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Ann Nelson (1958–2019)

8 August 2019

Students and colleagues describe the impact of the theoretical particle physicist on their careers.

Ann Nelson in the mountains.
Photo courtesy of David B. Kaplan

Ann Nelson, a theoretical physicist at the University of Washington, Seattle (UW), died on 4 August in a hiking accident. She was 61 years old. Nelson leaves behind a legacy not only as an award-winning researcher but also as both a dedicated mentor and an unwavering advocate for diversity and inclusion in the physical sciences community.

Nelson’s focus on physics beyond the standard model included work on dynamical supersymmetry breaking, CP violation, and composite Higgs models. She was a recipient of the J. J. Sakurai Prize for Theoretical Particle Physics (2018) and a Guggenheim Fellowship (2004), and she was elected a member of the National Academy of Sciences and the American Academy of Arts and Sciences.

Ann Nelson.

Beyond her scientific accomplishments, Nelson stood out for her efforts to make the physical sciences a welcoming place for women, African Americans, Native Americans, Hispanic Americans, and others who have been long underrepresented in the field. In a 2017 Physics Today commentary, she challenged the community to take action: “If your career is established and you are not making an explicit and continual effort to encourage, mentor, and support all young physicists, to create a welcoming climate in your department, and to promote the hiring of diverse faculty members, you are part of the problem.”

Nelson is survived by her spouse and UW physics colleague, David B. Kaplan, and their two children; her two sisters; and her parents.

The University of Washington is collecting funds for an honorary professorship in Nelson’s name, to which you can donate here.

An obituary will appear in a future issue of Physics Today. In the meantime, we asked Nelson’s colleagues to share remembrances. Their tributes are below. Due to an overwhelming response, we’ve stopped updating the main text of the page. We welcome readers to share remembrances in the comments.

    1. David B. Kaplan
    2. Howard Georgi
    3. Carlos Wagner
    4. Nathaniel Craig
    5. Lisa Randall
    6. Nima Arkani-Hamed
    7. Spencer Chang
    8. Huangyu Xiao
    9. Ermal Rrapaj
    10. Christopher Vermilion
    11. Akshay Ghalsasi
    12. Flip Tanedo
    13. Neal Weiner
    14. David McKeen
    15. Seyda Ipek
    16. Jon Walsh
    17. Andreas Karch
    18. Michael Dine
    19. Kathryn Zurek
    20. Daniel Arovas
    21. Gilly Elor
    22. Catherine Kallin
    23. Mary K Gaillard
    24. Yuri Shirman
    25. Arti Garg
    26. Zackaria Chacko
    27. Patrick Fox
    28. Jesse Stryker
    29. Jakub Scholtz

David B. Kaplan

Professor of Physics, Senior Fellow at the Institute for Nuclear Theory, University of Washington

Ann, simply put, was my soulmate. I first laid eyes on her at age 18 as an undergraduate at Stanford in 1976. We were both in Advanced Freshman Physics and Honors Calculus, the former an electrifyingly exciting course taught by Mel Schwartz. Both classes had about 50–60 students, of whom about seven were women and the rest were men, most of whom harbored suspicions that they would be the next Einstein. Ann immediately stood out by sitting in the front row and then falling asleep, while consistently garnering on every exam the only A+ given. A fellow physics major who lived in Ann’s freshman dorm at the time and is now a distinguished law professor recently confided in me that “I often joke to my friends in law that it was people like Ann who convinced me I had no future in physics. On the evening before the first midterm, we were studying together in the common room. Ann walked into the dorm, and we invited her to study with us. She declined, saying (as I recall), ‘I just want to get a good night’s sleep. Then I can derive everything I need during the test.’ ” Ann had of course been the best at science and math in her high school, and the only thing I have ever seen rankle her as an injustice she had endured was that the math/science teacher had excluded her from the math team in favor of all boys. Ann’s parents are very intellectual and had raised her to feel that there were no limits to her horizons; they taught her to read when she was two, and she was never reticent about her intelligence, while at the same time never flaunting it. Years later one of her graduate students told me of recommending her to a junior student as an adviser, saying that it was remarkable that a brain that big had no room for an ego.

It was only spring quarter that freshman year, when the math class had dwindled down to seven students, that Ann first noticed me. We both had summer jobs at SLAC, me with Mel and Ann with Marty Perle. We fell in love that summer, at age 19, in 1977. She liked to say that she considered us to be the first internet couple: SLAC had email, which only existed at that time at government facilities, and we used it to flirt. Security was nonexistent, and Ann discovered she could send commands that were automatically executed on the recipient machine, so occasionally my terminal would switch to Greek fonts, or would start beeping incessantly, and I was clueless about how to stop it short of unplugging the machine. A month after we met, Ann declared, somewhat to my consternation, that we were going to get married. Two months later, she broke up with me. Decades later, when I held that up to her as evidence for a fickle nature, she replied that to the contrary, it showed she was a genius to realize that we were going to marry, and that at the same time we were much too young to do so. We got together again a year later and got married in 1987, fulfilling her prophesy. Her keen mind was a constant delight, and I got used to, for example, falling asleep as she started reading War and Peace and waking up when she finished it.

