Karl Strauch was born in Giessen, Germany, in 1922, where his father, George Strauch, was a Lutheran minister and his mother, Carola, was a divinity school graduate and the daughter of famed German writer Alfred Bock. George died only weeks after Karl was born, and Carola later began a relationship with Hans Lachmann-Mosse, the head of the Mosse publishing empire. Hans was exiled by the Nazis after they came to power in 1933, and Carola and Karl joined him in Paris after he and his wife, Felicia Lachmann-Mosse, divorced following their expulsion. Carola and Hans married soon after, and Karl enjoyed a warm relationship with his new stepfather. In turn, Carola and Karl were welcomed into the family by Hans’ children Hilde, Rudolf, and George. While the blended family was separated at different educational institutions in Europe and later settled in different areas of America, they remained in close contact and corresponded regularly.

While in Paris, Karl attended and graduated from high school, and he continued his studies in chemistry at the University of California, Berkeley, when the family immigrated to America in 1939. He was drafted into the American Navy after he graduated in 1944, and served as a radio instructor at Naval Station Treasure Island in San Francisco Bay, surprising many of his fellow Navy men with his German accent. Following his discharge in 1946, Karl returned to Berkeley and graduated with a PhD in physics in 1950. That year, he was elected to Harvard’s Society of Fellows and was later promoted to assistant professor of physics in 1953, associate professor of physics in 1957, professor of physics in 1962, and the George Vasmer Leverett Professor of Physics in 1975, ultimately retiring in 1993 with emeritus status. He also served as Chairman of the Harvard Physics Department from 1978-1982.

Karl was an experimental physicist whose research focused on the fundamental structure of matter in an attempt to discover the basic building blocks of nature. He conducted his research using giant accelerators, first at Harvard’s Cyclotron, then at Brookhaven’s Cosmotron, and later at the Cambridge Electron Accelerator (CEA), a joint venture between Harvard and MIT. His work there produced some of the earliest evidence for the existence of quarks, an elementary particle that had been theorized but not yet seen. Karl became the director of the CEA in 1967, overseeing a period of transition for the laboratory after it had been badly damaged in an explosion. Under his leadership, the accelerator was repaired and restored to full operation. Karl also undertook experiments at accelerators in Europe to investigate electron-positron collisions and interactions. He co-authored over 150 scientific papers over the course of his career, and was a highly influential member of the US-USSR Joint Coordinating Committee on Fundamental Properties of Matter, which was the chief conduit between the American and Soviet scientific communities during the Cold War.

At Harvard, Karl was a beloved professor whose warm and enthusiastic teaching style resonated with the generations of students who attended his lectures. He taught the university’s introductory electricity and magnetism course for physics majors, and regularly invited small groups of students to his home for dinner and informal discussions on physics. Beyond his teaching and research, Karl was also  involved in two major developments that significantly impacted the culture of Harvard. In 1975, he chaired the committee that recommended the merger of Harvard and Radcliffe’s admissions offices and the institution of an admissions policy of equal access for women, which ultimately began in 1980. He also chaired the committee effort to build and establish the Science Center, the first multi-disciplinary science building in the College, and continued as the chair of the Faculty Executive Committee that oversaw the operation of the Science Center from its opening in 1972 until 1975. 

Karl married Maria Gerson in 1951, and she became a commercial artist in Boston. The couple had two children, Roger and Hans, who now head The Mosse Foundation. Karl passed away in 2000, leaving behind a lasting legacy of scientific achievement and cooperation.