Reexamination of the187Rebound on the variation of fundamental couplings

We reconsider the ${}^{187}\mathrm{Re}$ bound on the variation of the fine-structure constant. We combine the meteoritic measurement with several present-day lab measurements to firmly establish the quantitative upper limit to the time variation over the age of the solar system. We find that the relative change of the fine-structure constant between its present value and $\alpha$ of $\sim 4.6\mathrm{Gyr}$ ago is consistent with zero, $\Delta \alpha /\alpha =[-8\pm 8(1\mathrm{}\sigma \left)\right]\times {10}^{-7}.$ We also rederive this bound in models where all gauge and Yukawa couplings vary in an interdependent manner, as would be expected in unified theories.