Wednesday, March 19, 2008

More Challenges Against Non-Local Hidden Variables Theory

Science Daily is reporting a new experimental measurement out of NIST and Maryland that challenges the validity of a certain aspect of non-local hidden variables theory.

Experiments so far have ruled out locality and realism as a combination. But could a theory assuming only one of them be correct" Nonlocal hidden variables (NLHV) theories would allow for the possibility of hidden variables but would concede nonlocality, the idea that a measurement on a particle at one location may have an immediate effect on a particle at a separate location.

Measuring the polarizations of the pairs of entangled particles in their setup, the researchers showed that the results did not agree with the predictions of certain NLHV theories but did agree with the predictions of quantum mechanics. In this way, they were able to rule out certain NLHV theories. Their results agree with other groups that have performed similar experiments.

I may have missed it, but I don't recall ever seeing any experiment on entanglement that hasn't produced any result that's consistent with QM. One can argue that such-and-such an experiment doesn't rule out that and that theory, but QM is batting with 100% hits here with zero strike-out. I find that rather impressive, and impressively convincing.



Anonymous said...

Hello Zapper: What's New of a few weeks ago said QM is wrong and a revolution is nigh. Following up on that lead me to your NLHV story. I looked up the papers you cite, and also Leggett (2003). You like QM because it bats 100%. Does any other theory bat 100% ? Is the point that the CN criterion imposes more and more restrictions on the NLHV theories like de Broglie Bohm etc, backing them into a corner ?

Clueless in Corvallis, OR.

Great blog, BTW--thanks.

Anonymous said...

Hello Zapper: me again. Eisaman et al (Phys Rev A v77 032339 (2008)) test inequalities developed by Groblacher et al (Nature, v446, p871 (2007)). Groblacher et al point out, just after their eq (4), that the de Broglie Bohm theory is so nonlocal that it does not have to satisfy their inequalities. The de Broglie Bohm theory, like standard QM, continues to bat 100%.

Which proves nothing.

Still Clueless in Corvallis, OR.