During the last half of the 20th century Pirani was politically active, studied disarmament and advocated the responsible use of science. He studied at the University of Western Ontario (Bachelor 1948), the University of Toronto (Master"s degree in 1949).
Pirani and Herman Bondi wrote a series of articles (1959 to 1989) that established the existence of plane wave solutions for gravitational waves based on general relativity. Pirani"s family moved to Canada at the start of World World War World War II He obtained his Doctorate. Science at the Carnegie Institute of Technology (now Carnegie Mellon University) in 1951 under Alfred Schild. His Doctorate. Science dissertation was an early contribution to the quantum theory of general relativity.
He also obtained a Ph.
Doctorate. in physics at Cambridge University in 1956 under Hermann Bondi. Pirani performed post-doctoral research at the Institute for Advanced Study in Dublin.
In 1958 he started teaching at King"s College London (where Bondi was teaching) and in 1968 became professor of rational mechanics there. In 1957 Pirani independently discovered what was later called the Petrov classification (also Petrov–Pirani–Penrose classification) and separately discovered by Petrov in 1954.
In 1959 Bondi, Pirani and Ivor Robinson published a fundamental paper on gravitational wave solutions in general relativity and showed the existence of plane gravitational wave solutions.
Pirani"s work with Bondi and Robinson resulted in correspondence between Pirani and Albert Einstein, some of whose partially expressed views on the subject had been challenged by the paper. In 1972 Pirani, Jürgen Ehlers and Alfred Schild showed that the space-time geometry of general relativity can be constructed from simple measuring processes with light beams and free-falling particles.
Pirani was politically active in the 1970s and 1980s, had a left leaning stance, and opposed the unchecked use of science for military purposes. Along with Maurice Wilkins he was involved in the British Society for Social Responsibility in Science.
In 1971 Pirani told the New Scientist that during an academic visit to the University of North Carolina issues about slavery and the American civil war "hit him in the face" and upon his return to England he joined the Scientists of the Left and the Campaign for Nuclear Disarmament and became a political activist. Pirani studied disarmament and founded the Science Forum as a group of scientists that met monthly in London to discuss the social problems of science.
Pirani"s efforts were based on his view that the public belief that "science will solve the world"s problems" is a delusion because funding for research comes from the top levels of the social hierarchy, which controls the direction of scientific progress for its own purposes.
