Name: なぜ「ルービックキューブを3秒未満でそろえること」は不可能なのか | Almost Impossible | WIRED.jp
Uploaded: 2022-10-12T18:00:22.000Z
Duration: 14 min 58 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

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most people are familiar with the Rubik's cube, but very few of them have actually solved it.

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And that's because if you don't know the moves the Rubik's cube is one of the most difficult mainstream puzzles ever created frankly.

A lot of that has to do with the fact that there are literally billions of billions of ways to scramble this thing.

But what's equally incredible is that with a few weeks of dedicated practice and a little bit of memorization, most people can learn to solve any of those scrambles in a few minutes, but there are some people who can solve it even faster a lot faster.

They're called speed cubers and the best of them can whip a Rubik's cube into shape in well under 10 seconds.

The single fastest solve ever recorded in competition is a ludicrous 3.47 seconds.

But could that time go down today, we're going to look at why solving a Rubik's cube in under three seconds is almost impossible to find out what it takes.

I spoke to a world record holder got a crash course in technique from some local speed cubers.

Now the problem here is you notice that things here on the edge don't match the problem here is that I don't even see that that's a problem here and talked about the mind boggling math behind the cube with a computer scientist, there are more positions on the Rubik's cube than there are grains of sand on all your speeches.

The Rubik's Cube was invented by Hungarian architect Erno Rubik in 1974.

It actually started out as an experiment, Rubik wanted to know if it was possible to design a cube made of smaller blocks that can move independently without falling apart.

It was only later that he realized he also created a puzzle And that puzzle got very popular.

It wasn't long before people were competing to see who could solve it fastest.

At the first World Rubik's Cube Championships in 1982, competitors took up to a minute to solve the Cube, but speed solvers like world record holder Felix's MDX have been chipping away at those times ever since almost 100 competitions all around the world, broken a bunch of world records and won a bunch of world championships.

One round in competition consists of five solve attempts.

A computer randomly generates the scrambles to make sure they're difficult enough and each competitor solves the same five scrambles You get asked, are you ready?

They'll take off the cover and then you have up to 15 seconds to look at the Cube and start the timer.

Then you have to place your hands down on the timer and then stole the Cube and then return your hands to like the stack.

Now is probably a good place to mention that Diehard cubers actually care more about average times than single solves fact is sometimes you just get a lucky scramble, a better test of a speed cubers skill is to have them solve five cubes and average the three middle times.

Xem Dags currently holds the average solve record of 5.69 seconds But single solve times still matter.

And Zendaya is used to hold that record too with a time of 4.22 seconds.

That was until Chinese speed Cuba Yusheng du demolished it last fall with a time of 3.47 seconds.

So how unexpected was it for somebody to come along and break your single solve record by like three quarters of a second.

Like in in speed cubing you don't often see those sorts of insane jumps in time, You can still get like a really incredibly quick solve just on one attempt if you have an easy scramble and a bit of luck and it just so happened that you know there's so many people going to so many competitions all the time that something like this was probably bound to happen but we didn't really expect it that soon.

Okay, so let's put speed cubing aside for a second because a lot of people myself included have never solved the Rubik's cube at all in any amount of and that's because truly solving one, like from scratch without any help from anybody without watching any online tutorial videos, it's really, really hard.

The truth is if you see somebody solving a Rubik's cube, they are almost definitely using a memorized sequence of moves to do it.

This is Tyson Mao, he's a co founder of the World cube Association and I asked him to teach me the basics.

I would say there are probably three things to think about in terms of what makes someone fast at solving the cube.

There are many methods for solving a cube but they all rely on something the Cubans call algorithms memorized sequences of moves that players use to solve the cube section by section.

Now, as a rule of thumb, the more algorithms, you know, the fewer moves, you'll need to solve the cube.

A beginner who has committed fewer than 10 algorithms to memory might solve a Cuban, say 100 and 20 moves.

While an expert who has memorized hundreds of algorithms can solve the Cuban closer to 50 or 60 moves and as you might expect fewer moves can translate to faster solves the second thing that contributes to you know, how long it takes to solve the cube is how fast you can turn to cube.

The fastest speed cubers in the world average around 10 turns per second over the course of an entire solve and a lot more than that in short bursts take this 16 move finishing sequence for example, it looks like this 1234 with this ring finger 5678.

And now you gotta push back with this ring finger 9 10 11, 12, pull 13 14, 15, 16, push The top people can execute those 16 moves in under one second.

The third thing that contributes to how long it takes to solve the Cube is, how long it takes you to process the information.

