Lecture 5: Hawking's original paradox
In this lecture, we examined Hawking's original version of the information paradox by reading key parts of Hawking's paper "Breakdown of predictability in gravitational collapse".
Hawking argued that this computation of black-hole radiation suggested that the final state on future null infinity would be thermal. Moreover, he argued that this was to be expected since an observer at future null infinity would be forced to adopt a "principle of ignorance" about the degrees of freedom that fell into the black hole. By tracing over all possible states of this "hidden surface", the observer would thereby conclude that the final state was mixed.
