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What's a low effort, but impressive, party trick to learn?
(lemmy.blahaj.zone)
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this post was submitted on 03 Aug 2023
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If you can solve a Rubik's cube, normal people will think you are a genius. On the other hand, actual cubers correctly assess that I am a dumbass if they see me do it.
Right? I can solve one in a minute to minute and a half. By normal people standards, impressive, by cyber standards I'm laughably slow.
I'm cool with that
To be fair, this is how most skills are in the internet era. It makes it way too easy to feel like you're not good enough just because it's so easy to find content from highly talented people.
OP here. In this case, I also just don't give enough of a rat's ass to learn to do it a better way, even though I probably could. I can solve a Rubik's cube reliably in a few minutes, as far as I can tell that's peak ROI for this form of toy proficiency.
I've learned how to solve in 3 minutes or less since the Reddit blackout protests. I have a friend who said his personal best was a minute and 10 so that's my target, and my personal best is a minute and a half as of last night.
It's not 3.1 seconds like the WR but since nearly everyone I have come across in the last couple months can't solve a cube at all, I'm quite impressive to them.
I sit and solve my cube on my break at work, it's literally to stop me spending all my time on my phone. It's a newish job so now everyone thinks I'm quite intelligent, which is nice.
I know exactly one party trick based on mathematical group theory, which I have actually used to impress non-mathematicians at a party.
There's a concept called the "center" of a "group", which is the set of operations that commute with every other operation in the group. The center always contains the identity operation of doing nothing. The group of scramblings of a Rubik's cube happens to contain exactly two elements in its center: the identity, and a move called the "superflip" which takes a little bit of effort to memorize how to do, but it's not so hard. Much easier than actually solving a scrambled Rubik's cube. It's like you do a simple move repeated 4x, and then you do that whole 4x set 3x with some rotations in between. Not terribly complicated. Importantly, once you memorize it it's not difficult to do just by feel, since it's a fixed sequence of mechanical motions.
So, the party trick goes like this:
You have a Rubik's cube that is exactly a superflip away from the solved state. You hand it to an unsuspecting party guest and say "go ahead and make one or two turns" (it's important to say something like "one or two" because if they do 3 the trick becomes challenging, and if they do 4 or more it might become impossibly difficult unless you're actually good at solving Rubik's cubes, which I am not). They take this obviously unsolved cube and make a couple more moves so now it appears even more scrambled.
You take the cube back and do the superflip behind your back, without looking at the cube.
Then you move the cube out from behind your back, and at the same time (trying to be slick about it) you undo the one or two moves remaining before it is solved. Everyone gasps and say "omg he solved it behind his back" (when really you did no such thing).
This works because if S is the superflip and X is the simple moves they did to it, S X S is equal to just X because S commutes with everything. (S is also its own inverse, so that S S = 1.)
Damn, that's neat. I might have to practice that.
Clearly, we just need more group-based popular toys. I would definitely buy a monster group cube, and then probably get crushed by it falling over on me (how many generators does that thing need, anyway?).
https://mathoverflow.net/questions/142205/presentation-of-the-monster-group mentions a presentation of the monster with 12 generators.
Creating a physical rotation puzzle that implements the monster group would be quite a task!
Wow, that's a lot less than I thought. I'm just noticing now there's also a (giant, terrible) 2-generator representation mentioned in the wiki. It's always cool how simple these huge structures can turn out to be.
I learned how to do it purely to get free food at a restaurant. The idiot proof method takes about a day to learn and a bit longer to do reliably. Recommended!
Learning to solve a Rubik's cube isn't exactly "low effort".
Believe it or not, it's actually not that hard unless you're trying to figure it out yourself, and once you can solve a couple you can solve them all. It's mostly muscle memory, and I think it took me a week to get it down. Not a week of work time, a calendar week.