Professor of Physics Tom Mehen is remembered as a pioneer in the field of nuclear and theoretical physics and an inspiring mentor who formed lasting connections with his students.
Mehen, 54, died Dec. 29 at his home in Chapel Hill.
“Tom was a brilliant theoretical physicist with a genuine passion for physics,” Lecturer of Physics Arya Roy wrote in an email to The Chronicle. “Whether it was a question from an introductory class like Physics 152 or a complex problem in quantum field theory, his area of expertise, Tom approached every problem with the same enthusiasm and rigor.”
Mehen’s research used effective field theory to describe particle structure, advancing the understanding of the strong nuclear force and unraveling the mystery of new “exotic hadrons” that had puzzled scientists. During his 22-year tenure at Duke, he revolutionized the fundamental understanding of how quarks combine to form particles, was presented with the Outstanding Junior Investigator Award in Nuclear Physics from the Department of Energy and garnered widespread respect within the physics community.
‘Always willing to learn’
Born in Honduras, Mehen moved to Virginia with his family at an early age. He received a bachelor’s degree in physics from the University of Virginia and a master’s degree and doctorate from Johns Hopkins University, later working as a John A. McCone Postdoctoral Scholar at the California Institute of Technology and a University Postdoctoral Fellow at The Ohio State University.
Mehen first joined Duke’s physics department in 2002 as an assistant professor and rose through the ranks to earn the professor title in 2016.
Mehen worked at the intersection of particle and nuclear physics, focusing on the strong nuclear force responsible for holding quarks together to create particles. His work specialized in effective field theories — elegant mathematical methods that simplify computationally complex tasks to describe how particles are structured.
Mehen’s most groundbreaking work focused on describing “exotic hadrons,” whose formation puzzled the scientific community. Particles like protons and neutrons are typically made up of two or three quarks, but a few years ago, particle colliders around the world began creating particles made up of combinations of four and five quarks. The structure and composition of these exotic hadrons amazed scientists, as their mere existence called for a new understanding of the strong nuclear force.
Mehen recorded these new understandings, using a combination of theoretical physics calculations and experimental data that allowed him to both explain and predict these particle structures.
In addition to being recognized as an outstanding researcher in his specialized field, Mehen also had broad knowledge across the scientific discipline.
“You could talk with him about almost any scientific problem, and he had his own deep insight into it,” said Berndt Mueller, James B. Duke distinguished professor of physics. “… That really is the kind of person I think we at Duke are looking for.”
Before his death, Mehen was collaborating with developers of a novel electron-ion collider that is being constructed at Brookhaven National Laboratory in Upton, New York. His research aimed to develop predictions on the data that would come from the facility and later assist in the actual data analysis.
He developed a robust body of work during his lifetime. A highly cited researcher with over 5,000 citations and many publications in high-impact journals, Mehen exhibited strong scientific rigor, and his colleagues believe his research will stand the test of time.
“Every ‘i’ was dotted, every ‘t’ was crossed,” Mueller said. “… And if he didn’t know the answer he wasn’t afraid to say so.”
Steffen Bass, Arts and Sciences distinguished professor of physics, agreed, noting that Mehen was “very humble” and “always willing to learn.”
‘The students loved him’
Beyond his academic contributions, Mehen was loved by his students, both the ones he mentored and the ones he taught in physics courses.
“While brilliance in physics doesn’t always translate to being a great teacher or mentor, Tom was a rare exception,” Roy wrote.
Roy described Mehen as an outstanding thesis adviser who shared a genuine care and “unwavering support” for his students. Roy recalled Mehen’s joy when Jie Hu, Graduate School ‘05 and ‘09 and Mehen’s first graduate student, defended her thesis, likening it to the pride he would feel “if his own daughter had earned a Ph.D.”
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For Marston Copeland, a fourth-year graduate student who was advised by Mehen throughout his doctoral program, Mehen was a great mentor who encouraged him to think outside the box.
“I thought the absolute world of Tom,” Copeland said. “I totally admired him in every way, as a physicist and as a mentor and as a friend.”
Copeland shared that Mehen’s advising style encouraged his students to “grow as individuals.” He recalled that Mehen fostered independent thinking among his students and allowed them to develop their own identity as scientists. Mehen ensured his students had a robust understanding of the physics concepts they were working with, asking difficult questions that “got to the heart of the matter.”
Inside the classroom, Mehen taught both introductory and high level graduate courses in physics. He was involved in the development of the University’s new introductory Physics 121/122 sequence, which was designed for non-physics majors in the Trinity College of Arts & Sciences and introduces students to calculus topics along the way.
According to Mueller, Mehen’s lecture style also appealed to both doctoral and undergraduate students. Mueller noted how “students loved [Mehen]” for his ability to deliver advanced, rigorous concepts in “a model of clarity” to make sure that his students succeeded.
‘Kind and generous’
“Tom was totally brilliant,” Copeland said, but “he never let his brilliance get in the way of how he treated people.”
Copeland recalled that while attending an international conference with Mehen, they walked past a basketball court, and he soon found himself shooting hoops with his adviser.
In fact, according to Bass, Mehen’s love for basketball earned him recognition in front of NBA Commissioner Adam Silver, Trinity ‘78 and current chair of Duke’s Board of Trustees, to whom he was introduced as “the best basketball player among the physics faculty.”
Mehen’s colleagues attested to his sense of humor and smart remarks, as well as his careful listening and thoughtful advice.
“Tom was a kind and generous person who left a lasting impression on everyone he met. He was selfless, loyal, and always willing to help,” Roy wrote. “… I will miss teaching with him, discussing physics and the simple pleasure of stopping by his office for a conversation about anything and everything.”
The department of physics held a service in Mehen’s memory Jan. 11 and will hold a memorial symposium at the end of the semester to further commemorate his impact on the field.
Ana Despa is a Pratt sophomore and an associate news editor for the news department.