Planet Nine or "Planet Ten"? Pluto's 3:2 Resonance and a Dual-Window Outer-Solar-System Hypothesis in Universal Physics

Abstract The hypothetical existence of a distant planet beyond Neptune remains an open question in Solar System dynamics. Conventional Planet Nine searches employ numerical orbital models and the observed distribution of distant trans-Neptunian objects to constrain possible planetary parameters. This paper introduces a complementary, explicitly testable hypothesis derived from the Universal Physics (UP) framework. Within this model, Pluto's established 3:2 mean-motion resonance with Neptune motivates its interpretation as a ninth structural resonance node, independently of its formal planetary classification. The hypothetical additional body is consequently designated Planet 9/10 within the UP structural nomenclature. Using Kepler's third law and an idealized inclined-shell projection, two candidate orbital scales are proposed: a 57:1 projection-associated window at a semi-major axis of approximately 462.7 AU and a 64:1 Neptune-period window at approximately 481.1 AU. For an assumed orbital inclination of 16°, their associated geometric projections are approximately 444.8 AU and 462.5 AU, respectively. An additional geometric compatibility condition yields an inclination of approximately 15.8195°, linking the two selected resonance scales. A separate phenomenological mass diagnostic proposes a candidate mass of approximately 6.17 Earth masses, while an anti-aligned perihelion configuration is considered as a potential observational discriminator. The analysis distinguishes orbital semi-major axes from instantaneous heliocentric positions, projected geometric quantities from physical orbital coordinates, and mathematical resonance relations from independently established dynamical mechanisms. The proposed windows are therefore presented as conditional predictions rather than evidence of an already detected planet or a demonstrated macroscopic vacuum topology. Future astrometric observations, orbital reconstructions, and dynamical stability analyses may test whether the proposed parameter combinations correspond to a real trans-Neptunian planetary body.