  Black hole complementarity posits that the interior of a black hole is not
independent from its Hawking radiation. This leads to an apparent violation of
causality: the interior can be acausally affected by operators acting solely on
the radiation. We argue that this perspective is misleading and that the black
hole interior must be viewed as existing in the causal past of the Hawking
radiation, despite the fact that they are spacelike separated in the
semiclassical description. Consequently, no operation on the Hawking radiation
-- no matter how complex -- can affect the experience of an infalling observer.
The black hole interior and the radiation only appear spacelike separated in
the semiclassical description because an infalling observer's ability to access
complex information is limited; the chaotic dynamics on the horizon, as viewed
from the exterior, then converts any effect caused by such an observer to
information in the Hawking radiation which cannot be accessed at the
semiclassical level. We arrive at the picture described above by considering a
unitary exterior description in which the flow of information is strictly
causal, which we extend to apply throughout the entire history of black hole
evolution, including its formation. This description uses the stretched event
horizon as an inner edge of spacetime, on which the information inside is
holographically encoded. We argue that the global spacetime picture arises from
coarse-graining over black hole microstates, and discuss its relationship with
the exterior description.
