Andrew Whitaker

John Bell’s work moved discussion of quantum theory forward, from the sterile situation dictated by the Copenhagen interpretation, to one free from restraint, where a wide variety of new ideas were put forward, and no careers were ruined. His work was central in most of the new ideas, but even over and above that, his open-minded ethos encouraged fresh thinking in every area. In particular it played a substantial part in the emergence of quantum information theory.

When John Bell graduated from Queen’s in mid-1949, he was lucky that, following the invention of radar and the atomic bomb in the Second World War, physics was very much in favor with the powers-that-be. In particular, under the leadership of John Cockcroft, the Atomic Energy Research Establishment at Harwell was just getting into its stride. Doubtlessly, many physicists would have liked to get a job there, so it was remarkable that a new graduate without experience. and without even a PhD, was appointed, and more than that, there was even competition for his services. The organization's aim was fundamental research in atomic physics, with no commercial or defence work, and John Bell was highly valued.

John Bell made contributions to many areas of physics, including accelerators, quantum field theory, and the physics of elementary particles, but his most important work was the so-called Bell's inequality, which reopened the study of the fundamental nature of quantum theory and made important conceptual advances. There have been many applications, both theoretical and practical.