Quantum Physics and Theology: An Unexpected Kinship
By John Polkinghorne (Part 3c) — Lessons from History
We are reviewing the book, “Quantum Physics and Theology: An Unexpected Kinship” by John Polkinghorne. Today we will look at the third part of Chapter 3- Lessons from History. John continues his comparative study of science and Christian theology with some additional historical examples of how the discovery of further truth proceeds in these two disciplines. Last time we looked at: (2) Collateral developments. Further examples considered. This week we look at:
(3) Tides of fashion. The questions considered significant, and the style of thinking found appropriate to answering them, are influenced by contemporary intellectual and cultural attitudes.
(a) Relativistic quantum theory. Science, like any human endeavor, is not immune from the tides of fashion. Being a community of humans, sociological factors are certainly at work, although Polkinghorne asserts that it is a gross exaggeration to suggest they determine the nature of the conclusions eventually reached. Polkinghorne illustrates these effects in his description of the development of relativistic quantum theory.
In 1928, Paul Dirac, working in his small, cloistered room in St. John’s College in Cambridge, developed quantum field theory and came up with the celebrated equation of the electron (which is engraved on his memorial tablet in Westminster Abbey).
It was soon realized that all relativistic quantum equations needed to be treated as field theories. In physics, a field is a physical quantity, represented by a number that has a value for each point in space and time. For example: an electric field can be thought of as a “condition in space” emanating from an electric charge and extending throughout the whole of space. When a test electric charge is placed in this electric field, the particle accelerates due to a force. Physicists have found the notion of a field to be of such practical utility for the analysis of forces that they have come to think of a force as due to a field.
Dirac’s equation was verified experimentally, and this success, coupled with the conceptual clarification of wave/particle duality and also Dirac’s successful prediction of the existence of antimatter, clearly showed that quantum field theorists were on to something.
However, when more refined calculations were attempted, instead of yielding the small corrections that were to be expected, they gave nonsensical results, for the answers turned out to be infinite! Something was going badly wrong. As a result, for a while people lost interest and confidence in quantum field theory.
The post-WW2 physicists then found an ingenious, if somewhat sleight-of-hand, way around the problem. In quantum electrodynamics (the field theory of the interaction of electrons with photons, abbreviated as QED), it was discovered that all the infinities could be isolated in terms that simply contributed to the mass and charge of the electron. If these formally infinite expressions were replaced by the actual finite values of these constants, the resulting calculations were not only free of infinities, but they also proved to be in stunning agreement with experiment.
Quantum field theory had regained its popularity, but it did not last. When attempts were made to apply the same techniques to interactions related to nuclear forces, they failed to give satisfactory answers. Physicists began to question the whole field idea again. It is based on the supposition that one can describe what is happening by means of a formalism (a description of something in formal mathematical or logical terms) expressed in terms of all points of space and all instants of time. Of course, in a laboratory there is only limited access to what is going on. The basic technique used is a scattering experiment, described simply in terms of colliding particles coming in and scattered particles coming out.
It was therefore proposed that fields should be replaced by a much leaner account, simply linking “before” to “after” the scattering interaction. The resulting formalism was called S-matrix theory (S for scattering). Certain mathematical properties of the S-matrix were known to be implied by relativistic quantum mechanics, and it was hoped that these properties would provide the basis for a new theoretical formulation. It looked promising, and a good number of theorists devoted themselves to the task. In the end, however, the theory became so complicated that it simple collapsed under its own weight.
Just about this time, developments began that were to give field theory a new lease on life. A new class of field theories was identified, called gauge theories, in which interactions were found to become weaker as distances increased. This meant that some of the old techniques could, after all, be used to discuss nuclear matter in certain circumstances. Field theory once again became the place where the young and ambitious theorist would want to be. This phase has continued so far, and all contemporary theories that are favored in elementary particle physics are gauge field theories.
(b) The historical Jesus and the Christ of faith. In the realm of theology, fads and fashions are, as the saying goes, “a target-rich environment” to say the least. Polkinghorne chooses as his analogy with the fluctuating quantum field theory the “search for the historical Jesus”. Critical historical study of the gospel material had its origin in the later eighteenth century under the influence of the spirit of the Enlightenment. It is characterized by an aversion to any suggestion of the miraculous and a commitment to a flat historicism based on the axiom that what usually happens is what always happens. For example, H.S. Riemarus (1778) suggested in his book that the disciples stole the body of Jesus and concocted a story of his resurrection in order to promote their dead leader as a spiritual redeemer. They committed this deceitful act, Riemarus believed, to conceal the fact that Jesus had been more concerned with nationalistic issues than religious matters.
Most people have heard of the Jefferson Bible (although Jefferson never referred to his work as a bible) where he literally (using a razor and glue) excised every reference to the miraculous. One of the most notable proponents of such an Enlightenment approach was David Friedrich Strauss, whose Life of Jesus (1835) made extensive use of the category of myth in giving explanation of the content of the gospels. Strauss was willing to attribute any miraculous element to symbolic value only. The orthodox Christian claim that Polkinghorne defends in this book is that there well may be mythical components to the gospels but (after C.S. Lewis) they are enacted myths, not only true symbolically, but also true historically.
The liberal nineteenth century view of the historical Jesus makes Jesus look remarkably like a nineteenth century liberal, as catholic writer George Tyrrell remarked wittingly about Carl Gustav Adolf von Harnack, who was a German Lutheran theologian and prominent church historian, that: “the Christ Harnack sees, looking back through nineteen centuries of Catholic darkness, is only the reflection of a liberal Protestant face, seen at the bottom of a deep well”.
These fads continue on down through the 20th Century with Rudolf Bultmann, whose opinion is that the gospels need demythologization of the miraculous in order to be acceptable to persons living in a scientific age. Polkinghorne says:
Yet commitment to a person unanchored in history because so little could reliably learned about him might well prove to be commitment to an illusion. In my opinion, a positive evaluation of the relationship between the Jesus of history and the Christ of faith lies at the heart of a credible Christology. Christians cannot rest content with a purely symbolic figure. The religion of the incarnation is inescapably concerned with the issue of the degree of actual enactment that can properly be seen to be involved in the origin of its myth. Least of all in a scientific age can we be satisfied with less than a careful investigation into the historically embedded motivations for Christian belief about the unique significance of Jesus. To treat him as a symbolically evocative, but historically unknown, figure is to lose contact with his reality. It is not surprising that in the second half of the twentieth century, Christological fashion changed again and, in my opinion, changed for the better. A “new quest” was inaugurated in search of the historical Jesus. It continues vigorously today, in its contemporary phase laying great and justified emphasis on the need to take full into account the context of first century Judaism within which Jesus’ life was lived. Just as quantum physics was driven to seek a more detailed, and consequently more illuminating understanding than that afforded by the veiled account of S-matrix theory, so Christology had to return to its foundational roots in the life, death and resurrection of Jesus the Messiah.
John is asserting that, just as in the progress in quantum physics that led to a truer and more useful understanding, real progress has been made in our theology of Christ. We have moved from a naïve and unsophisticated historicism, through a period of rigorous and scathing skepticism, to a nuanced appreciation of the mystery of the incarnation and the reality of “God with us”. I wonder if such a movement in history is also reflected in the life of a believer as our faith, hopefully, matures and deepens.