 Hidden variables (Bohm): Hidden variable theories, of which Bohm theory (Bohm 1952) is the best available example, provide a realistic and deterministic interpretation of quantum mechanics. The similarity between RQM and Bohm theory is in the realistic interpretation of some variables, such as the position of a particle. A difference is in the sparse ontology of RQM, compared to the assumption of quantities unobservable in principle which is implicit in Bohm theory.