Order Emerging

"Serious science on a table top" is how Harry Swinney described his research during the 14 July colloquium at ICTP entitled "Emergence of Order in Physical, Chemical, and Biological Systems." Swinney is a professor at the University of Texas at Austin (United States), where he studies instabilities, chaos, and pattern formation in systems being driven away from equilibrium.  His presentation focused on the emergence of patterns, which Swinney called "one of the world's most durable mysteries."

"Science is always looking for patterns," Swinney explained. Patterns help researchers to unify phenomena, quantify behaviour, and compare systems.

Perhaps the best-known of Swinney's experiments examined waves formed in a vibrating container of cornstarch and water. As many cooks know, a cornstarch mixture  behaves like an ordinary liquid when stirred slowly but strongly resists attempts to stir rapidly. The researchers increased the amplitude of the vibrations of the cornstarch container, and observed at a certain vibration amplitude that  the smooth surface of the cornstarch broke into a distinct, regular wavy pattern. When the vibration amplitude was increased further, at some point the pattern of regular waves developed bizarre wiggly worm-like structures. This experiment demonstrates the accessibility of the types of projects Swinney does, which are constrained not by the cost of the equipment, but mainly by the intellect and creativity of the researchers.  The original cornstarch experiment was published in Physical Review Letters, but plenty of high-schoolers have replicated it, or even thought up original variations like using different types of starch.

The study of pattern formation is much more than child's play, though. This field has plenty of practical applications, Swinney explained, and he offered many familiar examples during his presentation. Spiral wave patterns in the heart can lead to rapid and irregular beating and trouble pumping blood, and understanding those patterns is leading to the development of a pacemaker that could correct them. Studying the way an air bubble expands in a layer of oil explains why many oil derricks start pumping water when there's still lots of oil trapped underground. Meanwhile, studying the patterns that bacterial colonies form has led to the discovery of a new class of toxins that could potentially be used as antibiotics.

One of Swinney's current research interests is granular media, and he hopes to develop an understanding of  pouring, mixing and separation from first principles. Swinney noted that everyday life is full of granular media, ranging from sugar to coal and from cement to medical tablets, but that the behaviour of these materials is poorly understood. As a result, seemingly simple tasks like getting ingredients distributed evenly throughout pharmaceutical pills are actually quite difficult.

Swinney also spoke briefly about The Hands-On Research in Complex Systems Schools, an ICTP-sponsored program that he directs, where young scientists from developing countries learn to use common household materials and consumer electronics to study questions on the frontiers of physics research.

Three schools have been held since 2008, one each in India, Brazil, and Cameroon. Each session lasts 2 weeks, with participants conducting a different experiment each day.  In addition to introducing students to "inexpensive, yet very powerful instrumentation," Swinney said that the courses include information on computational methods, networking and communication skills like writing research papers and giving scientific lectures.

"Hands-on research is fun," Swinney said. "Try it. You'll like it."

Though Swinney's experiments are conceptually simple, they touch at questions that have perplexed scientists for the last century. Under what conditions do patterns start to form? Can the emergence of order be predicted? Several famous scientists early in the 20^th century, including Lord Kelvin and Lord Rayleigh, tried and failed to answer those questions. But if there is an underlying general rule, the answer will probably emerge from a tabletop somewhere.