Wu, Chien-Shiung (1912–1997)

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Wu, Chien-Shiung (1912–1997)

Chinese-American experimental physicist who supplied the proof for the hypothesis that the principle of the conservation of parity was invalid, overthrowing what had been a fundamental concept of physics . Name variations: Wu Chien-Shiung. Pronunciation: CHEN-shoong WOO. Born Chien-Shiung Wu on May 29, 1912, in Shanghai, China; died in New York City after suffering a stroke on February 16, 1997; daughter of Wu Zhongyi (a school principal) and Fuhua H. Fan Wu; National Central University, Nanjing, B.S., 1934; University of California, Berkeley, Ph.D., 1940; married Luke Cha-Liou Yuan (a physicist), on May 30, 1942, in Pasadena, California; children: son, Vincent Weichen Yuan (b. 1947).

Hired as physics instructor, Smith College (1942); became physics instructor, Princeton University (1943); joined scientific staff, Division of War Research, Manhattan Project, Columbia University (1944–45); was research physicist, Columbia University (1945–81); received tenure as associate professor at Columbia (1952); became naturalized citizen (1954); determined invalidity of principle of parity (1957); received Research Corporation Award (1958); was seventh woman elected to the National Academy of Sciences (1958); promoted to full professor at Columbia (1959); named "Woman of the Year" by the American Association of University Women (1962); was first woman to receive the National Academy of Sciences Comstock Award (1964); won the National Medal of Science (1975).

Selected writings:

"I. The Internal and External Continuous X-Rays Excited by the Beta Particles of 32/15P. II. Some Fission Products of Uranium" (Ph.D. dissertation, University of California, Berkeley, 1940); "Recent Investigations of the Shapes of Beta-Ray Spectra," in Reviews of Modern Physics (Vol. 22, October 1950, pp. 386–398); with I. Shaknov, "The Angular Correlation of Scattered Annihilation Radiation,"in Physical Review (Vol. 77, 1950, p. 136); with Ernest Ambler, Raymond W. Hayward, Dale D. Hoppes, and R.P. Hudson, "Experimental Test of Parity Conservation in Beta Decay," in Physical Review (Vol. 105, 1957, p. 1413); with Luke C.L. Yuan, Nuclear Physics (2 vols., NY: Academic, 1961–63); "The Universal Fermi Interaction and the Conserved Vector Current in Beta Decay," in Reviews of Modern Physics (Vol. 36, 1964, p. 618); with Steven A. Moszkowski, Beta Decay (NY: Interscience, 1966); with Lawrence Wilets, "Muonic Atoms and Nuclear Structure," in Annual Reviews of Nuclear Science (Vol. 19, 1969, p. 527); "One Researcher's Personal Account," in Adventures in Experimental Physics (1973); edited with Vernon W. Hughes, Muon Physics (3 vols., NY: Academic, 1975–77); "Subtleties and Surprises: The Contribution of Beta Decay to an Understanding of the Weak Interaction," in Annals of the New York Academy of Sciences (Vol. 294, November 8, 1977, pp. 37–51).

On January 16, 1957, at a press conference held at Columbia University in New York City, a petite Chinese-American woman, her hair twisted into a bun, declared the results of an experiment in nuclear physics she had recently completed. Nuclear particles, said Chien-Shiung Wu, did not always behave symmetrically. The scientific principle of conservation of parity was therefore proved invalid. If the nature of her pronouncement were arcane, the scientific implications of it were huge. For the first time in the relatively short history of the science of physics, one of its universally accepted laws regarding the structure and behavior of the universe was being struck down.

For the 45-year-old research physicist, the experimental results were the culmination of her life's work. Explaining the reward she found in physics research, Wu later told Gloria Lubkin, senior editor of Physics Today, "I've always felt that in physics you must have total commitment. It's not just a job. It's my whole life."

