By Donald Gilpin

John Hopfield
(Princeton University; Office of Communications; Denise Applewhite,1999)

John Hopfield, a Princeton University professor emeritus in the life sciences and molecular biology with associated faculty status in physics and neuroscience, has won the 2024 Nobel Prize in Physics “for foundational discoveries and inventions that enable machine learning with artificial neural networks,” according to the Royal Swedish Academy of Sciences, which announced the award on Tuesday, October 8.

Hopfield, 91, who shares the award with Geoffrey E. Hinton of the University of Toronto, has made contributions that “have fundamentally changed the world,” said Princeton University Molecular Biology Department Chair Bonnie Bassler, as quoted in a Princeton University Office of Communications press release. Their discoveries in machine learning paved the way for current rapid advancements in artificial intelligence.

The prize amount is 11 million Swedish kroner, about $1 million, which the two prize winners share.

“John Hopfield’s brilliant scientific career has transcended ordinary disciplinary boundaries, enabling him to make lasting contributions to physics, chemistry, neuroscience, and molecular biology,” said Princeton University President Christopher L. Eisgruber. “His pathbreaking research on neural networks, for which he is honored today, exemplifies beautifully the power of curiosity-driven research to advance the frontiers of knowledge and create new tools for addressing some of the world’s most profound challenges.”

The Swedish Academy noted that Hopfield “created an associative memory that can store and reconstruct images and other types of patterns in data.”

Praising Hopfield’s “groundbreaking” work, Bassler noted, “John’s discoveries show how research at the interface of disciplinary boundaries can transform our understanding of nature and deliver practical applications that benefit society.”

She continued, “John combined physics, biology, and neuroscience approaches to probe the brain, developing neural networks to explain how the brain recalls memories. Those discoveries led to the creation of artificial neural networks that are now routinely used by machines like smartphones and self-driving cars.”

Mala Murthy, director of the Princeton Neuroscience Institute that Hopfield helped to establish, described him as “a foundational figure in the creation of neuroscience at Princeton.” She pointed out that his work “paved the way for the deep learning revolution that has now touched nearly every aspect of society.”

James Olsen, Princeton University Physics Department chair, added, “John is a visionary scientist who transcended boundaries and illuminated the deep connections between theoretical physics and a wide range of phenomena across myriad fields of science. As a member of the physics department in the 1960s and ’70s, John was a passionate teacher and mentor to generations of undergraduate and graduate students inspired by his brilliance and unique approach to studying nature.”

At a press conference held Tuesday afternoon in Taylor auditorium on campus, Hopfield joined in remotely from his summer home in England. He spoke about the importance of breaking down traditional boundaries between departments and the discoveries that can be made in the spaces between disciplines.

He also commented on the risks of artificial intelligence. “When you get systems that are rich enough in complexity and size they can have properties which you can’t possibly intuit from the elementary particles you put in there,” he said. “You have to say the system contains some new physics.”

He continued, “One is accustomed to having technologies which are not singularly only good or bad, but have capabilities in both directions.”

In his opening remarks, Eisgruber said that for Nobel Prizes “the world stops for a moment and recognizes the special importance of fundamental research and scholarship. I think here at Princeton University, we have a tradition of celebrating these prizes the way that some universities celebrate national athletic championships.”

For more information on Hopfield and Hinton and their prize-winning accomplishments, visit nobelprize.org.