Islands in Schwarzschild black holes

Understand

We study the Page curve for asymptotically flat eternal Schwarzschild black holes in four and higher spacetime dimensions.

• Before the Page time, the entanglement entropy grows linearly in time.
• After the Page time, the entanglement entropy of a given region outside the black hole is largely modified by the emergence of an island, which extends to the outer vicinity of the event horizon.
• As a result, it remains a constant value which reproduces the Bekenstein-Hawking entropy, consistent with the finiteness of the von Neumann entropy for an eternal black hole.