Lecture 15: low energy tests and perspective on black hole information
In this lecture, we started by illustrating the physics of the principle of holography of information in flat space using a simple thought experiment. Consider a pulse that arrives at scri-+ near u = 0. We showed that using gravitational effects, and measuring correlations of fluctuations of the metric and dynamical fields, it is possible to completely characterize the pulse through observations near u -> -\infty before the pulse actually reaches scri-+!
This simple thought experiment also helps to illustrate other aspects of the physics including the nongravitational and classical limits in which usual notions of information-localization are recovered.
We then returned to a discussion of black hole information. The principle of holography of information is the converse of Hawking's principle of ignorance and so it implies a specific error in Hawking's original argument for information loss.
We then revisited the monogamy paradox. We showed that if one insists that the Hilbert space, in a theory of gravity, should factorize just as it does in a local quantum field theory, it is possible to construct a version of the monogamy paradox even in empty AdS
