  Charge, like mass in Newtonian mechanics, is an irreducible element of
electromagnetic theory that must be introduced ab initio. Its origin is not
properly a part of the theory. Fields are then defined in terms of forces on
either masses--in the case of Newtonian mechanics, or charges in the case of
electromagnetism. General Relativity changed our way of thinking about the
gravitational field by replacing the concept of a force field with the
curvature of space-time. Mass, however, remained an irreducible element. It is
shown here that the Reissner-Nordstrom solution to the Einstein field equations
tells us that charge, like mass, has a unique space-time signature.