Our first physics collaboration was during spring quarter of our final year at Stanford, the senior lab project, where we had to perform some experiment from scratch. Under loose supervision by Assistant Professor Stuart Freedman, we chose to re-create the landmark but unrecognized experiment by R.T. Cox, who discovered parity violation in the weak interactions in 1928 by measuring the polarization of beta rays via Møller scattering off a polarized target. Our experiment was brilliant, largely due to the electronics that Ann created, which periodically reversed the polarization of the iron-foil target, turning off the coincidence counters during the transition. The experiment was also a fiasco, largely due to my convincing her we could reduce background scattering by filling the box with helium. We destroyed six of the phototubes SLAC provided us with before Stuart noticed and explained to us that helium has a low breakdown voltage. We graduated by necessity with no data, firmly convinced that we (or at least I) should not become experimentalists, which might have been the point of the Stanford requirement.

We ended up at grad school at Harvard, one year apart since I took a year off in Geneva and France. The Harvard particle theory group when I arrived in Fall 1981 was a very intense place; the students, postdocs, and faculty were all brilliant and feverishly productive. Researchers there at the time included Georgi, Glashow, Coleman, Weinberg, Preskill, Dimopoulos, Alvarez-Gaume, Polchinski, Wise, Ginsparg. It felt like a competitive environment; one had to have something very interesting to say if one wanted to be heard. At the same time, Ann’s graduate class was small and close, the proud instigators of the Harvard Puppet Show, which they put on for our entering class’s benefit. Ann was quickly taken on by Howard Georgi as one of his star students and worked on flavor physics, proton decay and CP violation. It was interesting to hear them talk together, it was like Morse code since they understood each other so well. Her paper on “Naturally weak CP violation” from that time offered the first symmetry-based model for how the observed CP violation in the standard model could arise from spontaneous CP violation while still having negligible strong CP violation. She discovered the mechanism while looking at models for proton decay; I recall staring blankly at a big matrix full of phases while she showed me excitedly why its determinant would be real. An anachronistic expression for what I was feeling at the time was insufficient RAM. But then, I had watched her diagonalize 4 x 4 matrices in her head as an undergraduate, so I was not surprised. I could see that all the faculty respected Ann. There were some other students, however, who would bait Ann with discussions on why women weren’t as good as men in physics; she never said anything bad about those people but just tuned them out. It was pretty easy to tell when one had been tuned out by Ann. It took me a little longer than her to find my footing at Harvard, but soon I was also doing research with Howard and loving every exhilarating moment of it. I recall our work schedule as grad students was roughly 7:00am–1:00am, six days a week. We would take one day off to go hiking, cross country skiing, or gorging on Sunday brunch at the S&S deli. We graduated, Ann in 1984 and I in 1985, and we both got into the Harvard Society of Fellows.

Life remained intense, exhausting, and incredibly exciting at Harvard. I recall that the second the news of the b-quark lifetime measurement had been made, Shelley Glashow rushed into the office to say that Vub must be tiny and that there could be visible CP violation in the B system. Georgi and Dimopoulos invented the MSSM; Preskill, Wilczek, and Wise showed, along with two other simultaneous papers, that the axion could be the dark matter. Alvarez-Gaume, Polchinski, and Wise showed that the top quark Yukawa coupling could drive the electroweak symmetry breaking in minimal supergravity, if it was ridiculously heavy, around 55–200 GeV. Ann and I collaborated for the first time then on kaon condensation in dense matter. We ended up writing 19 papers together, on electroweak baryogenesis, supersymmetry, flavor, CP violation, and axions. Many of these were with our friend and fellow student, Andrew Cohen, and the three of us could be considered a collaboration of opposites, we each did physics in such different ways. It led to frustration and arguments, but more often than not an interesting paper. I think in the 32 years we were married, the only heated arguments Ann and I ever had were when we did physics together. Meanwhile, on her own and with others, Ann was writing blockbuster papers on neutrinos, SUSY, Little Higgs, and dark matter, leading to her election to the American Academy of Arts and Sciences in 2011, to the National Academy of Sciences in 2012, and to being awarded the Sakurai Prize in 2018. Throughout her research career, she delighted in working with students and postdocs, and she mentored a large number of each, many of whom have advanced to senior positions by now and are well known in their own right. Including, to endless confusion that amuses us both, another David Kaplan.

On leaving the Harvard Society of Fellows, Ann was offered a faculty position at Stanford in 1987, the first female to have a tenure-track position in that department (although SLAC had previously hired the eminent Helen Quinn). I was unable to get a job at Stanford but accepted one at UC, San Diego, where Ann joined me the following year. We had five happy and productive years there but for personal reasons decided to accept jobs at the University of Washington, Seattle in 1994.

