Econophysics: can statistical physics contribute to the science of economics?

We address a current question in econophysics: Are fluctuations in economic indices correlated? To this end, we analyze 1-minute data on a stock index , the Standard and Poor index of the 500 largest stocks. We extend the 6-ye ar data base studied by Mantegna and Stanley by including the 13 years 1984 -1996 inclusive, with a recording frequency of 15 seconds. The total number of data points in this 13 years period exceed 4.5 million, which allows fo r a very detailed statistical analysis. We find that the fluctuations in th e volatility are correlated, and that the correlations are well described b y a power law. We also briefly describe some recent scaling results in econ omics, specifically some surprising features that appear to be common to th e growth rates of business firms, countries, research budgets, and bird pop ulations. (C) 1999 Elsevier Science B.V. All rights reserved.