Wolfram goes on to suggest that his restriction to simple models is an important one. In particular, he finds a natural bound on the computation a system can perform, and once this bound is reached, there is a universal equivalence that can allow one system to emulate another, as long as we are free to manipulate the inputs and reinterpret the outputs. Moreover, the suggestion is made that most systems (including some of the very simple ones he explores) have achieved this equivalence milestone.
