Chien-Shiung Wu (1912–1997) was a Chinese-American experimental physicist whose precision work transformed nuclear and particle physics. Known as the “First Lady of Physics,” the “Chinese Marie Curie,” and “Madame Wu,” she made foundational contributions to the Manhattan Project, demonstrated the violation of parity conservation in weak interactions, advanced understanding of beta decay, and conducted early experiments relevant to quantum entanglement.
Born on May 31, 1912, in Liuhe (near Shanghai) in Jiangsu province, China, Wu grew up in a progressive household. Her father, Zhong-Yi Wu, an engineer and intellectual who participated in revolutionary movements, founded one of the region’s first schools for girls and strongly supported education for women. Her mother, Fanhua (or Funhua) Fan, was a teacher. As the middle child with two brothers, Wu attended her father’s Mingde School, then boarding school in Suzhou, graduating at the top of her class. She studied at National Central University in Nanjing (initially mathematics, then physics), graduating at the head of her class in 1934. Inspired by Marie Curie and mentored by female physicist Jing-Wei Gu, she conducted early research in X-ray crystallography before deciding to pursue advanced study abroad.
In 1936, with family support, Wu sailed to the United States. She enrolled at the University of California, Berkeley, working under Ernest O. Lawrence (inventor of the cyclotron) and interacting with figures such as Emilio Segrè and J. Robert Oppenheimer. Her Ph.D. research (completed 1940) examined fission products of uranium and identified isotopes relevant to nuclear reactors. After graduation, limited opportunities for women and Asian scientists in research positions led her to teaching roles: first at Smith College, then as the first female instructor in Princeton University’s physics department. In 1942 she married fellow physicist Luke Chia-Liu Yuan; they later had a son, Vincent, who also became a physicist.
During World War II, Wu joined the Manhattan Project at Columbia University’s Substitute Alloy Materials (SAM) Laboratory. She worked on radiation detection and the gaseous diffusion process for separating uranium isotopes (U-235 from U-238). Her expertise also helped diagnose xenon-135 poisoning that had shut down the Hanford B Reactor. After the war she remained at Columbia, rising to full professor and later the Michael I. Pupin Professor of Physics. She became a U.S. citizen and continued meticulous experimental work on beta decay, refining and confirming aspects of Enrico Fermi’s theory.
Wu’s most celebrated achievement came in 1956–1957. Theoretical physicists Tsung-Dao Lee and Chen Ning Yang suggested that the long-accepted principle of parity conservation (mirror symmetry of physical processes) might not hold for the weak interaction. Wu designed and led a decisive experiment using polarized cobalt-60 nuclei cooled to near absolute zero so their spins could be aligned by a magnetic field. Measuring the directional preference of emitted beta particles (electrons), her team at Columbia and the National Bureau of Standards found a clear asymmetry: more electrons were emitted opposite to the nuclear spin direction. This demonstrated parity violation—nature distinguishes left from right in weak interactions. The result, announced in early 1957 and published promptly, upended a fundamental assumption of physics and helped shape the Standard Model. Lee and Yang received the 1957 Nobel Prize in Physics for the theoretical proposal; Wu was not included, despite the experiment’s centrality and her later nominations. The experiment is widely known as the Wu experiment.
Earlier, in 1949–1950 with student Irving Shaknov, Wu performed a coincidence experiment on annihilation radiation that verified quantum electrodynamics predictions and produced evidence of correlated (entangled) photon pairs—work later recognized as pioneering in quantum information contexts. She continued refining beta-decay studies, confirmed the conserved vector current hypothesis (with collaborators in 1963), and applied nuclear techniques to biological questions, including molecular changes in hemoglobin related to sickle-cell disease. Her 1965 book Beta Decay remains a standard reference.
Throughout her career Wu faced gender and racial barriers yet accumulated major honors. She was the seventh woman elected to the National Academy of Sciences (1958), the first woman to receive the Research Corporation Award, the first woman to win the National Academy of Sciences’ Comstock Prize in Physics (1964), recipient of the National Medal of Science (1975), the first woman president of the American Physical Society (1975), and the first recipient of the Wolf Prize in Physics (1978). Princeton awarded her its first honorary doctorate to a woman. An asteroid (2752 Wu Chien-Shiung) was named for her in 1990 while she was still living—the first such honor for a living scientist in that context. In 2021 the U.S. Postal Service issued a commemorative stamp in her honor.
Wu retired from Columbia in 1981 but remained engaged with science and education. She advocated for women and underrepresented groups in physics and maintained ties to Chinese scientific communities. She died of a stroke in New York City on February 16, 1997, at age 84; her ashes were interred at the Mingde School in China.
Wu’s legacy rests on experimental rigor, intellectual courage, and the willingness to test deeply held assumptions. By showing that parity is not conserved in weak interactions, she helped open the path to modern understanding of the weak force, neutrinos, and asymmetries that may relate to the matter-antimatter imbalance in the universe. Her career illustrated both the power of precise measurement and the persistent obstacles faced by women and immigrants in mid-twentieth-century science. Today she is remembered as one of the foremost experimental physicists of her era, whose work continues to influence particle physics, nuclear science, and the broader culture of scientific inquiry.