The Kepler conjecture, now proved, posited that cubic and hexagonal close packing are the densest possible sphere packings.

third part of Hilbert's 18th problem

formulation date | 1611 (414 years ago) formulator | Johannes Kepler status | proved proof date | 2005 (394 years later) (20 years ago) prover | Thomas Callister Hales

proved conjectures | solved mathematics problems | mathematics theorems