Chien-Shiung Wu: The First Lady of Physics
Today, we are going to talk about a legendary Chinese-American scientist who devoted her life to the study of nuclear and particle physics and made significant contributions to the Manhattan Project.
On May 13, the 18th National Conference on Nuclear Physics was held in Huzhou of East China’s Zhejiang Province. More than 700 experts, scholars, and students from 95 universities and 27 research institutes, including the Institute of Modern Physics at the Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Peking University, Fudan University, and China Institute of Atomic Energy, participated in the conference to discuss the latest research in the field of nuclear physics theory and its application over the past three years, as well as to explore the direction of future development and frontier themes.
When talking about nuclear physics, it is unavoidable to do so without mentioning the woman universally acclaimed as the “First Lady of Physics”, the “Chinese Madame Curie” and the “Queen of Nuclear Research” – Chien-Shiung Wu.
On May 31, 1912, Wu was born in the town of Liuhe in eastern China’s Jiangsu Province, the place where Admiral Zheng He departed for his seven epic voyages during the Ming Dynasty, which lasted between 1368 and 1644.
The Wu family was full of scholars. Her father Wu Zhongshi graduated from Nanyang Public School, now Shanghai Jiaotong University. In order to promote women’s education, he founded the Mingde Girls’ School in Liuhe, which specialized in teaching girls cultural and vocational skills.
Under her father’s guidance, Wu grew up studying classical Chinese books, making her own crystal radio set, and was curious about everything. In 1923, Wu was admitted to Suzhou Women’s Normal School with excellent grades. This was where she first read Marie Curie’s biography, learned about the development of European sciences, and touched on the delicate relationship between humans and the vast universe.
During a lecture on “Modern Women”, Wu met Hu Shi for the first time. Hu was a famed scholar and, later, an ambassador to the United States from 1938 to 1942. This open-minded and gentle man entered her academic life. After graduating from high school, she went with reverence to Shanghai China Public School, where Hu taught.
In 1929, Wu was admitted to the mathematics department of the National Central University in Nanjing of Jiangsu Province. After the first semester, she was transferred to the Department of Physics. Wu completed her dissertation under the supervision of Sze Shih-Yuan, the only Chinese physicist who had worked under Madame Curie at the Radium Institute of the University of Paris.
On July 6, 1934, Sun Guangyuan, a mathematician and dean of the Faculty of Science at National Central University, presented Wu with her degree amid a standing ovation. At that time, few female students were enrolled at the university, and women graduates from its physics department were rare.
After graduation, Wu worked as an assistant professor in the physics department of Zhejiang University and then, on the recommendation of Hu Shi, went to work at the Institute of Physics at the Central Academy. When Wu arrived, she was greeted by an enthusiastic female doctor named Gu Jinghui.
Gu became a member of the American Physical Society in 1929 and, two years later, received her doctorate in physics from the University of Michigan, becoming the first female physicist in modern Chinese history. Upon her return to China, she worked as a researcher at the Institute of Physics at the Central Academy. She and Wu shared similar interests and were both fascinated by exploring the mysteries of the atom.
But the good times did not last long. After the Japanese launched an all-out invasion of China, the research institute had to close. Gu saw that Wu had great potential in physics, and recommended that she continue her research at the University of Michigan. Wu soon found herself aboard a cruise ship headed to the US. Before its departure, Wu stood on the deck and waved goodbye to her parents, unaware that it was the last time she would see them.
In August 1936, Wu arrived in the US with plans to attend the University of Michigan. She decided to first visit her friends at the University of California, Berkeley. Chia-Liu Yuan, the grandson of Yuan Shikai, the self-proclaimed president of the new Republic of China, was studying at Berkeley, and he gave Wu a tour of the campus.
They visited the southeast corner of the campus and came to a simple hut with a closed door. Yuan told Wu it was the radiation laboratory of Ernest Orlando Lawrence, who was awarded the 1939 Nobel Prize for physics. Wu had heard of Lawrence during her college years, but she didn’t ever expect to be standing in such close proximity to Lawrence or his work.
Lawrence shot to fame for his invention of cyclotron particle acceleration in the early 1930s, and later established the University of California Radiation Laboratory. The Radiation Laboratory is a highly regarded facility, with a 37-inch cyclotron, which was built to perform atomic nucleus experiments.
This, along with an incident at a student center in Michigan, which banned female students from entering through the front door, changed the course of Wu’s career. It was her first taste of sexism, and a preview of many more similar incidents that would follow. At the time, physics was a male-dominated field, and women were largely excluded, or only allowed to contribute in a supporting role.
Wu chose to stay at Berkeley at a time when physics was shining in atomic nucleus research and the campus was full of talent. She studied with George Volkoff, later president of the Canadian Association of Physicists, and a young Julius Robert Oppenheimer – the future “father of the atomic bomb” – taught her quantum mechanics, as well as Emilio Segre, the famous Italian physicist who supervised her doctoral thesis, and would become the 1959 Nobel Laureate in Physics.
In 1938, Wu began her experiments under the direction of Lawrence, director of the Radiation Laboratory, and in 1939, in collaboration with Segre, she conducted experiments on neutron impact on uranium nuclei, analyzing their output using the cyclotron. The following year, the experiment results were published in the Physical Review, a leading journal in American physics.
On May 30, 1942, the day before her 30th birthday, Wu and Chia-Liu Yuan got married in the garden of Robert Andrews Millikan, dean of the California Institute of Technology and Nobel Prize winner for physics in 1923. Millikan raised a glass of champagne and toasted the newlyweds saying, “Experiments come first and life second.”
