  We show that the canonical purification of an evaporating black hole after
the Page time consists of a short, connected, Lorentzian wormhole between two
asymptotic boundaries, one of which is unitarily related to the radiation. This
provides a quantitative and general realization of the predictions of ER=EPR in
an evaporating black hole after the Page time; this further gives a standard
AdS/CFT calculation of the entropy of the radiation (without modifications of
the homology constraint). Before the Page time, the canonical purification
consists of two disconnected, semiclassical black holes. From this, we
construct two bipartite entangled holographic CFT states, with equal (and
large) amount of entanglement, where the semiclassical dual of one has a
connected ERB and the other does not. From this example, we speculate that
measures of multipartite entanglement may offer a more complete picture into
the emergence of spacetime.