The name Chien-Shiung Wu means "Courageous Hero," a fitting designation for the daughter of a fighter in the Chinese Revolution of 1911. Wu Zhongyi was a former engineering student, and his only daughter was born the year after he helped in the overthrow of the Manchu Dynasty. Enlightened about gender issues by his reading of Western books, he established a girls' school and became one of the foremost feminists in China. "I want every girl to have a school to go to," he declared. "I want everyone who has suffered to have a place to go to air his [or her] sufferings."

Chien-Shiung Wu was on born May 29 (other sources cite the 31st), 1912, in the Chinese port city of Shanghai. She grew up some 30 miles away in the small town of Liuho, in Chiangsu Province, where her father's school was located. Wu's mother Fuhua H. Fan Wu visited local families to persuade parents to send their daughters to her husband's school, and to end the ancient and brutal Chinese practice of binding young girls' feet. School principal Wu Zhongyi, committed to preparing both young men and women for life in a modernized China, filled the family's home with scholarly books and encouraged questioning and the exploration of new ideas in his daughter and two sons; at night, the family read together. Wu Zhongyi held the culture and traditions of China in high regard, and believed music, arts and literature enriched the lives of his children and helped to prepare them for the future.

"It was a wonderfully happy life. I had a fortunate and happy childhood," Wu told biographer Edna Yost. Curious about the world around her, she enjoyed playing with other children, but was particularly delighted by the solving of problems her father would pose for her. In Liuho, where few people recognized the scope of political change then abroad in China and the Far East, Wu Zhongyi advised his daughter, "Ignore the obstacles. Just put your head down and keep walking forward." Father and daughter grew especially close.

Chien-Shiung Wu knew from an early age that she wanted to be a scientist. When she was nine, she completed the training available at her father's school and asked to be allowed to go to boarding school. Her great-great-grandmother, the family matriarch, insisted that she be sent to the best school available. A teacher at the Soochow Girls School who was a family friend agreed to be her guardian, and the school's Western curriculum opened many new subjects to her, including English. Lecturers came from such prominent American schools as Columbia University, where she was to spend most of her career.

At Soochow, girls entered either an academic program or a training course to become a teacher. Wu elected at first to pursue the teaching curriculum because it was free and prepared students for jobs. Soon, however, she became fascinated by what friends in the academic program were learning in their science classes. She would get students in her dormitory to loan her their science textbooks during the evening so that she could learn the principles of physics, mathematics and chemistry for herself. The puzzles

posed by physics intrigued her most. "Somehow I soon knew," she later said, "it was what I wanted to go on with."

In the seven years she spent at Soochow, Wu also led the local chapter of China's under-ground student movement, protected from expulsion by her father's revolutionary record and her excellent grades as she represented the students at meetings and strikes. Graduated in 1930 at the top of her class, she received notice that summer of her selection as a student at the National Central University, the elite government-supported school located at Nanjing, the capital of the nationalist government. Eager to study physics, she confessed her doubts about her background in mathematics and science to her father. "There's ample time to prepare yourself," responded Wu Zhongyi, who bought her three advanced textbooks—in mathematics, chemistry, and physics—which she studied until the school year began.

It is the courage to doubt what has long been established, the incessant search for its verification and proof that pushed the wheel of science forward.
—Chien-Shiung Wu

Enrolled initially in mathematics, Wu had enough confidence by her sophomore year to transfer to physics. Thriving in this intellectual setting, she completed every physics and mathematics course she could and led every class. In the tumultuous atmosphere of pre-World War II China, she also participated in the students' nationalist movement, boycotting Japanese products and protesting at the presidential mansion of General Chiang Kai-shek. With other student leaders, she appeared before the general to urge his resistance against Japanese aggression. In 1934, despite her political activism, she completed her thesis on X-rays and was awarded a degree in physics.

