Mathematical physicist
Professor & Associate Dean Emeritus, School of Mathematics
Georgia Institute of Technology
For fifty years I have been asking a stubborn question: what does the spectrum of a differential operator know about the shape of the world it lives on? Lately I have also been trying to get that question out of the seminar room and onto a stage.
I was born in Indianapolis in 1950, studied at Stanford, and took my doctorate at Princeton in 1976 under Barry Simon, writing on Schrödinger operators with singular perturbation potentials. What followed was the usual itinerant decade — postdoctoral and teaching positions at Haverford, the University of Vienna, and MIT, then a tenure-track post at Johns Hopkins — before I came to Georgia Tech in 1983 and, somewhat to my own surprise, stayed.
My research is on the Schrödinger equation, which describes nonrelativistic matter at the atomic scale, and on differential equations that behave like it. The thread running through all of it is the relationship between geometry and spectrum. Hang a drum and you can hear its shape; the mathematical version of that idea — how the eigenvalues of an operator encode the geometry of the space beneath it — has kept me occupied for five decades and shows no particular sign of running out.
Along the way I have supervised eight doctoral dissertations and two master's theses, and written papers with something upward of thirty-five coauthors, which I consider the better statistic of the two. From 2005 to 2014 I served as Associate Dean for Research in the College of Sciences, and before that I looked after the graduate programs in the School of Mathematics. I am now emeritus, which has turned out to mean the same work with fewer meetings.
Somewhere in the middle of all this I became convinced that mathematics is a performing art that has simply forgotten to book a venue. With that in mind I co-founded Mathematics in Motion, a production company that puts mathematics on stage — at the Atlanta Science Festival, at Mathapalooza, and in a piece called The Seven Bridges of Königsberg that turned Euler's 1736 walk around a Prussian city into music and dance and set it loose on the Georgia Tech campus.
The same impulse has taken me to lecture halls in Benin, Senegal, Mali, and Tunisia, and once to a street corner in Atlanta doing what we called guerrilla math. In 2025 Science ATL gave me the David B. Hartnett Award for Public Engagement with Science, which I choose to read as encouragement. I remain of the view that the difference between a research seminar and a street performance is mostly a question of lighting — and there is a whole page about that.
Travel, world cultures, and science–arts partnerships, in roughly that order and often all at once. A conference in Kairouan becomes a week in the Tunisian interior; a lecture series in Dakar becomes an argument about music with a taxi driver. I have taken part in scientific meetings and teaching programs across the developing world, and I have never once regretted the detour.
When there is no conference to justify the trip, there is usually a trail. My wife Mo and I are happiest somewhere with bad cell service.
The opinions on these pages are my own, or else satirical, or honest errors. — a standing disclaimer, kept from the old site