We propose a radical extension of the relativity principle - observational relativity - according to which all observable physical quantities (energy scales, lengths, matter/ antimatter identity) are relative to the observer’s own energy scale level and mirror branch. The fundamental ontology is a unique modular quantum flag manifold von Neumann algebra. Its modular operator possesses a Z₂ spectral inversion symmetry that glues the ultraviolet (Planck) scale and the infrared (Hubble) scale into a closed involution loop. The modular flow evolves eternally and unidirectionally (IR→UV), driving a universal contraction of all intrinsic scales and an elevation of energy scales. Black holes and cosmic space are manifestations of the same energy scale flow under different relative gradients. The observer is an emergent structure at an intermediate energy scale level, simultaneously residing inside black holes and observing them. We formulate the theory as a twisted spectral triple induced by the modular flow. Three axioms are given: (1) the modular quantum flag manifold algebra; (2) the external Euclidean spectral triple for macroscopic space; (3) the modular covariance of the total Dirac operator. From these we derive two lemmas (twisted first‑order condition and spectral action expansion) and a main theorem: the low‑energy limit of the spectral action yields the Einstein–Hilbert action with the correct cosmological constant magnitude ₂₎ₒ₌₎ (lP/RH) ² 10^-122, while the internal algebra produces the Standard Model gauge group and three generations of fermions via quantum Borel–Weil theory. The model resolves the black hole singularity, the information paradox, and the matter‑antimatter asymmetry, and gives falsifiable predictions (neutrino normal mass ordering, running of dark energy, variation of the fine‑structure constant at high redshift).
Zheng Xinyu (Wed,) studied this question.