Lecturing in Palestine in 2017.
Ann Nelson lectures at a summer school in Palestine in 2017. Photo courtesy of David B. Kaplan

Judging from the emails I received after her death, Ann had a great impact on young female physicists by simply being a highly visible physicist at the top of the game who allowed them to picture how one might simultaneously do research, raise children, and be unapologetically brilliant. She was easily approachable and would tolerate ignorance while correcting it incisively. People who did not like being corrected incisively might not have enjoyed the experience. However, not feeling that being a role model was enough, as Ann got older she became increasingly active in social justice issues. For her, increasing diversity in physics was not just a politically correct posture but an urgent question of fixing a gross inequity. She felt that most physicists did not realize how soul crushing it can be to be the object of slights and prejudices day in and day out in one’s avocation. She wrote a commentary to that effect in Physics Today, “Diversity in physics: Are you part of the problem?” but more than that, she practiced what she preached. In a a couple of cases she provided a safe haven at the University of Washington for minority physicists whose careers were in jeopardy, where they could continue their research until tenure-track positions opened up. She also took great pleasure in lecturing at a summer school in Palestine. Ann was the only person in our department to sport a Black Lives Matter pin on her blouse every day at the height of that controversy, and I saw African American strangers come up to her and tell her how meaningful it was for them to see it. I learned from a card from a female graduate student of color that Ann began graduate quantum mechanics class each fall with a declaration that harassment on the basis of gender or color would not be tolerated in the class, and how much that had meant to her to hear. Ann learned about current gender politics in discussions with our daughter and began including a tagline in her professional emails that read: “Pronouns: she/her. Some people identify with or use pronouns that may not be obvious based on their appearance. By stating mine clearly I hope to encourage others to share theirs. Please help make our culture more inclusive, safe, and comfortable for everyone.”

Ann had many passions, including spending time with me roaming the beautiful mountains in Washington: hiking, scrambling, and low-level climbing. On 4 August we were on a backpack trip she had always wanted to do in a remote and exceptionally beautiful part of the mountains. It was supposed to be a leisurely backpack trip with friends, to take a break from the more rigorous climbing we had been doing this summer. We had to traverse a gully on the rock-strewn face of a mountain, and she was the last of the four of us to go; as I waited on the other side, she lost her footing and I looked up to see her tumble into the steep gully and down about 100 feet. I climbed down to her as fast as possible, but it was evident that she had died right away. As hard as it is to bear the loss of the love of my life, seeing the reflection of all her accomplishments in the hundreds of tributes that people have emailed to me has made me understand that I can channel that regret into practicing yet another lesson from her, that the more you give the more you have.

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Howard Georgi

Professor of Physics, Harvard University

Ann Nelson was much more than a student to me. She was one of the most remarkable people I ever had the privilege of knowing. My wife and I thought of Ann and David as members of our family. I have had many fabulous students who are better than I am at many things. 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. Like every great physicist, Ann had her own unique way of thinking about physics. Ann understood from personal experience the issues of conscious and unconscious bias, and she worked to promote diversity in physics both publicly and behind the scenes. It would be a fitting tribute to this wonderful person if we could all redouble our efforts to nurture and support students and colleagues who do not look or talk or act like us.

Carlos Wagner

Professor of Physics, University of Chicago; Head of High-Energy Physics Theory group, Argonne National Laboratory

Ann Nelson, along with David, was an example of how to balance a successful career in physics with a rich family life. She was a role model for younger generations. Furthermore, only a few scientists had a stronger impact on my work. Her work with Patrick Huet on electroweak baryogenesis defined the way we consider the baryon number generation taking into account all relevant dynamical variables. Her work with Michael Dine on low-energy supersymmetry breaking had an extremely strong impact on the young scientists who were analyzing gauge-mediated models in the late 1990s. Her work with Andrew Cohen and David on the more minimal SUSY model introduced me to the interrelation of flavor and the scalar spectrum. Her work with the same authors on effective theories and black holes entertained me for more than a year playing with its cosmological consequences. And her work on the little Higgs, Dirac gaugino masses, and mass varying neutrinos had a similar effect. I would like to express my gratitude for all that she gave to our scientific community. Ann’s scientific legacy will live with us forever.

Nathaniel Craig

Associate Professor, University of California, Santa Barbara

Like many people, I never had the chance to convey to Ann my gratitude for both the inspiration and guidance she provided throughout my career. I first met her in the last year of my PhD, when she invited me to give a seminar at UW. This was right as I was applying for postdocs, and I was suffering from a full-blown case of impostor syndrome that kept me up most nights. I remember going to dinner with her at a little pupuseria near campus, and she spent the meal telling me stories from her Harvard days and asking about my research plans. I came out of that visit feeling like I might have a place in the physics community after all. While that day with Ann was pivotal to me, in some sense it was a typical day for her—saving the universe one person at a time.

Ann’s brilliant physics was also a lodestar for me throughout my career, from effective SUSY to Nelson–Strassler to supersoft supersymmetry and beyond. Most of my early work was an attempt to build on those ideas, and my more recent work is constantly inspired by her fearless model building. Ann’s tireless work to improve diversity has been equally powerful. Her 2017 piece in Physics Today was eye opening, and I think daily of the message at the heart of the letter: “If your career is established and you are not making an explicit and continual effort to encourage, mentor, and support all young physicists, to create a welcoming climate in your department, and to promote the hiring of diverse faculty members, you are part of the problem.” That letter defined my post-tenure mission.

Ann, I’m sorry I never had the chance to thank you for all that you did, both for me and for so many others in our community. Thank you. You live on in all of us.

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Lisa Randall

Frank B. Baird Jr Professor of Science, Harvard University

Ann Nelson always made an impact. She certainly made one on me when I was a first-year graduate student and encountered her for the first time. I was initially intimidated by this brilliant cipher unlike anyone I’d ever met. I often didn’t understand what she was saying, which was especially frustrating because it was often a rich penetrating insight that I just couldn’t yet comprehend.

