Ebrahimi is a principal research physicist in the Princeton Plasma Physics Laboratory’s Theory Department and an affiliated research scholar in Princeton University’s Department of Astrophysical Sciences. She strives to fully understand what many believe could be the answer to unlimited, clean, and reliable energy: nuclear fusion. She mirrors the very subject she studies, driven by seemingly limitless energy to help direct the future of the field.

Although nuclear fusion — a means by which the sun produces its own energy — has been achieved in laboratory settings, current strategies are neither efficient nor reliable for producing energy on a large scale. Researchers, including Ebrahimi, are working to better understand and control fusion on Earth to develop a sustainable method that produces more energy than it uses.

“It will be fantastic. The whole world will change,” Ebrahimi says of the day when this method becomes a reality.

In her pursuit to understand the mechanics of nuclear fusion, Ebrahimi stands out for her desire to discover why things work the way they do. In addition to collaborating with fellow physicists, she takes walks and pulls late nights to think through problems alone. In her day-to-day research, Ebrahimi also explores unconventional approaches to fusion and calculates the physics behind her computer simulations.

“[Ebrahimi] has very good physical insight into the physics problems, and she complements the computer calculations with … calculations on pencil and paper to try to benchmark and understand the output from the large computer codes,” says Stewart Prager, who was Ebrahimi’s doctoral adviser at the UW and is now a professor at Princeton. “This capability, plus her appreciation for experiments, I believe distinguishes her from many other computational physicists.”

As a part of understanding the physics she computes, Ebrahimi fuses her work in laboratory physics with astrophysics. In one of her recent studies, she examined the behaviors of plasma (a hot, ionized gas present in fusion) and how they may affect studies about both Earth and space.

For one of these behaviors — magnetic reconnection, a process believed to be related to solar flares — she found that it has the potential to degrade the performance of a fusion reactor. Gaining a foundational knowledge about this process helps solar physicists and astrophysicists understand the nature of solar flares; understanding flares has become important for researchers to further study how to control fusion.

Nuclear fusion is a process that releases energy when lightweight atomic nuclei — such as forms of the hydrogen atom — join. In some reactors, scientists apply extreme heat to these hydrogen atoms to form plasma. The plasma is then controlled using magnetic confinement, allowing for the fusion of atoms.

As opposed to some of today’s energy sources, fuels for fusion reactors could be extracted from water and would not emit carbon dioxide. Ebrahimi also says fusion would not produce radioactive waste, and that it would be reliable — unlike the unpredictability of weather-related factors needed to power solar panels and wind turbines. Together, these factors help make nuclear fusion a coveted candidate for a new energy source.

Ebrahimi grew up in Tehran, Iran, during the turbulent times of the Iran-Iraq War.

“I was able to continue my education. But it affects [you], you have these memories,” she says, noting that everyone living in Tehran faced scarcity of “almost everything” — from foreign goods to food. “I also have memories of being wakened by air-raid sirens and running for shelter, and sometimes temporarily [evacuating].”

In high school, Ebrahimi first discovered her curiosity about physics. She naturally excelled at it and found herself wanting to understand the physical laws that determine how matter and energy interact. She wondered if there was a unified law that could explain it all.

“I think that was the thing for me,” she says. “The universality was something I was looking for.”

She went on to earn her bachelor’s and master’s degrees in physics at the Polytechnic University of Tehran. During these years, she explored several areas of the subject — including plasma physics — and wanted to understand how they worked together to govern the universe. But she found herself gravitating more and more toward plasma physics. Although an area less focused on a universal law, it’s one in which several branches of physics overlap.

Ebrahimi then moved to Sweden to begin a doctoral program at the Royal Institute of Technology, where she started specializing in plasma physics and fusion. After a year, however, she decided she wanted to continue her research in the United States.

“Something was missing [in Sweden],” Ebrahimi recalls, adding that research there lacked a multidisciplinary approach. Researchers from the U.S. also had visited — including some from the UW, where a world-leading fusion experiment was located. “There was something special about the research environment in the U.S. It was clear from the scientists that I wanted to be there, and I wanted to work with them.”

Shortly after, Ebrahimi applied to a doctoral program at the UW. “I applied for other places, too, but I think I just felt that this was the right place for me to go to do my PhD,” she says. At UW–Madison, Ebrahimi saw opportunities to learn within a plasma physics program that offered a wide breadth of fusion experiments located on campus — important features that were difficult to find elsewhere.

