It's not that simple, due to the gauge invariance of the theory (not all mathematical degrees of freedom correspond to physical ones) and the approximations inv

It's not that simple, due to the gauge invariance of the theory (not all mathematical degrees of freedom correspond to physical ones) and the approximations involved in deriving wave solutions. The argument was finally settled by Feynman's "sticky beads": http://en.wikipedia.org/wiki/Sticky_bead_argument http://en.wikipedia.org/wiki/Sticky_bead_argument