Inverse Fine-Structure Constant

The reciprocal of nature's electromagnetic coupling — about 137.036, physics' most famous bare number.

Specifications & Metrics

symbol

α⁻¹

status

Measured — CODATA 2022 adjustment

value

137.035999177 ± 2.1 × 10⁻⁸

Relative Scale in Constants

Core Principles & Analysis

• Measured to 0.16 parts per billion from the electron's anomalous magnetic moment.
• Sets the fine splitting of spectral lines that gave the constant its name.
• Its dimensionless value is the same for every observer — a pure number of the universe.