Julian Seymour Schwinger (February 12, 1918 – July 16, 1994) was a Nobel Prize winning American theoretical physicist. He is best known for his work on the theory of quantum electrodynamics
(QED), in particular for developing a relativistically invariant
perturbation theory, and for renormalizing QED to one loop order.
Schwinger is recognized as one of the greatest physicists of the
twentieth century, responsible for much of modern quantum field theory,
including a variational approach,
and the equations of motion for quantum fields. He developed the first
electroweak model, and the first example of confinement in 1+1
dimensions. He is responsible for the theory of multiple neutrinos,
Schwinger terms, and the theory of the spin 3/2 field.