Home Page Science Frontiers

No. 47: Sep-Oct 1986

Issue Contents

Other pages

Other Interesting Sites











Unpredictable Things

Simple spherical pendulums are fixtures of physics labs, to say nothing of grandfather clocks. It is now widely recognized that pendulums can behave chaotically; that is, unpredictably. As the pendulum bob swings farther away from its rest position, the restoring force becomes nonlinear; i.e., not proportional to the displacement. At some combination of displacement and driving frequency, a region of chaos may develop, in which theory is powerless to tell what is going to happen next. "It is not just the behavior of pendulums that has sprung this surprise. Systems as diverse as simple electrical circuits, dynamos, lasers, chemical reactions and heart cells behave in an analogous way and the implications extend far beyond these examples -- to matters such as weather forecasting, populations of biological species, physiological and psychiatric medicine, economic forecasting and perhaps the evolution of society."

(Tritton, David; "Chaos in the Swing of a Pendulum," New Scientist, p. 37, July 24, 1986.)

Comment. Some of the anomalies we record may be the consequence of simple systems gone wild. Chaotic motions of some asteroids and at least one solar system moon are already suspected. Imagine what might happen in much more complex systems, such as biological evolution (hopeful monsters?), brain development (idiot savants?), etc.

From Science Frontiers #47, SEP-OCT 1986. 1986-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987