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Henry Segerman
United States
Приєднався 21 жов 2006
Mathematical making: 3D printing, dice, virtual reality, generative art, etc. Also see www.segerman.org, @henryseg
Wild knots
A video about some infinitely complicated, fractal knots.
The paper by Ralph Fox is:
"A remarkable simple closed curve", Ann. of Math., (2) 50, 264-265.
www.jstor.org/stable/1969450
Hsin-Po Wang ( symbolone1) came up with this awesome animation of undoing the wild slipknot (which is, of course, impossible):
www.desmos.com/3d/ng4mkltbi3
Wild knot:
Shapeways - shpws.me/TL3p
Printables - www.printables.com/model/889143-wild-knot
Wild slipknot:
Shapeways - shpws.me/TL3q
Printables - www.printables.com/model/889700-wild-slipknot
Background music by Quiet Bison:
open.spotify.com/artist/5PmmaiHnrygDvhj3kaPT0f
quietbison
The Achilles image is from en.wikipedia.org/wiki/Achilles#/media/File:Achilles_fighting_against_Memnon_Leiden_Rijksmuseum_voor_Oudheden.jpg
The paper by Ralph Fox is:
"A remarkable simple closed curve", Ann. of Math., (2) 50, 264-265.
www.jstor.org/stable/1969450
Hsin-Po Wang ( symbolone1) came up with this awesome animation of undoing the wild slipknot (which is, of course, impossible):
www.desmos.com/3d/ng4mkltbi3
Wild knot:
Shapeways - shpws.me/TL3p
Printables - www.printables.com/model/889143-wild-knot
Wild slipknot:
Shapeways - shpws.me/TL3q
Printables - www.printables.com/model/889700-wild-slipknot
Background music by Quiet Bison:
open.spotify.com/artist/5PmmaiHnrygDvhj3kaPT0f
quietbison
The Achilles image is from en.wikipedia.org/wiki/Achilles#/media/File:Achilles_fighting_against_Memnon_Leiden_Rijksmuseum_voor_Oudheden.jpg
Переглядів: 66 421
Відео
Symmetry and gears: Six axis racks
Переглядів 200 тис.4 місяці тому
A kinetic sculpture in which 12 sticks with 24 racks interact with 12 gears. Print one yourself: www.printables.com/model/736088-six-axis-racks Print the diagonal racks demo: www.printables.com/model/736078-diagonal-racks-demo
Real-life fractal tree zoom
Переглядів 89 тис.6 місяців тому
3D print supplied by JLC3DP. Check them out at jlc3dp.com/?from=henry to let them know you came from my video. Fractal Tree No. 2, by Robert Fathauer. www.robertfathauer.com/FractalTree2.html Copyright 2007 Robert Fathauer, used with permission. 3D file (good luck printing this on a filament based printer!): www.printables.com/model/688795-fractal-tree 00:00 Trees and fractals 00:43 Robert Fath...
Slide-glide cyclides
Переглядів 218 тис.7 місяців тому
3D printing files: www.printables.com/model/651714-slide-glide-cyclides Mathologer video: ua-cam.com/video/5q_sfXY-va8/v-deo.html Andrew Kepert's playlist on lunes and cyclides: ua-cam.com/play/PL9JP5WCX_XJY9GmMO-kotRR5bRYOPOtn9.html
Recursive racks
Переглядів 1000 тис.10 місяців тому
An expanding recursive mechanism, plus some variants. You can download the files to print these mechanism for yourself from www.printables.com/model/557760-recursive-racks
Using topology to close a rubber band bracelet
Переглядів 480 тис.11 місяців тому
With Sabetta Matsumoto and Saul Schleimer. It seems impossible, but you can make a giant loop out of lots of little (not very stretchy) loops. So you can wrap a broken suitcase using hair ties, without any cutting or knotting. Or you can finish off a rubber band bracelet without using a clip and, again, without any cutting or tying knots. We explain the problem, the solution, and some of the ma...
Lost in the Multiverse Library with @TomRocksMaths
Переглядів 10 тис.Рік тому
Tom from @TomRocksMaths and I get lost in a four-fold branched cover of the library at St Edmund's Hall, Oxford. Tom and I also made an explanation video describing what's going on - you can see it over on Tom's channel at ua-cam.com/video/32iMuqq4MI4/v-deo.html
The Ames room optical illusion
Переглядів 57 тис.Рік тому
A version of the Ames room at a scale that works for Lego minifigures. 3D files: www.printables.com/model/491127-ames-room-optical-illusion
Real-life fractal zoom
Переглядів 1,1 млнРік тому
Making a real-life fractal zoom. Follow-up video in which I also pull focus!: ua-cam.com/video/uH8w7I1Og1I/v-deo.html Feliks Konczakowski's work: konczakowski.tumblr.com/ My project with Paul-Olivier Dehaye: www.segerman.org/printgallery/ (Bart de Smit turned our logarithmic image into the looping video.) The 3d print is available to buy from shpws.me/Ttp5 The file is available to download from...
Screw/screw gearing
Переглядів 1,7 млнРік тому
Exploring gears with different kinds of motion. You can buy a copy of the screw/screw gearing model from Shapeways at shpws.me/Ts69 You can also try printing out your own. You can download the files from www.printables.com/model/519173-screwscrew-gearing
Geared cube net
Переглядів 111 тис.Рік тому
Available from shpws.me/TqA2 Joint work with Sabetta Matsumoto.
