Considering a Rubik’s Cube is scrambled randomly everytime and there can not be one single approach to all the configurations, how do speed cubers solve it in such a little time?
In: Mathematics
There is ultimately a fairly simple algorithm that you can learn and apply to solve a Rubik’s Cube fairly quickly.
These people have learned that algorithm and have practiced applying it very quickly. Not much different from doing anything else very fast.
A couple of tricks:
1. They have tons of different patterns recognized. You know how in chess, there are tons of unique openings all with their own pros cons and name? Well cubing is the same. Cubers look for specific patterns.
2. Memorization. Your hands can move faster than your eyes can track so memory is important. You’ll see speed cubers get a few seconds to study the cube before starting. They are looking for those patterns and memorizing where everything is so their hands can just fly.
3. Optimization. Once you have the first two down, you can start to find short cuts. Why make three moves when you can do two?
Combine all three of these and you get a WR
There is only one possible solution to a Rubik’s Cube. The center pieces are fixed. The basic method is as follows: You first do the cross on the bottom face, You then complete the first two layers from the bottom. You finish by completing the last layer.
The last step has a limited number of configurations (56 IIRC) which you can all learn. Doing the cross is trivial. The second step is the one that really requires you to plan how you will approach it. With experience you get used to it and you can solve it by just looking at the scrambled cube. Speedcubers do most of the solving before the timer start. They build a set of moves to get to the solution and then they just have to execute it.
The current record is 3.13 seconds by Max Park.
He used a method called CFOP. It has 78 algorithms to learn.
Before solving speedcubers get 15 seconds to inspect the cube. This is when they are actually solving the cube, by recognising important patterns and preplanning all their moves.
They will use a special speedcube which allows easier moving of multiple faces at once.
Because they randomise the starting cube, the fastest times are generally the ones with the starting cubes closest to solved already.
When they finally go it’s all about dexterity. Almost competitive speedcubers are under 20.
Speed cubers use a combination of memorized algorithms, advanced techniques, and muscle memory to solve the cube quickly. They practice recognizing patterns and configurations, so even though the cube is scrambled differently each time, they can efficiently execute a series of pre-learned moves that adjust the cube towards its solved state.
Think about how fast people can type. It’s a very complicated and precise activity, and yet there are people in every office building who could easily type a sentence in the time it takes the best cubers to solve a cube. That just the power of human dexterity and muscle memory. It’s just that most people have a lot more practice typing than solving a Rubik’s cube.
In addition to the algorithms others have mentioned, the world records still require an element of luck. The top cubers may be able to consistently get under 10 seconds, but the 4 and 5 second solves are still relatively rare lucky events.
They don’t “solve it” in 5 seconds. In speed cubing competitions you are able to look at the cube and come up with a plan before the timer starts. So they will have already figured out how to solve the cube. The timer is just how fast they can physically manipulate it. Also the cubes for speed cubing are very different then a normal rubik’s cube. They are able to be moved around a lot faster.
In addition to what’s already said here, there may be a lot of configurations but the problem is broken down into smaller problems involving fewer pieces. Each of these smaller problems have a much smaller set of possible configurations that are easier to memorize.
When you chain these smaller problems in steps, first layer, middle layer, etc, then as certain pieces are solved the number of configurations the remaining pieces could be in also become smaller. One can then memorize these solutions.
For example, in the standard CFOP method, by the time you get to the top layer, there are two problems left to solve. The first has 57 configurations and the second has 21. These will take a few weeks of practice to memorize but can be executed in under 5 seconds if you’re very good.
It’s just moving things around to a known position and then following a bunch of memorized algorithm moves. The only hard part really is memorizing the algorithms. It’s actually *far* less difficult than it seems…if you can memorize sets of moves like F R U R’ U’ F’ (front clockwise, right clockwise, upside clockwise, right counterclockwise, upside counterclockwise, front counterclockwise), that’s all it really is.
First off, using better quality cubes. Rubik brand cubes are shocking poor for speed cubing, even there “speed” version is pretty poor. Various companies have made there own “Puzzle Cubes” that are identical but have much better designs such as magnetic levitation to make turns smoother and snappier and better lubrication.
Secondly, solving a cube is generally done through the use of algorithms, deterministic ways of solving the cube. Solving the cube is typically done using a method called CFOP. In this, first you form a Cross on one of the sides, than you solve the First two layers. Those can be done purely visually, and most cubers can learn to do it intuitively. The last two steps, Orientation and Permutation of the last layer (shortened to OLL and PLL), are generally done using algorithms. First during orientation, we make the top side of the cube solved, but the edges of that layer not yet solved. There are 57 possible orientations of pieces after doing the first two steps. If you memorize all 57 possible algorithms to solve for the OLL, you can solve it at a glance. After, PLL will solve the cube and there are only 21 possible cases. Learn all 21, and with 78 total algorithms memorized and you can solve the cube INCREDIBLY fast.
Third of course, is practice. A lot of it. Using simplified versions of CFOP, you can easily get times down. My fastest with beginner methods was around 90 seconds which is pretty slow, but you can easily get faster. Start learning the algorithms, get better at the first two steps, and your time will slowly fall.
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