Bell’s Theorem explained

In 2009, I wrote an explanation of Bell’s Theorem that could be understood by popular audiences. I wanted to repost it, but ended up rewriting it completely.

Although the predictions of quantum theory are well-understood, its interpretation is famously difficult. Because quantum mechanics only makes probabilistic predictions, many people have desired a “hidden variable” interpretation, where quantum objects have definite states, despite appearances to the contrary. But hidden variable interpretations are generally not accepted.

It is certainly possible to create a hidden variable interpretation that agrees with the all the predictions of quantum theory, and de Broglie-Bohm theory is an example of such a interpretation. However, de Broglie-Bohm has a number of unsatisfying properties. Indeed there are a few theorems that prove that any hidden variable interpretation must have unsatisfying properties.

The most important of these is Bell’s Theorem, formulated in 1964. What follows is an explanation of the thought experiment, the mathematical proof, and its implications.

The setup

Bell’s Theorem considers a particular thought experiment, in which two electrons are emitted simultaneously from a single source in opposite directions. This source emits electrons that are “entangled”, meaning that their quantum states are correlated with one another. If you perform the same measurement on both electrons, both measurements will always produce the same result.1
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Data feels

cn: rape, sexual violence, & CSA juxtaposed with cold data. This is being crossposted to my other blog.

Some of my most important activist work is in volunteering technical skills for the Asexual Census, a survey of English online ace communities. This past week, I’ve been on a roll analyzing our 2015 survey. No numbers will be reported here, this is just a personal account.

Unsurprisingly, as soon as I was done with prep work, my attention was drawn to the statistics on sexual violence. As a programmer, I’ve been trained to always use descriptive variable names. Now I’m looking at variables named “rape” and “rapeCombined”.
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Paper: The Chaos within Sudoku

The Chaos within Sudoku” is a paper about solving Sudoku puzzles with physics. They simulate an imaginary physical system, let it run, and when it stops the puzzle is solved. See the video below:

The thing about Sudoku is that Sudoku is hard. More specifically, when Sudoku is generalized to grids of arbitrary size, it’s NP-complete. What happens when you translate an NP-complete problem to a physical simulation? The authors find chaotic dynamics.  And in the process, they identify the hardest Sudoku puzzle…
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