Chien-Shiung Wu

Chien-Shiung Wu — the First Lady of Physics — was a Chinese experimental physicist, whose work on beta decay and parity violation made seminal contributions to the field of nuclear physics.

Chien-Shiung Wu — Sci-Illustrate Stories

Featuring artwork & words by Dr. Eleonora Adami, Sci-Illustrate Stories. Set in motion by Dr. Radhika Patnala.

You most certainly have heard about Marie Curie, but do you know that the nickname “first lady of Physics” was coined for an Asian scientist?

Early years

Chien-Shiung Wu was born in Liuhe (Jiangsu province), China, in 1912 in a well-to-do family. Her father was a progressivist supporter of women equality and strongly encouraged her interests, resilience and tenacity. In 1929 Chien-Shiung was admitted to the National Central University in Nanjing, one of the oldest and most prestigious institutions in China, majoring in mathematics; only later she transferred to physics. She was one of the top students at the University and for 2 years after graduation she worked as an assistant at Zhejiang University and became a researcher at the Institute of Physics of the Academia Sinica. Her supervisor was a female Professor — Gu Jing-Wei — who had studied in US and encouraged her to spread her wings and consider a PhD abroad. This mentorship was very important for building up confidence in the young Chien-Shiung, who, following her supervisor’s advice, enrolled at Berkeley.

Graduate studies and the Manhattan Project

On the other side of the ocean, many started to recognise her talent and brilliance; She quickly became Emilio Segre’s favourite student, as they worked together on beta decay — a field in which she eventually became an authority. She completed her PhD in 1940s and was elected to Phi Beta Kappa, the US academic honour society. Two years later, she moved to the east coast of the United States, as she managed to secure a junior faculty position at Smith College, and later at Princeton, where she became the first female faculty ever hired in the physics department.

At this point, World War II was a sad and tangible reality and an anti-Asian sentiment that was growing in the US. Chien-Shiung was however recognized as one of the most brilliant minds in physics at the time and was recruited to join the Manhattan Project’s Substitute Alloy Materials (SAM) Laboratories at Columbia to work on radioactive uranium separation with Segre and Fermi. Later on, like many of her colleagues, she distanced herself from the Project, due to its destructive outcome.

ROBERT W. KELLEY/LIFE PICTURE COLLECTION VIA GETTY IMAGES

Does the universe have an innate sense of “direction”?

In her post-war research at Columbia, she continued to focus on beta decay and one specific moment conclusively crowned her as the First Lady of Physics. In the mid 1950s, she was asked by Lee and Yang, two Chinese colleagues, to set-up an experiment to test whether the law of conservation of parity held true in beta decay. Parity symmetry was previously studied for the electromagnetic and strong interactions, but they were wondering whether it also applied to weak interactions. According to parity symmetry, laws of physics should not differentiate between up/down, left/right, since these are arbitrary, as they would be defined according to a reference system.

Acc. 90–105 — Science Service, Records, 1920s-1970s, Smithsonian Institution Archivess — Wikimedia Commons

In an experiment that became known as the Wu experiment, she proved that parity symmetry is not conserved for all interactions of elementary particles: radioactive cobalt atoms decayed by emitting electrons not randomly (!) but in certain preferred directions, opposite to the atom’s nuclear spin. It can be thought of as a test of chirality of a physical phenomenon. A mirrored experiment, where left and right were swapped, and so the atoms’ spin, would give different results, violating parity symmetry principles.

Principle of Wu experiment 1956 to detect parity violation in nuclear beta decay. The result of this experiment proved that the current world would not behave identically to its mirror image. © Nagualdesign CC BY-SA 3.0

The discovery of parity violation was earth-shattering in particle physics and led to the development of the Standard Model. For this pioneering work, which also had ramifications such as leading to an operational definition of left and right, with no reference to a fixed perspective (eg. the human body), her male colleagues received the Nobel Prize in Physics in 1957. Though her role in the discovery was critical, it was not acknowledged publicly until 1978 (21 years later!), when she was awarded the inaugural Wolf Prize.

Acc. 90–105 — Science Service, Records, 1920s-1970s, Smithsonian Institution Archives — Wikimedia Commons

As I am doing the research to write this article, I find myself thinking how she must have felt for all those years, until she found the courage to be outspoken about the gender discrimination she had faced.

“I wonder whether the tiny atoms and nuclei, or the mathematical symbols, or the DNA molecules have any preference for either masculine or feminine treatment” (Chien-Shiung Wu at MIT, 1964).

It is incredible to realise that even if she was the top player in her field, it was not until 1975 that her pay was adjusted to make it equal to her male colleagues.
She continued to do outstanding work, inspiring young scientists even after her retirement in 1981. She was a huge advocate for equal opportunities in STEM and for human rights issues ( protest against the Tiananmen Square massacre of 1989) until her death in 1997.

© 2021 U.S. POSTAL SERVICE

Timeline
1912 — Born in Liuhe (Jiangsu province), China
1936 — Moves to USA
1940 — Obtains her PhD at Berkeley
1942 — Faculty at smith College and later at Princeton
1944 — Joins the Manhattan Project
1945 — Associate research professor at Columbia
1957 — She is overlooked by the Nobel Prize Committee, an incident many in the scientific community defined as preposterous.
1978 — Receives first Wolf Prize
1997 — Dies aged 84

About the author and artist

DR. ELEONORA ADAMI

Content editor and contributing artist
Women in Science, Sci-Illustrate Stories

Eleonora is a proud descendant of ancient Romans. Besides that, she is currently a postdoctoral research fellow at Duke-NUS in Singapore, working in the cardiovascular and metabolic diseases area. She has a biotechnology (BSc) and functional genomics (MSc) background, and has obtained her PhD in molecular biology and genetics in Germany before going to the far east.

Eleonora thinks of herself as a carrier pigeon, always on the go, trying to find new adventures and challenges. Ok, maybe pigeons are not very adventurous, but they were once useful to deliver important messages. One of the messages she likes to bring across is that we need more art in scientific practices. Creative thinking benefits both disciplines.
A passion for illustration has always accompanied her and percolates in her scientific work. She started the collaboration with the Sci-Illustrate team after attending their course on scientific illustration.

About this series:

Not enough can be said about the amazing Women in Science who did and continue to do their part in moving the world forward.

Every month, through the artwork & words of the Sci-Illustrate team, we will bring to you profiles of women who touched our hearts (and brains) with their scientific works, and of many more who currently hold the flag high in their own fields!

-Dr. Radhika Patnala, Series Director

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