2020 Nobel Prize Lectures in Physics

How can black holes be established both as a consequence of gravitational theory and as objects in the sky? Roger Penrose examines the mathematical development of gravitational collapse and space-time singularities, explaining why black-hole formation does not depend on perfectly symmetric idealisations. Reinhard Genzel and Andrea Ghez trace the observational effort to establish a massive compact object at the centre of the Milky Way. Their accounts connect infrared observations, improvements in imaging through atmospheric distortion, and long-term measurements of stellar motions around Sagittarius A*. Together, the lectures present the theoretical and observational foundations of the 2020 physics prize: the robustness of black-hole formation in general relativity and the evidence for the Galactic Centre’s supermassive black hole.