
 David Guarrera's Worldsheet: Magnetic Monopoles 
  In fact, things are actually much nicer with magnetic charge, as Maxwell's equations are perfectly symmetric between E and B fields (I would write them out if I knew how to do equations in my blog, anybody know?), so the physics is much more beautiful if magnetic charge exists. 
  Well, you might ask: what about the vector potential A? We know that B= \del X A, and that if magnetic charges exist \del (dot) B=m \delta^3 (r) (up to a constant for a monopole at the origin, where m is the "magnetic charge", and the delta is the Dirac delta function). 
  So, we can put back the monopole if we just get rid of the vector potential (which, for classical electrodynamics, is not necessary), and just use E and B in our calculations. 
 web.mit.edu /guarrera/www/2005/02/magneticmonopoles.html (1092 words) 
