John Stewart Bell

Biography

John Stewart Bell was born in Belfast, Northern Ireland. He studied physics at Queen's University Belfast, then received his doctorate from the University of Birmingham. He spent most of his career at the European Organization for Nuclear Research (CERN) in Switzerland, working on accelerator theory and particle physics. In his free time, he pondered the foundations of quantum mechanics. In 1964, he published his famous theorem, which showed that any local theory contradicts the statistics of experiments with entangled particles. For this work, he received many awards, including the Hughes Medal and the Heineman Prize.

Key discoveries

• Bell's theorem: he derived inequalities that must hold if quantum mechanics is supplemented with local hidden variables. Experiments by Alain Aspect and others violated these inequalities, confirming the nonlocality of nature.
• Interpretation of quantum mechanics: an active proponent of objective reality, he believed that the standard Copenhagen interpretation was unsatisfactory and sought ways toward a more complete theory.
• Contribution to accelerator physics: he developed stability criteria for particle beams in cyclic accelerators, which helped in the construction of the Large Hadron Collider.