Professor Emeritus Robert Kohn (1953-2026)

January 13, 2026

We are saddened to announce that Robert Kohn, Professor Emeritus of Mathematics, passed away yesterday after a long illness. "It would be difficult to overstate Bob's influence on our community," wrote Gérard Ben Arous, Dean of the Courant Institute School, "Since he first arrived as a postdoctoral fellow in 1979, Bob became a pillar of Courant and a bridge between our past and our present."

Sylvia Serfaty, Silver Professor of Mathematics, and Rustum Choksi, Professor of Mathematics at McGill University, have written an obituary which highlights some of Professor Kohn's many accomplishments. Thank you, Bob, for your decades of service to Courant and to the broader mathematics community. 

Robert Kohn passed away in the early morning of January 12, 2026, after a five-year battle with cancer.

Bob was an extraordinary mathematician, remarkable both for the depth of his scientific insight and for his rare ability to connect ideas and people across disciplines. After his undergraduate studies at Harvard, Bob completed his PhD at Princeton University in 1979 under the supervision of the geometric measure theorist Fred Almgren. He then spent his entire academic career at the Courant Institute of Mathematical Sciences, first as a two-year NSF postdoctoral fellow and then as a member of the faculty, rising to the rank of Silver Professor of Mathematics. Bob retired in 2022.

Early in his career, together with Luis Caffarelli and Louis Nirenberg, he proved the seminal result on the partial regularity of weak solutions to the Navier-Stokes equations. This work—now universally known as the Caffarelli–Kohn–Nirenberg theorem—has withstood the test of time and was recognized with the 2014 AMS Leroy P. Steele Prize for Seminal Contribution to Research. During these early years, Bob also made fundamental contributions linking geometric measure theory and the calculus of variations to problems in plasticity, thin films, and shape optimization.

He went on to become one of the pioneers of what is now commonly referred to as mathematical aspects of materials science, with groundbreaking work on cloaking, coarsening driven by energy-minimizing interface motion, composite materials and homogenization, epitaxial growth, interface motion laws, martensitic transformations, mechanical metamaterials, micromagnetics, polycrystalline plasticity, shape-memory materials, structural optimization, and the wrinkling of thin elastic sheets. Bob coined the term energy-driven pattern formation, the title of his plenary lecture at the 2006 International Congress of Mathematicians.

Beyond physics and materials science, Bob’s interests in the application of mathematics ranged widely across other fields, including connections to economics and finance. His influential work on two-person games—initially making connections with PDEs—naturally led him to the study of prediction with expert advice. His extraordinary ability to grasp the central idea of any scientific talk and synthesize it clearly for the audience (and often for the speaker themselves) was truly remarkable.

Bob worked tirelessly for the Courant Institute, serving as deputy director for many years and playing a central role in both the Master’s program in Mathematical Finance and curriculum development for that program as well as the undergraduate program. He was beloved by students at all levels at NYU and was one of the few mathematicians to receive the University’s Distinguished Teaching Award. Bob also dedicated himself to the broader mathematical community, most notably through his longstanding involvement with SIAM.

Yet to so many, Bob will be remembered above all as a uniquely generous and deeply supportive mentor. His generosity extended far beyond his own students and postdoctoral researchers to countless young mathematicians and colleagues throughout the field.  On his retirement in 2022, a conference was held at the Flatiron Institute: Applied Analysis: from the calculus of variations to materials science, finance and data science – a celebration of the science of Bob Kohn. It was an occasion for so many colleagues to show their profound appreciation and respect.

He was a singular force in applied mathematics, one who never declined an explicit or implicit request for help, insight, or guidance. At the same time, he was a singular force in life, again offering help, insight, and guidance to those around him. His influence on generations of mathematicians and scientists is truly remarkable. He will be deeply missed.

Our thoughts are with his beloved wife, Leslie Anker.