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Mathematicians have found a hidden 'reset button' for undoing rotation

(www.newscientist.com)
184 points mikhael | 1 comments | 16 Oct 25 15:47 UTC | HN request time: 0s | source
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v7n ◴[21 Oct 25 19:12 UTC] No.45660268[source]▶
I was immediately reminded of the anti-twist mechanism, perhaps unrelated but "reset rotation, twice/half" comes up there as well.

https://en.wikipedia.org/wiki/Anti-twister_mechanism

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amelius ◴[22 Oct 25 08:32 UTC] No.45666297[source]▶
Huh, looking just at the link at the top of the box, and forgetting the remainder of the links, this cannot work. I tried it with a flat cable. If you rotate it like that, it becomes twisted.
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1. empiricus ◴[22 Oct 25 11:03 UTC] No.45667328[source]▶
well, if you look at the animation, it surely seems to work, there is no place where it fakes the untwist. I can also replicate that with a belt, but not so smoothly. manually with the belt, the twist from 2 full rotations of the cube are undone by one rotation of the belt around the cube.