Her ideas earned Nobels but she didn't win one herself.
Chien Siung Wu, Madam Wu to her peers, was born on May 31, 1912 in Liehu, a small town near Shanghai. An outstanding student, her epoch-making experiment at the Columbia University in 1956, ultimately led to two Chinese Scintists, Chen Ning Yang and Tsung Dao Lee, winning the Nobel Prize. This time the Nobel prize was awarded for disproving an existing theory. Madame Wu passed away last year on this day at the age of 85.
The fact that a phenomenon and it's mirror image are both possible or impossible is called Conservation of parity. In other words, the molecules, atoms and nuclei behave symmetrically and nature cares two hoots whether observers look
Famous physicist Richard Feynman, had a very interesting example to explain it. Consider this: One builds a clock with things wound up inside. Another clock is built, which is a mirror image of the original piece. If the first one had a screw on the right, this one Tsung Dao Lee
has one on the left. If the first one had the spring wound right, this one has its spring wound left and so on. Now if one looked into the mirror image of the second clock, he would feel that it was the first clock and not the second one.
This was something that disturbed Madam Wu. It all started with what is popularly known as 'tau-theta' puzzle involving two mesons tau and theta. While tau disintegrated into three pion, theta decayed into two. What was baffling was that every other property, but for the mode of decay, was similar for these two mesons Chen Ning Yang. The obvious question which arose then was that could they be the same ?
However, decay of a single particle in two different modes were certainly permitted by the theory just as two twin brothers could die of two different diseases.
In spite of this, Tsung Dao Lee from the Columbia University and Chen Ning Yang, then at the Institute of Advanced study, Princeton, smelt something wrong there. They took the stand that where the mirror invariance from which the parity conservation idea was derived, might hold true in all other world's, but NOT in the world of tau and theta. Their argument was that the decay of tau and theta belonged to the 'weak interaction' type of reaction discovered in 1933 by legendary Italian scientist, Enrico Fermi. They argued that if a weak interaction does not conserve parity, the dilemma vanishes and that it required more experiments.
Immediately after Lee and Yang's paper was published, a group of physicists from Columbia University led by Madme Wu conceived the experiment. She chose radioactive Cobalt 60 for the test as it's decay life time was much longer. She cooled Cobalt 60 to near Absolute Zero and used a very strong Magnetic field to align the tiny Atomic magnets. Not exactly an easy task, even with today's high-tech gadgets. In the Fifties, it took her six months to prepare the experimental setup. She succeeded in her experiment fully. Beta particles, the electrons emitted by the lined up Cobalt nuclei went predominantly in one direction; the left could be easily distinguished from the right. Mirror invariance was no longer true. At least in the case of weak interaction.
The experiment stunned the scientific community. Every one, from Pauli to Feynman, two scientific giants of different generations was too startled to react. Feynman even paid a visit to Madame Wu's lab to see whether what she was claiming was true.
The New York Post wrote, "This small modest woman was powerful enough to do what armies can never accomplish. She helped destroy a law of nature." Lee, Yang and Wu appeared on the front pages of prestigious publications like Time, Newsweek and New York Times. Ten months later, in 1957, Lee and Yang won the Nobel Prize for Physics. In fact this was the fastest Nobel Prize awarded to these scientists in which experimental verification came only six months after the theory was declared. For reasons unknown, Madam Wu was left out.
But this was nothing new for the Nobel Committee. In 1914, Max Von Laue suggested the priciple of X-ray diffraction in a conversation that he had never published. Two University colleagues performed an extremely difficult experiment proving that the technique worked and published their results. Yet, Laue won the Nobel for being the first to think of the idea.
In an interview in 1994, in Calcutta, famous physicist E C G Sudarshan had commented, "In beta-decay work Madame Wu, Robert Marshak and I were left high and dry. Salam-Weinberg's theory could not have been thought without our work."
Wu had an uncanny ability to choose the right problems. She used her knowledge of beta-decay to confirm another basic law of nature - Conservation of vector current in beta-decay hypothesised by Murray Gell-mann and Richard Feynman. Another important contribution of her's was on the unified theory of fundamental forces.
When she joined Berkeley University, it was at the zenith of its glory with luminaries like Earnest Lawrence, Robert Oppenheimer and Emelio Segre around. She never fought shy of competing with the best brains of physics there.
Deeply concerned about the position of women, she had once commented, "Men have always dominated the field of Science and Technology. Look at what an environmental mess we are in today." Wu went on to say, "I wonder whether the tiny atoms and nuclei or the DNA molecules have any preference for masculine or feminine treatment." According to her, "A nice husband, a home close to work, and good child care" were the prerequisites for married women succeeding in science.
Rarely could one see her in Western dresses; she always wore exotic Chinese dresses with high collars and slit skirts. Robert Oppenheimer used to call her 'Jiejie', an affectionate term for elder sister in Chinese. Segre, her doctoral guide at Berkeley, had once remarked, "Wu's will power and devotion to work are reminiscient of Marie Curie, but she is more worldly, elegent and witty."
She kept her revolutionary spirit alive even in the Eighties, but succumbed to a stroke in New York last year leaving behind her physicist husband, C.L. Yaun and their son Vincent Yaun, a researcher at Los Alamos.
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