A Bell Test Violates Local Realism w/ Loophole-Free Electron Spins 1.3km Apart

[bhobba]

Quantum logic doesn't imply the invalidity of classical logic. People certainly use classical logic in reasoning about quantum mechanics.

That's right. Its a purely formal part of certain axiomatic treatments. Its better to look on it as a boolean algebra.

Thanks
Bill

 

[Simon Phoenix]

The credibility of this article: http://www.drchinese.com/Bells_Theorem.htm written by the user DrChinese and talking about Bell's Theorem is quite low.

Wow - well I've been reading these forums for quite a while (but participating only recently). Not that he needs a vote of confidence, but Dr Chinese has been posting excellent stuff, particularly on entanglement, ever since I started reading this forum - and probably for a good while before then.

And you base your estimation of his 'credibility' on a historical sketch which puts things in context? Even if he got a few bits of this wrong (and I'm not saying he did) who gives a flying thingamabob? Sheesh.

Anyway - the history of that period is endlessly fascinating - and one can only imagine the confusion and sheer incredulity as bit by bit the classical world-view was found to be seriously wanting. I like to think it was Einstein who first really saw the storm brewing. There was a paper of his written around 1909 (not 100% sure of the date to be honest - it might be later, even around 1917) in which he showed that for black body radiation some of the fluctuations could be attributed to a particle-like behaviour and some to a wave-like behaviour. I suspect he thought "holy crap" at about that point, or the equivalent in German, but I could be wrong :-)

Entanglement is about much more than just correlation - Bell's original paper is an absolutely brilliant piece of work that gives us an experimental way of deciding this issue by examining correlations between observables, but the implications go much further, as Bell was only too well aware.

 

[bhobba]

What do you mean by "logic"? As I understand it there are different kinds of logics in mathematics - depends on your starting rules (eg do you want to hold the law of the excluded middle as valid? Again as I understand it, it's perfectly possible to construct mathematically sound logics in which this principle is not deemed to hold).

That's correct. Its simply a formal system and forms what's called a Boolean Algebra:
https://en.wikipedia.org/wiki/Boolean_algebra

It turns out in QM the usual Boolen Algabra of standard logic is not what its based on. A technical discussion of logics in general can be found in Chapter 1 of Varadarajan - Geometry of Quantum theory. Its relation to QM an be found in Chapter 4 - Logics Associated With Hilbert Space. This is tied up with a famous theorem called Pirons Theorem:
http://stanford.library.usyd.edu.au/archives/sum2008/entries/qt-quantlog/#5

Its all part of a very mathematical treatment of QM. It is often said that when mathematicians get a hold of a physical theory they change it to something unrecognisable

It certainly is a LOT harder. My background is math not physics and that book by Varadarajan stretchers me to my limit. I can follow it with time (a lot of it) and effort (again a lot of it) - but just.

Thanks
Bill

 

[Dale]

A bunch of off topic and inflammatory posts have been deleted and this thread is closed.