5 still feasible. One such analysis will be presented in a follow-up paper. In any case, our results already show how fairly stan- dard astrophysical observables can place strong con- straints on high-energy physics models that would other- wise be difficult to test in laboratory or accelerator set- tings. With the significant gains in sensitivity expected for the next generation of ground and space experiments these constraints will become much stronger, and the early universe will become a key laboratory in which to probe fundamental physics. sults indicate that the current data gives no clear indica- tion about the relative sign of the variations, but already prefers that any relative variations in α should be of the same sign of G for ∼ 1% variations. We have also shown that, under the assumption that there’s no rolling dur- ing the radiation era, much tighter constraints can be obtained by adding BBN data. 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