The fine-structure constant as a scaled quantity.

The fine-structure constant α≈1/137 is traditionally regarded as a fundamental dimensionless parameter. I argue instead that α is a scaled quantity that arises only where the structural scales contributed by classical electromagnetism (e), quantum mechanics (ħ), and special relativity (c) intersect. None of these theories, taken individually, supplies the independent scales required to define α. The constant first appears when relativistic corrections are added to the Schrödinger-Bohr description of hydrogen (Sommerfeld), and it becomes the structural coupling in quantum electrodynamics, where quantum and relativistic effects modify the classical electromagnetic interaction. Expressing the governing laws in canonical form reveals this dependence and eliminates representational artifacts that make α appear fundamental. The running of α in QED further demonstrates its status as a scale-dependent coupling rather than a universal constant. I conclude that α is a domain-specific structural ratio reflecting contingent relationships among independent physical scales.