Physicist Ann Nelson broke barriers—for herself and for those who’d come after her

Physicist Ann Nelson broke barriers—for herself and for those who’d come after her thumbnail

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When Ann Nelson died in a tragic hiking accident in 2019, the loss went far beyond the pain felt by her many mentees in physics, myself among them. Her death was a devastating blow to the entire theoretical Physics community. She was a brilliant thinker. Nelson spent her career at the edge of particle Physics, imagining the universe and never worrying about whether her questions were too strange. When I eulogized her for Quanta, I wrote about how she described her approach to new ideas: put the purple scarf on the moose and worry later about why it’s there. Nelson also acknowledged that her achievements had given her social capital. She used that to make physics a place where everyone could call home.

Born in Louisiana in 1958, Nelson spent the bulk of her childhood in California. She decided to become a physicist. Although there were many people who discouraged her, such as high school teachers and classmates, she didn’t let that stop her from becoming a physicist. She knew the field was her intellectual home. This interest led her to Stanford University, then Harvard. She earned her Ph.D. there and was made a Junior Fellow of Harvard’s Society of Fellows. This is a prestigious lifetime membership that grants scholars three years of support for their independent research. Nelson returned to Stanford in 1987 as the first female tenure-track professor in the physics department, following in the footsteps of Helen Quinn, who was the first at nearby Stanford-affiliated federal lab, SLAC, in 1979.

She once said to me that Stanford people were too concerned about this superlative. Despite the university community’s apparent willingness for it to brag about breaking this barrier it didn’t keep her. She eventually went to University of California San Diego to live with David Kaplan, a fellow theoretical physicist. They moved to Washington where they created a life and a remarkable legacy.

Over the years, Nelson made significant contributions to particle physics in a variety of areas. Her work focused on gaps and inconsistencies within the standard model, which is the math that elegantly describes all we have seen in a laboratory (except gravity). The model, however, contains a prediction about neutrons that does not match what particle physicists have seen in experiments; as Ph.D. candidate at Harvard in 1984, Nelson published a mathematical solution to this tension–a singular achievement for a scholar who had not yet completed her Ph.D.

Part of what makes that first publication notable is that she had no ego about it. She didn’t attach herself to ideas just because they were hers, but she was more concerned with whether they were interesting or plausible. Because of that, she’d go on to publish another alternative answer to that same issue, which is known as the Strong CP problem. And she’d publish a solution to yet another of the field’s biggest puzzles: how the idea of supersymmetry–a notion that there should be a set of new particles that are partners to the known particles, a concept that impacts astrophysics and cosmology, including, potentially, the dark matter problem–might work in our universe.

In 2018, she and theoretical physicist Michael Dine shared the J. J. Sakurai Prize for Theoretical Physics, one of the most prestigious awards in the field. The prize citation notes the pair’s “groundbreaking explorations of physics beyond the standard model of particle physics.” Nelson’s Ph.D. advisor, Howard Georgi, himself a prominent theoretical physicist and Harvard Society Fellow, understood her singular intellect, writing in his Physics Today remembrance: “Ann was the only student I ever had who was better than I am at what I do best, and I learned more from her than she learned from me.”

Nelson loved Physics, but she didn’t just enjoy her academic success. She was conscious of social injustice and was the only UW physics professor to wear a Black Lives Matter pin every day in her final years.

This was not a performative act, but one part of a multi-pronged strategy to create better conditions for Black people and other marginalized folks who shared her love for physics. Nelson realized that her intellectual prowess was what had allowed her to get through a door that was closed for most. Many of her Ph.D. students and postdocs were women from a variety of racial, national and ethnic backgrounds. My experience is that, even though she made mistakes, she worked hard to ensure that we had the same freedom as her. She not only hired marginalized scholars to her own group, but she also chaired the UW graduate committee and fought for institutional changes.

In the wake of her passing, the UW Physics department embarked on a hiring spree for particle theory researchers that included several women. Although none of them could replace her, I am certain she would agree that it isn’t the point. Every woman in physics can be her own person and, given a space of her own, could radically alter our understanding of the universe.

Chanda Prescod-Weinstein

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