If we return again to the situation of molecules in a gas, we can say that we form equivalence classes in which we look only coarsely at the positions of molecules, in “Buckets” defined by simple, bounded computations—and we don’t look at their finer details, with all the computational irreducibility they involve. And it’s because of this way of looking at the system that we conclude that it follows the Second Law of thermodynamics, exhibits fluid behavior, etc.
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We’ve discussed how “observers like us” perceive models of physics of the type that arise in our Physics Project. But how will we perceive the whole ruliad? It begins with a generalization of the story for branchial space. Because now as well as having different branches associated with different updatings according to a particular rule, we have different branches associated with updatings according to different rules. page 