Me too. I was given a Rubik's cube when I was twelve.
I'll let you know when I complete it.
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"There are exactly 43,252,003,274,489,856,000 permutations, which is approximately forty-three quintillion. I hear that there is going to be a 5 cubes per side one soon.
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cant you still buy rubiks cubes?
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I used to complete a Rubik's cube in 50-60 seconds normally. Less than 8 seconds is amazing.
The very first time I did the Rubik's cube was more by chance and it took weeks on and off. Eventually had a system.
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The fastest was actually 7.31 seconds. The fastest for the overall winner was 7.36 seconds. But what's 5 hundreds.
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>> I used to complete a Rubik's cube in 50-60 seconds normally
About 20 seconds quicker than me then.
A few times lately I've been to pick my daughter up from various friends' houses and spotted a jumbled Rubik's Cube on a shelf or windowsill whilst talking to the parents. It gives me a little kick to pick it up, idly solve it and put it down again without breaking off the conversation :)
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I've tried a couple of times, but got bored quickly. Never had the interest to figure out how to do it.
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And me too - no attention span.
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When I was referring to completing it in 50-60 seconds I was referring to when I was 10! I could do the Rubik's cube in under 60s then. But this was before I went to comprehensive school (I am not joking) I'd have to figure it out again now I am 42!
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Were you de-skilled in some way at the local Comp ?
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It took me ages. The second time was quicker, but still ages. I could see that by training, the memory partly, one could imrove still further, but at that point lost interest.
An ingenious do-nothing invention. Must have made some big, big bread for a few people. Mr Rubik among them one would hope.
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>> There are exactly 43,252,003,274,489,856,000 permutations....
I'm reasonably confident that figure is wrong, as you can't have any part of the cube in any position on the cube:
the 8 corners are only ever corners, but can move with respect to one another, and be wrong orientation with respect to the centres (wrong corner colour facing the centre piece).
the 6 centres are always centres and never move with respect to one another as they are the "spider" that holds the thing together.
as memory serves that leaves 12 pieces which live directly between two corners.
If you want to wind a "solver" up, you can take one piece out and turn it through 180 degrees and put it back in and the cube can't be "solved".
It took me weeks to work out how to solve one in the 1980's, and I still don't understand how the kids do it so quickly.
Last edited by: AnotherJohnH on Tue 30 Jul 13 at 18:39
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I think that number of permutations came from Wikipedia:
The original (3×3×3) Rubik's Cube has eight corners and twelve edges. There are 8! (40,320) ways to arrange the corner cubes. Seven can be oriented independently, and the orientation of the eighth depends on the preceding seven, giving 37 (2,187) possibilities. There are 12!/2 (239,500,800) ways to arrange the edges, since an even permutation of the corners implies an even permutation of the edges as well. (When arrangements of centres are also permitted, as described below, the rule is that the combined arrangement of corners, edges, and centres must be an even permutation.) Eleven edges can be flipped independently, with the flip of the twelfth depending on the preceding ones, giving 211 (2,048) possibilities.
So that is then:
8! x 38 x (12! / 2) x 211 = 43,252,003,274,489,856,000
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Very convincing mathematics, but I contend that you can't get all the combinations without pulling the thing apart and putting it back together in a way which cannot be solved without pulling it apart:
try taking a piece out and putting it back again turned through 180 degrees, then solve it.
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I was just saying how that figure above was derived - not defending it.
Though to prove your theory, someone who can complete a cube might prove you wrong. You might have to mix it up quite a bit to begin with but then you might be able to solve it. One piece rotated couldn't be solved in a few turns - in fact that would be more mixed up a position than random. And maybe unsolveable. I'm not sure I could remember the system I followed to solve any cube... and sometimes I'd have to follow part of my system to get it into a state I could then solve.
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I never got Rubik's Cube.
Why would anyone bother?
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Because it's there.
George Mallory
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>> I never got Rubik's Cube.
>> Why would anyone bother?
There are a few people who enjoy solving problems/puzzles - even if they are pointless.
Last edited by: AnotherJohnH on Tue 30 Jul 13 at 20:04
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>> Though to prove your theory, someone who can complete a cube might prove you wrong.
I don't know if I still can, but I used to be able to solve the (3x3) cube from any position.
Not quickly, maybe 5 or 10 minutes, but solved without dismantling/reassembly.
It took me weeks to compile a set of movements which move specific parts of the cube in a predictable way, and leave all the other bits where they were when I started. Then use those moves to solve a cube.
The only times I've been defeated are when somebody has had a piece out as described up this thread - it's easy to spot as there's just one piece wrong when you "finish", and I can't get one piece wrong by twiddling a known good cube.
