A possible estimate of the elementary length in electromagnetic interactions

The difference of 0·2 MHz between the theoretical and experimental values of the Lamb shift of the hydrogen terms 2s _1/2 and 2p _1/2 is used to estimate the elementary length λ in an electromagnetic interaction. The calculated difference of the hydrogen terms in the Bopp-Podolsky potential field\(\varphi (r) = \frac{e}{{4\pi r}}(1 - e - ^{r/\lambda } )\) is compared with the given difference Δ?0·2 MHz. From this we then get for the elementary length λ?0·1× 10^-13 cm. The distribution of the electric charge in the proton\(\varrho (r) = \frac{e}{{4\pi \lambda ^2 }}\frac{{e - ^{r/\lambda } }}{{^ - r}}\) leads to the Bopp-Podolsky potential if the Coulomb interaction is assumed to be valid in the whole space.