Wolfram Physics Q&A

In our model, many possible rules yield causally disconnected regions of spacetime, often corresponding to disconnecting parts of the spatial hypergraph. In addition, there can be disconnected regions of branchial space, corresponding to causally disconnected branches of quantum evolution. These kinds of non-communicating regions are still operating according to the same underlying rule. But rule-space relativity in our models suggests that even universes with different rules are equivalent to observers embedded within the universe, implying that there cannot meaningfully be “other universes” that somehow run in parallel to ours with different rules. There can be different forms of description for our universe that are incoherent with each other, but they are still describing the same universe. The only possibility in our model for “other universes” with fundamentally different rules is for these universes to perform computations at a higher level in the arithmetic hierarchy, i.e. hypercomputations. However, such universes would inevitably be disconnected from us, effectively separated by the analog of a cosmological event horizon.