Indeed Ann was part of an amazing crew of students of Howard Georgi at the time, including David Kaplan, Andy Cohen, and Aneesh Manohar. They could talk to each other, but we new students were mystified. Happily, Ann was assigned as my “big sister,” and I rapidly found her a lot less intimidating and she became a good friend. Over the many years since, I have  come to know her as the generous, amazing person that she was.

At her PhD graduation at Harvard.
Ann Nelson (center) celebrates receiving her PhD from Harvard in 1984 with her father, Howard, and mother, Dorothy Ann. Photo courtesy of David B. Kaplan

Ann worked with David and Andy on a definitive paper on baryogenesis in the standard model. They also worked on kaon condensation and its potential implications for neutron stars. She and Michael Dine determined how gauge mediation works—a new way of breaking supersymmetry. Her many other contributions to supersymmetry include effective supersymmetry, supersoft supersymmetry, and some clever scaling ideas. Ann’s interests were wide, with more clever work on CP violation, neutrinos, dark energy, and black holes. Her papers always had some unique insight and were always worth paying attention to.

As if that wasn’t enough, Ann wasn’t just good at physics. She was a skillful backcountry skier and a phenomenal hiker. She could garden. She could set up houses in a weekend. She was beautiful and with her husband David Kaplan raised two beautiful children. I admired so many things about her. And yes, Ann was a woman doing physics in what still remains a very male-dominated field. But this was incidental to her  phenomenally successful career, where she succeeded entirely on her considerable merits. Her being an anomaly affected her only when she saw the bias that prevented others from succeeding, and she worked to address it.

I last saw Ann when I visited Seattle last year. We took her daily half-hour walk from her house to the physics department and admired wood ducks and other creatures along the way. I watched her intensity in the gym and the same intensity when she met with experimental colleagues to discuss ideas. I know her last hike was met with this same intensity and love of nature, her husband, and of life—an intensity, curiosity, and keen clear thinking that I have always admired, along with the warmth and desire for goodness in the world that I wish everyone shared. I and many others will miss her. Our lives have a big piece missing now.

Nima Arkani-Hamed

Professor, Institute for Advanced Study

Ann was a genius; working with her was an intellectually exhilarating adventure. She was also funny, deep, and thoughtful, one of the very greatest people I knew in physics.

Spencer Chang

Associate Professor, University of Oregon

I had the great fortune to have interacted with Ann Nelson starting as a physics graduate student through now as a faculty member. Notably, at every stage of my career, Ann treated me as an equal, always ready with an open ear and critical but positive feedback on even my most nascent, undeveloped ideas. Discussing physics with Ann was a distinct pleasure. Every exchange was filled with open joy and constantly punctuated by her unique giddy giggles. In the high-energy community, Ann was a mentor and hero to so many of us. She never ceased to be a champion for particle physics, and I often sought out her thoughtful insights on current issues afflicting the field. On top of her down-to-earth personality, she was without question one of the most brilliant people in the world. Her research covered a wide range of topics in particle physics and was remarkable for its impact and innovation. In many areas, Ann was without peer, as perfectly illustrated by a conversation with Nima Arkani-Hamed. We were discussing the possibility of discovering Little Higgs theories at the Large Hadron Collider when Nima said, “Do you think god is as good of a model builder as Ann Nelson?” For those who were lucky enough to have known Ann, we already knew the answer to that question.

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Huangyu Xiao

PhD student, University of Washington

Ann Nelson was a brilliant theoretical physicist, an independent thinker. Even though many of her theories have not been confirmed by experiment, it will be remarkably original and forceful if any supporting evidence is found. Her work was always elegant and understandable. Take an example I am familiar with: our recent work about new physics that was based on an idea of hers, which made predictions that were testable in the near future. It is unusual for theoretical physicists to make such strong predictions. Both theorists and experimentalists were surprised that we could explain the origin of asymmetry between matter and antimatter with such a simple model that had unique signals. It seems to be easy to find those signals, but nobody has looked for them. This work is drawing experimentalists’ attention and will be tested soon.

She told me maybe our theory will not be favored by nature, and it was risky for students like me to spend too much time on it. She recommended that I work on other topics as well. She was always such a caring person. She cared about my future, encouraging me to work with other people for a broader vision in physics, even though that may occupy some of my time that was supposed to be spent on our projects. She won the teaching award the two years when teaching graduate quantum mechanics. She was always passionate about helping students, and she was loved by all of them. She showed how intelligent, influential, and reputable a female physicist could be even in a community that had been dominated by men for many years. She was also known as an advocate for diversity in science, helping and encouraging many people from diverse backgrounds to pursue physics.

When attending academic talks, she was always able to rebuild the material in her own way and to confirm with the speaker if she understood it correctly, which was also helpful for the audience. Those were usually the shining parts of what people had worked on for months, and she was able to digest it in an hour. Her thinking process allowed her to absorb knowledge from others and reconstruct it within her own thinking framework.

Her passing is a loss for the physics community and even the world, but this is not the complete reason that we are sorrowful. She was always moving ahead calmly and leading the way with her unique intuition about physics. She was always encouraging and giving others a hand along the way. The desert of physics seems to be darker and the exploration is less warming without her.

