Page states what unitarity requires of the radiation
Don Page pointed out that if evaporation is unitary, the entanglement entropy of the emitted radiation must rise while the hole is large, turn over at roughly the halfway point, and return to zero when the hole is gone. Hawking's calculation produces a curve that only rises. The Page curve turned a philosophical disagreement into a quantitative target: any proposed resolution has to reproduce a specific shape, and for twenty-six years none did from within gravity itself.
Historical — it happened, and the record is settled.
Subjects
- The black hole information paradox · concept · not located
- Black hole entropy · concept · not located
Evidence
Partly verified — Core facts are sourced; some optional detail is deliberately absent.
Information in black hole radiation
States the entanglement-entropy behaviour that unitary evaporation requires, now known as the Page curve. V55 VERIFICATION BASIS: not consulted in session; no research tool was available. Volume and page are from recall and must be checked. The 2019-2020 island and replica-wormhole papers that reproduce this curve are deliberately NOT cited anywhere in this pack, because their authors and venues could not be confirmed.
Physical Review Letters · 1993 · Partly verified
Don N. Page, Physical Review Letters 71, 3743 (1993)
Recorded on The black hole information paradox
Related
Related because they share a subject in the Atlas — never because the text looks similar.