(June 6, 2013 at 3:25 am)apophenia Wrote:(June 5, 2013 at 8:47 am)little_monkey Wrote: The probability is equal to the square of the amplitude is a fundamental postulate of QM. Its interpretation may be several, but its calculation isn't. There has been a debate about "hidden variables", also called "non-locality" or the one I prefer, "spooky action at a distance". None of that ever panned out. Unfortunately, once in a while you'll get a title from some magazine or website, someone testing Bell's theorem, and indeed QM is weird, spooky action has reared its ugly head. But once you read the article, it's nothing but a quantum system violating Bell's theorem, which a QM system will do on theoretical grounds due to... guess what? Well, to the fact that probability is calculated differently in QM than in classical physics.
There was something in Nature communications last year where somebody was claiming that they'd demonstrated that conventional QM had as much or more predictive ability than any hidden variable theory. Me not being a physics person, sticking largely to philosophy, never followed up to determine whether that was a trustworthy result or not. (My physics knowledge and research skills, are, to be plain, poor.)
Do you know any more about it?
Perhaps you are referring to Colbeck and Renner who have published a proof that any extension of quantum mechanical theory, whether using hidden variables or otherwise, cannot provide a more accurate prediction of outcomes. What they have argued is that even if one assumes that the wavefunction in QM represent reality, its future behavior cannot be predicted with certainty. This means that there is an inherent randomness in nature.
