Is there a science of economics? Can we actually conduct experiments to test its hypotheses? For once, the ethical and practical answers match: even were we willing to experiment on our fellows, our power to effect precise changes or to isolate control groups is limited, to say the least. But what if we could experiment on a smaller, simpler version of the world market? John L. Casti points the way toward just such a science once-removed of complex phenomena in Would-Be Worlds, an accessible overview of the use of computers in modeling and simulation. From the Cambrian explosion to the Albuquerque transportation system to the NFL, we are shown how a few simple rules can give rise to dazzling complexity, yielding insights undreamed of before the silicon revolution. Casti touches on mathematics, evolutionary biology, biochemistry, economics, logic, literature, and meteorology, always with clarity and sympathy for the lay reader. At a time when children spend hours with their computers building and maintaining cities, ecosystems, and planets, Would-Be Worlds shows us how this play foreshadows the investigations these young scientists will pursue in the future. --Rob Lightner