In “Quantum Magic’ Without Any ‘Spooky Action at a Distance” (ScienceDaily, June 25, 2011), we learn:
Quantum mechanical entanglement is at the heart of the famous quantum teleportation experiment and was referred to by Albert Einstein as “spooky action at a distance.” A team of researchers led by Anton Zeilinger at the University of Vienna and the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences used a system which does not allow for entanglement, and still found results which cannot be interpreted classically.
The physicists used a “qutrit” — a quantum system consisting of a single photon that can assume three distinguishable states. “We were able to demonstrate experimentally that quantum mechanical measurements cannot be interpreted in a classical way even when no entanglement is involved,” Radek Lapkiewicz explains. The findings relate to the theoretical predictions by John Stewart Bell, Simon B. Kochen, and Ernst Specker.
Bell was an interesting Irish physicist who at first hoped to show that Einstein was right, that you could make quantum mechanics finally settle down and get a job in the real world. He managed to convince himself of the opposite:
The result is known variously as Bell’s inequality and Bell’s theorem. Although it proved impossible to test Bell’s inequality in terms of the reactions described in the 1964 paper, later workers have produced equivalent formulations that are testable. The most convincing of these, the Aspect experiment performed by Alain Aspect of the Institute of Optics at the University of Paris in 1982, using correlations between polarized photons, established that the inequality did not hold. The conclusion seemed to be that nature preferred to act ‘spookily’ at a distance rather than using Einstein’s reality principle.
At first Bell’s five-page paper was ignored. Only when experimentalists such as John Clauser at Berkeley in 1969 took his work up did Bell’s argument become widely known. Bell’s views on his own work, more tentative and less extreme than those of many of his followers and popularizers, were collected in his Speakable and Unspeakable in Quantum Mechanics (1987).
We don’t live in the world we think we do.