|MadSci Network: Physics|
Sorry to take so long getting to your question. I was distracted by work and it took a little more time to research your question than I thought it would. :-)
Two thoughts about this physics question. 1) Can an electron stop moving (and if so, is it really still an electron, and what happens if an atom reaches absolute zero? do the electrons stop moving, or just the atom's nucleus?) 2) If those electrons stopped spinning, would they fall into the nucleus? If so, do the protons turn into neutrons?
Can an electron stop moving? In short, and under natural conditions, no. We need to define what electron spin is within the realm of quantum mechanics. "Spin" (a misnomer for what may actually happen), actually refers to the intrinsic angular momentum of the electron. The intrinsic angular momentum is the resultant vector of the bound forces in an electron. Since this is inherent to an electron, then, no, electrons can't stop moving under natural conditions.
As far as electrons being absorbed into the nucleus of an atom, this only happens in isotopes where the nucleus is unstable due to a missing neutron(s). The process is referred to as electron capture, a form of radioactivity, and results in the creation of a neutron.
As for what happens when matter reaches absolute zero, no one is quite sure yet. Current theory(Bose-Einstein Condensation) suggests that atoms 'congeal' into a more solid, and new, form of matter, and as you will see in the links below, BEC condensates have been produced. Some good sources for these theories, and their experimental results, are:
CHILL by David H. Freedman
News on Bose- Einstein Condensation by Ard-Jan Moerdijk
I hope this answers your question. If not, feel free to post a
Try the links in the MadSci Library for more information on Physics.