attract by Ampere's law with all 4 iron d electrons having a parallel orbital attraction, not a spin attraction. And when electrons start to pair up in orbitals, as iron adds four more electrons, it is the spin that is a minimum principle in that the spins are attraction force.
Exercise: take your right hand and thumbs up rotate and it is counterclockwise, now your left hand with thumbs up is clockwise, but if you have your left hand with thumbs down, it too is counterclockwise. Here we see that spin up and spin down are in the same direction and thus an attraction force of Maxwell Equations.
So here we have evidence that as you pair the suborbitals of d for iron or of p for carbon that as those suborbitals are filled with two electrons in each, the one electron turns into a positron and so the electron is paired with a positron.
And this explains also in radioactivity, that many Beta decays are not electrons but rather positrons, and they occur from suborbitals that had two electrons. At least my memory is that Beta decay of positrons are from paired up electrons in suborbitals, have to check to be sure. --
Approximately 90 percent of AP's posts are missing in the Google newsgroups author search starting May 2012. They call it indexing; I call it censor discrimination. Whatever the case, what is needed now is for science newsgroups like sci.physics, sci.chem, sci.bio, sci.geo.geology, sci.med, sci.paleontology, sci.astro, sci.physics.electromag to?be hosted by a University the same as what Drexel?University hosts sci.math as the Math Forum. Science needs to be in education?not in the hands of corporations chasing after the next dollar bill.?Besides, Drexel's Math Forum can demand no fake names, and only 5 posts per day, of all posters which reduces or eliminates most spam and hate-spew, search-engine-bombing, and front- page-hogging. Drexel has?done a excellent, simple and fair author- archiving of AP sci.math posts since May 2012?as seen?here: