Watch: Solving a Rubik's Cube in 5.25 seconds, new world record


How does one equitably set up the cube to measure solving times. If the cube is not set up in the same starting position each for each trial then are the trials comparable? But if the cube is set up in the same starting position each trial then the analysis portion of the solution process is minimized.


I believe the analysis portion takes place entirely before the solving process begins - if you watch closely you can see him examining it for a few seconds, then putting it down on the table before he starts. Presumably he analyzes the pattern on the cube and calculates the necessary moves in his head so the actual solving is simply a series of rote patterns he’s memorized beforehand.

I can’t comment on what is considered a sufficiently randomized cube, but I’m guessing there are rules governing that sort of thing.

And here I can’t even solve a Rubik’s cube. sigh

There are rules, including rules for scrambling the cube. The short version:

Puzzles must be scrambled using computer-generated random scramble sequences.

For the long version see:

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You know, like nunchuku skills, bow hunting skills, computer hacking skills… Girls only want boyfriends who have great skills.


Besides the fact that computer-based algorithms are used to create the random initial states, which may themselves enforce a minimum distance away from the solution, this answer at Math StackExchange states that, given any randomly-arranged cube, there is a 99.75% chance it is at least 16 moves away from being solved. The answer above it states that the maximum possible distance is 20 moves. So, however you randomly arrange them, there is a 99.5% chance that two cubes will both be 16-20 moves from the solution, and only 0.5% chance that one of them is closer than 16 moves away.

I guess a contestant could complain that 20 moves is significantly different than 16 (although I believe the probability of randomly getting a 20-move puzzle is very low), but world-records are like that. Marathon records may be invalidated by high tail-winds, but even within the prescribed limits there are variations in temperature and what-not that may give slight advantages on one day vs another.

I don’t know, but I expect that if a computer enforced that all starting cubes must have exactly 16-move solutions, that restriction could be hacked to give knowledgable solvers a slight edge.

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