On Oct 8, 9:35 am, "Edward K. Ream" <edream...@gmail.com> wrote:
> This thread will, from time to time, highlight primary scientific research > articles. You don't need to be a scientist to understand these articles. It's like reading court decisions. After a while you will get a feel for the general shape of things. You can skip what you don't understand, perhaps looking up unfamiliar terms. >From the Sept 25 issue of science: http://www.sciencemag.org/content/vol325/issue5948/index.dtl The article: On Universality in Human Correspondence Activity http://www.sciencemag.org/cgi/content/full/325/5948/1696 The abstract: QQQ The identification and modeling of patterns of human activity have important ramifications for applications ranging from predicting disease spread to optimizing resource allocation. Because of its relevance and availability, written correspondence provides a powerful proxy for studying human activity. One school of thought is that human correspondence is driven by responses to received correspondence, a view that requires a distinct response mechanism to explain e-mail and letter correspondence observations. We demonstrate that, like e-mail correspondence, the letter correspondence patterns of 16 writers, performers, politicians, and scientists are well described by the circadian cycle, task repetition, and changing communication needs. We confirm the universality of these mechanisms by rescaling letter and e- mail correspondence statistics to reveal their underlying similarity. QQQ Perhaps more interesting, the first two paragraphs of the article: QQQ Power law statistics are a hallmark of critical phenomena. A less obvious characteristic of criticality is the emergence of universality classes that capture the similarity of seemingly disparate systems. For example, despite the fact that water and carbon dioxide have different chemical properties, they were observed to behave in the same manner when close to their respective critical points (1). This is because idiosyncrasies, such as the existence of electric dipoles or the ability to form hydrogen bonds, become irrelevant near the liquid/gas critical point. For physical systems, renormalization group theory (2, 3) has enabled researchers to understand the deep connection between the symmetries of a system and the mechanisms that underlie its behavior. The similarity of different fluids near their respective liquid/gas critical points is often demonstrated by rescaling their statistics so that they collapse onto the same universal curves (often power law curves),which have particular scaling exponents. By grouping different substances into the same universality class, as identified by its scaling exponents, one discovers that fluids are described by the same statistical laws near the liquid/gas critical point as uniaxial magnets are near their paramagnetic critical point (1). One can also differentiate the behavior of these systems from the behavior of polymers near the sol/ gel transition, which belong to a different universality class (1). In addition to describing critical phenomena, power law scaling has also been widely reported in biology, economics, and sociology (4–10). Renormalization group theory therefore offers a tantalizing hypothesis for the prevalence of particular power law scaling exponents in social systems: Social systems, in analogy with physical systems, may operate near critical points and can therefore be classified into a small number of distinct universality classes. A heated debate has consequently ensued in the literature concerning the "universality of human systems" (in the statistical physics meaning of the phrase). Is there enough statistical evidence for the asymptotic power law description of the heavy-tailed distributions reported in human systems (11–14)? Is it reasonable to postulate that social systems, like their physical counterparts (2, 3, 15), can be classified into universality classes according to scaling exponents (16)? QQQ What exciting about this is the wide range of applicability of group theory, a standard mathematical tool, and the deep connections that are therefore revealed about physical and social theories. Edward --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "leo-editor" group. To post to this group, send email to leo-editor@googlegroups.com To unsubscribe from this group, send email to leo-editor+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/leo-editor?hl=en -~----------~----~----~----~------~----~------~--~---
