February 12, 1918: Julian Schwinger is born
Julian Schwinger (1918-1994)
Scientific field: Physics
Known for: Quantum electrodynamics
American physicist and Nobel Prize winner, Julian Schwinger helped formalize the field of quantum electrodynamics, a discipline that combines quantum theory and relativity theory, and has to do with the behavior of charged particles in electrical fields. Schwinger shared the 1965 Nobel Prize in physics with Japanese physicist Tomonaga Shin’ichir? and American physicist Richard Phillips Feynman.
Before formulating the contribution that would bring him fame, Schwinger studied work that other physicists had done in areas relating to quantum electrodynamics. Earlier work by British physicist Paul Dirac applied quantum mechanics to an analysis of the electromagnetic field. Dirac predicted that particles such as the electron would have an infinite quantity of energy, which led to other predictions that contradicted experimental observations. Schwinger reworked Dirac’s mathematics in the theory so that those infinite quantities no longer appeared. This adjustment made Dirac’s theory consistent with observation, and permitted physicists to predict the magnetic and other properties of particles and radiation. Tomonaga and Feynman made similar adjustments in Dirac’s theory, working independently of Schwinger and each other.
Schwinger also postulated the existence of two different neutrinos associated with the electron and the muon (a negatively charged particle heavier than an electron), and predicted the discovery that massive charged particles carry weak nuclear forces. Experimental physicists later confirmed both of these theories.(1)
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