# Entanglement, Bell's Theorem, Nonlocality, Technology

**URL:** <https://boards.straightdope.com/t/entanglement-bells-theorem-nonlocality-technology/447382>\
**Category:** Factual Questions\
**Created:** [April 29, 2008, 6:54pm UTC](https://boards.straightdope.com/t/entanglement-bells-theorem-nonlocality-technology/447382 "2008-04-29T18:54:17Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\
**Post date:** [April 29, 2008, 6:54pm UTC](https://boards.straightdope.com/t/entanglement-bells-theorem-nonlocality-technology/447382/1 "2008-04-29T18:54:17Z")

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What is the best guide for the intelligent layman concerning the topics listed in the title?

Two questions I’m particularly interested in hearing about:

–Why do we know that entanglement is due to non-locality and not due to hidden variables? Because of experimental results interpreted under Bell’s Theorem, of course, but my question is, how was Bell’s Theorem itself demonstrated to be true? (In summary, for the layman, if possible.)

–Measurement of an entangled particle results in a fixing of its partner “instantaneously.” What instant is that? What does “instantaneous” mean when, acc. to Relativity, there is no such thing as absolute simultanaity?

Thanks for any help,

-Kris

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [April 29, 2008, 7:02pm UTC](https://boards.straightdope.com/t/entanglement-bells-theorem-nonlocality-technology/447382/2 "2008-04-29T19:02:29Z")

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Here’s one good book: **Where does the Weirdness Go? : Why Quantum Mechanics is Strange, but Not as Strange as you think** by David Lindley

> **[Where Does The Weirdness Go?: Why Quantum Mechanics Is Strange, But Not As...](https://www.amazon.com/Where-Does-Weirdness-Go-Mechanics/dp/0465067867)**
>
> Buy Where Does The Weirdness Go?: Why Quantum Mechanics Is Strange, But Not As Strange As You Think on Amazon.com ✓ FREE SHIPPING on qualified orders

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**Author:** ![Pasta](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Pasta](https://boards.straightdope.com/u/Pasta)\
**Post date:** [April 30, 2008, 12:59am UTC](https://boards.straightdope.com/t/entanglement-bells-theorem-nonlocality-technology/447382/3 "2008-04-30T00:59:29Z")

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If you’ve got an hour to kill, here’s a talk on the matter:  
[abstract](http://www-ppd.fnal.gov/EPPOffice-w/colloq/Abstracts/Leggett_3_05_08.htm) and [video](http://vmsstreamer1.fnal.gov/VMS_Site_03/Lectures/Colloquium/080305Leggett/index.htm)