Physicists, with their flair for exotic nomenclature, have named the strong attractive force that holds nuclei together, “the strong force”. There is also a weak force involving nuclear decay and other particle interactions, named “the weak force”. Wu, a brilliant experimentalist, was a world-famous authority on weak interactions, especially as applied to beta decay: the emission of an electron (aka beta particle) in nuclear reactions. She was instrumental in testing other fundamental theories of particle physics. Her most famous experiment was that which confirmed the theory of T. D. Lee and Chen Nin Yang that parity was not conserved (viz., changed) in weak interactions. Parity is a kind of reflection symmetry such as that in a telescope lens, which inverts planet images. It had been assumed that parity was conserved until the theory of Lee and Yang and its confirmation by Wu. Lee and Yang were awarded the Nobel Prize.