## Bell's inequalities and non-locality

Online Graduate Mathematical Physics Seminar, Rutgers University, New Jersey, USA

#### February 16 2023

John Stuart Bell proved that quantum mechanics is non-local, which means that an action can, in principle, have an effect instantaneously and arbitrarily far away. This fact has since been demonstrated experimentally by the 2022 physics Nobel laureates and their collaborators. In this talk, I will give two simple proofs of Bell's theorem, and discuss the physical implications of this result.

### Slides

PDF:

LaTeX source:

- tarball: 23rutgers_online-1.0.tar.gz
- git repository: 23rutgers_online-git (the git repository contains detailed information about the changes in the slides as well as the source code for all previous versions).

### Related content

This presentation is an extension of two videos I posted on Youtube:

**(Non-)Locality, the Einstein-Podolsky-Rosen argument, and Bell's inequality**

In this video, I discuss how the winners of the 2022 Nobel Prize in physics have shown that the world is NOT LOCAL. This means that, at least in principle, it is possible for an action taken somewhere on Earth to have an effect arbitrarily far away, even in the most remote corners of the universe. The Nobel Prize winners achieved this by proving that an inequality, called Bell's inequality, is violated in nature. In this video, I describe the argument made by John Bell that a violation of Bell's inequality implies that there is no locality. This argument starts from the Einstein-Podolsky-Rosen "paradox" (EPR), which I describe as well.**A proof of Bell's inequality**

This is a companion video to "(Non-)Locality, the Einstein-Podolsky-Rosen argument, and Bell's inequality" in which I discussed the relation between Bell's inequality and locality. In this video, I give a full proof of Bell's inequality in a very general setting, starting only from the assumption of locality.