On October 18, 2003, my colleague in the department and former collaborator, Henry Emil Kandrup, passed away unexpectedly of a heart attack in his apartment at the age of 48. This was a grievous loss for all of us in the department, both professionally and personally.


Some time later, on December 6, a memorial service was held to celebrate Henry’s life. It was attended not only by faculty, staff, and students from the Astronomy Department and as many of Henry’s former students as could be present, but also by members of the physics and mathematics departments who had known him as well as friends. (Henry held a joint appointment in the Institute for Fundamental Theory in the Physics Department.) The location was the Baughman Center on the University of Florida campus, a beautiful structure of wood and glass described as a modern interpretation (on a modest scale) of the soaring Gothic cathedrals*; to my mind, and more appropriately considering Henry’s Danish origins, it at least as much resembles a transparent version of the stave churches of Scandinavia. It sits literally by the side of Lake Alice, a pond in a quiet area away from the main part of campus. The day was cold but bright and sunny.


On this occasion several of us who had known Henry made statements about him. As far as I know these were not recorded. However, I was speaking from an outline and followed it more or less. Here I will try to approximately reproduce what I said that day, with a few slight embellishments. I’m sure my recollection of what I said will not correspond exactly to other people’s; I hope that does not matter. I had hoped to sit down and write this sooner after the event but was unable to.


*****


When I learned that Henry Kandrup would be joining our department in 1990 I was delighted. I already knew something about Henry’s work through a conversation with Jim Ipser in Physics, who had been Henry’s Ph. D. supervisor. [He spoke about that experience at the service.] It was clear that Henry would be a tremendous asset to the department – as indeed he was – and because of our common interest in the gravitational N-body problem he would be very helpful for my work in particular. It was not long before we had begun a collaboration that would span several years, one that produced six papers, four of them in an Ap. J. series on the sensitivity of N-body numerical integrations to initial conditions.


What I brought to the collaboration was experience with the integrations and statistical methods for analyzing integrated N-body systems as well as familiarity with the astronomical literature on that subject. I thought in terms of the deleterious effects of the unavoidable integration errors and their exponential growth , originally discovered by Dick Miller at Chicago, on individual orbits, but Henry made me aware of the broader context and the connection between chaos (of which the exponential growth was the signature) and mixing and so-called violent relaxation. For his part Henry brought what seemed to me to be a vast knowledge of physics and nonlinear dynamics. Also, he knew a lot more people than I did, including all the major players in related subjects and what they were doing. He frequently traveled to specialist meetings and was several times a co-organizer of the Florida Workshop on Nonlinear Dynamics. Every year Henry especially looked forward to going to Aspen for a summer workshop, where he could immerse himself in science and mix with the other top people without any of the usual distractions of academia. It was the high point of the year for him. (Being summer, it was also not quite so expensive as usual!) We worked together with various of Henry’s students, some of whom are speaking today.


In our work Henry always aimed at a profound understanding of the physics and clarification of the important outstanding issues. He was never content with descriptive or superficial approaches, which are great temptations when dealing with the N-body problem, especially among astronomers. Nor was he reticent in criticizing erroneous ideas regardless of the consequences. Henry was unfailingly scornful of bandwagons, both in public and privately. On occasion this antipathy would bring out his mischievous streak, prompting a caustic comment or two. (This aspect of his personality may be seen in some of his likenesses: a certain impish expression may be seen on his face.) He was outwardly very much an individualist, which was just as true of his inner self. The motivation for his individualism was not a mere desire to stand out from the crowd but rather his total commitment to the highest standards of scientific practice. He was dedicated to the advancement of the science and often expressed to me his concern that stellar and galactic dynamics was suffering from an unhealthy excess of simulation without deep theoretical understanding. Although as I have indicated much of my experience was with simulation, viz. N-body integrations, I tend to agree with his assessment.

 

Working with Henry on a paper was a revelation. He could produce overnight a polished draft of a manuscript, written in an elegant but highly lucid style, that seamlessly incorporated the various contributions of the rest of us with his own. It was done with the seeming effortlessness of the true professional. The stamp of his erudition was on every paper; the theory, the masterful discussion of the literature, and the assessment of the work’s place within the field were almost entirely his.


Of course I cannot speak first hand about Henry’s teaching – that is for his students – but I did serve on peer review committees with Henry a number of times, and we talked quite a bit about good and bad teaching. I know that, as with research, he had very high standards. I also know from conversations we had that he had high expectations of his students, which seemed to draw out the best from them. The success of his former students attests to that. He won awards for outstanding teaching everywhere he taught.


After several years our interests diverged, and I became involved with my present area of research. Henry and I still talked about dynamics and about the department, but less and less frequently. Then one day, with that characteristic mischievous expression, Henry announced to me that he was going to be doing experimental stellar dynamics. Naturally my reaction was puzzlement; after all, everybody knows you cannot do experiments with star clusters and galaxies in the laboratory! He went on to explain that he was collaborating with some physicists working with a particle accelerator and that they would be using the spreading of particles in beams as a test of mixing theory and relaxation. He was really enthusiastic about this new enterprise and anticipated great things from the collaboration. For the first time the simulation methods of stellar dynamics could be tested against real systems, with the confrontation as a crucial check on the theory. My hope is that despite this tragedy the collaboration will press ahead with this very important work.

 

Henry was a remarkable person in a number of ways, but foremost among those in my opinion was his commitment to science. It was the engine that drove his evident voracious appetite for knowledge and his fierce, uncompromising integrity. While most of us cannot approach his breadth and depth of knowledge, we can try to emulate the dedication that he exemplified, each in his or her own way. That might just be the most fitting way to honor his memory.


* For more views of the Baughman Center there are these photos taken by a former undergraduate student of mine who was married there.