@henryseg@mathstodon.xyz
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henryseg

@henryseg@mathstodon.xyz

Mathematician working mostly in three-dimensional geometry and topology, and mathematical maker/artist working mostly in 3D printing and virtual reality.
#Math #Maths #Art #3DPrinting #Geometry

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henryseg, to random
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Peaucellier–Lipkin linkage, made by my brother Will and me.

A 3D printed linkage draws a straight line with a pencil.

henryseg, to random
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New video with @sabetta and @saulsch: You can make a chain out of hair ties (or rubber bands) in lots of different ways. But how do you close it up to make a bracelet, again using only hair ties?
https://youtu.be/Cyhqc8l03GE

henryseg, to random
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Is anyone familiar with straight line mechanisms? (https://en.wikipedia.org/wiki/Straight-line_mechanism) The problem is to construct a linkage that converts rotation into linear motion. Unless I'm missing something, this is also a solution?

video/mp4

henryseg,
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@Vergo Ah yeah I think that's it! I don't see an easy way to fix it.

henryseg, to random
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@gregeganSF goes through most of a first year graduate topology course in this webpage describing his short story DIDICOSM: https://mathstodon.xyz/@gregeganSF/110586662122965493

Ianagol, to random

Preprint posted to the arxiv “Chainmail links and L-spaces”

https://arxiv.org/abs/2306.10918

A chainmail link is what it sounds like, a link made out of circles (actually the links considered in the paper can’t always be made of round circles, such as the Borromean rings, but ones with round projections to the plane).

image/png

henryseg,
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@Ianagol But none of these great pictures of chainmail are in your arxiv paper?

MotivicKyle, to random
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In love with this gif of the free modular lattice on 3 generators. (Attributed to Jesse McKeown at https://blogs.ams.org/visualinsight/2016/01/01/free-modular-lattice-on-3-generators/.)

Rotating gif animation of the free modular lattice on 3 generators.

henryseg,
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@MotivicKyle @caten Yeah, particularly if you want a metal version for earrings, they can do that as well (they print in wax then cast in various metals).

divbyzero, to random
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Inspired by the pixel puzzle @icecolbeveridge posted yesterday, here's one I made.

Toggle TWO pixels (off to on OR on to off) so that this is a true mathematical statement.

Please don't post the solution without a "content warning."

henryseg,
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@divbyzero @icecolbeveridge This is what I thought the other problem was about!

masonporter, to random
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PSA for almost 100% of professors (including the ones who are very famous for their research) at research-intensive institutions: Our mentorship and training of junior people matters orders-of-magnitude more than any of our research ever will.

henryseg,
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@masonporter Training them to produce more research? Or training them to mentor more junior people to…

henryseg, to random
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Premiering on YouTube in about 5 hours, Tom Crawford (of TomRocksMaths) and I get lost in a branched cover of the library at St Edmund’s Hall, Oxford.

https://youtu.be/f8C8hlAmdVc

Henry rolls a football on a table towards a “branch point”. The football magically splits into two footballs on passing through the branch point.

henryseg,
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Tom and I also made an explanation video describing what's going on. You can see it over at Tom's channel at https://youtu.be/32iMuqq4MI4

henryseg,
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@standupmaths @bornach After the four years since I took the footage, I’m not exactly sure now where the original version is. Well, I’ve probably got it on a hard drive at home but I’m now on the road for a month or so.

henryseg, to random
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Juggling on a torus - playing with a green screen with @sabetta, Rémi Coulon, and Steve Trettel.

Henry drops a ball from his hand - it falls off the bottom of the screen and back on the top, where he catches it. He then throws the ball to the left - it wraps around and he catches it coming in from the right.

henryseg, to random
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Why is blue bigger than red?

Video: https://youtu.be/Sbt-iFm0zTA

henryseg,
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Here’s an animation showing the trickery. Full video at:
https://youtu.be/Sbt-iFm0zTA

Two Lego space explorers, investigating a strange spacial anomaly (The Ames room optical illusion).

henryseg,
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Behind the scenes shot of the blue Lego space explorer being dragged away by a robot snake. Even seeing the second view and knowing what the shape of the room really is, when I look at the view from the first camera my brain tells me that blue is shrinking!
Full video at:
youtu.be/Sbt-iFm0zTA

video/mp4

csk, to random
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I created an interesting new (free, web-based) puzzle app for mobile devices (works best on iPads, less-well-to-not-at-all on other devices). Want to try some challenging puzzles that blend spatial reasoning and manual dexterity? Just Slide to Unlock! https://slide.isohedral.ca/

henryseg,
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The last two-player level, but played with three people (@stevejtrettel did all the work, @sabetta and I supplied fingers.)

Playing "slide to open" with three people, one controlling a lazy susan on which the iPad is sitting.

andrewt, to random
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I feel like managed to make Breath of the Wild's most annoying feature much more palatable by actually making it even more pronounced — it's hard to care that your weapons keep breaking when every weapon in the game is already garbage.

Nintendo wanted the weapons to feel disposable and now they truly do.

henryseg,
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@andrewt Mask of the Majora.

henryseg, to random
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I added a laser to my real-life fractal zoom. If the line goes through the top of the fractal it matches up with itself around the loop.
Full video at https://youtu.be/S1kpqOqSttA.

Zooming into a 3d printed fractal. A line of laser light shines on one side of the fractal.

henryseg,
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With the lights down low you can see the diffusion of the laser better.

video/mp4

henryseg, to random
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Real-life fractal zoom with added rotation! With the extra degree of freedom in the system, the feedback control code got quite a bit more complicated (I'm not sure how much the extra complexity helped).
Full video at https://youtu.be/S1kpqOqSttA

A camera moves towards a spinning 3D printed fractal, slowing down exponentially so that the view from the camera forms a looping video.

henryseg, to random
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A real-life fractal zoom, made with 3d printing and motion control photography. Full video at https://youtu.be/S1kpqOqSttA

henryseg,
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@jason Thanks Jason!

I could get sharp focus when close, but then I'd be out of focus when far away. I could have looked into automated focus control (Edelkrone sell one: https://edelkrone.com/products/focus-zoom-module-for-headplus) but it seemed like a lot of expense for not much gain.

I could also do multiple runs with the camera focused differently, but then I'd have more transitions to manage and I wouldn't be able to play with the laser across the transition.

And if I did get things in focus when close I think it wouldn't look much better - the near and far views will still look different just because you can see the difference in detail of the 3d print.

henryseg, to random
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The community is starting up a monthly seminar series, starting on May 12th with @saulsch speaking about “Illustrating Geometry (and Topology)”. Details at https://illustratingmath.org/node/42

henryseg,
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Now with a more human-readable link!: https://illustratingmath.org/seminars

henryseg,
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@isomorphismes Here’s a (temporary) link to the discord server: https://discord.gg/C9Av4uhF

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