From 1veritasium, 2veritasium, or sciencium.

How an argument between Einstein and Bohr changed quantum mechanics forever.

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Thank you to Dr Adam Becker for his help with this video – check out his book here https://ve42.co/WhatReal

And special thanks to Thierry Avignon, Benjamin Vest, and Lionel Jacubowiez of the Institut d’Optique Graduate School – Laboratoire d’Enseignement Expérimental (LEnsE)

Correction:
30:53 Electrons and Positrons not Protons

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0:00 The Speed of Gravity
3:07 Spooky Action at a Distance
5:21 The Copenhagen Interpretation
9:12 The EPR Paradox and Hidden Variables
17:25 Einstein vs Bohr
20:51 John Bell and Entanglement
22:14 Bell’s Theorem
29:30 The Bell Inequality Test
33:41 The Most Misunderstood Experiment in Physics
35:06 The Locality Problem
40:37 The Many-Worlds Interpretation

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References:
Adam Becker (2018). What is Real?. Basic Civitas Books – ve42.co/WhatReal
Einstein-Podolsky-Rosen paradox via Wikipedia – ve42.co/EPRWiki
Einstein, A. et al. (1935). Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?. American Physical Society (APS) – ve42.co/EPR
Solvay Conference via Wikipedia – ve42.co/SolvayConf
Owen Willans Richardson Photo Galley via nobelprize.org – ve42.co/SolvayPhoto
Bohr-Einstein debates via Wikipedia – ve42.co/BohrEinDeb
Bacciagaluppi, G and Valentini, A (2009). Quantum Theory at the Crossroads. Cambridge University Press – ve42.co/Crossroads
Bohr, N. (1935). Can Quantum-Mechanical Description of Physical Reality be Considered Complete?. American Physical Society (APS) – ve42.co/BohrResp
The Solvay Conference via rarehistoricalphotos.com – ve42.co/SolvayImg
Kragh, H. (2022). Chemists Without Knowing It?. Firenze University Press – ve42.co/BhorsConferenceImg
Einstein Attacks Quantum Theory. The New York Times via nytimes.com – ve42.co/EinsteinAttackQT
Oral History Interviews via repository.aip.org – ve42.co/BohrInterview

Images & Video:
Image and video references can be found here – https://ve42.co/BellsImRefs

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Special thanks to our Patreon supporters:

Adam Foreman, Albert Wenger, Alex Porter, Alexander Tamas, Anton Ragin, armedtoe, Balkrishna Heroor, Bertrand Serlet, Blake Byers, Bruce, Damien, Dave Kircher, David Johnston, David Tseng, EJ Alexandra, Evgeny Skvortsov, Garrett Mueller, Gnare, gpoly, Hayden Christensen, Ibby Hadeed, Jeromy Johnson, Jon Jamison, Juan Benet, KeyWestr, Kyi, Lee Redden, Marinus Kuivenhoven, Matthias Wrobel, Meekay, meg noah, Michael Bush, Michael Krugman, Orlando Bassotto, Paul Peijzel, Richard Sundvall, Robert Oliveira, Sam Lutfi, Tj Steyn, Ubiquity Ventures, wolfee

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Writers: Mithuna Yoganathan, Casper Mebius & Derek Muller
Producer & Director: Mithuna Yoganathan
Editor: Spencer Wright
Camera Operators: Mithuna Yoganathan, Derek Muller and Maxime Beauquesne
Animators: Alex Drakoulis, Fabio Albertelli, Emma Wright, Andrew Neet and Peter Nelson
Illustrators: Jakub Misiek, Katheryn Chan, Grace Nemanic, Isaac McCree and Natalky Zhuk
Assistant Editor: James Stuart
Researchers: Gabe Strong and Sophia Long
Thumbnail Designers: Abdallah Rabah, Ren Hurley & Ben Powell
Production Team: Katy Southwood, Josh Pitt, Anna Milkovic and Matthew Cavanagh
Executive Producers: Derek Muller & Casper Mebius

Additional video/photos supplied by Getty Images, Storyblocks
Music from Epidemic Sound

Notes

*When we show the Stern Gerlach experiment we’ve chosen to flip the polarity of the machine when measuring a positron. This is because both its spin and charge should oppose the electron’s. This would mean both would bend in the same direction! We’re interested in seeing the difference in the spins so we flip the machine to make this clearer.

**We show curved spacetime using Flamm’s Parabaloid, which we discovered is controversial, more notes on that here – https://ve42.co/HBDFlamm