Theoretical calculation of the fine-structure constant and the permittivity of the vacuum
Light traveling through the vacuum interacts with vacuum fluctuations similarly to the way that light traveling through a dielectric interacts with ordinary matter. And just as the permittivity of a dielectric can be calculated, the permittivity $ε_0$ of the vacuum can be calculated, yielding an equation for the fine-structure constant $α$. The most important contributions to the value of $α$ arise from the interaction of photons with charged lepton-antilepton vacuum fluctuations that appear in the vacuum as on-shell, bound states. Considering these contributions only to first order in alpha, the fully screened $α\cong 1/(8^2\sqrt{3π/2}) \cong 1/139$.