Short Nature letter announcing the original result: quantum effects cause black holes to emit particles with a thermal (blackbody) spectrum and to lose mass, implying they are not perfectly stable but evaporate — the first statement of what became “Hawking radiation.” Precedes the full derivation in Hawking 1975 (Commun. Math. Phys. 43). relevance_note: original public announcement of the mechanism (evaporation) Premise A of the safety case entirely depends on.