The Unique Self-Sustaining Spacetime: From Ontological Necessity to Physical Ground State

This paper develops a complete ontological and metaphysical framework that derives the unique fundamental structure of reality from the principle of absolute self-sustenance. Starting from Absolute Nothingness—a primordial background stripped of all rules, attributes, and constraints—we show that existence is permitted by the absence of prohibitions, and only structures capable of eternal self-stabilization can be real. Through rigorous classification of geometric manifolds, we prove that the only mathematically consistent, topologically rigid, and eternally self-sustaining spacetime is the non-orientable three-dimensional real projective space \mathbb{RP}^3/\mathbb{Z}_2, obtained by quotienting out the redundant global orientability of the standard \mathbb{RP}^3. This structure eliminates internal stress contradictions via orientation-reversing closed loops, achieves automatic self-zeroing of geometric tension, and uniquely satisfies all conditions for absolute stability without external input. This unique manifold serves as the ultimate physical ground state for M-theory. Furthermore, we show that all cosmic structure, elementary particles, quantum phenomena, and standard model physics emerge naturally as geometric stress folds of this foundational spacetime. The framework unifies ontology, geometry, and fundamental physics, providing the ultimate first-principle foundation for the unique vacuum of M-theory.