It doesn't help you if it takes you five seconds to figure out what the next step is.

Your goal is to try to look ahead and see what the moves for the next step are while you're doing the current one and reducing the pause between those steps.

As you can see there are lots of different types of three by three cubes from the old school version which was clunky stiff and hard to turn to fancy new models that spin with ease and include tiny magnets to help the faces snap into position.

The actual hardware itself has evolved to the point now where it's like, it's really, really good.

Like if you give me a cube from five years ago, it's probably taking off like a second off myself time.

If you're going to be a good cuba back in the day, you have to learn how to make, you have to learn how to prepare a cube and make it good.

And so that would involve is you take the cube apart.

You know if there are imperfections, you might send some of those things down.

You lubricate it with some silicone, let it dry, put it back together, re sticker, you know adjust the tension on the screws.

It was, it was a big effort over time as more manufacturers entered the space um cubes just got a lot better in quality.

Um so the kids these days they don't know how good they have it.

Like the improvement in the cube technology has caused a change in some of these economics that move that I showed you earlier.

There was absolutely no way you could make a turn with this fourth ring finger the way that people turn the key And the you know the hand movements that people use evolved as a result of cubes getting better.

So now taught me a method for solving the cube that he shows the beginners following his instructions.

It took me 45 minutes to solve the Cube for my very first time.

What I think if you spent the next two weeks on this you probably get your time down to about 90 seconds, 90 seconds.

Okay, I'm gonna try To get to a point where I can solve the Cube consistently using the Method Tyson has given me today in under 90 seconds and we'll see how just that actually.

So I took my new cube and got to practicing in the first few days I went from needing around 20 minutes to solve the cube to just under three.

Not bad for a newbie but that's still an eternity for someone like Tiffany Chen a local speed cuba who averages just under 10 seconds per solve.

She can solve a cube blindfolded and one handed just solved a Rubik's cube with one hand More than three times faster than I can solve it with two when you pick up a cube you don't look the way I look when I pick up a cube which is like it's manic.

My hands can definitely move faster than like my brain can during the solve so it's limited not by how fast my hands can move than like what my brain can see when my eyes can see.

So are you exercising that kind of restraint throughout the entirety of the solve?

So my strategy in competition is definitely to like solve it as smoothly as possible like with no pauses uh because I find that if I try to turn quickly when I'm nervous I'll turn very poorly.

I had her critique my solving, I'm gonna mess up real bad.

Oh no damn that's a slow 11 minute 41 seconds I'm ashamed.

Okay so do you have any tips based on that for starters?

She said I should try opening with a more efficient.

Move the second tip is more general for the entire self.

I noticed that you spend a lot of time like turning the whole cube around or like using your whole hand to turn the cube around.

So like during while you're doing the second layer you see the piece over here so you go like this or something but you can see pieces that are like on the other side of the cube.

So you shouldn't need to do so many rotations of the whole cube.

So given what we've learned about speed cubing, what is the lower limit, How fast can we go to figure that out?

It helps to understand some of the math behind the cube.

And for that we turn to computer scientist tom Ricky.

There's 43 billion billion positions which is 43 quintillion right?

Rocky has been fascinated with the cube ever since he was a kid and around the turn of the millennium he started puzzling over one of the great unanswered questions of the cube.

This is a little confusing at first but stick with me Of those 43 quintillion configurations.

There are some of them like this that are very easy to solve.

If I handed you the Cuban the state, you know that it takes just one move to resolve it but most of the scrambles on the cube are a lot more complicated than that.

So the question Rocky wanted to answer was this, what is the maximum number of moves that would ever be required to solve the cube no matter how scrambled it is mathematicians call that figure God's number.

And it went unknown for more than 30 years until Rocky and his colleagues figured it out.

We used um a really fast program with all sorts of clever tricks let us solve about a billion positions a second and then we used a billion seconds of computer time.

And really it is except for if you've got thousands of computers, it's a lot less.

So what is God's number when it comes to the Rubik's cube 20 No matter how complicated the scramble gets, you're never more than 20 moves away from being completely solved and it's usually less than that.

Almost all positions require fewer than 20 moves 18 is the most common.

So your typical scramble you're going to get from your timer is going to take 18 moves to solve optimally.

Now you'll remember that the fastest speed cubers on Earth average about 10 turns of the cube per second If you divide God's number which remember is never more than 20 by 10 turns per second and you get solved times of under two seconds and look here's proof that it is physically possible to solve one in that time.