 At \(t_0\), an observer aiming at predicting the evolution of this space-time region has basically two choices: she can take into account (what Dennett calls) the physical level, and compute pixel by pixel the value of each cell state at each time step; or, she can focus on the design level, and employ high-level concepts such as those of glider and eater to ground her predictions (Dennett 2003: 39). The first option is perfectly deterministic, but has a flaw: it is time consuming, in such a way that, by the time you have made the required computation, the world has already evolved (this is especially true of a universal CA—as we have already hinted at above, and shall expand on soon). The second option is much faster: you know without much calculation what is going to happen to a glider meeting an eater. The predictions though, cannot be 100% reliable: 