"If it hadn't been for my father's encouragement," Wu later said, "I wouldn't have had the courage to select physics as a major field and I would be teaching grade school somewhere in China now." As it was, graduation was followed by a teaching position at a provincial university, then research work, in X-ray crystallography, at Shanghai's National Academy of Sciences. At the academy, a female physicist with a Ph.D. from the University of Michigan became an influential mentor, encouraging Wu to attend her alma mater for graduate physics courses unavailable in China.

Wu's parents supported her desire to go to the U.S.; at that time she saw the degree she could get in America as a way to help in the modernization of her country. An uncle who had made a fortune establishing China's first long-distance bus company financed the trip, and at age 24, in the fall of 1936, she set sail across the Pacific.

In San Francisco, friends of her family introduced her to Luke Cha-Liou Yuan, a graduate student in physics at the University of California at Berkeley. The grandson of a famous Chinese general, Luke Yuan warned her against the University of Michigan, with its large Chinese student population and rules that did not even allow women to use the student union. Berkeley, on the other hand, had one of the best physics programs in the world. Eager to meet Americans and put off by thoughts of discrimination, Wu followed his advice and enrolled at Berkeley.

In the fascinating and demanding program she entered, some of the world's best nuclear physicists were teaching and carrying out their research. Dr. Ernest O. Lawrence, director of the radiation laboratory, was then devising an atom-smashing cyclotron, and won the Nobel Prize in physics for research in atomic structure and transmutations while Wu was his student. In the classes of Robert Oppenheimer, she heard lectures about new quantum theories, concerning the behavior of atoms and subatomic particles. She was unintimidated among these brilliant figures, later explaining, "I didn't see a man there who could compare with my father."

At ease in the classroom, Wu had some difficult cultural adjustments. In the cafeteria of the International House, where Asian, European and American graduate students lived together, she was bewildered by the confusing buffet faced at breakfast time instead of the expected rice. Going off campus to find Chinese food, she met a German student, Ursula Schaefer, in a bakery, and they became friends. The two learned about the cooking and customs and civilization of America while sharing opera, theater, books and their native foods. Wu grew fond of Western folk songs and classical music.

In her slit-skirt, high-collared dresses, Wu was exquisitely exotic to Berkeley's male students. One described her as "a smasher—a gorgeous, willowy girl with a smile that would melt anybody's heart." Wu, in turn, was dignified and reserved, addressing everybody formally by their titles. Her students called her "Miss Wu," and only Oppenheimer and close friends dared to address her affectionately as "Jiejie," meaning "elder sister" in Chinese. Charming, modest and polite, she also insisted on rationality and truth, even when her opinions forced her to be disapproving of friends. Schaefer described Wu as "the only one who gave me real hell," and also "an absolutely, totally reliable friend. If anything happened she would be right there. She's very reserved, but very, very human and warm."

At Berkeley, Wu focused on the study of atomic particles, including protons, electrons, neutrons and other invisible components such as mesons, that were central to research in nuclear physics at the time. Emilio Segré, who assisted Lawrence and was known for his rudeness to many students, including Wu (when she forgot to secure a mercury bottle, he left her a note, "The vapor is poisonous. Do you want to see your grandchildren?"), admired her. "Wu's will power and devotion to work are reminiscent of Marie Curie ," he once commented, "but she is more worldly, elegant and witty." Urging her to read more physics and spend less time in the laboratory, Segré advised, "You have to stand back from things and see the whole picture."

In the classroom and laboratory, Wu performed admirably; her professors considered her work to be brilliant, original and insightful. Because they were Asian, however, both she and Yuan were denied fellowships; $200 each to grade papers was the best they could get. Yuan left for the California Institute of Technology in southern California to accept a $600 fellowship.

In July 1937, learning that Japan had invaded China, Wu realized she was cut off from all contact with her family. "We are all very, very sorry," she was told by the chair of the physics department. "But you don't have to worry about yourself. We will take care of you now." In International House, two Japanese students sent her flowers. Worried about her family and friends, she endured months of reading about Japanese atrocities against Chinese civilians.

