WC Archive

Sometimes, the methods used to discover something overshadow an otherwise fairly useful research result; this may be one of those cases, particularly due to the nature of the discovery. The summaries of the article (which appears in the January 26 edition of Nature, so is behind a subscriber wall) quite reasonably focus on the mathematical results. For the curious, they are:

First, the distribution of travelling distances decays as a power law, indicating that trajectories of bank notes are reminiscent of scale-free random walks known as Lévy flights. Second, the probability of remaining in a small, spatially confined region for a time T is dominated by algebraically long tails that attenuate the superdiffusive spread. We show that human travelling behaviour can be described mathematically on many spatiotemporal scales by a two-parameter continuous-time random walk model to a surprising accuracy, and conclude that human travel on geographical scales is an ambivalent and effectively superdiffusive process.

Epidemiologists will thrill to this discovery, but for most of the rest of us, the novelty comes from the use of what amounts to an idle laugh on the web (the creators of Where's George say they created the site "for fun and because it had not been done yet") as the basis for serious -- and potentially quite valuable -- research into how travel relates to the spread of disease. The value of Where's George came from mapping currency transfer to physical movement; there may not be many other studies that will require the same kind of data. But the bigger idea arising from this is that narrow, quirky social networks may turn out to be useful collections of scientific data about human behavior, if we're willing to look beyond the surface amusement.