  The Cartesian material space approach to Maxwell's equations reveals the
analytical solution of the continuous radial density for the extended
elementary charge. Radial charges and their Coulomb fields carry equal passive
and active imaginary energies. The Einstein mass-energy formula can be updated
for electricity in complex numbers. The Principle of Equivalence works
universally for active/passive masses and for active/passive electric charges.
Maxwell's equations for complex continuous charges become 4-vector identities
for locally paired flows of energies that correspond to the Chinese yin-yang
approach to the nature. Cartesian relativistic physics has its own nondual
analog of the Einstein Equation, which leads to geodesic equations for the
motion of Ricci material densities and to vortex states of the elementary
mass-extension. Non-empty space physics modifies the Navier-Stokes equation by
kinematic "living forces". This inertial feedback enables a conceptual choice
between Newtonian and Cartesian universes (with localized or extended
elementary masses, respectively) because of new predictions of pressure and
temperature gradients across laboratory flows of liquids and gases.