Ermal Rrapaj

Postdoctoral researcher, University of Minnesota and University of California, Berkeley

I had the fortune to take courses with Professor Nelson during my first couple of years in graduate school. It was easy to notice what a bright scientist she was and yet so easy to approach. Even after the end of the courses, throughout my PhD program, she was always available to discuss any whimsical idea I would have about dark-matter particles. Being able to freely ask questions provided an atmosphere ideal for research, and having access to what I would consider a living thesaurus would help steer away from erroneous paths. It was deeply saddening to hear that such a bright mind and kind person was taken away so early from us.

Christopher Vermilion

Software developer, Remix Labs

Ann was my teacher, colleague, and friend over several years as a graduate student at UW. She was brilliant, of course, but also kind, joyful, and a tireless advocate for others in the field.

I took a peek at my pile of old grad school papers, and I kept class notes from exactly one course: Ann’s indelible Quantum Mechanics. My notes are filled with quoted asides: “This is pretty fun to prove!”, “Cute result!”, etc. Not only were her lectures a model of clarity and rigor, it was impossible not to share in her simple delight in the beauty of the material. I have no doubt the impact of her teaching will reverberate through generations of physicists.

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Akshay Ghalsasi

Postdoctoral researcher, University of California, Santa Cruz

When I first went to UW, Ann was the only person I wanted to work for, since she was the only one that did cosmological phenomenology at UW. At first she said no because she had too many students at the time. After I took quantum field theory and cosmology with her, I asked her again, and she gave me a chance by giving me a project to work on. For that I will always be grateful to her. After I finished the project, she took me on as a student.

Ann was a great adviser. She never pressured me for results, but her door was always open to me to go and ask questions if I was stuck on something. Her insights were always piercing. I can’t count the number of times I went into her office and had my fog of confusion lifted in a few minutes of conversation. My sense of what’s worth pursuing in physics and what is not comes from her. In spite of my shortcomings, she made me the physicist I am today.

After graduation I used to visit Seattle often. One of the things I always used to look forward to was going to the department and talking to Ann. I couldn’t meet her on a recent visit to Seattle because she was out of town. I wrote to her saying I will see her next time I was in town, but that wasn’t to be. She was truly a great physicist and a great person, and I will miss her dearly.

Flip Tanedo

Assistant Professor, University of California, Riverside

David Kaplan, Tim Tait, Flip Tanedo, Mario Martone, Ann Nelson.
Left to right: David Kaplan, Tim Tait (seated), Flip Tanedo (standing), Mario Martone, and Ann Nelson enjoy a dinner during a workshop at the Aspen Center for Physics in 2018. Photo courtesy of Flip Tanedo

Ann Nelson has been one of the visionaries and guiding lights of particle theory. Her impact on beyond-the-standard-model physics is indelible, and her perspicacity lives on in those she mentored. She reminded us that we are more than just scientists and that we hold value as human beings. She showed us that this does not compromise our physics, but rather enhances it. Ann used her position to push for inclusion in academia. She looked after junior colleagues. She cared deeply about the physics community and our role in society. She leaves us a research legacy that continues to influence the direction of our field; she also leaves us with a charge to uphold the principles of kindness and community that she embodied.

Neal Weiner

Professor of Physics, New York University

I had the privilege of being a postdoc with Ann for four years. I learned many things from Ann, both physics and nonphysics, but perhaps the biggest one was just to see someone who fully prioritized life. She loved her family and was proud of them. She loved physics and could get lost in it. She loved the world, traveling, and nature. Somehow she had time to live every important element of life and wasted little time on unimportant things.

Anyone will tell you that Ann was brilliant. Models and ideas would flash through her mind. As you sat there they would be picked up or discarded for various reasons. When you could keep up it was fantastically fun. Fun. I think this is perhaps the hardest thing to convey for me—just how much she enjoyed physics.

I remember getting excited about a project and sitting outside of the physics building as we came up with names for hypothetical particles, with Ann giggling furiously at some of the absurd suggestions. She was very serious about her work, but that seriousness didn’t prevent some silliness and a joyful approach to new ideas.

She was a great person to talk to about life and academics. How to make big decisions and even to know what really were the big decisions. She would never tell you what decision to make, she would simply help you find a process that worked for you to decide.

She cared about the lives of her many students and postdocs, and was regularly in touch to stay abreast of life events, major and minor. After the birth of my first child, she wrote me, “Now you know what a zeroth-order phase transition feels like.”

She supported you and backed you. She saw what you had to offer and treated you as a peer even when you were a green PhD. She would have confidence in you and see things in you that you wouldn’t see yourself. She was somehow both superhuman and human. I will miss her.

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David McKeen

Research Scientist, TRIUMF, Vancouver, Canada

I first started working with Ann Nelson when I moved to the University of Washington in 2013. It was immediately obvious that she was a shockingly talented physicist as well as a profoundly kind human being. Any time I was confused about a physics question, I could count on her to patiently and succinctly explain it in just the right way for me to understand. She was a wonderful mentor and had an enormous impact on my way of doing physics. I will always be grateful for that. In many ways she drove the entire particle physics field forward, influencing the way we thought through her creative and fearless model building. This was a joy for me to witness.

