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Control unit, in this long period of development is not a quick mind, not of men is the social pressure, but in the world of nature, as it is revealed more in-depth investigation.           In the Light of New Truths       Discovery is the name of the game. The pay-off for the rigours and longueurs of scientific research is the consequent gain in understanding of the way the world is constructed. Contemplating the sweep of the development of some field of science can only reinforce that feeling.   Consider, for example, our understanding of electricity and magnetism and the nature of light. In the nineteenth century, first Thomas Young demonstrated the wave character of light; then Faraday's brilliant experimental researches revealed the interlocking nature of electricity and magnetism; finally the theoretical genius of Maxwell produced an understanding of the electromagnetic field whose oscillations were identifiable with Young's light waves. It all constituted a splendid achievement. Nature, however, proved more subtle than even Maxwell had imagined. The beginning of this century produced phenomena which equally emphatically showed that light was made up of tiny particles. The resulting wave/particle dilemma was resolved by Dirac in 1928 when he invented quantum field theory, a formalism which succeeds in combining waves and particles without a trace of paradox. Later developments in quantum electrodynamics (as the theory of the interaction of light and electrons is called) have led to the calculation of effects, such as the Lamb shift in hydrogen, which agree with experiment to the limits of available accuracy of a few parts per million. Can one doubt that such a tale is one of a tightening grasp of an actual reality? Of course there is an unusually strong element of corrigibility in this particular story. Quantum electrodynamics contains features completely contrary to the expectations which any nineteenth-century physicist could have entertained. Nevertheless there is also considerable continuity, with the concepts of wave and field playing vital roles throughout. The controlling element in this long development was not the ingenuity of men nor the pressure of society but the nature of the world as it was revealed to increasingly thorough investigation.   Considerations like these make scientists feel that they are right to take a philosophically realist view of the results of their researches; to suppose that they are finding out the way things are.             — J.C. Polkinghorne, The Quantum World             Indexes/03