Key points are not available for this paper at this time.
The fine structure constant at red shifts 0. 2, corresponding to an epoch around two billion years ago, has been determined using the wavelengths of a pair of O III emission lines measured in the spectra of five radio galaxies. We find (z=0. 2) (lab) =1. 0010. 002 probable error.
Bahcall et al. (Mon,) studied this question.