You are always moving.

As a problem in mathematical physics, it is possible to re-write the classical Maxwell equations in a form consistent with four-dimensional space-time. The Maxwell equations (there are traditionally four of them) describe how electric and magnetic force fields vary in strength, propagate and interact with their sources, charges and currents. These equations, already known separately, were a master stroke of insight when James Clerk Maxwell added the last piece, a so called "displacement current" that ties them together. The stunning realization was that electricity and magnetism were different attributes of a unified energy field that in a particular format can also be called light.

Einstein, when trying to unify gravitational forces with the phenomenon of acceleration likewise made use of an already available notion that time could be considered as just a fourth additional and, with small exception, non-distinct dimension to the already familiar spatial three. Normally, the Maxwell equations are written in a format that gives the time dimension special treatment.


Having gone through the exercise of reformulating these equations in four-space, it is astonishing to see how the Maxwell equations reduce to a single tensor relationship where electric fields are equivalent to magnetic fields and a stationary charge is actually a generalized four-current in the new dimension that was formally called time. And, at that point one says Eureka! because it is so intuitive. As we all travel down the river of time, our static charges are actually moving charges, and so they must be currents.

To me that is just another one of those fantastic realizations that explain my love of science.