  A state selected at random from the Hilbert space of a many-body system is
overwhelmingly likely to exhibit highly non-classical correlations. For these
typical states, half of the environment must be measured by an observer to
determine the state of a given subsystem. The objectivity of classical
reality-the fact that multiple observers can agree on the state of a subsystem
after measuring just a small fraction of its environment-implies that the
correlations found in nature between macroscopic systems and their environments
are very exceptional. Building on previous studies of quantum Darwinism showing
that highly redundant branching states are produced ubiquitously during pure
decoherence, we examine conditions needed for the creation of branching states
and study their demise through many-body interactions. We show that even
constrained dynamics can suppress redundancy to the values typical of random
states on relaxation timescales, and prove that these results hold exactly in
the thermodynamic limit.
