#### Filipe Teixeira

##### Member

**What are the limits of speed cubing?**

Any algorithmic set which can be performed by a human must be limited to a couple of hundreds at most thousands of algorithms. These algorithms need to be performed in a fast manner without too much thinking. This puts limits on the amount of time needed to solve the cube. If there was a hypothetical person who could see the shortest or the almost shortest algorithm right away in the beginning (which is quite improbable), he or she would need about 2 seconds, provided the farthest position is around 20 face moves at the twist rate of 10 moves per second. Since the assumption for this estimate will probably be unrealistic for many years to come, I estimate the limit for speed cubing at 5 seconds (the average time). One should totally abandon the concept of a record time since it has very little informational value. If somebody messes up the cube carelessly, one can take advantage of it and solve the cube in a few seconds. Therefore, for comparing purposes, I suggest to use an average of 10 consecutive times. For my system, I defined the concept of a modified record: I discarded record times whenever more than one stage was skipped during the cube solving. By skipping a stage, I mean: placing the four edges using less than 3 moves, too much luck for the four blocks (in the second layer), skipping the orientation of 8 cubicles from the last layer, skipping the permutation part in the last layer. For the first two layers, it is hard to estimate the probabilities, but the last layer can be calculated exactly. The probability that after solving the second layer, the last layer will have the correct color is 1/216, and the probablity that after orienting the cubes in the last layer one will not need to permute them, is 1/72. So, for example, if the last layer got assembled by chance right after the second layer, I discarded the time since the probability of that happening is too small: 1/(216*72). So, what is my modified record? It is 11 seconds. My best average out of ten was often 17 in 1983. I kept myself in a good shape for many years, and I can still get to an average of about 18 after all those years. Going back to 17 or lower would require a lot of effort, good cube, and a complete devotion that only a rookie can possess. So, good luck everybody and do not give up!