The physical interpretation of the fine-structure constant α ≈

We announce a statistical-interpretation of the fine-structure constant related to the atomic Hydrogen line-spectrum at 45 µeV and introduced in 1916 by Sommerfeld expression:

and here generalized for any line of a given atomic-spectrum as:

being e the unit charge, h the Planck's constant, 0 the vacuum permittivity, c the light velocity in vacuum, with δN 2 line the variance of the instantaneous photon-number inside a black-body (bb) cubic cavity in thermal equilibrium at an energy corresponding to that of the line, line , and a side length of the bb cavity given by L bb = 3.3 cm exact. The definition above is in full agreement with the Sommerfeld value and generalizes the pioneer Sommerfeld concept of fine structure constant to any line of given energy for the spectrum of any atom pertaining to the Mendeleev Table.