where ω I,q is the angular velocity component corresponding to the q axis. For the left-and right-hand sides of Eq. ( ) to be consistent, they must have the same functional dependence on the angular velocity ω I,q , which is shown in section SIII of the SM to be the case if the fluctuations of I FG,I,q are small compared with its mean. (For a Gaussian distribution of I FG,I,q , this condition corresponds to the standard deviation of I FG,I,q being much smaller than its mean, i.e. (I FG,I,q -⟨I FG,I,q ⟩ R I ,Ω I ) 2 1/2 R I ,Ω I ≪ ⟨I FG,I,q ⟩ R I ,Ω I .) In this case, Eq. ( ) reduces to