Mathematical Digest
Short Summaries of Articles about Mathematics in the Popular Press"Circles in the Sky: Detecting the shape of the universe," by Ivars Peterson.Science News, 21 February 1998, pages 123125. This article describes recent work on a fundamental question in astrophysics:What is the shape, or topology, of the universe? Just as humans have usedvarious means to study the shape of the earth and have concluded that it is asphere, scientists are collecting data in an effort to understand what formour threedimensional universe takes. Mathematicians, who have intensivelystudied the topology of threedimensional shapes, are now collaborating withastrophysicists on this intriguing question.  Allyn Jackson
