The factor 2 in fundamental physics
arXiv:physics/0110069
Abstract
A brief history is given of the factor 2, starting in the most elementary considerations of geometry and kinematics of uniform acceleration, and moving to relativity, quantum mechanics and particle physics. The basic argument is that in all the significant cases in which the factor 2 or 1/2 occurs in fundamental physics, whether classical, quantum or relativistic, the same physical operation is taking place.
37 pages