I am sad to announce the death of James W. York (Jimmy) on Dec 17th 2023,. He was 84 years old. Jimmy was famous for his classical work on the formulation of the initial values problem in general relativity. This work was essential for enabling numerical solutions of Einstein equations. Among his other contributions is the formulation of a quasi-local energy and the concept of the boundary quasi-local stress-energy-momentum tensor, which is known as the Brown-York tensor.
James W. York joined the faculty of Princeton University after graduating from North Carolina State University. In 1973, he joined the University of North Carolina faculty at Chapel Hill, where he spent most of his career. After retiring from North Carolina, he joined Cornell University and then North Carolina State University. More on his work and achievements can be read in the dedication to his 2003 Danne Heineman Prize for Mathematical Physics https://www.aps.org/programs/honors/prizes/prizerecipient.cfm?first_nm=James&last_nm=York&year=2003
Tsvi Piran