Where does the arrow of time come from here?

Because there is no shortcut to the end state, the system has to be run forward step by step to reach it — and Wolfram argues that an observer who is themselves computationally bounded can only coarse-grain what they see, from which the Second Law of thermodynamics (the one-way slide toward disorder) emerges. [derived-in-model] This is a model-internal story for the thermodynamic arrow, distinct from how relativistic time and ordering arise from the causal graph. Treat it as a derivation within the model, not a settled theorem about why our universe's time runs one way.