≡ Menu

Every position of Rubik’s Cube can be solved in twenty moves or less.

Rubik's cube

I was a big Rubik’s Cube fan. When I was about 10 years old, I locked myself in my room with a solution book and became the kid in class who could solve the thing in under a minute.

There are 43,252,003,274,489,856,000 possible varying positions for the Rubik’s Cube. (That’s 43 QUINTILLION, people.) Thanks to some resources donated by Google, a team of mathematicians and programmers has now determined that any of these varying positions can be solved within 20 moves.

It gets even gnarlier:

Every solver of the Cube uses an algorithm, which is a sequence of steps for solving the Cube. One algorithm might use a sequence of moves to solve the top face, then another sequence of moves to position the middle edges, and so on. There are many different algorithms, varying in complexity and number of moves required, but those that can be memorized by a mortal typically require more than forty moves.

One may suppose God would use a much more efficient algorithm, one that always uses the shortest sequence of moves; this is known as God’s Algorithm. The number of moves this algorithm would take in the worst case is called God’s Number. At long last, God’s Number has been shown to be 20.

Comments on this entry are closed.