I What Is Bell's Theorem and Why Does It Matter?

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Bell's theorem addresses the fundamental nature of quantum mechanics and the concept of entanglement, demonstrating that certain predictions of quantum mechanics cannot be reconciled with classical physics. It introduces Bell inequalities, which serve as a testable criterion for distinguishing between classical and quantum correlations. Understanding Bell's theorem requires minimal mathematics, primarily involving linear algebra and concepts related to spin and polarization states. The implications of the theorem are profound, challenging classical intuitions about reality and suggesting that particles can be interconnected in ways that defy classical explanations. Resources for further reading, including a clear treatment by S. Weinberg, are available for those seeking a deeper understanding.
golya
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TL;DR
How can you explain it to someone with limited knowledge?
Hi everyone,

I need some help getting the gist of Bell’s theorem and his notion of inequalities.
How would you explain it to someone with limited knowledge of mathematics?
What are the potential implications?
 
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Can you post links to your reading so far? What explicit questions do you have about that reading?
 
There's a minimum of mathematics you need to understand this, but it's not too difficult mathematics. You just need some linear algebra in the 2D complex unitary space of spin-1/2 (or helicity ##\pm 1## for photons) and a bit of operators representing spin components (polarization states of photons). A very clear no-nonsense treatment can be found in

S. Weinberg, Lectures on quantum mechanics.
 
golya said:
TL;DR Summary: How can you explain it to someone with limited knowledge?

Hi everyone,

I need some help getting the gist of Bell’s theorem and his notion of inequalities.
How would you explain it to someone with limited knowledge of mathematics?
What are the potential implications?
On the homepage of the forum member @DrChinese you certainly will find the essentials: https://www.drchinese.com/Bells_Theorem.htm
 

Thread 'The Power of QM and QFT'

We often see discussions about what QM and QFT mean, but hardly anything on just how fundamental they are to much of physics. To rectify that, see the following; https://www.cambridge.org/engage/api-gateway/coe/assets/orp/resource/item/66a6a6005101a2ffa86cdd48/original/a-derivation-of-maxwell-s-equations-from-first-principles.pdf 'Somewhat magically, if one then applies local gauge invariance to the Dirac Lagrangian, a field appears, and from this field it is possible to derive Maxwell’s...
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