Physicist — John Stewart Bell (Belfast, 1928 – Geneva, 1990) was a Northern Irish theoretical physicist, for most of his career at CERN, where he worked on accelerator physics. In his spare time he cultivated his true passion: the foundations of quantum mechanics. In 1964 he proved the celebrated theorem that bears his name, showing that no local hidden-variable theory can reproduce all the predictions of quantum mechanics. His inequalities turned a philosophical dispute — the Einstein–Bohr debate on entanglement — into an experimentally decidable question. Subsequent experiments vindicated quantum mechanics, paving the way for quantum information.
Trivia
The experimental work inspired by his theorem led in 2022 to the Nobel Prize for Aspect, Clauser and Zeilinger; Bell, who died of a stroke in 1990, could not receive it, as the Nobel Prize is not awarded posthumously.
Theories and contributions
- Bell’s theorem — No local hidden-variable theory can reproduce all the correlations predicted by quantum mechanics.
- Bell’s inequalities — Constraints on correlations between measurements that local theories must satisfy but that quantum mechanics violates: , while QM reaches .
Featured in chapters
Linked atoms
2 linked atoms.