This paper proposes a radical principle of observational relativity: there exist no absolute energy scales, absolute scales, or absolute matter-antimatter identities. All observable physical quantities are relative manifestations of the observer's own energy scale level and mirror branch. The ontological foundation of the universe is a unique modular quantum flag manifold algebra whose modular operator possesses a Z₂ spectral inversion symmetry that glues the ultraviolet end (Planck scale) and the infrared end (Hubble radius) into a closed involution loop. The modular flow ₓ evolves eternally and unidirectionally (IR→UV), driving the contraction of all scales and the elevation of energy scales. Black holes and cosmic space are manifestations of the same energy scale flow under different relative gradients. As an emergent structure at the intermediate energy scale level, the observer resides within black holes while simultaneously observing them, forming a self-referential loop. This framework requires no free parameters, naturally derives the cosmological constant ₂₎ₒ₌₎ (l/R₇) ^2 10^-122, and provides a unified explanation for core puzzles including dark energy, black hole singularities, the information paradox, and matter-antimatter asymmetry. It also puts forward falsifiable predictions such as the evolution of the cosmological constant with redshift, antimatter abundance characteristics in black hole jets, and tiny variations of the fine-structure constant at high redshifts. This paper argues that the ultimate form of the relativity principle is "observational relativity", whose ontology is a set of dual mathematical structures rather than any absolute entity.
Zheng Xinyu (Mon,) studied this question.