How can a 5-year-old solve a Rubik's cube even before learning how to properly write their name? It's amazing to see kids solving Rubik's, some of them even under a minute. How do they do it? and most important, can you do it, too?

The history behind Rubik's Cube

The Rubik's cube was invented in 1974 by Hungarian sculptor and professor of architecture Ernő Rubik. It is now the most sold puzzle in the world, with many different versions: 3x3x3, 4x4x4, 25x25x25. Some of them aren't even cubes: cylinders, pyramids and many other shapes.

Hands solving the Megamix. Photo by ALAN DE LA CRUZ on Unsplash

What is most fascinating about the Rubik's cube is that it is really difficult to solve if you don't know how to do it, but really easy if you know the proper method. You may try to solve it randomly or with your intuition, but there are 88,580,102,706,155,225,088,000~~(I don't even know how to spell this number)~~ possible permutations of the cube. It may take a life time to solve it this way.

They've cracked the code

It took a month for Ernő to solve the puzzle the first time. But since then, people have solved it thousands of times, including the astonishing 3.47 seconds world record. Researchers, mathematicians, programmers and many others came up with a way of solving the cube, which involves taking some meticulous steps. For example, at first you should choose one color to be a base for the cube and solve it. Afterwards you start building your way to the top. Solve the second layer, and finally the last layer.

Okay, but you still haven't told us how to do it, Thiago! That's a good point. Frankly, I'm not the best person to tell you how to do it, there are plenty of good rubik's cube tutorials online. What concerns us here is why everyone can solve it.

Solving a Rubik's cube is a matter of following some rigorous steps. The method is the same everytime, what changes is each of the different permutations you may come across as you solve the cube.

There are beginner and advanced methods and each requires a certain amount of time to learn. Learning the advanced methods will help you solve it faster but will require more muscle memory and lots of training.

Rigorous steps

In order to describe such methods a notation was created. For example, if I told you, do this "LU′ R′ U L′ U′ R U2", would you have any idea what to do with your cube? Probably you wouldn't, but it is actually a way of describing which pieces of the cube to move and in which direction. Here are some of the movements you can do with your cube, and the notations that indicate them(from Wikipedia):

• F (Front): the side currently facing the solver
• B (Back): the side opposite the front
• U (Up): the side above or on top of the front side
• D (Down): the side opposite the top, underneath the cube
• L (Left): the side directly to the left of the front

The a prime symbol ( ′ ) after a letter denotes an anticlockwise face turn and a letter followed by a 2 denotes two turns.

In the end, you could memorize each step with a combination of F's and B's and U's, but you could also memorize them visually. If you watch one of the tutorials, shared in the previous section, you see that it actually makes sense and works, you just need to follow the steps outlined in the video.

This repetition of movements and actions defined by how your cube is in a moment can also be called an algorithm.

Algorithms, again?

Yep! Programmers love Rubik's cubes because they follow a pattern, an algorithm. If I have a red middle piece right next to a blue one and want them to switch places, I can do a F B F2 L and put it in the right place. Wheter I just memorized that pattern in a written, visual or singing-a-song way, it works every time. If, in the end, it doesn't work, it means that I did something wrong along the way.

It is also a challenge to solve the Rubik's cube faster and faster. It's an amazing thing to see how computers solve the cube. Some researchers created an algorithm that optimizes the way to solve the cube. It's basically an algorithm that tries to be better than other algorithms. It's really meta.

Now, what?

Computers, children, and anyone else can solve the cube — you just need to give them an algorithm, a path to follow. Rubik's cubes having been around for a while and are still a challenge, but they don't need to be.

I encourage you to learn how to solve the cube and understand what an algorithm is about. It can help you with many other things that you don't know about yet. Also, if you want to keep reading different articles, but don't know which one to choose: click on the serendipity roulette and be surprised by an expected permutation in the world of articles.