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

newscientist.com

31–40 of 125 posts

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

#31

Doesn’t this sound like a sneaky way for a mathematician to work on time travel?

Baby steps, first is the roulette table.

> Often dabo girls were specifically instructed by their employers to distract players into losing. A common saying in dabo was "Watch the wheel, not the girl."

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

#32

I've been trying to understand as much of "maths" as I can (now enough to write that in quotes, as there isn't a "single" maths) and still a layman, I love reading about discoveries like these, and the fact that you still can have discoveries in things thought to be so fundamental..

Neat factoid: there is something special about rotations in 3D. They are not "simply-connected", which means that there are 2 distinct classes of rotations. And this property is deeply important in quantum physics.

It's a bit more complicated than "2 classes of rotations", though there is magic indeed. I've tried to explain it in this post https://dandanua.github.io/2021/08/23/the-spin-of-a-human-bo...

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

#33
Quaternion libraries have work to do now.

Positive potential:

Simplified “undo” mechanism: this result suggests that a given traversal (sequence of rotations) might be “reset” (i.e., returned to origin) using a simpler method than computing a full inverse sequence. That could simplify any functionality in libraries, like SpinStep[0], that deal with “returning to base orientation” or “undoing steps.”

The libraries could include a method: given a sequence of quaternion steps that moved from orientation A to orientation B, compute a scale factor λ and then apply that scaled sequence twice to go from B back to A (or A to A). This offers a deterministic “reset” style operation which may be efficient.

Orientation‐graph algorithms: in libraries used in robotics/spatial AI, the ability to reliably reset orientation (even after complex sequences) might enhance reliability of traversal or recovery in systems that might drift or go off‐course.

[0] https://github.com/VoxleOne/SpinStep

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

#34

Earlier quoted context omitted.

Neat factoid: there is something special about rotations in 3D. They are not "simply-connected", which means that there are 2 distinct classes of rotations. And this property is deeply important in quantum physics.

It's a bit more complicated than "2 classes of rotations", though there is magic indeed. I've tried to explain it in this post https://dandanua.github.io/2021/08/23/the-spin-of-a-human-bo...

There is also this one, which goes into a lot of detail: https://www.youtube.com/watch?v=b7OIbMCIfs4

Unfortunately this subject is above my pay grade, so I gave up :)

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

#35
post #7

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

Damn, that's beautiful. I hope that Mr. Adams mentiond in the article got a good return from his patent.

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

#37
post #21

For those who struggle with the pay wall: check your local library's (online) membership, it might come with the worldwide library card, which might include the New Scientist magazine. Mine does, and therefore I can "borrow" (read for free) articles that make it to the mag.

In this case we can just wave bye-bye to the magazine and head to the freely available Arxiv paper they are writing about.

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

#38
post #7

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

What?! Thank you! I'm working on a robot with a very expensive slip ring, and need to send high fidelity data through it with shielding. I had no idea this was possible this will make things so much easier! I found a related video you might find interesting. https://www.youtube.com/watch?v=gZvimEf6DFw I'm currently studying group theory and SO3 rotations (quaternions & matrix groups) and I'm also curious about the co…

I see it, yet I can barely believe it.

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

#39
post #7

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

What?! Thank you! I'm working on a robot with a very expensive slip ring, and need to send high fidelity data through it with shielding. I had no idea this was possible this will make things so much easier! I found a related video you might find interesting. https://www.youtube.com/watch?v=gZvimEf6DFw I'm currently studying group theory and SO3 rotations (quaternions & matrix groups) and I'm also curious about the co…

Always happy to share! I came across this while planning a 3D scanning (photogrammetry) rig. Perhaps you'll be the one to figure out gravity can be modelled as a rotation around an axis in a fourth dimension, wrapping clingy spacetime around itself? ;) I'm not clever enough for that.

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

#40
post #21

For those who struggle with the pay wall: check your local library's (online) membership, it might come with the worldwide library card, which might include the New Scientist magazine. Mine does, and therefore I can "borrow" (read for free) articles that make it to the mag.

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