Our daily experiences with life and silicon constantly remind us that computation requires energy. Prima facie, an attractive analogy with steam engines suggests itself -- perhaps computers are machines to convert energy into computational work . On the other hand, careful analysis by Charles Bennett has led him to suggest that computation can be done for arbitrarily little energy per step. I will describe the first steps of a research program that seeks to reconcile this apparent conflict, in the hope that such analysis will some day aid the study of biological processes, where computation is ubiquitous and Darwinian evolution provides great incentive to be efficient.