While completing her doctorate at the UW, she continued to study a fusion method she’d begun in Sweden. She worked with the Madison Symmetric Torus located in Chamberlin Hall, conducting simulations to understand how to efficiently sustain a steady, controlled plasma current for an extended period of time — something that physicists today are continuing to study, as it will be necessary to harness if we are to use fusion for energy.

Ebrahimi collaborated with others in the lab to put her computational results into practice, hoping to understand the physics behind these simulations. This effort to validate computational research against a laboratory experiment is important because it helps provide more confidence in the results, says Ellen Zweibel, a professor in the UW’s Departments of Astronomy and Physics.

Ebrahimi met Zweibel while conducting her postdoc studies and research at the UW. They worked together through the UW’s former Center for Magnetic Self-Organization (CMSO), which joined the studies of phenomena seen in both astrophysics and plasma physics.

Although mainly focused on laboratory plasma research, Ebrahimi gained exposure to astrophysics by working at CMSO and with her adviser Stewart Prager, Zweibel, and a mentor whom she’d met in Sweden, the late Dalton Schnack of the UW’s Department of Physics.

This cross-disciplinary approach taught her to think of problems differently, applying knowledge from her fusion research in the laboratory to astrophysics and vice versa.

“It is a strength of Fatima’s that she is able to … walk over and collaborate with experimenters and help them understand what they’re seeing in the experiment,” Prager says. “She also has had collaborations with astrophysicists who don’t study plasmas in the laboratory at all, and she’s able to bridge that gap and apply her work to both laboratory and astrophysics.”

Zweibel notes that she and Ebrahimi were the only senior women involved in CMSO while it was still on campus. Since that time, Zweibel has noticed that the number of women in astronomy remains consistently higher than the number of women in plasma physics.

Despite the numbers and her hopes for more women to follow, Ebrahimi focuses on what she can control — pursuing her passion to solve the puzzle of nuclear fusion.

“You find a problem that you’re excited about, and you work on it. That’s it,” she says.

“Women are underrepresented in the U.S. fusion community, especially in senior positions,” she adds. She also recalls an experience when, for nearly a year, she faced delays in obtaining a visa to return to the United States for her postdoc at the UW — all while she continued to pay rent for her Madison apartment until her UW colleagues helped store her belongings. “In my case, being an immigrant was even harder, and until I became a U.S. citizen, several times it stalled my career.”

At the Princeton Plasma Physics Laboratory, Ebrahimi works with the National Spherical Torus Experiment Upgrade (NSTX-U) — one of the most powerful experiments of its type.

Some of her research builds from where her doctoral work left off, but it focuses on a different innovative method. She models her research using the NSTX-U — which is more compact than conventional fusion devices used by some researchers — to understand how to efficiently create a lasting, steady plasma current.

“You want to think out of the box,” Ebrahimi says, and — by taking on compact, non-boxlike approaches (a torus, after all, is more of a doughnut shape) — she does just that. “I think that’s what fusion also needs.”

By studying innovative methods, such as using compact devices, she says researchers may be getting closer to finding a sustainable, controllable solution — the ticket to using fusion as an energy source.

Although researchers have made large strides in the past few decades, Ebrahimi says that it’s difficult to predict when we will use nuclear fusion as a source of energy.

“Fusion is hard,” she says. It takes a global team: a variety of fusion projects are happening around the world, all of which help physicists gain a more comprehensive understanding of fusion. This multitude of projects is expensive but necessary, Ebrahimi says. The payoff, though, is expected to be well worth it.

“It’s unlimited [energy] for mankind,” she says. “It’s not for one generation. It’s for many, many generations to come.”

The UW–Madison Vilas Professor’s story is a lesson in dichotomy. She grew up in dire poverty on the streets of Hong Kong as her wealthy father traveled the globe as the Ginger King, so named for his success in the preserved-ginger industry. She had $40 to her name when she arrived in the United States — 10 years later, she had a PhD from Harvard. And then she devoted her life to a rarely reciprocal field dominated by men.

Wu has played a core role in three major discoveries in particle physics, advancing what we know about the tiniest parts of matter — and therefore, the world around us. Along the way, she’s advised more than 60 UW graduate students and 40 postdoctoral researchers. “On track record alone, both with scientific output and with students, she’s unique,” says Steven Ritz MS’82, PhD’88, a professor of physics at the University of California–Santa Cruz and one of Wu’s first graduate students.

