[Paleopsych] Fw: Synchronization
metzger at disinfo.com
Thu Jul 1 19:03:48 UTC 2004
>From Robert Anton Wilson's elist
>Decoding the Science of Synchronization
>by Nigel Goldenfeld
>Physics Today, June 2004
>After a prolonged and difficult adolescence, the science of complex
>systems has finally come of age. No longer dismissable as being long on
>hype and short on results, the field boasts some remarkable and
>genuinely wide-ranging discoveries that are starting to make an impact
>across the spectrum of scientific endeavor-from mathematical physics to
>cell biology, genomics, and even social science. The recent developments
>are especially notable because they are detailed quantitative analyses
>or predictions, clearly moving beyond the grandiose collection of
>aphorisms and paradigms that, to some, characterized the field's early
>days and drew the ire of skeptics.
>Advances in the characterization of networks are arguably the most
>fundamental insights that have arisen in recent years. How can one
>describe the structural complexity of networks? How do networks evolve?
>What new features emerge when dynamical systems are strongly coupled
>into complex networks? These questions would be a fruitless line of
>inquiry if the answers exhibited sensitive dependence on the specifics
>of the networks. But remarkably, it turns out that some generic
>applicable principles permit useful idealization, classification,
>quantification, and even insight. Answers to these questions are
>relevant to a whole host of real-life systems, such as food webs,
>microbial communities, metabolic and gene networks, the power grid, the
>Internet, and social or affiliation networks.
>Two network phenomena are of special interest to researchers:
>synchronization and connectedness. Synchronization refers to the way in
>which networked elements, due to their dynamics, communicate and exhibit
>collective behavior. Connectedness describes the architecture of
>networks. For example, are there just a few highly connected "hubs"
>(think airline route maps) from which lots of short hops are made? Or is
>everything connected to everything else in a way that has no
>recognizable, simple structure? Connectedness is an important aspect of
>networks that determines, among other things, their efficiency and their
>vulnerability. We now know that many real networks are not random
>collections of nodes and links. Real networks are connected in special
>ways that have functional significance. Perhaps no one has been closer
>to the epicenter of the recent progress than Steven Strogatz, the author
>of the smart, carefully written, and fascinating account that is Sync:
>The Emerging Science of Spontaneous Order.
>Sync is a collection of vignettes about spatially-extended dynamical
>systems that fall (or fail to fall) into synchronization-often in
>spectacular ways. The captivating opening chapter describes the massive
>displays of synchronized firefly flashing that are observed in Southeast
>Asia. The chapter then moves rapidly into the synchronization of cells
>in a beating heart and the general problem of the effect of pulse
>coupling on a set of identical nonlinear oscillators. In a beautifully
>simple explanation that faithfully captures the elements of his rigorous
>proof, Strogatz shows that, regardless of the initial conditions, the
>oscillators will inevitably become synchronized.
>Indeed, the first section sets the tone of the book, which has crystal
>clear explanations of mathematical proofs-often geometrical or
>topological-that are enlivened by thumbnail descriptions of the key
>protagonists. Strogatz uses a discussion of entrainment and Christiaan
>Huygens's discovery of the synchronization of pendula to launch a
>fascinating chapter on the examples of synchronization in everyday life,
>such as lasers, power grids, computer chips, global positioning systems,
>and orbits of celestial bodies. Strogatz even finds examples of quantum
>synchronization in superfluidity and superconductivity, especially in
>the phenomena associated with Josephson tunneling.
>But this is not merely a book about mathematical results on idealized
>models. Strogatz clearly describes experimental observations, sometimes
>putting into perspective the mathematics that is his central interest.
>For instance, a lengthy account of the sometimes grueling experimental
>exploration into the sleep cycle suddenly segues into Strogatz's
>graduate work at Harvard University. His research helped provide firm
>evidence in the circadian cycle of forbidden zones during which sleep
>onset has a very low likelihood.
>One of the many nice things about Sync is its disarmingly frank account
>of the personalities and careers of some of the people whose work has,
>in some sense, been related to synchronization. Most affectionately
>recalled is Arthur Winfree, a brilliant and unconventional thinker who
>has had a profound influence on many people. I will never forget my own
>excitement when I corresponded with Winfree in the early 1980s. He was
>kind enough to send me my own Belousov-Zhabotinsky reaction kit, which I
>treasured until all the reagent was used up. Perhaps the most difficult
>chapter, on scroll wave patterns in three-dimensional chemical
>reactions, is enlivened by Strogatz's personal account of his summer
>work with Winfree. The work involved trying to model the sought-after
>wave forms with pipe cleaners, dental floss, and modeling clay. The
>eclectic array of brilliant and sometimes quirky thinkers who also make
>an appearance in the book include Brian Josephson, Norbert Wiener,
>Yoshiki Kuramoto, and Charles Peskin. Strogatz evidently is fascinated
>by his colleagues and paints their portraits in ways that are generous
>and true to life yet refraining from judgment.
>To my surprise, only at the end of the book does Strogatz devote a
>slightly short chapter to what is perhaps his most widely recognized
>work: the field of small-world networks. The prime example is known as
>"six degrees of separation," which refers to the parlor game in which
>one tries to link a given actor to a target (historically actor Kevin
>Bacon) through the smallest chain of movies sharing common costars.
>Strogatz describes how small-world networks are intermediate between
>regular and random networks. A few shortcuts that link random points in
>a regular network have a drastic effect on the connectivity: The average
>path length goes down significantly, while the local order in the
>network is hardly affected. Small-world networks have been found in
>numerous situations, such as in the nervous system of the worm C.
>elegans, the US power grid, and the Internet. But their influence is not
>always benign: Viruses and epidemics, for example, can easily spread
>Sync is one of those rare books that can profitably be read and enjoyed
>by both experts and laypeople. It comes with a very complete set of
>notes that provide detailed literature citations and technical comments.
>The book could even serve as an excellent reading assignment for an
>introductory course on complexity. So go read Sync. And if you like it,
>tell all your friends about it.
>On second thought, don't bother. I already have.
olga666 at rattlebrain.com
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