Ball: Critical Mass

From Scienticity

Current revision as of 23:48, 14 April 2009

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Philip Ball, Critical Mass : How One Thing Leads to Another. New York : Farrar, Straus and Giroux, 2004. 520 pages with notes and index.

Ball's thesis is easily summarized: that modern concepts and models from a discipline of physics known as condensed-matter physics (encompassing thermodynamics, statistical physics, fluid dynamics, critical phenomena, chaos theory and others) can be usefully applied to the behavior of large groups of people, leading to deeper understanding of collective human behavior in sociology, economics, and such. Now, since my research interests as a working physicist were nearly all contained within condensed-matter physics, one can safely predict that my reaction to this book then will be anything but tepid: either I would love it or hate it.

Fortunately, I loved it. What thermal physicist would not be wooed by this attitude the author reveals in the following paragraph?

Most people who have encountered thermodynamics blanch at its mention, because it is an awesomely tedious discipline both to learn theoretically and to investigate experimentally. This is a shame, because it is also one of the most astonishing theories in science. Think of it: here is a field of study initiated to help nineteenth-century engineers make better engines, and it turns out to produce some of the grandest and most fundamental statements about the way the entire universe works [referring to the concept of entropy and the Second Law of Thermodynamics]. Thermodynamics is the science of change, and without change there is nothing to be said. [p. 37]

I don't know that I'd go quite so far as "awesomely tedious", but it's true that its elegance as a science is more in the concepts than in the mathematical formalism. Nevertheless, thermodynamics is usually talked about in the pejorative even by its partisans, so it's exciting and unique to see Ball adopt such an enthusiastically positive attitude.

In a succession of chapters, Ball elucidates some key concepts quite well and looks at recent research that aims to use concepts and models from condensed-matter physics to investigate a wide range of topics: traffic jams, the stock market, world trade, economics, the growth of businesses, alliances in international politics, globalization, networks, and some others. It's a breathtaking array of applications with appropriate quantification as a unifying idea for organizing and comprehending its diversity.

Here, for example, are some concluding thoughts after a discussion of a model for the growth of companies based on the complex interaction of individual worker agents and their motivations:

IF we believe that such a simplified model can tell us anything at all about the real world, then we learn some revealing things about firms. First, they are not maximizers. Firms as a whole maximize neither profit nor overall utility (as conventional theories would have us believe). Individual agents do try to maximize their utility, but this does not induce such behavior in the group as a whole.

The firms that do best are not those that aim to make the most profit. Rather, longevity in a company stems from being able to attract and retain productive workers. A firm fails not when its profit margins are ended but when it is infiltrated by slackers.

The notion that putting profits first does not make a firm successful should not come as a surprise to those in the business community, although they have sometimes been reluctant to acknowledge it. Some market fundamentalists regard profit maximization not just as a principle of sound management but as a social obligation: it is the notorious "greed is good" paradigm. But as the British economist John Kay points, out, it simply doesn't work. If the employees suffer from the profit motive, so does the firm: "The piece-rate systems of car factories were abandoned because they destroyed social relationships in the workplace, provoked endless negotiation and confrontation, and established a working environment in which no one cared about the quality of the product." [p. 268]

From the summary chapter:

The notion that we could ever construct a scientific "utopia theory" is, then, doomed to absurdity. Certainly, a "physics of society" can provide nothing of the sort. One does not build an ideal world from scientifically based traffic planning, market analysis, criminology, network design, game theory, and the gamut of other ideas discussed in this book. Concepts and models drawn from physics are almost certainly going to find their way into other areas of social science, but they are not going to provide a comprehensive theory of society, nor are they going to make traditional sociology, economics, or political science redundant. The skill lies in deciding where a mechanistic, quantitative model is appropriate for describing human behavior, and where it is likely to produce nothing but a grotesque caricature. This is a skill that is still being acquired, and it is likely that there will be embarrassments along the way.

But properly and judiciously applied, physical science can furnish some valuable tools in areas such as social, economic, and civic planning, and in international negotiation and legislation. It may help us to avoid bad decisions; if we are lucky, it will give us some foresight. If there are emergent laws of traffic, of pedestrian motions, of network topologies, of urban growth, we need to know them in order to plan effectively. Once we acknowledge the universality displayed in the physical world, it should come as no surprise that the world of human social affairs is not necessarily a tabula rasa, open to all options.

Society is complex but that does not place it beyond our ken. As we have seen, complexity of form and organization can arise from simple underlying principles if the are followed simultaneously by a great many individuals. John Stuart Mill already recognized this in the nineteenth century: "The complexity does not arise from the number of the laws themselves, which is not remarkably great, but from the extraordinary number and variety of the data or elements—of the agents which, in obedience to that small number of laws, cooperate toward the effect." [pp. 451—452]

Since condensed-matter physics in general, and critical phenomena in particular, was once my area of expertise. I will venture to correct one small error that Ball makes in describing fluctuations in fluids near the critical point. He writes

One experimental peculiarity that the theory [a late 19th century by physicist van der Waals) did embrace was the extraordinary sensitivity of the critical point. A system near its critical state becomes extremely responsive to disturbances. If you squeeze a substance, it shrinks in volume. The resistance it offers to the is compression is a measure of its so-called compressibility A rubber ball is more compressible than a steel, ball, and a gas is typically much more compressible than a liquid--one can squeeze it more easily. At the critical point of a liquid and gas, the fluid becomes absurdly compressible--in fact, more or less infinitely so. In principle, the gentlest squeeze is sufficient to collapse a critical fluid into invisibility. This sounds absurd, and experimentally one can never observe such extreme behavior, because maintaining a substance exactly at its critical point is too difficult--the critical state is too unstable. but one can see the compressibility start to increase very rapidly as the critical point is approached. [p. 228]

This capture the essence, but the fluctuations (in density, which correspond to fluctuations in local temperature) are unstable only below the critical temperature. Above the critical temperature the fluctuations can grow to nearly macroscopic sizes but they remain stable, although it does take quite a bit of work to contrive getting a system that close to the critical point and keeping it there.

Ball writes with what I've come to expect as his accustomed clarity on some pretty challenging concepts; he gets the important meanings across through good exposition, without the use of silly and imprecise analogies. On nearly every page I found stimulating ideas and informative, exciting writing. This is another book that requires some investment in time to get through it, but the reader is well rewarded for the effort.

-- Notes by JNS