Meanwhile, she immersed herself in her work. "I have always felt that in physics, and probably in other endeavors too, you must have total commitment," she once said. "It is not just a job. It is a way of life." Patterning her career after that of Marie Curie, who also emigrated to a new home and labored to succeed in physics, Wu worked late into the night. Caring professors would request that a graduate student drive her home so she would not walk alone in the dark. Wu panicked at each test, afraid that a failure in schoolwork would leave her with nowhere to go, and celebrated in Chinese restaurants when she passed. Insecure about her pronunciation of English, she carefully wrote out each lecture. But she was happy in her work. "It is hard to push the door open and to get inside a subject," she explained. "But once you understand it, it is very interesting."

In 1940, Wu completed her Ph.D. in nuclear physics and was elected to Phi Beta Kappa. For her doctoral dissertation, she performed two investigations. The first involved ingeniously devised methods of separating two types of rays emitted during beta decay, a type of radioactivity (known as a weak interaction) in which a nucleus ejects high-speed electrons and becomes another element. Wu studied the electromagnetic energy emitted when a particle traveling through matter decelerated, validating her theoretical predictions with her experimental results.

In her second investigation, she studied radioactive noble gases derived from uranium fission (the atomic nucleus was first split by German scientists in 1939). Working with Dr. Segré, she demonstrated that "two complete chains of radioactive decay" resulted "with the half lives, radiations and isotope numbers completely identified." The wartime climate of secrecy prevented the work from being published at that time, but the results were requested by and delivered to the U.S. government's Los Alamos Laboratories.

No major research university employed a woman as a professor of physics at the time; and in the discriminatory atmosphere against Asians, especially on the West Coast (although the Chinese were U.S. military allies), Berkeley's administrators refused to hire Wu for such a position. Berkeley's physics department, hoping to retain their outstanding young physicist, created a position for Wu in the radiation laboratory as a research assistant to Dr. Lawrence. Gaining expertise in fission, she lectured throughout the country in 1941.

On May 30, 1942, in the midst of World War II, Wu married Luke Yuan in the garden of Nobel Prize-winner Robert Millikan. The couple moved to New Jersey, where Yuan was employed to design radar devices for RCA and Wu was hired to teach physics at Smith College. Within that same year, she was invited to become a lecturer on nuclear physics at Princeton University. While she was reluctant to leave a position in which she could influence female students, Wu finally elected to teach at the all-male Princeton, where she became the first woman instructor, in order to have access to physics research equipment that was unavailable at Smith. She had been at Princeton only a few months when she was interviewed to work for the wartime Manhattan Project at Columbia University.

Pleased to be able to contribute to the Allied war effort, Wu joined the scientific staff of the Division of War Research at Columbia, in New York City, in March 1944. In a converted automobile warehouse, she worked on designing radiation detectors for the atomic bomb project and perfecting Geiger counters, as well as neutron and uranium enrichment research.

In 1945, with World War II ended, Wu finally received news that her family in China was alive. At Columbia, she became a senior investigator for a large federal research grant. In 1947, her son Vincent Weichen Yuan was born, and the family moved into an apartment at 15 Claremont Avenue, only two blocks from her laboratory. Filled with Chinese art, furniture and cooking utensils, the apartment was Wu's place to relax and enjoy her family. Luke commuted to Brookhaven National Laboratory on Long Island, where he designed accelerators, and Vincent went to local private academies and European boarding schools. Wu considered "a nice husband," a home near work, and reliable child care as essential for married female scientists.

In her research, Wu now renewed her studies of beta decay. Because of discrepancies between theories and experimental results due to the primitive state of beta spectroscopy (the optical examination of a particle's spectrum), she attempted to discover new ways to study the shapes of beta spectra and their interaction during beta decay. She developed a technique for spectra study, using a scintillation counter and beta detector inside a magnetic spectrometer, and after several years of research with thin copper sheets, she offered proof in support of Enrico Fermi's theory of beta decay about the travel of electrons at specific speeds.

