One immediate and obvious question, dating back to the original invention of the cube, is, given a particular configuration of a cube, what's the smallest number of moves needed to solve the puzzle?
Relatedly, what is the smallest number of moves needed to solve any configuration of the Rubik's Cube, a number that cube aficionados refer to as "God's number? As Erno Rubik put it in a recent interview with Business Insider , this question is "connected with the mathematical problems of the cube. Amazingly, it took 36 years after the invention of the toy to come up with an answer.
In , a group of mathematicians and computer programmers proved that any Rubik's Cube can be solved in, at most, 20 moves. One reason it took so long to answer such an apparently straightforward question is the surprising complexity of the Rubik's Cube. An analysis of all the possible permutations of where the smaller constituent cubes often called "cubies" can end up shows that there are about 43 quintillion — 43,,,,,, — possible configurations of the Rubik's Cube.
Going through and trying to find the shortest solution for every single one of those configurations, then, is essentially impossible. The key to answering a question like finding the smallest number of moves to solve any configuration is to take advantage of the relationships between different configurations.
In , mathematician Michael Reid found a Rubik's Cube configuration called a "superflip" and proved that it required at least 20 moves to solve.
That sets a lower limit on what God's Number could be. The remaining question, then, is whether or not there are any cubes that need more than 20 steps to solve.
Over the decades, various upper bounds were proven. An early mathematical analyst of the cube, Morwen Thistlethwaite, was able to prove that any cube could be solved in at most 52 moves. Computer programmer Tomas Rokicki came up with a strategy for finding relatively short solutions for Rubik's Cube configurations. The strategy was based on earlier work developed by mathematician Herbert Kociemba that broke solving a cube into two steps, based on a special set of about Step one, then, is to move the cube into one of those configurations, and step two is to use the short solution for that partially solved configuration.
Kociemba's algorithm is the basis of many computer-operated robotic cube solvers, like the one in the video below:. Previous work using this strategy showed that it would take at most 30 moves to solve any cube: Each of the configurations in the smaller special set take at most 18 steps to solve, and any cube configuration takes at most 12 steps to get to one of the special states. Rokicki took the strategy a step further by grouping together configurations using the special partially-solved configuration set.
Needs better explanation. Party Games. Drinking Games. Lawn Games. Creative Writing. Card Games. Magic: The Gathering. Comic Books. Harry Potter. Board Games. Performing Arts. Musical Theater. Circus Arts. Tabletop Gaming. Metal Detecting. Outdoor Hobbies. Model Trains. List of Rubik's Cube Algorithms. Step Algorithm 1. Getting the "white cross" F' U L' U' 2a. First layer right corner D' R' D R 3a.
Finishing the cube R' D' R D. Related Articles. By Mark Wipfler. By IQplusone. By SmartAndFun. By Zach. By Liz Elias. By Aficionada. By Christopher Wanamaker. By Angela Michelle Schultz. By kerryg. Elite speedcubers will commit hundreds of algorithms to memory and practice performing them in their idle moments. Knowing which to use when boils down to pattern recognition: Each algorithm corresponds to a different arrangement of colored squares on the cube.
When a speedcuber spots an arrangement they recognize, they perform the corresponding algorithm, bringing the cube one step closer to solved. Stringing algorithms together is a skill unto itself. A kind of short-throw clairvoyance, look-ahead enables cubers to plan for future algorithms a fraction of a second in advance.
This minimizes time-consuming pauses and can give observers the impression that a speedcuber is solving the cube in one uninterrupted string of maneuvers. Using algorithms and look-ahead, the most fleet-fingered cubers in the world average between 50 and 60 moves per solve, which they can execute almost without thinking. But there's one variable we still haven't accounted for: Luck. On rare occasion, by sheer chance, a cube will be scrambled in such a way that it requires fewer moves than usual to solve think 40 to 50 moves, instead of 50 to On rarer occasions still, a lucky scramble will find itself in the hands of a world-class cuber.
And on the rarest occasions of all, that cuber will execute their algorithms not just swiftly but seamlessly, dancing through their solution with near-perfect fluidity. When all these things happen at once, an incredible time can materialize seemingly out of nowhere. That's precisely what happened last May, when Zemdegs performed a single solve in a then-unprecedented 4. And it's what happened just six months later, when, at a competition in Wuhu, China, a relatively unknown speedcuber named Yusheng Du solved a cube in just 3.
It's not that he didn't think somebody would break his record "I've had enough of them broken over the years that I'm pretty numb to it by now," he says , he just didn't expect it to fall so quickly, or by so much. Not since , when the single solve record jumped from 8.
0コメント