General Colloquium:
April 6 - 4:00pm Phys 223
(Coffee at 3:30p.m. in room 242)

Professorof Physics Emeritus
Robert S. Knox
University of Rochester
Department of Physics and Astronomy

Title: "Albert Rose revisited: will increasing the usage of non-solar energy warm the planet?"

Abstract
In 1979, using the simplest model of the earth's radiative balance, Albert Rose predicted that global warming would occur with certainty as humankind increased its production and consumption of non-solar energy. Using a broader model that allows the greenhouse effect to be considered, we revisit his prediction. The new model assigns a small number of optical parameters to the atmosphere and surface and modifies the Rose prediction: while maintaining its qualitative force, that prediction is shown to be rigorous only if parameters other than the quantity of energy produced are unchanged. The new model is not complicated and can serve as an aid to an elementary understanding of global warming. Our results will be discussed in the context of current global warming concerns.

Research Interests
Photosynthesis begins with the absorption of sunlight by a set of colorful molecules. Their further function is to enable the transfer of the absorbed energy to those places in the photosynthetic cell where primary chemical reactions will take place. It is this part of photosynthesis, preceding the chemical steps, that interests us. The time involved in the physical transfer process is quite small (about 100 picoseconds).

Our research is theoretical, but we work closely with experimental groups. Exciton theory is used to study photosynthetic systems by predicting their rates of energy flow, their ultrafast optical properties, and their overall efficiencies. This work in biological physics can be described as molecular physics, or chemical physics, or even condensed matter physics, but its focus is on the complex apparatus of photosynthetic systems.

Recently we have been working on a generalization of the theory of Kennard and Stepanov, sometimes known as the "Universal Relation" connecting fluorsecence and absorption spectra. See the article in Pure and Applied Chemistry (listed below) for references and an introduction. On the basis of this extended theory as applied to observed spectra, we have hypothesized a new fluorescing state of the chlorophyll molecule.

Global warming is directly affected by photosynthesis because of the continuous exchange of oxygen and carbon dioxide between plants and the atmosphere. In addition to the well-known effects of human activity on the chemical composition of the atmosphere, there is a possibility that over-usage of the non-solar energy will also have an effect on global temperature. Although this effect is currently "down in the noise", we consider it important to study. Our group is currently working on an update of the work of A. Rose, "A global view of solar energy in rational units," Physica Status Solidi a 56, 11-26 (1979).