It is easy to make out three areas where scientists will be concentrating their efforts in the coming decades. One is in physics, where leading theorists are striving, with the help of experimentalists, to devise a single mathematical theory that embraces all the basic phenomena of matter and energy. The other two are in biology. Biologists-and the rest of us too-would like to know how the brain works and how a single cell, the fertilized egg cell, develops into an entire organism