Richard Garwin, who died on May 13, 2025, at the age of 97, was sometimes called "the most influential scientist you've never heard of." He got his Ph.D. in physics at 21 under Enrico Fermi - a Nobel Prize winner and friend of Einstein's - who called Garwin "the only true genius" he'd ever met.

A polymath curious about almost everything, he was one of the few people elected to the National Academy of Sciences, the National Academy of Engineering and the National Academy of Medicine for pathbreaking contributions in all of those fields. He held 47 patents and published over 500 scientific papers. A giant trove of his papers and talks can be found in the Garwin Archive at the Federation of American Scientists.

Garwin was best known for having done the engineering design for the first-ever thermonuclear explosion, turning the Teller-Ulam idea of triggering a fusion reaction with radiation pressure into a working hydrogen bomb - one with roughly 700 times the power of the Hiroshima bomb. He did that over the summer when he was 23. Over the decades that followed, he contributed to countless other military advances, including inventing key technology that enabled reconnaissance satellites.

Yet Garwin was also a longtime advocate of nuclear arms control and ultimately of nuclear disarmament. Working on nuclear deterrence and arms control, now at the Harvard Kennedy School of Government, I got to know Garwin as a tireless and effective participant in dialogues with scientists and current or former officials in Russia, China, India and elsewhere, making the case for steps to limit nuclear weapons and reduce their dangers.

Garwin was an early participant in the Pugwash Conferences on Science and World Affairs, which won the Nobel Peace Prize in 1995 for its disarmament work. He was also a founding member, in 1980, of the National Academies' Committee on International Security and Arms Control, where he continued discussing ideas for reducing nuclear dangers with foreign colleagues throughout his life.

The deep respect that top Russian and Chinese nuclear weapons scientists had for him was palpable - even though he was often blunt in telling them where he thought their arguments were wrong. Once, at a workshop in Beijing, after listening to the leader of China's program to develop nuclear "breeder" reactors lay out his program, Garwin started his remarks by saying, "This is a poorly designed breeder program that will fail" - and then laying out why he thought that was the case.

Because nongovernment experts have a freedom to explore ideas that government negotiators lack, these kinds of dialogues played a key role in developing the concepts that led to nuclear arms control agreements and, I would argue, contributed to ending the Cold War. As an example, one committee team that included Garwin helped convince Chinese weapons scientists that their country had no more need for nuclear tests and should sign the Comprehensive Test Ban Treaty - which it did soon after the discussion.

Only weeks before his death, he and I and others participated in a Zoom meeting with Russian nuclear weapons experts discussing what initial steps should be taken if U.S.-Russian political relations improved enough for them to resume discussions of nuclear restraint and risk reduction.

Garwin's mind seemed to be interested in everything at once - and he had a wry sense of humor that could enliven a dry meeting. When I was directing a National Academies study about dealing with the plutonium from dismantled nuclear weapons after the Cold War, he would send an email with a penetrating insight on some issue in the study, followed by an equally long query about the parking arrangements for the meeting.

We put him in charge of assessing all the especially strange options for dealing with the plutonium. Once, while diagramming on a chalkboard the option of diluting the plutonium in the ocean, he drew the ship that would be doing the work and then began drawing many smaller vessels. Someone asked him what those were, and he said: "Oh, those are the Greenpeace boats."

Garwin's unbelievable energies focused on three broad areas: fundamental science, new technologies and advising the government.

In fundamental science, he made major contributions to the detection and study of gravitational waves, and he helped to discover what physicists call parity violation in the weak nuclear force - a discovery that was one of the building blocks for what is now the standard model of the fundamental forces of the universe.

In new technologies, beyond weapons and satellites, he played a key role in the invention of touch screens, magnetic resonance imaging, laser printers and the GPS technology that enables us all to get directions on our cellphones. He was a researcher at IBM from 1952 to 1993.

Garwin advised the government on panels ranging from the President's Science Advisory Committee, to the JASON panel of high-level defense advisers, to leading the State Department's Arms Control and Nonproliferation Advisory Board (now called the International Security Advisory Board). He made major contributions to thinking about problems ranging from antisubmarine warfare to missile defense. He was a pungent critic of the "Star Wars" missile defense program launched in the Reagan administration, pointing out the wide range of ways enemies could defeat it more cheaply. His range was remarkable: He was called on to offer ideas for capping the blowout of the Deepwater Horizon oil rig and on managing the COVID-19 pandemic.

His curiosity was not limited to important matters. Once, as I was sitting next to him waiting for a meeting to start, he told me that if you took a Superball - a small, extremely elastic rubber ball - and bounced it diagonally on the floor so that it bounced up onto the bottom of the table, it would bounce back onto the same spot on the floor and back into your hand. I said I didn't believe it for a minute - surely it would keep bouncing forward until it got to the other side of the table. He gave me an explanation I didn't fully understand, involving energy of forward motion being converted to torque, and then converted into energy of backward motion.

When I got home, I received an express package from him containing an article he'd written in the American Journal of Physics, titled "Kinematics of an Ultraelastic Rough Ball," with pages of equations explaining how this worked. The first figure in the paper is a stick-figure drawing of bouncing such a ball, with a footnote: "This was first demonstrated to me by L. W. Alverez using a Wham-O Super Ball." Luis Alverez was a Nobel Prize winner in physics.

Garwin's brilliance was obvious to all who encountered him and won him wide recognition. In addition to election to all three national academies, he was awarded the National Medal of Science in 2002 by President George W. Bush. In 2016, President Barack Obama awarded him the Presidential Medal of Freedom.

Amid all this activity, Garwin was a family man. His marriage to his beloved wife, Lois, lasted over 70 years, until her death in 2018. They have three children, five grandchildren and one great-grandchild.

The advances Garwin contributed to have enhanced our understanding of the universe and benefited millions of people around the world. And as dark as nuclear dangers may seem today, the world is further from the nuclear brink than it would have been if Richard Garwin had never been born.