微細構造定数は重要な物理定数です。これは、電磁相互作用の強度を定量化する無次元数です。測定値は0.0072973525693で、ある程度のエラー、または約1/137です。

微細な構造定数は、原子モデルの最初の円形軌道と光の速度における電子の速度の比として解釈できます。
The Fine-structure constant is an important physical constant.  It is a dimensionless number that quantifies the strength of the electromagnetic interaction. It has a measured value of 0.0072973525693 with some error, or approximately 1/137. 

The fine structure constant can be interpreted as the ratio between the velocity of the electron in the first circular orbit of the Bohr model of the atom and the speed of light.