"Foams and Honeycombs," by Erica G. Klarreich. American Scientist, March/April 2000, pages 152-161.
This article discusses progress on an ancient question: What surface encloses the greatest volume with the least area? One form of this question has become known as the "honeycomb problem", because it raises the question of whether bees, in making honeycomb, use the shape that encloses the maximum amount of honey and uses the least amount of wax. The article discusses the history of this and related problems, as well as Thomas Hales's celebrated solution of the honeycomb problem, completed in 1999.
--- Allyn Jackson