Earnshaw's theorem applies in an inertial reference frame. But it is sometimes more natural to work in a rotating reference frame that contains a fictitious centrifugal force that violates the assumptions of Earnshaw's theorem. Points that are stationary in a rotating reference frame (but moving in an inertial frame) can be absolutely stable or absolutely unstable. For example, in the restricted three-body problem, the effective potential from the fictitious centrifugal force allows the Lagrange points L4 and L5 to lie at local maxima of the effective potential field even if there is only negligible mass at those locations. (Even though these Lagrange points lie at local maxima of the potential field rather than local minima, they are still absolutely stable in a certain parameter regime due to the fictitious velocity-dependent Coriolis force, which is not captured by the scalar potential field.)