Because she was a full-time researcher at Columbia, Wu was not promoted to associate professor of physics with tenure until 1952, when she began to teach part-time. This was an academic rank few women had achieved in universities or research laboratories. Two years later, in 1954, Wu became a naturalized American citizen. She and her husband had been invited to join the faculty of the National Central University in China, but they elected to become Americans due to China's civil war with the communists. Wu never saw her family again, and received only infrequent letters.

Dr. Wu advised graduate students focused on problems regarding beta decay, seeking new methods and materials with them for conducting their research. In the 13th-floor laboratory of the Pupin physics building, she had a reputation among some as a slave driver who expected her students to work as hard as she did, day and night, and on weekends. But according to Schaefer, "if she felt that a student was performing below par, she gave him hell, because she was anxious that he wasn't going to make it." A demanding teacher, known for the high-necked Chinese dresses she wore under her laboratory coat, she monitored experiments, adjusting equipment and criticizing her students' methods, while also warning them to guard their data until it was published to prevent intellectual theft. Most who worked under her admired her for her intense devotion to her research, and for her competitiveness, while she in turn was motivated by their youthful enthusiasm.

Some students showed their Asian bias by dubbing Wu the "Dragon Lady," after a comic-strip character defaming Madame Chiang Kaishek (Song Meiling ). Others regarded her as one of the nicest professors at Columbia, comparing her to male professors, in particular, with reputations for self-centeredness and disdain toward their students. Wu, in contrast, ate lunch with her students every Friday in Chinese restaurants, and hosted parties to celebrate the degrees and honors they earned; she was particularly caring toward her Asian students, warning them that they would have to work harder than others to overcome discrimination in their chosen field. With these loyal and dedicated students, Wu established Columbia as a center for some of the most outstanding experimentation being done in physics, and the work was monitored by other leading physicists, who sought her out for consultations.

In the spring of 1956, Wu was approached by two fellow physicists, both of Chinese-American background, with an intriguing proposition. Tsung Dao Lee was a colleague of Wu's at Columbia and Chen Ning Yang worked at the Princeton Institute for Advanced Study, and what they were seeking was help in testing the validity of one of the underlying principles of physics.

The so-called principle of conservation of parity belonged to the body of laws, including those of gravity, which are understood by physicists to govern the nature of the universe at the subatomic level. The principle of conservation of parity applied to the behavior of particles at the subatomic level, where an object and its mirror image were believed to be symmetrical. Albeit unproven, it had been accepted for three decades as one of the fundamental underpinnings of physics.

As early as 1946, however, the validity of the parity principle was brought into question by the work of some theoretical physicists. In the early 1950s, doubts were increased after the discovery of the subatomic particles known as K-mesons, which did not follow the pattern of disintegration that the principle of parity should have made predictable. Then when Lee and Yang, working together, began to investigate the principle, they found behavioral anomalies at the subatomic level and incomplete information. Suspecting by then that the principle was invalid, they sought out Wu to help in the proof of their hypothesis because of her lengthy experience with another type of subatomic particle, the electrons in the nucleus of radioactive substances known as beta rays. They proposed that Wu design an experiment using beta rays, to determine if particles were sloughed from the nucleus during beta decay, regardless of the direction in which the nucleus spun. If this were true in the case of beta rays, the conservation of parity would be proven invalid as a universal law.

The experiment would be extremely complex and difficult to set up; the odds against arriving at a conclusive proof were about one in a million. Wu's initial reaction was to loan the men her copy of the study Beta- and Gamma-Ray Spectroscopy. But in June 1956, when they submitted their article "Question of Parity Conservation in Weak Interactions" to Physical Review, she began preparing her approach to the problem, fearing some other scientist might get ahead of her. She even decided not take the ocean cruise to the Far East she and her husband had planned to celebrate the anniversary of their immigration.

