2009 Templeton Award goes to physicist/philosopher for proving . . . um, what?

March 17, 2009

The John Templeton Foundation   announced today the winner of the 2009 Templeton Prize, a £1 million ($1.4 million) award founded by the late US multi-millionaire entrepreneur and philanthropist Sir John Templeton to honor scientists who make "   an exceptional contribution to affirming life’s spiritual dimension, whether through insight, discovery, or practical works. "  (For those not in the know, the amount of the award is adjusted each year to exceed the Nobel Prize.)  This year’s award goes to physicist/philosopher Bernard d’Espagnat, whose work on the philosophical foundations of quantum mechanics proved . . . well, proved what?

Dr. d’Espagnat’s main work on the foundation of quantum theory occurred from the mid-1960s to the early 1980s when he carried out experiments testing the famed "Bell’s inequalities" theorem.  The best known of these experiments, carried out by Alain Aspect and others in the early 1980s, demonstrated that quantum particles behave in ways that seemed impossible under our pre-quantum understanding of the world.  By way of background, quantum theory famously predicts that you cannot simultaneously measure two "noncommuting" physical characteristics of a particle with unlimited accuracy.  The most famous examples of noncommuting observables , à la Heisenberg, are a particle’s position and momentum.  If the uncertainty in a measurement of the particle’s position is tiny, the uncertainty in the particle’s momentum must be large; the product of the two uncertainties cannot be smaller than a certain constant.

This feature of quantum theory yields some strange results.  When two quantum particles (e.g., electrons) interact, measurements of one particle’s properties (e.g., the electron’s spin parameter) become correlated with measurements of the second particle’s properties. But the correlation acts in a way that prevents us from accurately measuring both noncommuting properties of a given particle simultaneously; the measurement of one particle "poisons" the other, in an apparent conspiracy to keep us ignorant of the particle’s noncommuting properties.  Oddly, quantum mechanics predicts that the conspiratorial correlation will hold even when the previously-interacting particles are subsequently separated by vast distances. 

Einstein and other critics thought this quantum weirdness was absurd.  Einstein thought that in reality, each particle has definite physical properties that we should be able to know, in principle, with unlimited accuracy.  He posited the existence of "hidden" physical phenomena, unaccounted for by quantum theory, that would allow one particle to send instructions to the other about how to "poison" its measurement.  He then argued that because nothing can travel faster than light—according to his special theory of relativity, the fastest speed there is—then separating the two particles by a sufficiently large distance would prevent one particle from signaling to the other in time to "poison" its measurement.  Einstein thought that quantum theory would be proved wrong, because it wrongly predicts that particle measurements will "poison" one another when the particles are vastly separated.

Experiments by Aspect, d’Espagnat and others proved that Einstein, not quantum theory, was wrong.  Quantum theory’s prediction is right: measurements of "entangled" particles are poisoned, even when the particles are separated by large distances.  Allow the particles to travel to opposite ends of the galaxy; still, measurements of one particle’s attributes will poison measurements of the other particle, such that we cannot know both of the second particle’s noncommuting properties simultaneously.  Many physicists saw these experiments as proof that we cannot explain weird quantum behavior by assuming the existence of unknown, "hidden" physical properties, unless we are willing to stomach faster-than-light signaling (which itself gives rise to insuperable difficulties with our understanding of causality).  (For good further discussion of Bell’s inequalities and the Einstein-Podolsky-Rosen paradox, click   here and   here .)

All well and good.  But d’Espagnat goes well beyond this already immodest (if experimentally supported) conclusion.  He is enthralled by the thought that quantum weirdness prevents us from knowing ultimate reality in itself.   In his words , this shows that "[t]here must exist, beyond mere appearances . . . a ‘veiled reality’ that science does not describe but only glimpses uncertainly. In turn, contrary to those who claim that matter is the only reality, the possibility that other means, including spirituality, may also provide a window on ultimate reality cannot be ruled out, even by cogent scientific arguments."  This is the kind of attitude that gets the Templeton Foundation very excited.

Not everyone agrees with d’Espagnat’s conclusions about quantum theory’s philosophical import.   There are multiple interpretations of the meaning of quantum theory, some of which do not entail the existence of a "veiled reality" beyond our grasp .  But even if we take d’Espagnat’s interpretation as given, this would not constitute evidence for the existence of a spirit realm that contains a God (much less the benevolent, personal God of d’Espagnat’s faith). Nor would it constitute evidence that spiritualist musings yield knowledge about that realm.  At best, d’Espagnat’s work shows that we are ignorant about aspects of ultimate reality.  We cannot derive knowledge from our ignorance. Even if we cannot rule a spiritual reality out, quantum weirdness certainly doesn’t allow us to rule it in. A hidden realm might contain the God that d’Espagnat yearns for.  Then again, it might contain the lost island of Atlantis, or ham sandwiches, or (   to borrow from Douglas Adams ) all the missing ballpoint pens we have bought over the years.

This is not the first time that spiritualists have sought refuge at the fringes of scientific knowledge.  In the 19th century, mathematical speculations about the possibility of extra spatial dimensions led some to argue that heaven and hell reside at opposite ends of a fourth spatial dimension.  In our own day, some physicists have speculated that black holes provide doors to parallel universes.  Perhaps they, too deserve Templeton prizes, because - who knows? - angels might be in there.

Dr. d’Espagnat deserves to be recognized for his significant contributions to our understanding of quantum theory.  Too few physicists ponder deeply and at length about quantum mechanics’ meaning.  Too many treat it instead as a mere computational tool, with the hope that troublesome questions will not bother us if we choose not to think about them.  Surely we ought to encourage physicists like d’Espagnat to examine the foundations of quantum theory.  But we ought not to skew research by awarding large sums of money for pseudo-demonstrations of religious doctrines.  Too often, the result is to reward mere wishful thinking.