  Recently, a coherent picture of the quantum mechanics of an evaporating black
hole has been presented which reconciles unitarity with the predictions of the
equivalence principle. The thermal nature of a black hole as viewed in a
distant reference frame arises from entanglement between the hard and soft
modes, generated by the chaotic dynamics at the string scale. In this paper, we
elaborate on this picture, particularly emphasizing the importance of the
chaotic nature of the string (UV) dynamics across all low energy species in
generating large (IR) spacetime behind the horizon. Implications of this UV/IR
relation include O(1) breaking of global symmetries at the string scale and a
self-repair mechanism of black holes restoring the smoothness of their
horizons. We also generalize the framework to other systems, including Rindler,
de Sitter, and asymptotically flat spacetimes, and find a consistent picture in
each case. Finally, we discuss the origin of the particular construction
adopted in describing the black hole interior as well as the outside of a de
Sitter horizon. We argue that the construction is selected by the
quantum-to-classical transition, in particular the applicability of the Born
rule in a quantum mechanical world.