In February 1937, Nazi Germany began its Uranium Program. Six years later, following the attack on Pearl Harbor, the US joined the war and a group of scientists, including Albert Einstein, proposed building an atomic bomb before Nazi Germany succeeded in doing so. Thus, the “Manhattan Project”, a top-secret nuclear research program, was established. A large number of the world’s most outstanding scientists were pooled together to develop the deadly weapon.
At that time, Wu was about to start her PhD thesis, but she did not know why her supervisors were suddenly too busy to be seen. All she received was a note from Lawrence with a topic proposal: Testing the theory of tough radiation. One day, Enrico Fermi, known as the “architect of the nuclear age”, 1938 Nobel Prize winner and the originator of the tough radiation theory, visited the lab and gave her some guidance, asking her to keep the data and details of the experiments confidential, while acknowledging the nuclear fission experiments that Wu had already conducted.
Back then, Wu did not know that Fermi was second in charge of the nuclear bomb project. Lawrence, who proposed the title of her thesis, was one of the directors of the Uranium Advisory Committee, appointed by President Roosevelt. Segre, who always accompanied Wu in her experiments, was also a core member of the project. Oppenheimer, her classroom teacher, participated in the nuclear bomb project from start to finish.
After numerous experiments, Wu’s research progressed rapidly and she was eventually welcomed into the fold of the Manhattan Project. In March 1944, Wu joined the Key Laboratory for Atomic Bomb Research under the Manhattan Project and began contributing her talent.
On July 16, 1945, the first atomic bomb was successfully tested. Soon after, “Little Boy” and “Fat Man” were detonated in Japan, and World War II in the Pacific theater came to a controversial end, punctuated by two, devastating mushroom clouds.
Following her work on the Manhattan Project, Wu was involved in another research project – on the history, development, current status, and most critical issues of beta decay. Every Friday, she would take the train back home to Princeton University, which has a well-stocked library that is open day and night, where she spent several weekends reading almost all the books on the subject. Wu’s most notable contributions to physics have centered on the beta-decay variable.
In the summer of 1956, Chen-Ning Yang and Tsung-Dao Lee, the co-recipients of the 1957 Nobel Prize for Physics, examined the experimental basis of the concept of parity conservation and found that the academic community had only tested the law of cosmic conservation in strong and electromagnetic interactions, but had neglected the process of weak interactions.
They approached Wu for help. Wu buried her head in the work, retreating to the lab with a group of scientists, and observed that, in the decaying of the radioactive isotope cobalt-60, in weak interactions, parity was not conserved.
In 1957, Yang and Lee were awarded the Nobel Prize for their proof of parity nonconservation, but Wu, who had also made significant and outstanding contributions to the experiment, was not included in the list of winners. In 1988, Nobel laureate Jack Steinberger said that, without her experimental results, the theories of Yang and Lee would have been a mere conception, and Wu deserved to share the Nobel Prize.
For many years, Wu did not comment publicly on the matter. But in a letter to a friend in 1989, she said she devoted her life to the research on weak effects, and found joy in it. Although the motivation for her work was never to win the Nobel Prize, she was deeply hurt when her contribution was ignored.
During her studies and career, Wu was also frustrated by her status as a woman: she had trouble getting a scholarship because she was Asian, and she had trouble getting hired. But she continued to prove herself with boldness, meticulousness, and wisdom, and even took the first steps by any woman in many fields – the first female president of the American Physical Society, the first female winner of the Comstock Prize for physics given by the US National Academy of Sciences, the first woman to receive an honorary doctorate from Princeton University, and the first person to receive the Wolf Prize for physics.
What is most celebrated by the scientific community is the integrity and accuracy of her experimental work during her 40-year career.
In the 1970s, after relations between China and the US began to normalize, Wu and her husband returned to their hometown. After an absence of nearly 40 years, Wu’s parents had long passed away and only the Mingde Girls’ School, founded by her father, still remained. At the Great Hall of the People in Beijing, Zhou Enlai, then Chinese premier, personally received the couple.
On December 15, 1981, at the Hilton Hotel in Rome, Italy, Wu received the Woman of Distinction Award. She spoke with pride that she was rooted in the strength of traditional Chinese culture, yet had a strong faith in the power of Western culture and modern society.
In 1988, the couple donated US$1.7 million to build a two-story building on the Mingde campus. On May 18, 1990, with the approval of the International Minor Planet Center, the asteroid, number “2752”, was named “Chien-Shiung Wu” by the Purple Mountain Observatory of the Chinese Academy of Sciences in Nanjing.
On February 16, 1997, Wu died after a long illness. In accordance with her wishes, her husband laid her ashes temporarily at the Mingde Girls’ School, which was renamed Taicang Mingde Senior High School in May 1998. Later, a tomb was completed at the school. Her epitaph reads: “Here is buried the most prominent female physicist Chien-shiung Wu … she was a distinguished citizen of the world, but was forever Chinese.”
The black granite slab is also engraved with the words of Tsung-Dao Lee – “This is to commemorate the epoch-making beta decay scientific contribution of Chien-Shiung Wu.”
On February 11, 2021, the sixth International Day of Women and Girls in Science, the US Postal Service issued a new Forever stamp, honoring Wu as “one of the most influential nuclear physicists of the 20thcentury”.
Well, that’s the end of our podcast. Our theme music is by the famous film score composer Roc Chen. We want to thank our writer Lü Weitao, translator Du Guodong, and copy editor James McCarthy. And thank you for listening. We hope you enjoyed it, and if you did, please tell a friend so they, too, can understand The Context.