Don N. Page

Don Nelson Page was born in 1948 in Bethel, Alaska, where his parents were teachers in a Yup'ik village, and grew up partly in rural Alaska. He studied at William Jewell College and took his doctorate at Caltech in 1976 under Kip Thorne, with significant guidance from Stephen Hawking, whose work on black-hole radiation was then at its height. Page would become one of Hawking's closest scientific collaborators and, for a period, lived with the Hawking family while working with him in Cambridge.

Page's early work was technical and decisive: he computed the detailed particle-emission spectra of evaporating black holes, including the greybody factors that modulate the idealized thermal spectrum, and the rates at which holes of different masses lose energy. These calculations remain the standard reference for how a real black hole actually radiates and set bounds on primordial black holes from the observed gamma-ray background.

His most influential contribution came in 1993. Rather than argue in words about whether information is lost, Page asked a precise question: if evaporation is unitary, how must the entanglement entropy of the emitted radiation behave over time? Using general results about the entropy of subsystems of a random pure state, he showed it must rise, peak when about half the entropy has been emitted, and fall back to zero — the curve now universally called the Page curve. It converted a philosophical dispute into a quantitative prediction that any correct theory of evaporation must reproduce, and it became the target that the 2019 island and replica-wormhole calculations finally hit.

Page has spent most of his career at the University of Alberta, working on quantum cosmology, the arrow of time, the measure problem in inflationary cosmology, and the foundations of black-hole thermodynamics. An evangelical Christian, he has also written on the relationship between physics and theology. His name endures in the everyday vocabulary of the field through the 'Page time' and the 'Page curve' — the moment and the shape that define what unitary evaporation must look like.