Last year was a good year for scientific research in Ireland, capped by the Nobel Prize for Physiology or Medicine to Donegal-born William Campbell, a Trinity graduate who helped discover a cure for river blindness. Many recalled the Nobel physics award to Ernest Walton 65 years ago for his work on splitting the atom.
Another great Irish scientist, the Belfast-born Queen’s graduate John Stewart Bell, should also be recalled as the year turns. He died in 1990, aged 62, in Switzerland, at the Cern nuclear research centre where he had spent his career since the early 1950s. He had just been nominated for the Nobel Prize in Physics for his work on the logical foundations of quantum mechanics as applied to entangled particles. It could not be awarded because of his death.
Quantum physics deals with subatomic particles. Any time they interact they entangle. They become inseparable because an effect on one is thereafter simultaneously registered in the other, no matter how far they are apart. The phenomenon was discovered early in the last century in theorising and experimentation on energy and atoms. But it left the greatest scientists baffled theoretically and philosophically by its implications for understanding our world.
Einstein, most notably, could not explain how this “spooky action at a distance” worked, since entanglement seems to violate the law that nothing travels faster than light. “God does not play dice with the universe,” he famously declared.
With Boris Podolsky and Nathan Rosen he wrote a paper in 1935 arguing the theory was incomplete. There must be as yet undiscovered “hidden variables” at work capable of explaining entanglement in terms of the local causation of one entity on another and their physical separability that have underlain classical physics since Newton’s time.
Entanglement
Their argument was rejected by most other scientists in the field, among them the theorist of quantum waves Erwin Schrödinger, who first used the term entanglement that same year to describe the phenomenon. Schrödinger was invited to head the Dublin Institute of Advanced Studies by Eamon de Valera in 1940 and spent 14 years here before retiring.
Bell’s genius lay in resurrecting Einstein’s paper from neglect or disregard by other theoretical orthodoxies and by pragmatists satisfied that quantum mechanics gave an accurate picture of the subatomic world and worked in practice even if it was not fully explained. Writing in 1964 he proposed an inequalities theorem to test the effects of local causation using classical explanations and entanglement using quantum mechanics.
This led the way to a series of experiments from the 1970s that demonstrated with correlated measurements that entanglement at a distance is true and that no local causation is detected to be at work.
Newspaper headlines around the world last October proclaiming “Einstein got it wrong” convey the force of the latest experiments conducted by Ronald Hansen and colleagues at Delft University of Technology in the Netherlands on electrons and by another team on photons at the US National Institute of Standards and Technology in Boulder Colorado. Both were concerned to close possible loopholes in previous experiments and confirm entanglement or mutual influence. But they detected no signalling, which leaves Einstein’s speed- of-light constraint intact.
Bell was a theorist whose family members in working- class Protestant Belfast he described as "carpenters, blacksmiths, labourers, farm workers and horse dealers", as is told in Louisa Gilder's vivid and accessible history of quantum physics, The Age of Entanglement. He is honoured in a new Bell's Theorem Crescent in the city's Titanic Quarter.
Bell’s theorising, like Einstein’s and Schrödinger’s, straddled physics and philosophy because the questions raised by the new quantum realities radically challenge taken-for-granted accounts of everyday life and being. Non- local causation and inseparable individuals contradict assumptions of atomistic individualism and zero-sum conflict between groups in social as well as physical life.
An entangled or co-operative economics would be far removed from the economic “rationalities” that dominate existing theory and practice. The euro zone crisis politically entangles Irish, German, Greek, and Spanish citizens.
Exploring such consequences for social, economic and political life. Alexander Wendt's just-published study Quantum Mind and Social Science argues this scientific revolution can unify physical and social ontology, in a reference to the philosophy of being and the role of consciousness. That would be a heartening exercise worthy of Bell's intellectual originality. pegillespie@gmail.com