As one can see from the outpouring of feelings after her accident, she left a deep impression on many, many people through her kindness, empathy, and using her stature to help those who needed it.

I will always miss Ann, but I count myself extremely lucky that I was able to work closely with her even for a (too) short time.

Seyda Ipek

University of California President’s Postdoctoral Fellow, UC Irvine

Women's lunch at the Aspen Physics Center.
Seyda Ipek (front) at a women’s lunch at Aspen Physics Center, where she and Ann Nelson (front right) organized a workshop last year. Photo courtesy of Seyda Ipek

Ann was my PhD adviser. I always knew I was lucky to be her student, but now I am reflecting on the mentoring practices that came to her naturally. She was very generous and honest with praise. In a field filled with big egos, hearing a great physicist say “Good job!” is a rare and welcome gesture, especially for a graduate student. When Ann saw a problem, she wanted to solve it. This extended to the struggles of her students as well. If I was at a bad place, academic or personal, Ann would work with me to find solutions, instead of leaving me stranded or worse.

Her work in particle physics talks for itself, I do not need to say anything about her contributions to our field. Her knowledge and expertise was so wide and deep that everyone wanted to talk to her about their ideas. Ann often understood new models better than the people who came up with the models. It was awe-inspiring to watch her in physics conversations. She always wanted to learn more, always asking, “What about this? What if?” I remember the first group lunch we had after the Higgs boson discovery; she was the only one to ask, “This is great, but is there anything else we are missing?”

Ann Nelson with students.
Left to right: Paddy Fox, Seyda Ipek, Ann Nelson, and Jakub Scholtz. Photo courtesy of Seyda Ipek

I came to UW from Turkey. It was my first time in the US, and my first time living in a foreign country. I was nervous, to say the least, to be in a totally different physics and social community. Ann was one of the people in the department who always made me feel welcome. She enjoyed the Turkish delight I brought back whenever I visited Turkey. I was going to bring her another box in a month. Alas!

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Jon Walsh

Cofounder, Unlearn.AI

Ann was my doctoral adviser along with Steve Ellis. When I entered the PhD program at the University of Washington in 2005, I was unsure what I really wanted to do. But within a couple of weeks of Ann’s graduate quantum mechanics course, where she started with neutrino mixing, I knew that I wanted to do theoretical physics. With Ann. And I was fortunate enough to be able to do so, working with her on a few papers.

Life often takes you in new directions. I was also deeply interested in QCD and jet physics, and my work with Steve and others blossomed and filled my working time. Ann was always encouraging, and one of my largest regrets was not being able to learn more from her. Eventually life took me in a new direction, away from academic physics.

I am grateful to have worked with a number of talented, kind, and driven people during my time in physics. But Ann stands out in all three directions. She was driven to understand problems, and seeing her around the department you often got the sense she had a background process going to do just that. She was unfailingly kind; I was able to travel to do physics—the dream of a young graduate student—in Vancouver, Madrid, Geneva, and New York City as a result of this kindness. And her intellect was incredible. Ann had a genius so great that it was hard to understand. And impossible to forget.

Andreas Karch

Professor of Physics, University of Washington

With Ann our department lost one of its greatest minds and greatest teachers, a champion for inclusion and diversity. But to me Ann was so much more than that. Ann was the person who hired me at UW. Sure, there was a committee and all that. But Ann was the one who contacted me, guided me through the process, and supported me all along. Ann was the one who pulled me through the first few years, when tenure looked like an impossible feat. The combined burden of having to teach for the first time and taking care of my first child almost derailed my career. I am not sure I would have gotten through without Ann’s constant encouragement and support. Most of all, Ann, David, Gabe, and Sierra are the closest my spouse, my kids, and myself have to family in this country. With all our relatives living in either Germany or Japan, Ann and David took us in. My family spent every single Thanksgiving holiday at Ann’s place, always feeling welcome. They were there for us to talk to when we went through some of the roughest patches in our lives. Ann and David had agreed to raise our children should ever something happen to us. The world is a better place because Ann was in it. We owe it to her to keep on working on it.

Michael Dine

Professor of Physics, University of California, Santa Cruz

It was one of the great privileges of my career to have worked with Ann and to have counted her as a friend. I witnessed her brilliance firsthand, as I struggled to keep up during our intense and productive collaboration in the 1990s. She was always several steps ahead of me. We were both, at that point, parents of infants, so that added a further element of camaraderie as we worked together in our exhausted states. Not only have I counted Ann as a friend but also as a competitor. I cannot count the number of times I have woken up relieved that I had thought of this or that just in time not to be completely scooped by Ann (often in collaboration with David and Andy Cohen). These moments helped propel both me and the field to new directions. Throughout her career she always brought a perspective that was original and keenly insightful. My debt to Ann is enormous. It was one of the greatest honors of my career to have shared the Sakurai Prize with her.

