Swimming in the Primordial Soup

Soren Sorensen has earned some impressive (and interesting) titles between joining the faculty in 1984 and retiring in 2021. Chancellor’s Professor and Head. Macebearer. Muffin Man. All have to do with his commitment to both science and the people he’s encountered during his pursuit of it. The last speaks to his innate ability not to take himself too seriously, despite a laudable career in nuclear physics that began in a 1960s classroom in Denmark.

Sorensen grew up in the suburbs of Copenhagen, where he took his first physics class in sixth grade and was immediately intrigued by the idea that physics deals with the most fundamental aspects of nature.

"Initially I wanted to become an astronomer, but when I started in college and realized that I could be a student at the Niels Bohr Institute and learn from the world-class researchers there, I became hooked on studying physics," he said.

He went on to earn both master’s (1977) and doctoral (1981) degrees at the institute, housed at the University of Copenhagen. During a postdoctoral appointment he spent a year at Oak Ridge National Laboratory, which brought him to East Tennessee. By 1984 he was an assistant professor on UT’s physics faculty.

Sorensen studies nuclear matter—the stuff that makes up all atomic nuclei—and how it behaves under extreme conditions in terms of temperature and density. His interest in the fundamentals of nature goes all the way back to the Big Bang and the state of the universe immediately after, known as the Quark Gluon Plasma. His contributions to research on this "primordial soup," as he calls it, won him election as a Fellow of both the American Physical Society and the American Association for the Advancement of Science.

Sorensen’s work also put him in the company of countless other scientists and students over the years, including the PHENIX collaboration at Brookhaven National Laboratory and ALICE at the Large Hadron Collider. Spending time with colleagues from all walks of life proved to be a bright thread in the tapestry of his research.

"An important lesson that my career taught me, that was not taught during my time in college, was the importance of positive personal interactions with my peers," he said. "Science is a wonderful combination of solitary contemplations and intense human interactions, and I have come to appreciate the importance of these human interactions more and more as my career progressed."

In 2000 Sorensen took on a new challenge as head of the physics department. For 12 years he handled committee assignments, tenure dossiers, development and all other tasks, large and small, required in the role. Sometimes that meant budget hearings with the dean. Sometimes it meant sharing birthday cake in his office with the physics staff. Reflecting on that period, he counts hiring "wonderful people" as his proudest achievement.

"In a maybe too simplistic way you can say that the only thing that really matters for a head is to hire, and to give tenure to, the right people," he said. "And I feel we did hire many great people."

Sorensen’s commitment to the personal—to actively looking for every person’s potential and nurturing their growth—fuels his dedication to diversity initiatives across all levels: from the whole of physics to individual research groups. His combined scholarship and leadership have not gone unnoticed. In 2016 UT named him Macebearer—the university’s highest faculty honor. Alongside that accomplishment are two Teacher of the Year Awards, equally important to him, bestowed by the department’s Society of Physics Students.

Sorensen has always loved being in the classroom, typically teaching the introductory honors course for undergraduates. His students not only learned about mechanics and thermodynamics but also earned T-shirts emblazoned with "I survived Soren’s freshmen honors physics class." He’s been known to wear one himself, as he’s quick to appreciate a good joke.

This was evident in 2003, when one of his hobbies—using computational tools to rank football teams—took on higher stakes. Sorensen was among the "Pigskin Pick’em" group across campus, ultimately ending up in a final showdown with The Daily Beacon’s sports editor, who extrapolated from Sorensen’s Danish heritage a relationship with all pastry items and dubbed him the "muffin man." Sorensen wasn’t bothered in the least. He enjoyed being part of the campus community beyond his role as a physicist and professor.

With his August 2021 retirement, he’ll have more time for football fanship and other hobbies. (He plans to improve his sports team ranking system with modern tools like artificial intelligence.) He has a stack of books he wants to read, and is working on a biography of his father, who died when he was a young child. The top priority, in keeping with his way of doing things, is people, especially his wife Dianna and their kids and grandkids.

"The oldest of the grandchildren is 21 and studying art at UT and the youngest is eight months old and studying how to progress from crawling to walking," he said.

That doesn’t mean Sorensen won’t be around the department. He plans to mentor graduate students and will have a lifetime of experience to offer them. No doubt he’ll teach them a storied career is built by engaging with, and supporting, other people.