A five dimensional model of varying effective gravitational and fine structure constants

We explore the possibility that the reported time variation of the fine structure constant (alpha) is due to a coupling between electromagnetism and gravitation. We predict such a coupling from a very simple effective theory of physical interactions, under the form of an improved version of the Kaluza-Klein theory. We show that it precisely leads to a variation of the effective fine structure constant with cosmic conditions, and thus with cosmic time. The comparison with the recent data from distant quasars absorption line spectra gives a good agreement; moreover, this may reconcile the claimed results on (alpha) with the upper limit from the Oklo naturel Uranium fission reactor.