Unit 5 · Entanglement & Reality
Chapter21
Bell's Theorem & the End of Local Realism
The experiment that let nature vote — and nature voted quantum
Quantum Academy · presented by Dr. Quincy Quantenstein
CH 21X–Y
0:00 / 39:32OpeningTitle
Watch the lesson · Unit 5: Entanglement & Reality
Bell's Theorem & the End of Local Realism
The experiment that let nature vote — and nature voted quantum
- ≈ 40 min
- 59 scenes
- Narrated by Dr. Q
- Captions
Generated from the same script as the written lesson, so every word matches the text. Uses your device's voice when it has one; without one, the lesson plays silently with captions. Keys: Space play · ← → scenes · C captions · F full screen.
By the end you'll be able to
- Define local realism precisely and identify the assumptions of locality, pre-set outcomes and free choice of settings.
- State Bell's theorem and derive the CHSH bound of 2 for any local hidden-variable model.
- Calculate the quantum CHSH value, twice √2 or about 2.83, from the correlation law for entangled photons, and explain the Tsirelson bound.
- Explain why the CHSH game caps classical players at 75 percent while entangled players reach about 85.4 percent.
- Trace the experimental record from Clauser in 1972 and Aspect in 1982 to the loophole-free tests of 2015 and the 2022 Nobel Prize.
- Distinguish what Bell tests rule out from what they leave open, and explain why they never permit faster-than-light signalling.