Robert M. Wald

Robert M. Wald (; born June 29, 1947, in New York City) is an American theoretical physicist and professor at the University of Chicago. He studies general relativity, black holes, and quantum gravity and has written textbooks on these subjects.

Life and education He is the son of the mathematician and statistician Abraham Wald and great-grandson of the chief rabbi Moshe Shmuel Glasner. Wald's parents died in a plane crash when he was three years old. He earned his bachelor's degree from Columbia University in 1968 and his PhD in physics from Princeton University in 1972, under the supervision of John Archibald Wheeler. His doctoral dissertation was titled Nonspherical Gravitational Collapse and Black Hole Uniqueness.

Career and contributions Between 1972 and 1974, Robert Wald worked as a research associate in physics at the University of Maryland.

In 1977, Wald published a popular-science book titled Space, Time, and Gravity: The Theory of the Big Bang and Black Holes explaining Albert Einstein's general theory of relativity, and its implications in cosmology and astrophysics. The book also gives a survey of what was then ongoing research on gravitational collapse and black holes. This book grew out of a series of lectures Wald gave as part of the Compton Lectures at the University of Chicago in the spring of 1976. The Compton Lectures, given every Spring and Fall quarter, are intended to explain notable advances in the physical sciences to members of the general public.

He published the textbook General Relativity in 1984. Aimed at beginning graduate students, it covers spinors, the variational principles, the initial-value formulation, (exact) gravitational waves, singularities, Penrose diagrams, Hawking radiation, and black-hole thermodynamics. It is well-received, but has become outdated by the early twenty-first century.

Wald has taught first-year graduate courses covering a broad range of topics, including classical mechanics, quantum mechanics, statistical mechanics, and electromagnetism. He has also taught courses on general relativity, his specialty, at both introductory and advanced levels. A particularly effective teacher, he received the Graduate Teaching Award from the University of Chicago in 1997.

Wald investigates black holes and their thermodynamics, and gravitational radiation-reaction (or self-force). and subsequently the perturbations of black holes, following the publication of the Teukolsky equations by Saul Teukolsky in 1972. In 1993, he described the Wald entropy of a black hole, which is dependent simply on the area of the event horizon of the black hole.

He organized The Symposium on Black Holes and Relativistic Stars in 1996, in honor of the late Nobel Prize-winning theoretical astrophysicist Subrahmanyan Chandrasekhar. Distinguished speakers of this event included Stephen Hawking, Roger Penrose and Martin Rees. Although the event charged an entrance fee of $100, Wald made sure all University of Chicago students were admitted free of charge. Although Wald and Chandrasekhar never collaborated on any particular research projects, the two developed warm relations. He received the Einstein Prize from the APS Division of Gravitational Physics in 2017 for "the discovery of the general formula for black hole entropy, and for developing a rigorous formulation of quantum field theory in curved spacetime."

Wald delivered a public lecture at the University of Alabama on October 27, 2015, titled "The Formulation of General Relativity," celebrating the centennial of Einstein's theory. Wald is a member of the LIGO group at the University of Chicago, headed by astrophysicist Daniel Holz. The Laser Interferometry Gravitational-wave Observatory detected gravitational waves for the first time in 2015, one century after Einstein predicted their existence.

In 2025 he received the Albert Einstein Medal from the Albert Einstein Society in Switzerland for his studies of classical and semi-classical gravity. In the same year, Wald, Gary Gibbons, Gary Horowitz, and Roy Kerr were awarded the Dirac Medal from the International Center for Theoretical Physics in Italy for their landmark contributions to the study of gravity, in both the classical and quantum regimes.

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