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No. 115: Jan-Feb 1998

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Splitting The Electron's Charge

We all know that the atom can be split, but the electron's charge? No way! R.A. Millikan's oil-drop experiments, circa 1911, demonstrated conclusively that the basic, indivisible unit of electrical charge was that on the electron. Later, an exception was made for those quarks that are firmly locked up inside nuclear particles. They each have 1/3 the electron's charge -- but they never, never escape to the outside world.

It was, therefore, counterintuitive when R. Laughlin proposed in 1982 that fractional electrical charges actually could show up elsewhere in physics. The phenomenon that suggests this possibility is the Fractional Quantum Hall (FQH) effect. Physicists reluctantly accepted the likelihood of fractional charges in this well-verified phenomenon; but the experiments demonstrating fractional charge were a bit esoteric -- the fractional charges were not "palpable" enough.

Two new experiments have made fractional charges much more tangible. When a layer of electrons, held just above absolute zero, is subjected to a powerful magnetic field, you can almost "hear" the fractional charges. The signals from these experiments have been likened to hail hitting a tin roof. Just as you can gauge the size of hailstones from their impact, so you can estimate the electrical charges involved in these experiments -- they are 1/3 that of the electron.

(Ehrenstein, David; "Slicing an Electron's Charge into Three," Science, 277:1766, 1997. Also: Kane, Charles L., and Fisher, Matthew P.A.; "A Shot in the Arm for Fractional Charge," Nature, 389:119, 1997.)

Comment. Is there nothing in the subatomic world that is indivisible?

From Science Frontiers #115, JAN-FEB 1998. 1998-2000 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