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Kathryn Zurek

Professor of Physics, Caltech

I first met Ann Nelson as a prospective graduate student at UW. Coming to campus outside the normal visiting weekend, the department had set up some meetings for me with current grad students. While I was chatting with some of them in the common area, Ann stopped by. Though she didn’t interrupt the conversation or actually even say much, her presence showed that she valued having me as part of the department—it was remarkable that she took the time to stop and listen. While I eventually worked with David Kaplan for my thesis and never wrote a paper with Ann, I still learned a lot from Ann. I learned from Ann by watching her build models in her impressive way. I learned from Ann by listening to her ask questions in seminars. And as the years went by, she was for me the gold standard for an unapologetically brilliant theorist, who also happened to be a woman. She loved physics and finding things out, and she also valued life outside physics. She showed that this was not a contradiction. And she inspired me to try to do the same.

When news of her death came to me, I realized how much I had taken her for granted as a force for good. She will be missed. We have big shoes to fill.

Daniel Arovas

Professor of Physics, University of California, San Diego

David and I started our faculty careers at UC San Diego in 1988, and Ann came along about a year later. We soon became friends as well as colleagues. Ann was of course a brilliant and highly influential theoretical physicist, but I remember her especially for her wonderful sense of humor, her deep concern for students and for fairness, her quick wit, and her enormously positive attitude in all things. I have missed both of them since they moved to their dream jobs at Washington in 1994, but it has been gratifying to observe from afar the trajectories of their magnificent careers. In recent years it was nice to reconnect a bit on Facebook—seeing their amazing photos from their hikes and climbs would always leave me in awe of their adventurous and indomitable spirits. While Ann’s loss is tragic and devastating, there is also some satisfaction in reflecting upon a life so extraordinarily well-lived. Ann was a remarkable person in every possible way, and her spirit and inspiration will live on in her children, her students and postdocs, and her many friends and colleagues.

Gilly Elor

Postdoctoral researcher, University of Washington

For the last year and a half I have been Ann’s postdoc at the University of Washington. Of course, she was a brilliant physicist. But in addition to admiring her intellect, I was inspired by her pure, honest passion for nature. I saw this reflected not only in her work as a physicist but also in her enthusiasm for the outdoors. Perhaps this driving force explains how someone can be so brilliant without being arrogant, and so excited about life without ever seeming jaded. I am certainly not the first to say that Ann was a remarkably kind and caring person. Ann seemed to extend a hand in friendship that transcended social, cultural, or any other kind of artificial barrier. In the short time that I knew her, Ann had become my collaborator, mentor, and friend.

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Catherine Kallin

Professor of Physics & Astronomy, McMaster University, Hamilton, Canada

Ann and I were graduate classmates at Harvard; we both started in 1980 and graduated in 1984. Our class was small—there were 12 of us, including three women—and this likely contributed to us being a particularly close group who learned a lot of physics together and had a great deal of fun. Our class started the annual Harvard Puppet Show to roast our professors, we started a Women in Science group, and we threw many parties, some spontaneous, some more elaborate, including one that had us in costumes roaming the streets of Cambridge looking for clues that had been planted. Consequently, even though Ann and I joined different research groups— particle theory versus condensed matter theory—I had the great fortune of getting to know Ann, learning from her, sharing countless laughs and witnessing her deep capacity for joy. I admired her amazing intelligence and creativity and her strong sense of justice and fairness, and appreciated her kindness and humor.

After graduating, I saw Ann only sporadically, usually when we happened to overlap while attending different workshops in Aspen or Santa Barbara, but the special bond and admiration I felt for Ann remained. So when Ann called me four years ago to serve on a committee, I didn’t hesitate to say yes despite my wanting to reduce, not increase, my committee duties. And I’m so glad I did, as it was wonderful to spend time with her again. Ann brought her deep intelligence, insight, and sense of fairness to all her activities, and I continued to learn from her. I saw firsthand her passion and strong commitment for diversity and for supporting those who are often overlooked or marginalized. Ann was a role model and inspiration to me in graduate school and through the years, and even as I miss her, she will continue to inspire me.

Mary K Gaillard

Professor Emeritus, Professor of the Graduate School, University of California, Berkeley

I have always known that Ann was an outstanding physicist. And I knew of our shared concern for the underrepresentation of women in physics. But I am just now learning the depth of her passionate determination to encourage not only women, but all underrepresented groups. And I am just now learning the remarkable extent to which she emulated, and perhaps surpassed, her own mentor, Howard Georgi, in the mentoring and nurturing of younger physicists. We lost a superb physicist, a remarkable person, and a friend.

Yuri Shirman

Professor of Physics, University of California, Irvine

As a graduate student I was lucky to work with Ann on two papers. Ann’s ability to constantly come up with new ideas and immediately back them up with calculations was almost magical. Trying to keep up with her was challenging. At the same time it was also motivating and inspiring. While I never worked with Ann again, our interests continued to overlap. But competing with her was almost impossible, as evidenced by the widespread “You scooped Ann!” reaction Csaba Csaki and I received the one time we managed the feat. Ann’s work, her ideas, her judgment and taste in physics remained an inspiration and continued to influence and motivate my view of physics for the past 25 years. As will so many others, I will miss Ann, but she will certainly remain an inspiration in the future—not only through the papers she had time to write but also through the work of students and postdocs she taught and guided to maturity at the University of Washington.

Arti Garg

Emerging Market & Technology Director, Cray, Inc

My post-physics career has taken me to many places and introduced me to many people, but Ann’s unique combination of compassion, brilliance, and passion remains indelibly etched in my memory.

