The Physical Significance of the Imaginary Unit i : Shielding Penetration via Zeta Interference Fields and the Naturalization of Spin Structures

Preprint. Publicly released on Zenodo prior to journal submission.This preprint reinterprets the imaginary unit iii as a shielded information basis and formulates an operational bridge from protected ±i\pm i±i states to real-valued reported observables via a three-domain mapping: zeta-phase driving (Z-domain) →\rightarrow→ SU(2) spinor routing on a protected basis (B-domain) →\rightarrow→ Hermitian projection to reported quantities (O-domain). The readout-layer scalar κ=1+αBF\kappa=1+\alpha_{\mathrm{BF}}κ=1+αBF is treated as a universal penetration/efficiency factor: it attenuates the routed phase (effective angle) while simultaneously rescaling reported time, enabling a single-parameter description across channels without introducing new dynamical degrees of freedom. As a consequence, spin-12\tfrac{1}{2}21 behavior and 4π4\pi4π periodicity are naturalized as holonomy residuals of the shielding–routing–projection pipeline. The same evasion–retention–reprojection motif is also outlined as a unifying interpretation pattern for circuit reactance, complex quantum-state representations, and black-hole information retention under restricted observation. Related preprints: doi:10.5281/zenodo.18169038; doi:10.5281/zenodo.18169180; doi:10.5281/zenodo.18158537; doi:10.5281/zenodo.18158333; doi:10.5281/zenodo.18158453; doi:10.5281/zenodo.18159303.