As I ask Wu about the many obstacles and injustices she’s overcome, I expect an air of bitterness in her responses. Instead, I get lighthearted shrugs and her signature soft laugh: Well, that’s life. Eventually I learn why. To understand Wu is to view the world through the unwavering lens of her values: hard work, practicality, and perseverance.

Wu was born in Hong Kong in the early 1940s, as World War II began to rage. Her father, Tat Chee U, was a prominent businessman; her mother, Ying Lai, was the last of his six concubines — secondary spouses with inferior status, fewer rights, and no inheritance. (The practice, dating back 3,000 years, was legal in Hong Kong until 1971.)

Lai was in her teens when her cousin brought her from a poor village in southeast China to Hong Kong. As was customary, she was not allowed to go to school and grew up illiterate. She took a low-level job at a factory, where she met the successful and much older U — the eventual Ginger King, as a 1951 New Yorker article referred to him. “Mr. U is a short, friendly, authoritative man with liquid brown eyes, a slight stoop, and an excellent command of English,” the article read, noting that his name, fittingly, means “object — to be prosperous.” He went on to own 11 factories, amassing control of a growing industry and bringing successful commerce to the area. Britain’s Queen Mary once invited him to London for a personal visit. Even today, a street in downtown Hong Kong bears his name.

U’s prosperity scarcely trickled down to his sixth concubine and her children, particularly during war-torn times. When Lai became pregnant, she lived with U despite his primary wife’s protestations. She was tasked with menial housework and “treated like a servant,” Wu says. Just before Wu was born, Lai was cast out of the house to live in a slum on a meager allowance.

During the Japanese invasion in 1941, Lai ran in and out of bomb shelters with the newborn Wu wrapped in her arms. Wu’s younger sister, Yu Lan, was born about a year later. The name Yu Lan means moon orchid; Sau Lan means graceful orchid. They were tied together by birth name only. Unsettled by war, U insisted that the younger sister be given away, and a family caretaker took her to a nearby village. The unwilling mother cried every day.

“Life was very difficult at the time,” Wu says. Some years later, Wu and her mother traveled to the village to try to locate Yu Lan. But the village of wooden shacks had burned down earlier, and they never found her. “I regret very much that I didn’t make [more] effort to look for her,” Wu says, adding that she would have liked having a sister.

“We stayed very close together [throughout life],” Wu says of her relationship with her mother and brother, pictured here with her (at left, around age 11) in Hong Kong. Courtesy of Sau Lan Wu

Her father moved the family to a better region and a larger apartment when Wu was 12, and her mother enrolled her and her brother in respected missionary schools. “She was a very smart woman,” Wu says. “She always wanted to learn and felt very [deprived] that she could not read newspapers or write letters. She was extremely, extremely conscientious to make sure my brother and I were well educated.”

Wu excelled in school — particularly in math. She could multiply three-digit numbers in her head. Prior to enrolling, she had rarely seen her father, but now he visited for two hours each week and became invested in her academic success. Wu remembers the first time she impressed him: as he was leaving her family’s apartment, he quizzed her on why it was wet below all the cars except his. Because, she explained, he had arrived before it rained.

Her mother remained the steady, supportive presence. “Her life consisted of cooking for us and encouraging us to study,” Wu says. “She in fact had a very simple life. She felt very insecure — she often cried because she felt totally dependent on other people.”

Wu’s pull to practicality is most evident when she reflects on her father, someone she continued to love and respect despite the complex circumstances of her upbringing. He was “basically a decent person,” Wu says, noting that he resisted pressure from his other spouses to abandon her mother completely. “He was a very capable person. He worked very hard. He was just very successful professionally. After all, my father actually gave me a better life. … I admired my father, and in a way, he is my role model because he was very driven. [But] I love my mother, as she was really behind everything that gave me a chance to succeed.”

By the time she was 19, Wu knew only one thing for certain: she would live financially independent of men. “I saw how my mother suffered. I could not live in a life where I would need to open my palm and ask a man for support,” she says.

