Quantum theory predicts correlations in the spin-singlet state that do not satisfy Bell inequalities (Shimony 2009), and by now there is ample evidence from experiments on the analogous property of pairs of correlated photons that quantum theory is correct, and therefore one or more of the assumptions that go into the derivation of a Bell inequality must be faulty. While the claim has been made that the key assumption is locality, and therefore a violation of Bell inequalities implies that the real (quantum) world is nonlocal, a histories analysis identifies the problem as a different assumption made by Bell: the existence of classical hidden variables that are inconsistent with Hilbert space quantum mechanics. For more details see the   Further Reading supplement. Griffiths (2002a); also Griffiths (2011a, 2011b).--> 