Since Columbia's facilities were not adequate for the job, Wu contacted the National Bureau of Standards in Washington, D.C., where she could have the help of Ernest Ambler, who had pioneered research with radioactive nuclei at extremely cold temperatures. Working with the bureau's Low Temperature Physics Group and scientists from the Atomic Energy Commission, she was engaged in the project for the next six months, commuting between Washington and her students in New York every two weeks, and sleeping no more than fours hours a night.

Her design for the test involved a radioactive nucleus of cobalt 60, put into a complex cooling and vacuum system capable of being cooled with gases and crystals to the temperature of 0.01° above absolute zero (-459° Fahrenheit). The extremely low temperature reduced thermal motion during beta decay so that the spinning cobalt nuclei could be aligned with a magnetic field, and thus be more easily manipulated and observed. A scintillation counter recorded the results by enumerating the electrons discharged by the disintegrating cobalt nuclei. As Wu explained, "The essence of the experiment was to line up the spins of the Cobalt 60 nuclei along the same axis, then to determine whether the beta particles were emitted preferentially in one direction or the other along the axis." Scientists in Washington, intensely monitored by Wu, stayed with the equipment day and night, readjusting it as needed. Those hectic sessions, she said later, were "like a nightmare. I wouldn't want to go through them again."

As her careful measurements began to yield repeated verifications, Wu remained doubtful of her findings. Researchers at Columbia and the University of Chicago began to duplicate her results with experiments in meson decay, and her sleepless nights continued while she sought other means of confirming her results. Finally, after weeks of deliberation, she agreed to announce her findings, at the press conference hosted by Columbia.

Declaring her results, Wu asserted that nuclear particles did not always behave symmetrically. In fact, statistics proved that electrons preferred going in the opposite direction of the nuclei's spin in an almost predetermined pattern. Scientists began to suggest that Wu and her colleagues had revealed a "preference" in electrons for "handedness." Nuclear particles, like humans, could be designated as being right-handed or left-handed as they moved along the axis of rotation and were discharged according to the direction of their spin.

While physicists adjusted to the idea of discarding one of the fundamental concepts of their science, Wu enjoyed the "moments of exaltation and ecstasy" in what she described as the "sudden liberation of our thinking on the very structure of the physical world." According to the New York Post, "This small modest woman was powerful enough to do what armies can never accomplish," and she was featured on the front page of The New York Times as well as in Time and Newsweek. For Wu, however, the thrill was in the "new level of understanding" for physicists, and the meanings that still lay ahead. "When we arrive at this understanding," she said, "we shall marvel how neatly all the elementary particles fit into the Great Scheme. Indeed, how deeply privileged our generation is to have been challenged with this fascinating task."

Reaping the professional accolades due her for the research, Wu also ensured international acclaim for Lee and Yang, whose names appeared along with hers on her findings, published in the Physical Review (signed "C.S. Wu," as were all her articles). In 1957, the Nobel Prize in physics went to the two theoretical physicists, but not to Wu. According to the strict rules of eligibility, the award was given for discovery or invention, and did not cover the work of supplying the proof. Many physicists felt it an unjust over-sight, however, that the work of Wu and her experimental group was ignored.

At Columbia, Wu was promoted to full professor, and the following year she became the first woman to receive the Research Corporation Award, and only the seventh woman to be elected to the National Academy of Sciences. She also won the Franklin Institute's Wetherill Medal and $10,000 from Taiwan's Chi-Tsin Culture Foundation, and was elected to the Academy of Sciences of China. When she was awarded the first honorary doctorate in science ever given to a woman by Princeton University, its president declared that Wu had "richly earned the right to be called the world's foremost female experimental physicist," and congratulated her for revealing "the unwisdom of underestimating the powers of a woman."

In 1960, Wu was named Woman of the Year by the American Association of University Women; two years later, she was the first woman to receive the National Academy of Sciences Com-stock Award. In 1975, while Gerald Ford was president, she would receive the National Medal of Science, America's highest science award.

