Bell's theorem

A 1964 result, proved by John Bell, showing that no local hidden-variable theory can reproduce every statistical prediction of quantum mechanics: any such theory must obey an inequality that quantum mechanics itself can violate, making the dispute between local realism and quantum nonlocality experimentally decidable for the first time. Testing it requires measuring correlated particles along at least two directions that are neither parallel nor perpendicular to each other — a requirement several claims in this vault's Bohm-Aharonov-1957 cluster turn on, since the apparatus Bohm and Aharonov reanalyzed that year could not reach those angles. The practically testable form used in the first real experiments is the 1969 CHSH inequality, formulated by Abner Shimony, John Clauser, Michael Horne, and Richard Holt.

References

• claim-bohm-aharonov-1957-narrower-than-bell-wu-shaknov-angle-limit
• claim-bohm-aharonov-1957-epr-test-predates-bell-1964