Implications of quasar spectroscopy for constancy of constants

Abstract Given that the redshifts of quasars are due to the universal expansion, the details of their spectra can be used to check the constancy of certain dimensionless ratios of physics over look-back times comparable with the Hubble time and distances exceeding that of the particle horizon in the Einstein-de Sitter universe. With a,gp, ge, mp, me denoting the fine structure constant, and the gyromagnetic ratios and masses of protons and electrons respectively, the following upper limits to variability over such times and distances have been derived in this way: approximate 3tr upper limit to effect optical doublet splittings comparison of optical and 21 cm redshifts comparison of hydrogen and metal redshifts quantity CL ot?gvm J mv (or **(&/&) (me/mp)) m e/ m p variation 3% io- 3 50%