Fatal Zopiclone Overdose

20 rotations to solve the Rubik cube, and Google helps prove

Rubik's Cube came to light for the first time in 70 years. Since then a community of scientists and enthusiasts looking for the minimum number of rotations that are needed to reach from any initial position to the position with all the colors sorted. This minimum number is called God's number. And it turns out is 20. In any case it takes more than 20 rotations.

The proof of this result is not a lot of mathematical formulas, but a computer program that has all possible initial fixed hub. As stated on the website cube20.org , the official website of the project, current computer would take about 35 years to calculate all the solutions to be waiting a long time. And here comes Google who donated their time free of computers for calculation, reducing their time to a few weeks.

In principle there are 43,252,003,274,489,856,000 different positions of the cube. But some of these are equivalent in the sense that its solution is very similar. For example, an initial position is transformed into another by rotating the cube by 90 degrees, without rotating any of its parts. Although at first view seems to be another problem, the solution is the same. In this way, and other tricks could reduce the number of initial positions 55,882,296, and shortens the computation time tremendously. The vast majority of initial positions can be resolved in less than 20 rotations, some at 20, but there is no position that requires more than 20.

The search for the number of God to the Rubik's cube has come to an end. 30 years, much thought and a high computational capacity were needed to find it.