We now digress slightly to pick up some more concepts. 
           On this slide, we show a simplified physical model of a charged particle.  According to present particle physics, we
model it as an observable, spinning bare mass in the middle, connected to a spray of virtual particles on and off the mass in all directions. 
           It is the spin of the mass that "attaches" the spray of virtual particles to and from itself. 
          Note that, because of the spin, the gradient lines of flux will actually be spiral or vortex in nature. 
          Also note that, when EM theory was founded, no one knew that an electron was spinning.  Electron spin was therefore omitted from the foundations of present electromagnetic theory, and compensated for later by strictly ad hoc measures. 

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