Bipolar Mass Cosmology: A Bimetric Framework for Antimass Stability and Accelerated Expansion

This treatise presents a comprehensive analytical formulation of a cosmology based on the coexistence of two mass sectors with opposite gravitational signs, integrated through a spin-2 interacting geometric structure. We start from the premise that the direct insertion of negative mass in monometric General Relativity violates the Null Energy Condition (NEC) and triggers catastrophic instabilities, such as runaway motion and infinite vacuum decay. To resolve these pathologies without renouncing dipolar symmetry, we develop a ghost-free bimetric gravity theory based on the dRGT formalism. We derive the field equations using elementary symmetric polynomials, which guarantees a kinematic isolation that prevents direct contact between sectors and ensures Hamiltonian stability. We propose that, in this framework, the accelerated expansion of the universe does not require a cosmological constant or exotic dark energy, but emerges as a dynamic repulsive pressure generated by the metric segregation of antimass toward cosmic supervoids. Furthermore, the bimetric coupling provides a natural solution to curvature singularities in compact objects, transitioning toward regular Bardeen cores. Finally, we propose that temporal irreversibility is a direct consequence of the separation gradient between both metric sectors, unifying the arrow of time with the global dynamics of the spacetime fabric. This work resolves nothing more than my restlessness to compose on physics, offering a new paradigm where the complexity of the cosmos emanates from a single fundamental dipolar interaction.

UPDATE (March 31, 2026): A companion paper detailing the rigorous mathematical foundations, including the ADM stability proof and the resolution of the infinite mass catastrophe via the gravitational Schwinger effect, has been added to this record as Part 2.