Continuing her research in beta decay, Wu experimented on other weak interactions in nuclei. In 1963, with two Columbia colleagues, she confirmed a theory, proposed in 1958 by Murray Gell-Mann and Richard P. Feynman, concerning the conservation of vector current in beta decay, considered an important contribution to physicists' ongoing efforts to establish a unified theory of fundamental forces. Her review article, "The Universal Fermi Interaction and the Conserved Vector Current in Beta Decay," appeared in Reviews of Modern Physics and is often cited by physicists. Wu also measured X-rays and gamma rays emitted by muonic atoms (in which a muon, a particle 200 times heavier, replaces an external electron) to describe nuclear properties. With Lawrence Wilets, she published a watershed review article, "Muonic Atoms and Nuclear Structure," in Annual Reviews of Nuclear Science. The treatise Beta Decay, which she wrote with Steven A. Moszkowski in 1966, now considered a classic in the field; she also published Nuclear Physics with her husband and edited Muon Physics with Vernon W. Hughes.

Believing that "even the most sophisticated and seemingly remote basic nuclear physics research has implications beneficial to human welfare," Wu turned to research in biophysics in quest of a cure for sickle-cell anemia. Her proximity at Columbia to Harlem led to her interest in the genetic predisposition among African-Americans to produce the irregularly shaped blood cells that underlie this devastating disease, and Wu's work concentrated on molecular changes in hemoglobin.

In 1972, Columbia awarded Wu an endowed professorship. She also became the first living scientist to have an asteroid named in her honor. In 1973, she returned to China, but her parents were by then dead, and her brothers had been killed during the Cultural Revolution. Two years later, she became the first woman to serve as president of the American Physical Society, and she was made an honorary fellow of the Royal Society of Edinburgh.

In 1981, Chien-Shiung Wu, known as Madame Wu to colleagues and students, retired from Columbia University after a 36-year career. She continued to lecture in Asia and America, and her love for her homeland and for physics was passed on to her son, Vincent, also a physicist. Believing that more time and money had to be devoted to education and research if her adopted country were to remain politically and economically powerful, Wu also denounced attitudes that discouraged American women from pursuing physics. "I doubt that the tiny atoms and nuclei or the mathematical symbols or the DNA molecules have any preference for either masculine or feminine treatment," she asserted, and her financial prizes often went to fund scholarships. Wu died in Manhattan, after suffering a stroke, on February 16, 1997.

Shortly after disproving the parity principle, Chien-Shiung Wu spoke to student winners of the National Science Award, explaining the will-ingness and daring to doubt that lay behind her work in a way that could be taken as her personal philosophy. "The overthrow of the parity law drives home again the idea that science is not static, but ever-growing and dynamic," she said. "It is the courage to doubt what has long been established, the incessant search for its verification and proof that pushed the wheel of science forward."

sources:

Gilbert, Lynn, and Gaylen Moore. Particular Passions: Talks with Women Who Have Shaped Our Times. NY: Crown, 1981.

Lubkin, Gloria. "Chien-Shiung Wu, the First Lady of Physics Research," in Smithsonian. January 1971, pp. 52–57.

McGrayne, Sharon Bertsch. Nobel Prize Women in Science. Secaucus, NJ: Carol, 1993.

Noble, Iris. Contemporary Women Scientists of America. NY: Messner, 1979.

"Wu, Chien-Shiung," in Current Biography. NY: H.W. Wilson, 1959, pp. 491–492.

Yost, Edna. Women of Modern Science. NY: Dodd, Mead, 1959.

collections:

Photographs of Wu and material about American physicists are available at the American Institute of Physics, Center for History of Physics, Niels Bohr Library, New York City.

Elizabeth D. Schafer , Ph.D., freelance writer in history of technology and science, Loachapoka, Alabama

Women in World History: A Biographical Encyclopedia