Fig. 5: Extreme rays versus black hole evaporation.
In ref. 24 Page discusses black hole evaporation as a pure state in a box, divided into two parts: the black hole (whose size decreases in time) and radiation (which is complementary so its size increases in time). By Page's theorem29, the entropy of radiation in a random such state is the smaller of the two sizes, which gives the Page curve. A sliding division of a random multi-partite state into a black hole component (circled red) and radiation components effectively constructs flower graphs. In this figure time flows from left to right.
