We sadly report the passing of Niall O’Murchadha on October 7th 2021, after a short illness. Niall is survived by his wife, Donna, and sons Niall and Aongus, who have our deepest condolences for their loss.
After completing his degree in Physics at University College Cork, Niall left for Princeton, where he obtained his PhD in 1973 under the supervision of James York. He spent time at Cardiff University before returning to UCC in 1976. Over the following years, Niall became well known internationally for his important contributions to the initial value problem for the Einstein equations, in particular their elliptic part, the constraint equations. In recent decades he was in great demand as different groups struggled to solve the Einstein equations using supercomputer simulations and many sought his expertise. After these simulations became possible, he made key contributions to understanding the geometrical properties of the black-hole solutions. During these years he acted as a crucial bridge between mathematical and numerical relativists.
Niall was an influential mentor, brilliant collaborator and the best of good company throughout his life. He enlivened every conference or workshop he attended, and was an irrepressible catalyst of new research projects. He showed an intense interest in the work of everyone he met, no matter how junior or senior, and built up a group of collaborators from all over the world. These collaborations, some spanning four decades, led to important works such as, to name just a few, the boost theorem (with Christodoulou), investigation of the cosmic censorship hypothesis, results on trapped surfaces, and slicings of relativistic spacetimes.
In 2018 many of Niall’s friends and colleagues came to Cork to attend Niall Fest, a small conference held in his honour. It was the most eloquent testimony to his many wonderful personal qualities that so many colleagues made the trip to Cork, something which meant a great deal to him. The formal agenda of the meeting closed with a session in which Bob Wald, Bill Unruh and Kip Thorne spoke, and in which Niall himself gave a bravura performance, extemporizing a highly technical talk at the blackboard.
An inspirational teacher and supervisor of postgraduate students, Niall was also passionate about the Irish language, and proud of his Cork roots. His good company will be sadly missed by his many colleagues and friends in UCC, including those in an Seomra Caidrimh, a room set aside for Irish speakers in the college. And his relativity colleagues will miss the highlight of every conference, a chance to hear Niall’s latest stories and his most recent enthusiasms, and to seek his always insightful opinion.
Robert Beig, Paul Callanan, Mark Hannam, Bryan Kelleher, Daniel Kennefick, Edward Malec.