Successfully predicting stock market swings is as futile as searching for the fountain of youth, some people believe. UCLA physicist and complex-systems theorist Didier Sornette is not among them. Sornette says he has found patterns that occur in market crashes dating back for centuries. Their statistical signatures are evident long in advance, he concludes. Sornette has developed algorithms ? based on sophisticated mathematics, statistical modeling techniques and collective behavior theory ? that enable him to analyze more than two dozen stock markets worldwide. Applying techniques of physics to economic data, he has developed a quantitative model that can predict the signatures of a coming stock market crash.