High Quality Content by WIKIPEDIA articles! The Spekkens toy model is a conceptually simple model, introduced by Robert Spekkens in 2004, to argue in favour of the epistemic view of quantum mechanics. The model is based on a foundational principle: "If one has maximal knowledge, then for every system, at every time, the amount of knowledge one possesses about the ontic state of the system at that time must equal the amount of knowledge one lacks." This is called the "knowledge balance principle." Within the bounds of this model, many phenomena typically associated with strictly quantum mechanical effects are present. These include (but are not limited to) entanglement, noncommutativity of measurements, teleportation, interference, no cloning and no broadcasting theorems, and unsharp measurements. Much of the mathematics associated with quantum theory has strong analogues inside the toy model, such as the Bloch sphere and similar forms of transformations. The model is not, however, a restriction of quantum mechanics, as there are effects in the model not present in quantum theory.