Though only particle theorists were required to complete the full year of Ann’s QFT course, after one quarter I knew it was a rare privilege to have the opportunity to sit in her classroom—so I took the full year. And almost two decades later, I find myself reaching back in my mind to her explanations on the (admittedly rare) occasions when I need to draw upon my knowledge of QFT.

But the lessons she taught me extend beyond physics. When I found myself needing to make a major life and education decision, she offered straightforward, thoughtful advice that took into account everything from my personal life to cultural fit. To this day, I cherish that conversation. Hearing someone like Ann matter-of-factly acknowledge that all of these factors were equally important made it easier to feel like I could belong in a physics department without giving up other parts of myself.

I am so thankful for the time she took to share this message with women’s groups in physics departments everywhere. She was willing to speak about her career and her family without sugarcoating the challenges of balancing both. She candidly acknowledged the risks of delaying starting a family, sharing that she considered herself lucky but would not recommend following her timing. In doing so, she opened a conversation that few people, even today, are willing to broach despite the life-altering consequences at stake. By reflecting on her own life and acknowledging that hers was not the only—or even the best—way, she also modeled an approach to leadership I’ve rarely seen in others.

It’s been many years since I last saw Ann. When I first met her at a welcome barbecue for new students, her kids were about as old as mine are now. Looking back, that memory, this world-renowned physicist attending to her small children, at a departmental event, with the same focus I would later see her bring to physics, best represents what Ann taught me. Success, even in physics, does not have to be lopsided or compartmentalized. You can excel in your career while honoring every part of yourself.

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Zackaria Chacko

Professor of Physics, University of Maryland, College Park

It was my remarkable good fortune to have Ann Nelson as a mentor when I was a postdoc at the University of Washington from 1999 to 2001. Ann was a remarkable person, not just brilliant, but also wise and extremely kind. It was my first postdoctoral position, and I found the transition from student to postdoc difficult. Ann was incredibly supportive. She was generous with her time, a fount of research ideas, and an invaluable guide to the existing literature. Working with her was fun, because she was brilliant, upbeat, and had an amazing sense of humor. I look back to that time with great fondness, and am extremely thankful that I had such a fantastic mentor at that critical stage in my career. She was one of the most important influences in my development as a scientist, and I will always be grateful to her.

It goes without saying that Ann was a brilliant scientist. She made many important contributions to particle physics, and her ideas continue to shape the direction of the field. She also took the time to mentor to numerous students and postdocs, many of whom have gone on to have very successful careers. Ann had a great sense of fairness, and she worked hard to help junior scientists from underrepresented groups. As she once explained to me, “Sometimes, all you need is one person who believes in you.” The field has lost a titan. We are going to miss her terribly.

Patrick Fox

Senior Scientist, Fermi National Accelerator Laboratory, Batavia, Illinois

Ann was a truly exceptional physicist, a warm and caring person, and a superb mentor.  I am forever thankful that she took me on as her student. She taught me how to do physics and how to interact with everyone in our community. As a student it is natural to have an exaggerated opinion of the abilities of your PhD adviser. It was not until I graduated and saw more of the field that I could correctly put Ann’s creativity as a physicist and her thoughtfulness as an adviser and mentor into perspective. I had not exaggerated. I have always admired Ann’s approach to physics and life: She brought joy to everything she did, she had a mischievous sense of humor, and she had a completely open mind. I feel blessed to have witnessed that. Working with her was both awe-inspiring and humbling, but despite her incredible abilities she never made me feel inadequate. I summarized working with her to a fellow graduate student by saying, “When you realize how big her brain is, it’s amazing there’s no room in there for an ego.” This is all too rare in society, and in our field, and I hope Ann will set an example for future generations. I know she has done that for me.

Jesse Stryker

PhD candidate, NSF Graduate Research Fellow, University of Washington

Ann Nelson was first described to me as a rock-star physicist, and she proved to be nothing short of that.

Ann had incredible physical insight and energy for physics discussion. Even more uniquely, she was profoundly kind and benevolent. This is a true rarity in theoretical physics.

It was immensely helpful to have had someone of Ann’s caliber encourage me early on to pursue theoretical physics if that’s what I wanted, especially in spite of events where I would feel totally discouraged. Having a culture of such support as a first-generation graduate student is so invaluable to long-term success; we owe it to Ann to perpetuate that.

I am a weight lifter. Ann Nelson regularly frequented the UW gym and is the single physics professor I’ve ever caught doing dead lifts in the gym. Hence, Ann was the genius physicist that rose up in a male-dominated workplace, who climbed mountains, advocated for marginalized groups, had two kids—and was dead lifting well into her fifties! What an inspiration to me.

I wish I had gotten to know Ann better and had more one-on-one physics discussions. She was taken from us too soon. Her time on Earth, however, was well spent.

Jakub Scholtz

Junior research fellow, Durham University, UK

Ann was my adviser. What was truly striking about her is that from the very beginning she treated everyone as an equal. No matter the difference in experience or gap in ability, she always listened to what you had to say. She would consider your suggestions and then either kindly explain why that might not be correct/useful or, if correct, fully throw herself into figuring out the consequences of the model you built. Doing physics with her was like wandering through the sunlit forest of implications and consequences until you figured out the whole picture—it was fun, and it made me happy.

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