In the world of science, where discovery often leads to progress and sometimes even the advancement of mankind, the stories of those who have contributed to this pursuit are crucial in shaping our understanding of innovation and sustainability.
One such story is that of Chien-Shiung Wu, an extraordinary physicist whose pioneering work has left a lasting impact on history. Known as the "First lady of physics" and the "Queen of nuclear research," Chien-Shiung Wu's journey is a powerful example of how different identities can come together in science to inspire creativity, challenge conventions, and drive societal progress.
Chien-Shiung Wu's Early Life and Education
Chien-Shiung Wu was born in 1912 in a small town near Shanghai, China. Her family's dedication to education played a significant role in shaping her early life.
Chien-Shiung Wu showed exceptional intelligence from an early age. Although she initially studied mathematics at the renowned National Central University in Nanking, Chien-Shiung Wu quickly switched her major to physics, a subject where she would excel even more, graduating top of her class in 1934.
Choosing to study physics was a bold move, particularly for a woman in early 20th century in China.[1]
As a matter of fact, during that time, educational and professional opportunities for women were severely limited due to deeply ingrained patriarchal values. Higher education was predominantly reserved for men, and women were often discouraged from pursuing careers in fields like science, which were considered male domains. Chien-Shiung Wu's choice to study physics at a time when women were rarely encouraged to do so, exemplifies her determination to break through these barriers. Chien-Shiung Wu was fortunate to have a supportive family, particularly her father, who believed in the importance of education for girls and even founded a school for them. This familial support was instrumental in her academic journey.
Chien-Shiung Wu's academic journey eventually brought her to the United States, where she earned her Ph.D. in Physics from the University of Berkeley, California in 1940. Her research prowess quickly caught the attention of the scientific community, leading to her involvement in one of the most significant scientific projects of the 20th century—the Manhattan Project.
For those familiar with the film Oppenheimer directed by Christopher Nolan, which delves into the development of the atomic bomb, Chien-Shiung Wu's contributions provide a critical, though often overlooked, layer to the narrative. While the film highlights the complexities and ethical dilemmas faced by scientists like J. Robert Oppenheimer, it’s important to remember that Chien-Shiung Wu's work was instrumental in the project's success.
Scientific achievements
Separation uranium isotopes
At Columbia University, Chien-Shiung Wu played a crucial role in developing the method for separating uranium isotopes, which was essential for producing the materials needed for atomic bombs.
This method, called gaseous diffusion, involved separating uranium into its isotopes, U-235 and U-238.
To put it simply, isotopes are different forms of the same element. In the case of uranium, U-235 is the form that can sustain a nuclear chain reaction, making it vital for creating the bomb.
Chien-Shiung Wu's work on this process was critical to the Manhattan Project, but like many women in science during that time, her contributions were often overlooked.
The law of conservation of parity
After the war, Chien-Shiung Wu's career continued to flourish at Columbia University, where she conducted an experiment that would forever change the field of particle physics.
In collaboration with theoretical physicists Tsung-Dao Lee and Chen-Ning Yang, Chien-Shiung Wu designed an experiment to test the law of conservation of parity—a principle that had long been assumed to be true in physics.
The law of conservation of parity states that the laws of physics should work the same way, even if you look at them in a mirror. In other words, if you have a physical process happening, and then you look at its mirror image, the process should still work the same way. This means that left and right are treated equally in physics.
For example, imagine a spinning top. If you look at the top spinning clockwise, and then look at its mirror image, you would see a top spinning counterclockwise. But according to parity conservation, the spinning motion itself should be the same in both cases.[2]
The discovery
In 1956, Chien-Shiung Wu conducted an experiment that showed parity is not always conserved, especially in a type of radioactive decay called beta decay. Here's what happened:
Chien-Shiung Wu took a radioactive cobalt-60 sample and cooled it to very low temperatures. This caused the cobalt nuclei to line up in a certain direction. When the cobalt nuclei underwent beta decay, Chien-Shiung Wu found that the electrons were emitted more in one direction than the other. This meant the decay process was not the same as its mirror image.[3]
This was a huge discovery because it showed that the laws of physics can actually tell left from right in certain situations, breaking the symmetry that parity conservation requires. Chien-Shiung Wu's experiment proved that parity is not always conserved, especially in weak nuclear interactions like beta decay.
Impact on Physics
Chien-Shiung Wu's discovery changed the way physicists thought about the fundamental laws of nature. It showed that the laws of physics are not always indifferent to left and right. This opened up new ways of thinking about particle interactions and the nature of matter.
Advocacy for women in science
This discovery was worth a Nobel Prize. The theorists Tsung-Dao Lee and Chen-Ning Yang got it but Chien-Shiung Wu was denied of it.
Why was a woman whose groundbrealing discovery has changed the way we understand particle physics, unfairly overlooked for the Nobel Prize?
Because of sexism, gender discrimination prevalent there and now.
Nevertheless, her groundbreaking experiment remains one of the most important discoveries in 20th century physics.
Chien-Shiung Wu went on to do much more seminal work, based at Colombia University in New York. She became an outspoken critic both of gender discrimination in science and the repressive policies of the Chinese government.
Wu's legacy is not just one of scientific discovery, but also of empowerment and resilience. Her work continues to inspire scientists around the world, and her story is a powerful example of how intersectionality in science can lead to innovation and sustainability.
In 1995, her colleagues founded the Wu Chien-Shiung Education Foundation in Taiwan, providing scholarships to young aspiring scientists—a fitting tribute to a woman who dedicated her life to advancing knowledge and breaking barriers.
Conclusion
In celebrating Chien-Shiung Wu, we honour the legacy of a woman who not only changed the course of physics but also paved the way for future generations of scientists. Her story is a powerful reminder that innovation and sustainability in science are inextricably linked to the diversity of the voices that drive it. Let us continue to embrace intersectionality in science, recognizing that it is the key to unlocking our fullest potential as a global community.
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