Wigner Not the 'W' in WKB

September 2005, page 17

David Stevenson's Reference Frame piece on tsunamis and earthquakes (PHYSICS TODAY, June 2005, page 10) is excellent. However, I offer a correction and an emendation.

Although Eugene Wigner did many things, he did not cofound the WKB approximation in 1926. Physicist Gregor Wentzel did. I got that information from the online encyclopedia Wikipedia, which despite beginning with a W was also not founded by Wigner.

And in a story devoted to the linkages between the physical and Earth sciences, it's too bad Stevenson didn't refer more accurately to the approximation as "WKBJ," and thereby give due credit to geophysicist Harold Jeffreys, whose work on the subject actually preceded that of Wentzel and coworkers by three years.

John Knox

(jknox@engr.uga.edu)

University of Georgia

Athens

Stevenson replies: I thank John Knox and several others for pointing out my incorrect attribution of the W in WKB. The approximation predates their quantum mechanical application and was indeed to be found in the work of Harold Jeffreys. An interesting website, http://www.du.edu/~jcalvert/phys/wkb.htm, gives more historical details. The essential features of the so-called WKB or WKBJ approximation were known even earlier¹ but Lord Rayleigh already has too many things named after him.