Complementarity plus backreaction is enough

We investigate a recent development of the black hole information problem, in which a practical paradox has been formulated to show that complementarity is insufficient. A crucial ingredient in this practical paradox is to distill information from the early Hawking radiation within the past light cone of the black hole. By causality this action can backreact on the black hole. Taking this backreaction into account, the paradox could be resolved without invoking any new physics beyond complementarity. This resolution requires a certain constraint on the S matrix to be satisfied. Further insights into the S matrix could potentially be obtained by effective-field-theory computations of the backreaction on the nice slice.