Quantifying quantum.

Author:Whitten, Robert C.

Stephen M. Barr's "Faith and Quantum Theory" (March) gives an accurate portrayal of quantum theory as far as it goes. Barr, however, writes off David Bohm's approach to the subject by arguing that it "brings back Newtonian determinism and mechanism." Such an argument is fallacious, because Bohm's theory gives rise to nonlocal phenomena. By nonlocal, we mean that an event at point A can be correlated with an event at point B with no discernable connection between them.

Even in the classical Newtonian realm, the deterministic system of Laplace is impossible except, perhaps, with a very small number of interacting particles. For systems with very large numbers of interacting atoms and molecules, collective phenomena prevent any kind of prediction or, indeed, retrodiction. Such collective behavior was first studied by Poincare more than a century ago. The research stagnated until the advent of computers, which were needed to study the evolution of instabilities that announce the onset of chaos (in the scientific sense) and self-ordering. The onset of such instabilities is the cause of our inability to predict reliably the weather more than about a week in advance.

Robert C. Whitten

NASA (retired)

Cupertino, California

Stephen Barr explains that Peter E. Hodgson posits the Bohmian theory as the "only metaphysically sound alternative" with respect to interpretations of quantum theory. I like the fact that its being "metaphysically sound" is Hodgson's criterion for judging the veracity of the theory. And Barr seems to hold to the same criterion. With respect to the common themes and questions of traditional metaphysics, however, I was wondering if Barr would be able to explain in greater detail why he prefers the traditional Copenhagen interpretation of quantum theory.

Adam DeMuro

Naperville, Illinois

Stephen Barr voices his opposition to determinism in favor of the Copenhagen interpretation of Heisenberg's uncertainty principle, finding it sympathetic to biblical faith. Yet other religious scientists reject the Copenhagen interpretation, as Barr notes: "Hodgson insists that Bohmian theory is the only metaphysically sound alternative. He is unfazed that it brings back Newtonian determinism and mechanism."

Inasmuch as Barr holds that Christian orthodoxy requires the affirmation of free will, he stands on solid ground. That same affirmation, however, doesn't bolster any purely scientific argument in favor of the Copenhagen interpretation. Consistent with modern science's limits, Hodgson rightly observes that "physics can take no account of Divine intervention or of acts of free will, so in the course of scientific research the world is assumed to be strictly determined" (Science and Belief in the Nuclear Age). Hodgson goes on to explain that "God causes everything, but He also acts by secondary causality when he creates matter and gives it certain definite properties. Thereafter the matter behaves in accord with these properties. This does not happen by unbreakable necessity, because God has complete power over nature and can suspend or alter the laws of nature.... This means that Laplacian determinism is unacceptable.... [B]oth God and human beings can cause ... effects" that Laplacian determinism cannot explain.

If it were true that physical laws are absolutely inviolable, the natural order would seem to preclude miracles. Yet perfectly reasonable believers such as Hodgson and St. Thomas Aquinas affirm unequivocally the reality of miracles.

Despite Barr's earlier essay "The Miracle of Evolution" (February 2006), it isn't entirely clear whether he would admit without qualification the reality of miracles. If he does, then why wouldn't he accept the idea that physical laws may be broken through the insertion of human acts?

I would encourage believers to take Hodgson's work more seriously than they might otherwise do if they relied exclusively on the passing acknowledgement found in "Faith and Quantum Theory." (One should note that the back cover of Hodgson's Science and Belief contains several glowing recommendations, including one by Barr himself.)

Peter A. Pagan

Aquinas College

Nashville, Tennessee

While Stephen Barr is to be commended for his attempt to deal in a short essay with the complicated subject of the implications of quantum theory for religious belief, his article contains several misstatements...

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