A team led by physicist Chien-Shiung Wu obtained the first experimental confirmation of parity violation in the decay of Cobalt-60, #OTD in 1956.
Her theory colleagues received a Nobel for predicting this phenomenon, but she was left off the prize.
Image: Smithsonian Institution Archives
Chien-Shiung Wu’s colleagues Chen Ning Yang and Tsung Dao Lee, the theorists who proposed the effect, were rightly awarded the Nobel Prize in 1957. She was left off the prize, of course. Another disappointing exclusion by the Nobel Committee.
At a 1964 MIT symposium, Chien-Shiung Wu commented: “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.”
Image: @Smithsonian Institution
Last year the USPS issued stamps featuring Chien-Shiung Wu. And even though they did not use my proposal for the sheet, shown below, you should still buy some.
My arrangement of portraits on the sheet is just a joke meant to remind the viewer that parity is violated — there are more stamps facing one way than the other.
But the USPS sheet (with all portraits facing the same direction) is perhaps a better representation of parity violation in the weak nuclear force. Let me explain.
When we say "parity is violated," it means that some physical process works differently under the sort of left-handed / right-handed swap you get in a mirror's reflection.
The weak nuclear force "maximally" violates parity, in that it only produces neutrinos that are (in a technical sense) left-handed, and never right-handed. This is why first signs of parity violation were first seen in nuclear decays mediated by the weak nuclear force.
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