Using a popular Internet game that traces the travels of dollar bills, scientists have unveiled statistical laws of human travel in the United States, and developed a mathematical description that can be used to model the spread of infectious disease in this country.
In the game, participants can register a dollar bill, of any denomination, and monitor its geographic circulation. Using the game data, physicists developed a powerful mathematical theory that describes the observed movements of travelers amazingly well over distances from just a few kilometers to a few thousand. The study represents a major breakthrough for the mathematical modeling of the spread of epidemics.
Nature news release
"The scaling laws of human travel," Nature, Jan. 26, 2006, p462, D. Brockmann, L. Hufnagel and T. Geisel, doi:10.1038/nature04292.