The Fine-Structure Constant as Aperture: Physical Interpretation of the α/2 Correction from a Symmetry-Forbidden Circuit Experiment

This paper provides a physical interpretation for the previously introduced \alpha/2 correction in a geometric formulation of the speed of light. Rather than treating the correction as phenomenological, the work identifies it with aperture softness—the fractional leakage of power across a symmetry-forbidden boundary when a spectral partition operates near an unstable equipartition point. The interpretation is grounded in an independent analog circuit experiment that implements the crystallographic restriction via a resonator bank. The experiment demonstrates that ideal (hard) spectral apertures produce exact geometric bandwidth ratios, while real (soft) apertures with polynomial tails leak power from forbidden regions, producing systematic and measurable deviations. The deviation is shown to depend monotonically on filter steepness and can be quantified as a softness parameter. By structural analogy, the electromagnetic partition is interpreted as an extremely hard—but not perfectly hard—aperture. The residual deviation from the hard-aperture geometric prediction for c is identified with \alpha/2, interpreted as the minimal leakage permitted by nonzero electromagnetic coupling. The connection to cubic overflow clarifies why such leakage cannot be suppressed within a purely quadratic (Thales) geometric container. The work introduces no new constants, modifies no existing physical theory, and makes no cosmological claims. Its contribution is interpretive: it assigns a concrete, falsifiable physical role to the \alpha/2 correction and demonstrates the mechanism independently in a laboratory-scale circuit system.