My description there was pretty crude, apologies. The measurement problem is often loosely expressed in terms of metaphors like "live cat vs dead cat". But if y

My description there was pretty crude, apologies. The measurement problem is often loosely expressed in terms of metaphors like "live cat vs dead cat". But if you actually look at the quantum state of such a complicated system, it's this huge tangled mess of Hilbert dimensions lumped together into one big global wave function. The "alive vs dead" separation is just one possible perspective (technically it's a slicing of the Hilbert space into mutually orthogonal sub-spaces). There are infinitely many possible such ways of splitting the space up, i.e. infinitely many possible basis sets. It's not directly clear why, when we physically interact with the system, one specific basis is chosen for us to "collapse" into one branch of. Perhaps it could be better explained as "there's nothing to suggest which branching the agent will experience splitting into". I should note that the process of decoherence goes some way towards removing this obstacle (although not the following question of explanation of probabilities).