  The role of theory as an “enabling theory,” (i.e., one that allows calculation or estimation of the size of the expected effect and also the size of expected backgrounds) is also discussed by Galison. (See also (Franklin 1995) and the discussion of the Stern-Gerlach experiment below). Such a theory can help to determine whether an experiment is feasible. Galison also emphasizes that elimination of background that might simulate or mask an effect is central to the experimental enterprise, and not a peripheral activity. In the case of the weak neutral current experiments, the existence of the currents depended crucially on showing that the event candidates could not all be due to neutron  background.[6]