Since its invention, Rubik’s Cube has taunted mathematicians trying to figure the maximum number of moves necessary
to solve it from any of its
possible starting positions. Someone dubbed the effort a search for “God’s number,” ignoring the theological consensus that Einstein’s maxim “God does not play dice” is likely to apply to yo-yos, Slinkies, Rubik’s Cubes, and the whole range of handheld human amusements.
Whatever you call it, the search has ended. In 2010 a team of whizzes laid bare the uplifting truth: As hopelessly scrambled as one’s cube may appear, one is never more than 20 moves from rendering each of its six faces a solid color. “We were secretly hoping in our tests that there would be one that required 21,” team member Morley Davidson, a mathematician at Kent State University, told the BBC. But it was not to be.