After gaining his Master of Science at Melbourne University, Crewther was awarded a Fulbright scholarship to the California Institute of Technology. He studied under the tutelage of Nobel prizewinner Murray Gell-Mann and completed his doctorate, in 1971, after successfully defending his dissertation against the renowned theorist Richard Feynman. His thesis was entitled Spontaneous Breakdown of Conformal and Chiral Invariance.
Subsequently, he spent twelve years in Europe, six of them as a Staff Member of the European Laboratory for Particle Physics (European Organization of Nuclear Research) in Geneva, and the remainder as a Research Associate at the University of Berne, University of Dortmund, and at the Max Planck Institute in Munich. Crewther was then appointed as a senior lecturer in physics at the University of Adelaide. Having a keen interest in politics, Crewther is president of the University of Adelaide branch of the National Tertiary Union.
He also serves on the University Council, where he is considered a maverick and frequently rails against what he calls the corporate agenda of the university.
He designed the honours physics course "Gauge Field Theories." He also lectures on Quantum Mechanics III, Advanced Dynamics and Relativity, and Honours Quantum Field Theory. Although he no longer teaches the courses Quantum Mechanics II, Honours Relativistic Quantum Mechanics and Particle Physics, and Classical Fields and Mathematical Methods, his notes are followed by his successors.
Doctor Crewther also teaches a 4-week module of Physics 1B at the University of Adelaide where he hosts mechanics lectures that focus on the centre of mass, rotation, angular momentum and gyroscopic precession.
