Apparently God’s Number is 20 and Google was there to witness the discovery. This number represents the number of moves the Rubik’s cube can be solved in. But what is the big deal anyway? This number has been in question and worked on for nearly over 30 years.
So how did they solve the 43,252,003,274,489,856,000 positions on the cube? They partitioned the problem into 2,217,093,120 problems compromising of 19,508,428,800 positions. This allowed them to have problem sets that could be solved on a modern computer. Then some symmetry was exploited, some clever mathematical and programming tricks they were able to solve this problem. Oh yes, don’t forget they also used lots of computers which amounted to 35 CPU years. (How are CPU years calculated btw?)
The team consists of Morley Davidson, a mathematician from Kent State University, John Dethridge, an engineer at Google in Mountain View, Herbert Kociemba, math teacher from Darmstadt, Germany, and Tomas Rokicki, a programmer from Palo Alto, California. Feel free to e-mail Tomas Rokicki at rokicki@gmail.com if you have any questions. Let us know how it goes!
Now, if we would’ve known this, it would’ve saved me a couple of hundred moves.
