Cartesian relativistic physics has its own nondual analog of the 1915 Einstein Equation for pure field physics in nonempty space. This tensor field analog leads to the vector geodesic equations for relativistic accelerations of Ricci material densities. Extended states of inertial energy densities modify the Navier-Stokes equation by the kinematic 'living forces' for the slow motion of material media. The new inertial feedback enables a conceptual choice between Newtonian and Cartesian

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... ves (with localized or extended, respectively, elementary masses in the Universe) because of different pressure and temperature gradients across laboratory flows of liquids and gases.