R. Stephen Berry, a pioneering University of Chicago scientist who spent his life making fundamental contributions across the fields of chemistry and energy policy, died July 26. He was 89.
Berry, the James Franck Distinguished Service Professor Emeritus of Chemistry and the James Franck Institute, was known as a “Renaissance scientist;” he made both experimental and theoretical discoveries across a wide range of areas within his discipline and beyond. Many of his research themes, including measuring electron affinities, understanding structural transitions in clusters of molecules, and creating the foundations of finite time thermodynamics, are today central pillars of the field. He was also an early pioneer in sustainable energy analysis, inspired by the pollution in 1960s-era Chicago.
“Stephen Berry’s work and ideas have greatly influenced the development of chemistry and related areas of science, and have helped shaped our scientific perception,” said Stuart Rice, the Frank P. Hixon Distinguished Service Professor Emeritus of Chemistry and Berry’s colleague and close friend for six decades. “He stands out as being the most original person I have known. He was undoubtably one of the most broad-ranging and influential scientists in the United States, and in the entire scientific world.”
Born in 1931 in Denver, Berry recalled an early fascination with science and chemistry; he and his friends scavenged through trash bins for beakers and flasks. He graduated from East High School in 1948, but it was winning a Westinghouse Talent Fellowship that pivoted the course of his life, inspiring him to attend Harvard for his undergraduate and graduate degrees in chemistry. He received his Ph.D. in 1956 and taught at Harvard and the University of Michigan, then spent four years as an assistant professor at Yale before moving to the University of Chicago in 1964, where he would spend the rest of his life.
From the beginning, Berry displayed a talent for seeing connections and exploring questions that would later become key areas of inquiry. “He had a nose for what was interesting,” Rice said. In early work, Berry carried out pioneering measurements of electron affinities—how tightly bound electrons are in atoms and molecules. These numbers became a fundamental part of modern chemistry.
He also invented the concept of “pseudorotation,” an odd formation of atoms that is common within some types of molecules, and important for understanding how certain processes in living organisms are carried out.
His later work led to the first observation of transient reaction intermediates of radicals, an in-between stage of chemical reactions that had previously eluded chemists. “The impact of that work was tremendously important,” said Donald Levy, the Albert A. Michelson Distinguished Service Professor Emeritus of Chemistry and Berry’s longtime UChicago colleague. “If you don’t understand these reactions, then you don’t understand some of the most interesting chemistry there is.”
Another part of his legacy is central contributions to the understanding of structural transitions in molecular clusters. “Molecules are not frozen entities; electrons and atoms move around, and their motions are correlated,” said Steven Sibener, the Carl William Eisendrath Distinguished Service Professor in Chemistry, who worked alongside Berry for many years. “You need this to understand everything from nanoparticles to catalysis to biochemistry. This was an extraordinarily tough problem, and he was a pioneer in realizing and elucidating those motions.”
One of Berry’s most seminal contributions was stimulating the development of a field now known as finite time thermodynamics, which helps describe the actions of systems in flux. Classic thermodynamics, which is more than 200 years old, uses a model system with idealized and often unrealistic assumptions; finite time thermodynamics offers a way to analyze motion, heat and power closer to the real world.
“When I was in graduate school, no one wanted to study thermodynamics because we thought all the questions had been asked and there was nothing left to be done,” Berry told UChicago News in 2019. “But my own work in finite time thermodynamics shows how silly and wrong we were. Science doesn’t close, and that’s part of the thrill.”
But in the mid-1960s, he would develop another passion: addressing pollution. In those days, Chicago was heated mainly by coal, and the results were everywhere. “Chicago was smoky and smelly, and there’d be a layer of gray dirt on your windshield each morning,” he recalled in an interview last year. He wrote a letter of complaint to Mayor Richard J. Daley, which touched off a lifetime of interest in energy policy and sustainability.
Berry and scientist Margaret Fels created one of the first analyses of what came to be called life-cycle analysis—calculating the environmental and energy impact of a product all the way from the mining of its ingredients to how it’s recycled or disposed of. This is now part of the canon of energy policy.