  A coarse-grained description for the formation and evaporation of a black
hole is given within the framework of a unitary theory of quantum gravity
preserving locality, without dropping the information that manifests as
macroscopic properties of the state at late times. The resulting picture
depends strongly on the reference frame one chooses to describe the process. In
one description based on a reference frame in which the reference point stays
outside the black hole horizon for sufficiently long time, a late black hole
state becomes a superposition of black holes in different locations and with
different spins, even if the back hole is formed from collapsing matter that
had a well-defined classical configuration with no angular momentum. The
information about the initial state is partly encoded in relative
coefficients---especially phases---of the terms representing macroscopically
different geometries. In another description in which the reference point
enters into the black hole horizon at late times, an S-matrix description in
the asymptotically Minkowski spacetime is not applicable, but it sill allows
for an "S-matrix" description in the full quantum gravitational Hilbert space
including singularity states. Relations between different descriptions are
given by unitary transformations acting on the full Hilbert space, and they in
general involve superpositions of "distant" and "infalling" descriptions.
Despite the intrinsically quantum mechanical nature of the black hole state,
measurements performed by a classical physical observer are consistent with
those implied by general relativity. In particular, the recently-considered
firewall phenomenon can occur only for an exponentially fine-tuned (and
intrinsically quantum mechanical) initial state, analogous to an entropy
decreasing process in a system with large degrees of freedom.
