What is Sphere packing?
[[File:HCP Oranges.jpg|thumb|The stacking of [[orange (fruit)|orange]]s is a practical application of sphere packing.]] In [[geometry]], '''Sphere packing''' refers to a number of problems that try to arrange [[sphere]]s in space. Very often, the spheres all have the same size, and the space used is usually three-dimensional [[Euclidean space]]. The problem is part of [[packing problem]]s. When it is generalised, not all the spheres need to have the same size, and spaces can be n-dimensional Euclidean space, or [[hyperbolic space]]. A typical sphere packing problem is to find an arrangement in which the spheres fill as large a proportion of the space as possible. The proportion of space filled by the spheres is called the density of the arrangement. As the local density of a packing in an infinite space can vary depending on the volume over which it is measured, the problem is usually to maximise the [[average]] or [[asymptotic]] density, measured over a large enough volume. {{math-stub}} [[Category:Geometry]]