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Bell's inequalities
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Experiments rule out local hidden variables.
Bell showed that local hidden-variable theories satisfy certain inequalities, while quantum mechanics violates them; experiments (Aspect 1982, 2015 loophole-free tests) confirm the violation.
Nobel Prize 2022.
Rules out local realism.
In more detail
Bell's inequalities give a test of whether the correlations between measurements can be explained by local hidden variables. Experiments have violated them, supporting quantum theory.
Real-world uses
- Bell tests underpin quantum information science.
- They confirm the non-local nature of quantum correlations.
- Physicists test Bell's inequalities in experiments to show that quantum correlations cannot be explained by local hidden variables.
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Frequently asked questions
Who proposed Bell's inequalities?
John Bell in 1964.
Were they tested?
Yes, many experiments since the 1980s have violated them, and the 2022 Nobel Prize recognised this work.
What did the experiments show?
They violated the inequalities, supporting quantum mechanics over local realistic theories.
Related topics in Quantum Mechanics
Measurement and collapse · Schrödinger's cat · Entanglement · EPR paradox · Decoherence · Interpretations of QM