Critical Mass: How One Thing Leads to Another [Englisch] [Taschenbuch]

Readers of "Critical Mass" by Philip Ball will learn many new concepts and ideas from a skilled science writer with a doctorate in physics. His book opens with brief historical account that weaves the political confusion that engulfed Britain in the seventeenth century into early developments of science, but it is with the work of Thomas Hobbes that the author is particularly concerned. Although others had imagined ideal societies - Plato's "Republic", Thomas More's "Utopia", and Francis Bacon's "New Atlantis" come to mind - Hobbes attempted to deduce the laws of society from basic postulates in the manner that Isaac Newton had recently managed to explain planetary motion. In other words, Hobbes sought to establish a "physics of society" which is also the aim of Ball's book.

Sensitive to charges of "arrogance", Ball asserts that his work is "not an attempt to prescribe systems of control and governance, still less to bolster with scientific reasoning prejudices about how society ought to be run." Rather he would help us to understand how "patterns of behavior emerge - and patterns undoubtedly do emerge - from the statistical melée of many individuals doing their own idiosyncratic thing." Thus he uses the tools that have recently been developed in nonlinear science to understand collective social behavior. To this end, the historical introduction is followed by a discussion of the concept of probability and the corresponding growth of statistical physics that developed in the nineteenth and early twentieth centuries. The general reader who would understand these important ideas will benefit from the early chapters which clearly expound the notion of a phase change (think of boiling water or melting ice). As a central metaphor for much of the book, Ball carefully presents the Ising model, which comprises a two-dimensional array of rotating magnets (think of small compasses) each influencing the orientations of its nearest neighbors. Below a certain "temperature" (random vibrations of the magnets), the magnets all "freeze" into a certain orientation - a global effect that stems from local (nearest neighbor) interactions. To what extent, the author asks, do local interactions among people lead to the emergence of global social phenomena?

Beginning with discussions of snowflake growth, the formation of complex patterns in bacterial colonies, and the dynamics of flocking birds (in which the interactions are local), the author turns to collective phenomena involving humans, including the organization of passing rules on sidewalks and corridors, tragedies stemming from inept crowd control, path formation in parks, and the nonlinear dynamics influencing the growth of cities. These fascinating discussions are followed by a chapter on traffic flow (in which the dynamics of jamming are clearly explained) and several chapters on economics.

In the first of these, Ball considers fluctuating price levels, which Adam Smith deemed to be governed by the collective effect of an "invisible hand" as far back as the eighteenth century. An important aspect of price variations, well laid out in this book, is their statistics. If all the influences on prices were random, the variations would be governed by Gaussian statistics with large variations falling off as a negative exponential of the square. In fact, large variations are often found to be much more likely than in a random process, suggesting the statistics of Lévy flights used unconsciously both by foraging bees and also by Jackson Pollock in his famous drip paintings. Interestingly, an analysis of the S&P 500 market fluctuations shows a power-law distribution lying between Gaussian and Lévy statistics in which the likelihood of a variation is inversely proportional to a power of its magnitude. Power-law distributions have been found to govern many phenomena including the probabilities of avalanches and earthquakes, sizes of individual incomes, and growth rates of firms. From economics, Ball segues into the more slippery area of politics. Appealing to the Ising model, he considers analytic descriptions of the possible international alliances prior to the Second World War, statistics of recent voting patterns in Brazil (which are also found to follow a power law), and various models for investigating balances between social order and justice. Final chapters discuss the nature of interconnecting networks, the World Wide Web (in which the number of links to a site are governed by a power law) and analytic evaluations of strategies for international relations. Surprisingly, Ball ignores the application of collective dynamics to the human brain even though physicist John Hopfield has famously based such a description on the Ising model.

While this book is highly recommended, the author seems unaware of a seminal study of living systems published by Manfred Eigen and Peter Schuster a quarter century ago on how the first biological structures might have first become organized, which showed that three or more interacting hierarchical levels of organization are necessary for self-reproduction. In addition to being important for the emergence of life, this result has deep implications for the emergence of consciousness in our brains. Why? Human brains are organized into cognitive hierarchies, just as living organisms are organized into biological hierarchies, and cities are organized into social hierarchies. To better understand the dynamics of such intricate systems, we must move beyond the concept of emergence at a particular level of a nonlinear dynamic hierarchy to appreciate the possibilities of downward causation and positive feedback networks that extend over several hierarchical levels. Also, the author ignores the vast amount of work in cultural anthropology produced by physicist Franz Boas and his many brilliant students at Columbia University over much of the twentieth century, including Ruth Benedict's classic "Patterns of Culture".

Alwyn Scott

http://personal.riverusers.com/~rover/

This is a sometimes dense, often rambling and always interesting book about the history of science, the history of social philosophy and many points of congruence between the two, from how traffic jams happen to how communities self-organize. Author Philip Ball seems to include almost every notable physical scientist since Sir Isaac Newton as he traces how key scientific theories have influenced or been influenced by the speculations of economists and political scientists. Anyone whose acquaintance with science is minimal, but whose curiosity is deep, will find that reading this book is something like floating down a river that is a sometimes windy, sometimes swampy, sometimes roiling stream of discoveries, ideas, broken hypotheses and curious characters. There are two small flaws. First, the author identifies almost every scientist who ever worked on a problem remotely related to the book's subject and sometimes he does not clear the path through the thicket of names and experiments. And, second, in a social science discussion toward the end, Ball permits his political biases to color his story with occasional, apparently heartfelt, denunciations of right-leaning politicians. These quibbles aside, we say buy this book and enjoy an intriguing raft ride through interesting intellectual waters.

This book is an excellent historical look at how scientists and social scientists have attempted to measure,analyze and discuss the effects and causes of group interactions,be they the interactions of atomic particles or speculators operating on the New York stock exchange.The author provides a superb overview of herd effects,cascades, and other types of crowd effects,as well as a good discussion of how economists have attempted to model the interactive effects of crowd behavior.Readers who are interested in this topic will find a much more detailed discussion in"The Wisdom of Crowds",by J Surowiecki(2004).John Maynard Keynes and Benoit Mandelbrot are both given appropriate recognition for their pathbreaking contributions in this area.Ball recognizes,as did Keynes and Boltzmann before him,the faddish nature of much of the social sciences , economics in particular ,in attempting to mimic mathematical physics in its approach to the use of formal mathematical methods.In many cases this leads to fads which emphasize the mere use of the technique,irrespective of any quantifiable scientific results.Ball points out that the overuse of the normal(Gaussian)probability distribution among economists is an attempt to obtain the self ordering and equilibrating structure of gas particle models within the human domain even if there is no empirical support for such a distribution.Here both Pareto,Zipf,and Mandelbrot receive credit.