Wait, that paper discusses how the spin and magnetic moment of a single electron arise from energy in the electron's wave field. Where does the paper connect these ideas to the flow of electrical current? Does current really depend on a "spinning" electron interacting with the spin of a neighbouring electron? (I thought that'd only come up in explaining magnetism.) Is quantum mechanical spin necessary at all to understand classical current flow?

On first read, the mental model of atomic-scale gears meshing and turning at different rates (does direction matter? How do you think of amperage in terms of rotating shafts made of meshed gears?) more fraught with simplifying assumptions and unnecessary epicycle-style complications than the conventional hydrodynamic model.