 Moreover, the theorem is historically significant for the role it played in ruling out the possibility of hidden variables in quantum mechanics.A hidden-variable theory that is deterministic implies that the probability of a given outcome is "always" either 0 or 1.For example, a Stern–Gerlach measurement on a spin-1 atom will report that the atom's angular momentum along the chosen axis is one of three possible values, which can be designated formula_17, formula_18 and formula_19.