The Science of Sticky Spheres » American Scientist
Saturday, October 20th, 2012Interesting account of work on sphere packing. As the number of spheres increases from 4 (the tetrahedron), new things emerge : new seeds not built from previous solutions and flexible solutions that can have internal subparts twist without breaking contacts. Great animations of the later.
http://www.americanscientist.org/issues/pub/the-science-of-sticky-spheres