Mon - October 27, 2003

Societies may not be molecules, but some researchers claim that they do know from atom. 

Successful relationships are about good chemistry. Or maybe that should be "good physics." Because in fields as diverse as marriage, traffic flow, blog popularity, and war, researchers are searching for a physics to describe societies. And increasingly, they are finding it:

While the behaviours of the individual components are too numerous and complicated to follow in detail, the emergent effects are remarkably simple. No two water molecules, for example, are doing the same thing, but a large number of them reliably conspire to produce a freezing transition at 0 °C. The real surprise that emerges from the physics of society is that social behaviour is sometimes extremely simple and, moreover, governed by mathematical laws.

The idea behind social physics is as profound as it is simple: People, like atoms, interact with each other in a variety of predictable ways which cancel out individual preferences. This interaction doesn't eliminate free will, the physicists argue, but it does influence personal behavior by limiting the number of choices we may find acceptable to our neighbors. Social conventions such as speed limits reduce our need to make such choices by ensuring that the most of the drivers on a freeway will behave predictably—just as the laws of physics predict that most particles will behave consistently and predictably.

Social physics may not tell us how societies should be, but they are proving remarkably adept at describing how societies behave. For example, two London physicists who recently studied the effects of social pressures and economic incentives on marriage rates discovered that:

If the strength of social attitudes is weak, the model predicts that the proportion of married people simply increases as the economic inventive to be married increases. But if social attitudes are stronger, the outcome is different. Now two branches appear: a high-marriage and a low-marriage state of the population. In other words, the same set of social conditions can produce different proportions of married people, depending on whether we reached that situation from a starting point on the upper or the lower branch. A particular government policy could have two different outcomes, depending on the history. The two branches of the marriage curve are entirely analogous to the two fluid states—liquid and gas—in van der Waals' theory, which are connected by a phase transition. What is more, the model even shows a vanishing of the "loop" that joins the two branches, which is equivalent to a critical point.

Fascinating stuff. Thanks to Missing Matter for the link.