Readers offer their own magic moments with John Bell

I read with pleasure Reinhold Bertlmann’s article about remembrances of John Bell and his contributions to physics. Bell is famous for establishing an inequality between the prediction of quantum mechanics and local hidden-variable theories, and Bertlmann wrote that “so far, all experiments looking for violations in Bell inequalities have found them, so we have to conclude, along with John, that nature contains a nonlocality in its structure.” But that conclusion is valid only in the context of Bell’s conviction that classical “realism is the proper position for a scientist.”

Experiments have revealed that the nature of reality in the quantum world is different from our experience in the classical world. ¹ Properties like the direction of an electron spin and its position and momentum remain undetermined until a measurement has been performed, ² but the colors of Bertlmann’s socks are fixed after he puts them on. Albert Einstein’s famous quotation, “spooky action at a distance,” ³ that appears in Bertlmann’s amusing cartoon, is also misleading, because quantum correlations for entangled electron or photon pairs also occur at atomic distance of separation—for example, in the ground state of the helium atom. What would be spooky is if those correlations were altered when the entangled pair moved apart without further interactions, but experiments have shown that this is not the case.