source of electricity but will not begin to compete with the major fossil fuel source plants until costs come down further.

Wrighton's presentation, "Photosynthesis—Real and Artificial," was a closely reasoned, step-by-step discussion of the crucial stages in the chemical and molecular sequence of photosynthesis. His colleagues in the session were chosen for their expertise in one or another of these fundamental specialized areas of photosynthesis research. By the end of the session, they had not only provided a lucid explanation of the process, but had also described firsthand some of the intriguing experimental data produced. Douglas Rees of the California Institute of Technology (on the molecular details of biological photosynthesis), George McLendon of the University of Rochester (on electron transfer), Thomas Mallouk of the University of Texas (on the arrangement of materials to facilitate multielectron transfer chemistry), and Nathan Lewis of the California Institute of Technology (on synthetic systems using liquid junctions) all supplemented Wrighton's overview with reports about findings in their own area of photosynthesis research.

The science of chemistry is predicated on the atomic theory of matter. No matter how intricate the structure of an atom or molecule, its constituent parts will be conserved after the exchanges of a chemical reaction. In fact it was the development of the balance scale in the 18th century that led to the birth of modern chemistry. Once it was realized that the laws of thermodynamics and the principle of the conservation of energy provide an elegant set of constraints, chemistry became the ultimate puzzle-solving science. One could feel fairly confident—once most of the basic elements and compounds and their simple proportional relationships had been discovered—that the answer could be found in the laboratory, if only the pieces could be assembled into the proper, coherent picture. For chemists, this usually means recreating an interaction under conditions that are precisely repeatable.

The enabling paradigm was developed by British chemist John Dalton, who proposed the atomic theory of matter around the turn of the 19th century. Notwithstanding subsequent refinements due to quantum physics and to scientists' increasing ability to probe and examine these reactions directly, Dalton's basic description of the behavior and transfer of protons and electrons among and between elements and compounds—the opening salvo fired at every high school chemistry student—still sets the stage for the most advanced chemical research. Photosynthesis provides a vivid example of the type of drama that is played out effortlessly in nature but reenacted elaborately in chemical laboratories with painstaking concern for the intri-

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