http://pespmc1.vub.ac.be/KNOW.html Knowledge [Node to be completed] In cybernetics we say that a purposive cybernetic system S has some knowledge if the system S has a model of some part of reality as it is perceived by the system. Informally, a model of some process occurring in a system is a another system which somehow mimicks, or simulates, that process; thus by using the model it becomes possible to know something about the modelled process without actually running it, or predict developments before they actually happen. The definition of the modeling scheme includes an important assumption of non-interference: that the procedure R (which is a sequence of actions), when it acts on a state w of the world, does not change that state. But we know from quantum mechanics that this assumption, strictly speaking, never holds. When we deal with macroscopic phenomena we can, nevertheless, use the non-interference assumpiton, because the impact of the instruments we use in R on the state w can always be made insignificant. But on the atomic and subatomic levels, we cannot abstract from the action of the means we use to get information about the objects studied.