Constraining variations in the fine-structure constant with the cosmic microwave background - art. no. 023516

Any time variation in the fine-structure constant alters the ionization his tory of the universe and therefore changes the pattern of cosmic microwave background fluctuations. We calculate the changes in the spectrum of these fluctuations as a function of the change in cu, and we find that these chan ges are dominated by the change in the redshift of recombination due to the shift in the binding energy of hydrogen. We estimate the accuracy with whi ch the next generation of cosmic microwave background experiments might con strain any variation in ct at z similar to 1000. We find that such experime nts could potentially be sensitive to \Delta alpha/alpha\ similar to 10(-2) -10(-3) [S0556-2821(99)02114-1].