Chien-Shiung Wu
1912 – 1997 · China
Known for: The physicist whose cobalt-60 experiment proved that parity is not conserved in weak interactions
“She asked nature a plain question and accepted the answer.”
Biography
Chien-Shiung Wu was born on May 31, 1912 in Liuhe, a town in Taicang, Jiangsu province, the second of three children. Her father, an engineer and political reformer, had founded the Ming De School for girls, where she received her first lessons, and her mother was a teacher who held that daughters should be educated as fully as sons. At eleven she left home for a boarding school in Suzhou some fifty miles away, choosing the more competitive teacher-training track and placing ninth among roughly ten thousand applicants. She graduated at the top of her class, studied at National Central University in Nanjing from 1930 to 1934, moving from mathematics to physics and briefly serving as a student leader, and in August 1936 sailed for the United States.
She had planned to enroll at the University of Michigan, but after visiting Berkeley and its Radiation Laboratory, where Ernest Lawrence had built the first cyclotron, she stayed in California and completed her doctorate there. During the Second World War she joined the Manhattan Project, contributing to the separation of uranium-235 from uranium-238 by gaseous diffusion, and afterward settled into a long career at Columbia University, where she became one of the most exacting experimentalists of her generation. In 1956, when Tsung-Dao Lee and Chen-Ning Yang proposed that the law of parity might fail in weak interactions, Wu designed and carried out the decisive test, observing the beta decay of cobalt-60 nuclei aligned at very low temperature. The electrons came off preferentially in one direction, and a symmetry long assumed to govern nature was overturned.
The result, announced early in 1957, brought Lee and Yang the Nobel Prize in Physics that year; Wu was not included. She continued her research on beta decay, became the first woman elected president of the American Physical Society, and in 1978 received the inaugural Wolf Prize in Physics. Travel to China in the 1970s allowed her to see surviving members of her family after four decades apart. She died on February 16, 1997, and her ashes were interred at the school her father founded, where her own education had begun.