The AIXI thing was a joke; a Bayesian update on low-level physics with unknown initial conditions would be superexponentially slow, but it certainly isn’t uncomputable. And the distinction does matter—uncomputability usually indicates fundamental barriers even to approximation, whereas superexponential slowness does not (at least in this case).
The AIXI thing was a joke; a Bayesian update on low-level physics with unknown initial conditions would be superexponentially slow, but it certainly isn’t uncomputable. And the distinction does matter—uncomputability usually indicates fundamental barriers even to approximation, whereas superexponential slowness does not (at least in this case).