Remembering Marshall Onellion

Current and emeritus professors, department alumni, and colleagues are encouraged to send thoughts and memories about Prof. Marshall Onellion, who passed away November 20, 2022. Please email your submission to Sarah Perdue (

View the department obituary

Robert Sundling

I first met Marshall Onellion in 1992 when I was a sophomore in high school. He was volunteering, teaching a Saturday Morning Physics class for high school students in the conference room of the Synchrotron Radiation Center (SRC) in Stoughton. I was one of about ten students who signed up that year.

I had no idea that this would affect every aspect of my life going forward.

Marshall didn’t think of us as “just kids.” He didn’t teach us “high school physics” but instead taught us modern physics, in great detail. He taught us quantum entanglement, special relativity, Josephson junctions, Feynman diagrams, and much more. When we didn’t have the mathematical background for something, he taught us that too. Students back at my school were just learning algebra while I was working with differential equations—calculating solutions and writing papers on the effects of varying the parameters of the Duffing equation. Any questions we came up with, however bizarre or complex, Marshall would answer thoughtfully, scientifically, and thoroughly. He was unlike anyone I’d ever met, and this way of dealing with problems gave me a whole different way to think about approaching the world. He taught not only facts but how to think scientifically. As he explained to me years later, he felt strongly that the goal of science education was not to teach students how to solve specific problems, but rather to teach a way of thinking. His goal was to teach a form of pattern recognition through practice. With this ability, students could approach complex, ill-defined, and previously unsolved problems and render them solvable by applying judicious simplification.

As my knowledge progressed, I’d try to invent scenarios to trip Marshall up, as sport. He’d respond in kind. He and I would seek out gaps in each other’s knowledge or logic and try to exploit them. It turned out that this would actually fill them. This became a competition and a challenge, and a lifelong friendship was formed. We’d pounce on any error the other made with pointed ridicule and lighthearted mockery, and this quickly expanded to topics beyond physics, keeping each other both sharp and honest.

By the time I started college at UW–Madison, because of my three years with Marshall I’d already had the equivalent of several years of college physics classes, along with the associated mathematical knowledge. As an undergraduate, I majored in mathematics but worked with Marshall in his labs at the SRC and on campus fabricating thin films of superconductors and designing and building equipment for his experiments. (He actually kept my name on the door of an office in the basement of Sterling Hall for years after I graduated, although he probably wasn’t supposed to.)

The summer after I graduated, Marshall told me one of his collaborators in Germany was looking for someone with my particular skills. Marshall asked if he could refer me. Not thinking much of it, I said sure. I figured nothing would happen. Instead, the opportunity was a perfect fit and this launched my career as a freelance computational mathematician specializing in physics. I’ve been at that ever since. If it wasn’t for Marshall, my life would have taken a very different path.

Marshall and I stayed close friends during the 30 years we knew each other, through life’s ups and downs. We’d talk frequently, oftentimes daily, occasionally over a meal but mostly on the phone. Every once in a while, one of us would make a misstep or encounter a difficulty in life, and the other was always there to figure out a way to set things right. Marshall was always willing to listen patiently to understand any problem, even problems far outside his area of expertise, asking questions to fill in any gaps in his knowledge, and he’d work with me to devise a potential solution. And I did the same for him.

When Marshall received the news of his cancer, advanced and untreatable, I told him that for once I had no suggestions and didn’t know what to say. He said there was only one thing to say: “L’chaim.”

To life!

L’chaim, Marshall. L’chaim.