Michael Cohen

Michael Cohen, a co-founder of the Aspen Center for Physics (ACP), died June 30, 2024. He was 94.

After graduating Phi Beta Kappa from Cornell, where he studied with Mark Kac and was part of team that won the 1951 Putnam Competition, Mike did his Ph.D. and postdoctoral fellowship at CalTech under Richard Feynman, working on excitations in liquid helium. In an interview with the American Institute of Physics, Feynman, who’d go on to win the 1965 Nobel Prize in Physics, recalled how he’d given up on a particular set of calculations because he’d decided they were “too hard,” but Mike “found they weren’t as hard as I thought” and cracked them. On the strength of Feynman’s recommendation, Mike did a second postdoc with J. Robert Oppenheimer at the Institute for Advanced Study. Then – heeding the counsel of “Oppie” – he accepted a faculty position at the University of Pennsylvania in 1958.

Mike spent the next 66 years at Penn as an assistant, associate, full and, finally, emeritus professor. A condensed matter physicist, he studied the quantum mechanics of liquid helium, as well as ferroelectrics and phospholipid membranes. He particularly enjoyed leading a problem-solving seminar for physics graduate students preparing for the Ph.D. qualifying exam; for this work, he jokingly described himself as “the department’s Stanley Kaplan.”

In 1962, with George Stranahan and Robert Craig, Mike co-founded the Aspen Center for Physics (ACP). Mike’s initial role was to convince talented physicists to come to Aspen. His first big “get” came in 1963, when he recruited Hans Bethe, who headed the Manhattan Project’s theoretical physics division and would later win the Nobel. Over time, scores of other Nobel laureates have followed Bethe to the ACP, and hundreds of physicists who now seek to attend the summer program are turned away each year. “If I applied today,” Mike told Aspen magazine in 2002, “I doubt I’d be admitted.”

When the ACP became an independent nonprofit in 1968, Mike served as the first treasurer, keeping the books for six years. “With a physicist’s contempt for standard accounting procedure,” he remembered, “I invented a totally rational and simple bookkeeping system.” He surmised that at some point after he left the role – first to become vice president and then, for the ensuing 48 years, honorary trustee – “some auditor undoubtedly destroyed my creation.”

In addition to physics, mountaineering and rock-climbing were consuming passions for Mike, and the ACP sprung from his desire to merge the inner landscape of his mind with the outdoors. During his summers in Aspen, Mike always made time for the mountains. Indeed, he said he’d first imagined the ACP as “a bunch of physicists living in tents and exchanging thoughts when not fending off bears.” In 1963, with two other climbers, he completed the first ascent of the north face of Capitol Peak, a 14,137-foot summit that towers over Capitol Lake in the Maroon Bells-Snowmass Wilderness. Mike also blazed several rock-climbing routes near Aspen, and at least two still bear his name: Cohen’s Crown and, apropos of a physicist, Cohen’s Last Problem.

In retirement, Mike continued to climb into his late 80s, and he relished writing a classical mechanics textbook. Nothing would have made him happier than for you to refer your students to that textbook, which is available for free at:

https://www.physics.upenn.edu/sites/default/files/Classical_Mechanics_a_Critical_Introduction_0_0.pdf

Mike’s family requests that any donations in his honor be made to the ACP here. If you choose to give, you can notify Mike’s family of the donation by clicking the email notification box and entering cohena@omrf.org.

Alongside his three children and seven grandchildren, Mike’s proudest legacy was the ACP. And, ultimately, he was glad no one latched onto his initial idea of a tent city. When asked about it many years later, he laughed. “It never would have worked.”