The 3rd Foundation of the Spatial Cosmological Theory: Postulation, Axiom, and Mathematical Formulation

This paper presents the 3rd Foundation of the Spatial Cosmological Theory (SCT). It establishes that the stability of matter relies on the 'critical absence' of 'Space' caused by the extreme movement density of subatomic components. This absence creates a 'spatial vacuum' barrier known as the 'Eletrocapa', substituting the traditional 'strong forces' of the Standard Model. Furthermore, we present the Mathematical Formulation of this phenomenon, introducing the Locking Coefficient (Tc). By relating the internal Movement Density (ρ_m) to the macroscopic Space Conditionant (ρ_E) provided by the Vectorial Spatial Flux (VSF), this framework elegantly unifies atomic stability with the cosmological deceleration of the Solar System, providing a cohesive mechanical explanation for the radioactive decay of heavy elements as a direct consequence of the fluidic fatigue of the 'Eletrocapa'.