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>> Very convincing mathematics, but I contend that you can't get all the combinations without pulling
>> the thing apart and putting it back together in a way which cannot be solved
>> without pulling it apart:
Wiki says:
The preceding figure is limited to permutations that can be reached solely by turning the sides of the cube. If one considers permutations reached through disassembly of the cube, the number becomes twelve times as large:
{8! times 3^8 times 12! times 2^{12}} = 519,024,039,293,878,272,000.
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It also says the maximum number of moves required to solve it is 20 :o
EDIT: as AJH says, that only applies for valid arrangements obtained by twisting the sides
Last edited by: Focusless on Wed 31 Jul 13 at 08:32
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>> >> There are exactly 43,252,003,274,489,856,000 permutations....
>>
>>
>> I'm reasonably confident that figure is wrong, as you can't have any part of the
>> cube in any position on the cube:
Here's what Wikipedia says. en.wikipedia.org/wiki/Rubik's_Cube
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>> Here's what Wikipedia says. en.wikipedia.org/wiki/Rubik's_Cube
Well, I've had a look at that, and it looks like my grasp of the scale of the numbers is wrong - I stand corrected, again.
But, my statement that you can make a cube unsolvable by taking a piece out, turning it, and replacing it is right:
"The preceding figure is limited to permutations that can be reached solely by turning the sides of the cube. If one considers permutations reached through disassembly of the cube, the number becomes twelve times as large... ....which is approximately five hundred and nineteen quintillion possible arrangements of the pieces that make up the Cube, but only one in twelve of these are actually solvable. This is because there is no sequence of moves that will swap a single pair of pieces or rotate a single corner or edge cube. Thus there are twelve possible sets of reachable configurations, sometimes called "universes" or "orbits", into which the Cube can be placed by dismantling and reassembling it."
Edit - wot focusless said.
Last edited by: AnotherJohnH on Wed 31 Jul 13 at 08:31
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>> ............. I hear that there is going to be a 5 cubes per side one soon.
>>
They're already available on Amazon. www.amazon.co.uk/Rubiks-H5-5x5x5-Cube/dp/B0027OCB22
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I did it when it first came out in the early 80's, it took me the best part of a weekend to do but,
Once I'd done it, that was it, I wasn't interested in doing it any faster, I just had to satisfy myself that I could do it.
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There was a couple of lads at school (twins) who could solve it behind their backs. Christ knows how. They'd take one look at the jumbled up cube before starting and off they'd go working blind at it.
Last edited by: VxFan on Tue 30 Jul 13 at 21:21
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>> There was a couple of lads at school (twins) who could solve it behind their
>> backs. Christ knows how. They'd take one look at the jumbled up cube before starting
>> and off they'd go working blind at it.
>>
Perhaps it was a Braille version.
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>> There was a couple of lads at school (twins) who could solve it behind their
>> backs. Christ knows how. They'd take one look at the jumbled up cube before starting
>> and off they'd go working blind at it.
>>
www.yankodesign.com/2010/03/17/color-rubik-cube-for-the-blind/
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I cheated and bought a booklet which explained how to solve the 3x3x3 cube. I had a 4x4x4 cube which I never solved.
Last edited by: L'escargot on Wed 31 Jul 13 at 07:08
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>> I cheated
So did I. I just pulled the thing apart and reassembled it with the correct colours showing on each side.
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>>>> I never got Rubik's Cube.
>>>>
>>>>> Why would anyone bother?
>> There are a few people who enjoy solving problems/puzzles - even if they are pointless.
I've always thought it strange that people would ask why somebody would bother to engage in a given pursuit, be it mountaineering or Rubik's Cubes.
I could understand if the the pursuit was say, moving a 1p coin from one place to the other.
What about improving your golf game, going for a drive in the country, doing a crossword, watching TV, listening to music, reading a book, etc etc
All of those pursuits could be considered pointless, in that they don't create a tangible output.
But people enjoy them nonetheless, they might feel that they are improving themselves (mentally or physically), or challenging themselves, or just purely enjoying them.
Of course, some will like Rubik's cube, and some will hate them but like golf, or hate golf but like TV, crosswords and mountaineering.
But I still find it strange that one person would be dumbfounded as to why somebody might bother to engage in a "pointless" pursuit, when, if they look hard enough, they'd probably find that by the same definition many of their own pursuits are equally "pointless".
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The biggest puzzle I have about these things, not particularly having the mind for it, is what do they look like inside?
I haven't taken one apart and have no idea what's in there, so tried to sketch how the internal mechanism on the new 5x5 one might work. I gave up pretty sharpish.
I expect it's completely obvious to everyone else of course and a one minute sketch is all you need.
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Buy one and break it apart, far more entertaining than using it for its intended purpose.
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7.36 seconds to solve Rubik's cube - Crankcase
