Geometric Strain and the Proton Radius Puzzle: A Zero-Parameter Resolution

The proton radius puzzle—the persistent 4% discrepancy between electronic (0.8751 fm) and muonic (0.84087 fm) measurements of the proton charge radius—has remained unresolved since 2010 despite extensive theoretical and experimental effort. We propose that this discrepancy is not an experimental artifact or evidence of new physics, but rather a direct manifestation of geometric strain: the elastic deformation of measurement boundaries by probes of different information density. Defining channel stiffness as proportional to particle mass and treating the fine structure constant α as the elastic modulus of the vacuum geometry, we derive a universal strain law: Δr/r = α × ln(m_μ/m_e). This yields a predicted discrepancy of 3.89%, matching the experimental value of 3.91% to within 0.5%. The result suggests that the ‘puzzle’ reflects not missing physics but an unrecognized property of measurement itself: observers with different information density necessarily perceive different geometric boundaries.