She knew from an early age that her path to independence was education. After she graduated from high school in 1959, her father expected her to work and contribute to the family. Instead, she went to a library and pulled out a thick book with the names of U.S. universities and colleges. She selected 50 on a whim and secretly applied, asking for admission and financial aid to cover tuition and living expenses. All but four universities rejected her outright, saying they did not have full scholarships available. Only one — Vassar College, a top all-women’s school in New York — sent a telegram accepting her. “So, you can see that I [paged through] from A to Z — Vassar is V,” Wu says, laughing.

Her mother and brother accompanied her to the dock as she prepared to board a ship to America. She wouldn’t see them for nine years. Her father came to say goodbye under the cloak of the early morning, avoiding detection. He bought her ticket to San Francisco and gave her $40. They stayed in touch by letter, but his health declined, and he died in 1969, a year before she earned her PhD. He had planned to attend the graduation ceremony at Harvard. It took Wu nearly a month to travel by ship and train to New York. She spent most of the time conversing with passengers, determined to better her fledgling English. She barely ate, weighing just 90 pounds and worrying about every cent. When she first arrived in New York, she stayed with a Vassar alumna in an apartment near Central Park. “For the first time, I saw how the rich people live,” she says.

When school administrators found out that she had only a few dollars to her name, they covered her books and school supplies. Her student adviser took her shopping, paying for basic necessities, while Wu frequented a donation closet on campus for clothes. She fell in love with American breakfast foods — steak, eggs, toast, and orange juice — and ate as much as she could at the cafeteria.

In wider society, Wu faced two 1960 Americas: a land of opportunity, but also one of inequity. She remembers her first direct experience with racial discrimination: during a visit with friends to Virginia’s supreme court building, she went to the restroom and saw signs for “white” and “colored,” and wondered which applied to her. Later on the trip, she faced the same dilemma on a segregated city bus.

Wu found comfort in her coursework. To avoid distractions, she spent most of her time buried in the basement of Vassar’s library. She aced her physics and math courses, but was less enamored with the humanities, taking four months to read The Scarlet Letter. A summer internship at the Department of Energy’s Brookhaven National Laboratory in Upton, New York, sparked her lifelong passion for discovery and particle physics. She also met her future husband: Tai Tsun Wu, a visiting physicist from Harvard.

Sau Lan graduated from Vassar in three years with the highest distinction. Once again against her father’s wishes, she applied to the most prestigious graduate schools, selecting Harvard over offers from Berkeley, Columbia, and Yale. Princeton rejected her because it only accepted women who were married to male faculty members; Caltech wrote that it didn’t have a women’s dormitory and only accepted “exceptional” women.

When Wu arrived at Harvard, she quickly realized she was the only woman in the physics department’s first-year graduate class. Her cohorts often studied together, but because women were not allowed in the men’s dormitory, she worked long hours alone in the physics library. The librarian took notice of her work ethic and encouraged her to go on a date with Tai Tsun. “She said, ‘He’s a good guy,’ and ‘[You’re] working very hard in the library,’ ” Wu recounts, laughing. The two quickly bonded, finding compatibility in their love of physics and their homogeneity of work and life. They married in 1967.

“We talk about physics a lot,” Wu says. “He’s a theorist; I’m an experimentalist. I consult him a lot because I feel that theorists have … a broader picture than experimentalists — or me, anyway.”

Wu made a concerted effort to stand on her own. “My thesis adviser always introduced me as T. T. Wu’s wife,” Wu says. “Nobody wanted to know my name.” She insisted that they no longer attend conferences together. “After a while, people didn’t even know that he was my husband — but that’s what I wanted. I don’t want to be known as his wife and not myself.”

Wu received her master’s degree in 1964, the first year that Harvard awarded graduate degrees to women. A guard kicked her out of the commencement lunch, telling her that women had never been allowed to join the celebration and leaving her in tears. Hard work is a given in the field of particle physics — “A lot of people work hard,” Wu says — but the real challenge is the ability to sift through the clutter of infinite possibilities to know what to pursue, and how.

“She has a wonderful intuition for what’s going to be important,” says Steven Ritz, the Santa Cruz physics professor and her former student, who has served as chair of the Particle Physics Project Prioritization Panel (P5), a national advisory body. “You look at what she’s worked on over her career, and they’re among the things that in hindsight mattered the most.”

After receiving her PhD in physics from Harvard in 1970, Wu was hired by MIT as a research associate, working again at the Brookhaven lab. There she participated in the first major discovery of her career: the charm quark, which resulted in a Nobel Prize for her supervisor, Samuel Ting. A quark is an elementary particle that makes up larger particles, such as protons and neutrons, and leads to matter. Physicists knew of only three “flavors” of quark at the time — up, down, and strange. The charm quark became the fourth and opened up new possibilities in the field.

