Chien-Shiung Wu was a Chinese-American experimental physicist, nicknamed "the First Lady of Physics." Her 1956 experiment disproved the law of conservation of parity, upending particle physics. Unjustly passed over for the Nobel Prize awarded to Lee and Yang for that discovery, she remains one of the most important figures in twentieth-century physics.
Chien-Shiung Wu(1912 — 1997)
Chien-Shiung Wu
États-Unis, Taïwan, république de Chine
8 min read
Frequently asked questions
Famous Quotes
« "It is sad that only a tiny fraction of half of humanity contributes to the understanding of the great visible and invisible world that surrounds us."»
Key Facts
- 1912: Born in Liuhe, near Shanghai, into a family that encouraged girls' education
- 1944: Joins the Manhattan Project at Columbia University to help develop the atomic bomb
- 1956: Her cobalt-60 experiment disproves the law of conservation of parity, confirming the theory of Lee and Yang
- 1957: Lee and Yang receive the Nobel Prize in Physics for the theory Wu had experimentally proven — she is excluded
- 1975: First woman elected president of the American Physical Society
Works & Achievements
Landmark experiment proving that parity symmetry is not conserved in weak interactions, confirming Lee and Yang's theory. Considered one of the most important physics experiments of the 20th century.
Wu experimentally demonstrated the vector-axial structure of weak currents, validating the unified theory of Feynman, Gell-Mann, Marshak and Sudarshan on beta decay.
Series of pioneering publications establishing Wu as the world's foremost experimentalist in beta nuclear physics, with measurements of unmatched precision for the era.
Identification of xenon-135 poisoning as the cause of the Hanford reactor shutdown, enabling the resumption of plutonium production for the American nuclear program.
Definitive scientific treatise on beta decay, used by generations of nuclear physicists. Wu synthesizes decades of experimental and theoretical research within it.
Late in her career, Wu applied her nuclear physics techniques to the study of hemoglobin and sickle cell anemia, illustrating the fruitfulness of exchanges between physics and medical biology.
Anecdotes
In 1956, theoretical physicists Tsung-Dao Lee and Chen-Ning Yang proposed that parity symmetry might be violated in weak interactions, but no one had yet proven it experimentally. Chien-Shiung Wu took up the challenge and designed an extremely delicate experiment involving cobalt-60 cooled to temperatures near absolute zero. Her results, published in early 1957, confirmed the violation of parity and upended fundamental physics.
Lee and Yang received the Nobel Prize in Physics in 1957 for their theory on parity violation, but Chien-Shiung Wu, who had provided the decisive experimental proof, was excluded from the Nobel. This omission sparked lasting controversy in the scientific community and became one of the most cited examples of gender bias in the awarding of scientific prizes.
During World War II, Chien-Shiung Wu was recruited as part of the Manhattan Project. She worked at Columbia University on uranium enrichment through gaseous diffusion and helped solve a critical problem: the Hanford reactor was mysteriously shutting down; she identified that xenon-135, a fission product, was the cause, making it possible to correct the process.
Born in a small town near Shanghai, Chien-Shiung Wu was encouraged from childhood by her father, a progressive schoolteacher, to pursue scientific studies at a time when this was exceedingly rare for a girl in China. She left her country in 1936 to pursue a doctorate at Berkeley, expecting to return quickly, but did not go back to China until decades later, after the death of her parents.
In 1975, Chien-Shiung Wu became the first woman to serve as president of the American Physical Society. In her inaugural address, she directly challenged her male colleagues on the underrepresentation of women in science, declaring that the obstacles were not intellectual but social and institutional.
Primary Sources
If parity is not conserved in beta decay, one should observe a forward-backward asymmetry in the distribution of the beta particles with respect to the direction of the nuclear spin. The present experiment was designed to measure this asymmetry.
I have been working very hard on the beta-decay experiments and the results seem to be consistently pointing in one direction. I believe we are close to a definitive answer on the question of parity.
The experimental confirmation was provided by C.S. Wu and her collaborators at the National Bureau of Standards, whose courageous and skillful experiment on oriented Co60 gave clear and definite evidence for parity nonconservation.
I wonder whether the tiny, almost imperceptible [discouragement] which some individual scientists may have unwittingly encountered in their early formative years has been multiplied many times over in the academic world.
Key Places
Chien-Shiung Wu's hometown, where her father ran a progressive co-educational school. This family environment, supportive of women's education, was a defining factor in her scientific vocation.
Wu earned her doctorate here in 1940 under the supervision of Ernest Lawrence. It was there that she received advanced training in experimental physics and met her future husband, physicist Luke Yuan.
The institution where Wu spent most of her career, from 1944 until her retirement. It was in its laboratories that she conducted the parity violation experiment and her work on beta decay.
The site where the parity violation experiment was physically carried out in 1956–1957, in collaboration with the bureau's cryogenics teams, whose equipment Wu needed to reach the required temperatures.
Manhattan Project nuclear facility where Wu contributed remotely to solving the xenon poisoning problem that was crippling the first plutonium production reactor.
Liens externes & ressources
Références
Œuvres
Expérience sur la violation de la parité (expérience Wu)
1956-1957
Confirmation de la théorie V-A de Fermi
1963
Travaux sur la désintégration bêta (thèse et articles)
1940-1950
Contribution au Projet Manhattan – résolution du problème du xénon
1944
Beta Decay (ouvrage de référence)
1965
Recherches sur l'anémie falciforme
1970-1980
