ABSTRACT
Many years ago, our Yale colleague Ed Bolton designed a fabulous toy. He framed two glass plates the size of a book at a distance of about half a centimeter. Then he filled the space between them with a freon-based viscous fluid, in which guanine flakes (microscopic particles reflecting light like mirrors) were dispersed, and finally sealed it. When one holds this picture horizontally without shaking and presses the other hand to it from below, the outlines of this hand appear on the silvery upper surface. It is painted with a fascinating pattern resembling an enlarged picture of our own fingerprints. Unfortunately, such a toy can no longer be made, because the viscous fluid used was banned after the discovery that it contributes to the destruction of our ozone shield. Nevertheless this now historical experiment makes us aware that similar principles of self-organization play a role in the physical as well as the biological world.