In 1977, Wu was hired as an assistant professor at UW–Madison, becoming one of the first two female professors in the century-old physics department. Within two years on the faculty, she played a leading role in the discovery of the gluon, a particle that binds — or “glues” — quarks together to form protons and neutrons. That discovery put her on the fast track to a full professorship in 1983, though her compensation lagged in comparison to other researchers with her level of federal funding. Donna Shalala, the UW’s first female chancellor, later advocated for her and realigned her salary.

Wu spent much of the interim — 32 years, to be exact — chasing the Higgs boson, which was hypothesized to give mass to elementary particles (and therefore all matter in the universe). “Looking back, I’d say that most of us thought it was 50–50 that the Higgs particle really exists,” says Ritz, who did research related to the Higgs under Wu in the ’80s.

Over the years, thousands of physicists collaborated at the European Organization for Nuclear Research (known as CERN) in Geneva, Switzerland, where Wu spends most of her time today. The breakthrough in concrete evidence finally happened in July 2012, when Wu’s group was one of the first at CERN to see an experimental sign of the Higgs. Wu appeared with four other key physicists on the front page of the New York Times, and Science journal named it the biggest scientific discovery of the year.

“I was never alone in this long and difficult struggle,” Wu says of her pursuit. She credits the steady confidence of UW chancellors Shalala, John Wiley MS’65, PhD’68, and David Ward MS’62, PhD’63; deans Terry Millar, Martin Cadwallader, Phillip Certain PhD’69, and Gary Sandefur; provost Paul DeLuca; colleagues Wesley Smith and Francis Halzen; and computer scientist Miron Livny, who helped to develop the technology infrastructure that enabled the Higgs discovery.

It’s not hyperbole to say that Wu has devoted her life to science. “I would say that she’s so dedicated that she doesn’t have much life outside of physics,” says Haichen Wang PhD’13, an assistant professor at Berkeley, who was a key contributor at CERN during the Higgs discovery. “She usually came to the office in the late morning and stayed there until the early morning the next day.”

Wu rarely talks about her upbringing with her colleagues and students. “In some sense, I’m not surprised — that was before science entered her life,” says Ritz.

Such singular devotion hasn’t been without sacrifice. Until recently, she’d lived apart from her husband for most of their 50-year marriage. While she’s conducted research at collaborative centers in Europe, he’s taught several time zones away at Harvard. They once considered having children, but they feared that it would jeopardize her track to tenure. “In those days, that was a reality,” she says, adding that while she has no regrets from her career, she does envy parenthood.

Wu considers her students and postdocs at CERN her extended family. She proudly lists all of them on her website: 61 students have received their PhDs under her supervision, and 36 former students and postdocs are now professors at universities around the world. “I don’t know anybody who’s had as many students as she’s had,” says Ritz, noting that two of his current colleagues were former advisees. “She has quite a legacy.”

Wu connects her students to as many professionals as she can and helps focus their research. “The most important thing that she does as a mentor is to point out the right direction and create a platform for her students to perform,” Wang says.

But science is human, too. Discrimination has persisted, though Wu has seen substantial progress since entering the field. A passage she read in Life magazine has stuck with her throughout her career: if you are a man, people assume you are competent until you prove that you are not; if you are a woman, people assume you are not competent until you prove that you are.

“I took it as a part of life,” Wu says. “I noticed what happened, and I just had to either fight it or tolerate it and move on. If you move on, eventually you’ll be successful. That’s what I believe.” Through all the success, Wu has viewed her mother as the most inspirational person in her life — someone who selflessly put her children before herself. After her father died, Wu moved her mother to Europe to live with her until her brother settled into a successful career in applied physics in the U.S. Her mother died in 2014 at age 94.

That same year, Wu returned to Vassar to give the college’s 150th commencement address. She left the graduating class with words that only a story like hers could transform from cliché to awe-inspiring.

“I made the resolution to devote my life to science and to make a significant contribution to humanity,” she said. “Since then, I have experienced the joy of discoveries, in life as in science. The search may be long or difficult. Oftentimes, it is long and difficult. But when obstacles strike, you fall down, and you get back up. You believe in yourself. You hold true to your determination. And you will do something great.”