Charles Radin
Orbits of Orbs: sphere packing meets Penrose tilings
(338K, postscript)

ABSTRACT.  The venerable study of optimum density problems, such as packing 
spheres as efficiently as possible, has been revitalized by 
investigations on aperiodicity, a subject best known through the 
Penrose kite \& dart tilings. The result is a generalization 
of the basic notion of geometric symmetry for patterns in space.