Maxwell's Phenomenological Equations Lack Global Conjugate Foundation and Are Rootless First Reveal the Quantitative Data and Ontological Eigen Mechanism of Light Isotropy

The isotropy of light is a fundamental consensus within modern optics, electromagnetism, and cosmology, repeatedly confirmed by diverse experiments and astronomical observations. Nevertheless, mainstream theories developed over the past century remain limited to phenomenological generalization and mathematical fitting. They lack quantitatively defined, material‑based structural underlying mechanisms. Maxwell’s electromagnetic framework, the ΛCDM standard cosmological model, the 2025 optical‑propagation fitting equation proposed by MIT, and the Planck satellite statistical model for cosmic homogeneity are all local phenomenological constructions. These systems omit conjugate terms for the dominant cosmic baryonic substance, global microwave‑carrier constraints, and eigen‑angle and rotation parameters; they depend on ideal error‑free assumptions. Higher‑level models subjectively presuppose homogeneity, while lower‑level formulas rely purely on statistical fitting data. Consequently, they are rootless in physical origin and lack global coupling logic. Continuing the unified theoretical system established in the companion preprint The Phenomenological Equations of Einstein's Special Relativity Are Without Origin and the companion preprint Wave‑Particle Duality Does Not Exist; It Is the Two‑Sided Eigen Nature of One Integrated Entity, this paper adheres strictly to the Three Absolutes of the Natural Zeroth Law. Note: The Natural Zeroth Law proposed herein is an original postulate of the present theoretical system; it is distinct from the thermodynamic zeroth law of classical physics. The Three Absolutes: absolute precision, absolute error, and the rule that the ratio between distinct absolute‑error terms is never strictly equal to zero. Building upon three cross‑scale closed‑loop fixed eigen values: CMB characteristic angle (\boldsymbol{0.219996^\circ}), helium‑ion energy‑level shift (\boldsymbol{1.1054\times 10^{-4}\ \text{eV}}), and macromolecular rotation‑angle range (\boldsymbol{22.21^\circ\sim33.85^\circ}), this study adopts angle, rotation gradient, and warping‑eigen properties as its core axis. It anchors the well‑established observational result that more than 99 % of ordinary cosmic matter is composed of the hydrogen‑helium binary system. Through two‑way comparisons between authoritative legacy equations and the phase‑dependent eigen‑constraint equations proposed herein, combined with numerical checks and hierarchical model analysis, this paper demonstrates that light is not an independent fundamental particle. Instead, it represents an integrated two‑sided eigen response arising from degenerate conjugation and global coupling between the hydrogen‑helium warp‑spin dual‑eigen system and the cosmic microwave background. The 99 % hydrogen‑helium cosmic foundation exhibits globally uniform spatial distribution, isomorphic warp angles, and consistent rotational behaviour. Here isomorphism refers to consistent angular‑rotation pattern relationships across scales. This constitutes the sole objective physical origin of light isotropy. Trace heavy‑element components below 1 % cannot independently govern global physical rules without conjugating with the hydrogen‑helium system. Centred on equations, supported by fixed characteristic values, and focused on inter‑model comparison, this work addresses the long‑standing puzzle of light isotropy. It supplements the missing global terms within Maxwell’s formalism and establishes a closed‑loop ontological framework for optics characterised by quantifiable comparison and internal systematic consistency.