Solving Rubik’s cube blindfolded

Considering that there are quite a lot of problems in the world at the moment, I decided to take first things first and learn how to solve Rubik’s cube blindfolded, just as I said I would a week ago. I also guessed it would take slightly more than one week, which it did. Just to explain what I’m talking about here, this post is about solving Rubik’s cube blindfolded, i.e., first look at the cube, then obscure vision in some way (I turned off the lights in the room) and then solve the cube. It wasn’t pretty and it wasn’t fast, but just a few minutes ago I had the satisfying experience of turning on the lights and looking at a completely solved cube.

Most people, including me up to a few weeks ago, believe that solving Rubik’s cube blindfolded is almost impossible and that one has to be some kind spatial memory wizard to do it. This isn’t true. I’m fully convinced that an averagely talented person can learn to solve the cube blindfolded with some effort. My memory is good, but it isn’t exceptional. Of course, from scratch it would take a lot more than one week (my personal best at sighted cubing was around 43 seconds when I started). I’ve seen people recommend that one should be able to solve a cube in the normal fashion below one minute before attempting blindfolded cubing, or BLD as it’s commonly called. This is because one needs to be familiar with the cube and also be able to execute fairly long algorithms without a moments hesitation. Solving the cube blindfolded, one can (almost) never correct mistakes, one has to know it’s right.

I’m not going to explain how to solve the cube blindfolded in detail (see the links at the end for further details if someone is really interested, or go directly to Macky’s 3OP guide), but I am going to explain how it works in principle. To start with, solving the cube blindfolded is completely different from solving it sighted. Most sighted methods rely on a step-by-step approach where one can see what’s happening and figure out what needs to be done once a step has been completed. Naturally, such a method would be useless for blindfolded cubing, indeed requiring the kind of superhuman memory and spatial awareness most people would instinctively attach to it.

Instead, blindfolded cubing relies on manipulating as few pieces as possible, meaning that it’s possible to change the state of a couple of pieces and leave the rest of the cube unaffected. This entails that it’s possible to learn the condition of the scrambled cube and then memorise which algorithms need to be applied to turn each piece into its correct state. For permutation (where pieces are located, rather than how they are twisted), the method I used utilises cycles, thus being called 3OP (Three Cycle Orientation Permutation).

This is quite simple. Looking at an edge piece in position 1, one then looks where it needs to go, then where the one in that place needs to go, and so on, until the cycle is complete and back where it started. Thus, permutation of corners and edges can be remembered as two strings of numbers. Applying algorithms, three of these numbers are shifted and removed from the cycle. Continuously doing this will eventually remove all, which means that all pieces are positioned correctly (this isn’t strictly true, but it works as an example).

The biggest problem here is that the algorithms only can be applied under a strict set of rules and only from certain positions. This means that the cuber has to apply a number of set-up moves and then perform the algorithm. And then remember the set-up moves and do them in reverse order. These set-up moves constitutes the true challenge when solving the cube in this way, at least for me.

So, about memory, why doesn’t one have to be a mnemonic wizard to solve the cube blindfolded? This is what a sample memorisation looks like (I still remember it from my first successful solve). It’s not a difficult scramble, but as far as memorisation goes, it’s quite average.

EO: 4 8 5 6
CO: (2 3 4 cw) (6 8) (7 5)
EP: (1 9 6) (2 7 11) (3 12 5 10)
CP: (1 7 2 6 5 8 3)

Learning to memorise this set of numbers is pretty easy, using the right methods. For EO I use a translation from numbers to letters and then create words, so (4 8 5 6) becomes “ruby” and “accommodation”. CO is purely visual, I imagine myself using various colours to paint a room in the fashion the corners should be turned. For EP, I have a noun and a verb associated with each edge piece, so the numbers above become “smurfs flying like superman, landing on an oliphant”, “Santa Claus fires a crossbow at Ronaldo” and “Space police eating on Dart Vader, who explodes”. CP I use the same method as for EO, but combining them to make a story, in this case “a girl is fired by cannon, landing in Chile, which is burning merrily in pink fire”. Remembering this isn’t even hard, but it takes a while to learn how to create mnemonic methods effectively.

Then, one just goes through the various stories, applying the cycles and removing elements as they are solved. When nothing remains, the cube is solved. Scrumptious.

Links
My first post about Rubik’ cube (in Swedish)
My post about breaking one minute(sighted)
3OP as explained by Macky
Blindfold cubing (forum)
Lars Petrus’ method for sighted cubing (the one I use)

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