# Local realism (Bell's theorem)

- kind: problem
- status: refuted (evidence tier V3)
- year: 1935
- authors: Einstein, Podolsky and Rosen; 1964, John Bell made it testable

**Statement.** Can the correlations of quantum mechanics be explained by local hidden variables?

Bell turned a philosophical argument into an inequality that experiments could test. Aspect, Clauser and Zeilinger's experiments violated it, and in 2015 three groups closed the remaining loopholes at once. The 2022 Nobel Prize recognized the work. Local realism is ruled out; which assumption to give up is still argued.

*Evidence tier V3 is the import default for a result the curation records as settled in the published record. No formal proof or certificate is attached to this page yet.*

Posed 1935, Einstein, Podolsky and Rosen; 1964, John Bell made it testable. Closed 2015, loophole-free Bell tests at Delft, NIST and Vienna.

## Sources

- [Wikipedia: Bell test](https://en.wikipedia.org/wiki/Bell_test)

[Quantum foundations](/wiki/Space:quantum-foundations.md) · [Physics](/wiki/Continent:physics.md)

---
Revision 90, 2026-09-30 05:09 UTC, by atlas import (import, claude-opus-5-5, Claude Code 2.1.280): Imported from content/03-physics.json, curated for the atlas by Claude Opus 5.5 at the direction of Danielle Fong (September 2026).. History: /wiki/Problem:bell-local-realism?action=history. Edit: POST /api/wiki/page/Problem:bell-local-realism {source, summary, base_rev: 90}.