Knotty Analog Oscilloscope Art
Переглядів 32 тис.Рік тому
Matthias Goerner shows me his oscilloscope-generated knot art, made entirely by analog means. Our discussion about what "analog" means: ua-cam.com/video/j2YCGE7FXj8/v-deo.html Circuit diagrams: unhyperbolic.org/knotifier.html 0:00 Intro 3:14 What is knotty analog oscilloscope art? 7:00 Oscilloscope as Etch-A-Sketch 8:43 Integrator 10:24 Drawing a circle 14:17 Spirographs 16:39 Drawing a torus k...
Cannon-Thurston maps: naturally occurring space-filling curves
Переглядів 211 тис.Рік тому
Cannon-Thurston maps: naturally occurring space-filling curves
Why don't Rubik's cubes fall apart?
Переглядів 191 тис.2 роки тому
Why don't Rubik's cubes fall apart?
the string knots wouldnt get smaller and smaller because the string was thick on one end and thin on the other, if you made the string the same thickness it would not change size. the intro video is an illusion displaying false facts. if the knot itself were to keep getting smaller it would not be infinite, the smallest knot is dictated by the strings thickness, once there is no more space between the string it cannot continue unless the string ALSO gets infinitely thinner. that was a horrible fake example. there are no knots that infinitely get smaller unless youre using an infinitely small string. which by its own logic cant even exist.
In mathematical knot theory, knots are simple closed curves in space. They are infinitely thin. This is, of course, different from knots in real life.
Please make more of these
Just shake the slip knot to untie it
Isn’t the Universe wonderful!
The more point-like the light source the less fuzzy will be the edge regions.
This video feels like is a movie long and is boring but very interesting
Like fr 😑
Well done. ❤
This is brilliant. Thank you for making this video about Impossible triangles!
it’s SO COOL
And to think... I spent my weekend trying to get a perfect swirl of Easy-Cheez on a Triscuit.
i feel like this is more a demonstration of the limits of the definitions used and how they're applied, rather than proving that the infinite knot is not the unknot.
I understood everything until he said "This knot is wild"
Glass/transparent paterial or maybe strings?
someone should make a clear D120 and fill it almost full with water, the little air bubble at the top would make it easier to tell what you rolled
Harmonic relationships came to mind, particularly those involving ratios of small integers.
Very cool, and pretty too. Almost looks as if it's squishing, until you look more closely.
I instantly recognized the cube tree pattern. I've been playing with variations that imply a Sierpinski Triangle (what I call a ternary cube tree). In fact, I have a new one that I've been putting many hours into. I should be posting vids (on top of the ones I've already posted) within a couple of weeks, if I can just stop tweaking the damn things.
My ternary cube tree is one that I came up with on my own with no prior hinting that such a thing was possible. That means the date of my first posting, May 24, 2015, means the concept is at least 9-years old (ua-cam.com/video/8djZV2wtMXg/v-deo.htmlsi=3ssx9b_hVoS1MfgE, with a claim that I came up with it in 2012). Though, I wouldn't be at all surprised if something out there pre-dates this. What I would be most interested to find out is if anyone came up with the Sierpinski Triangle slice before me (which has some interesting variations, ua-cam.com/users/shortsVzwvcMIDKjI?si=lYS-CdvBVWwi27HL).
Crap, now you've got me thinking whether I can get a smooth zoom in the one's I've done most recently with the video game, Sauerbraten (yet to be posted). Something tells me that I won't get a really clean zoom, particularly with you're finding that zoom speed is a big deal, and the video game only has constant speed. Won't free me from thinking about it though.
Hi, Henry! Where did you get those magnetic rope ends? Or did you make them? Thanks!
I made them myself years ago. I found that one neodymium paired with one regular magnet together had the right amount of force.
Imagine seeing tgis on a 3 veiw with no isometric
Looking at any one "major" site, having 6 heighbors. It's like spherical packing, but of wavefronts on the surface of the sphere. What is the frequency of the primary oscillations with respect to n? Edited: Mod 3, I see now
I just received my set of OptiDice, which inspired me to check how numerically balanced the rest of my dice were. I was shocked how other than OptiDice, every dice set has 5-8 on the same side of the d8 and 7-12 on the same side of the d12. And a few sets didn't even make sure opposite sides added to 9 or 13 (respectively)! Numerical balancing needs to become the standard.
I think if we stop naming things after people, that does more harm than good. The core problem is the naming bias, not the practice itself. Trying to give names like the "length-angle invariant" will inevitably become ambiguous when additional such invariants are discovered, and they'll also invariably lead to proliferation of acronyms, which suck. I'm also not a believer that the person's name necessarily always needs to be the very first person who discovered a concept. If someone else did important work studying, expanding, or popularizing it, that can be as important as the initial discovery.
All the idiots that were fooled into thinking the flat planes were icosahedra…
so youre like a fractal expert? cooooool
Genetically superior d4
One thing that jumped out to me is the difference between infinite processes and infinite states. 0.9... is 1 because it's not an infinite process of something writing the number 9 on end, merely approaching 1, but every single infinite 9 is already present. However, the issue with the infinite slip knot is you can't undo all of it at once. You have to undo one slip before you can undo the next. IDK if that is actually accurate, but is one of the ways I parse infinities
this is so fascinating
A bit flat, so no intuition gained on how the wild slipknot might not pull out (or require an ordered complement.)
is there a model where lengths aren't distorted (regardless of angles)
i liked this vid and its niche but versatile concept. the music was a little distracting for me. I can tell its intended implemented was to be non-distracting, so i thought this feedback might be helpful. not subscribed but looking forward to the next niche concept!
Has anyone tried to make 4 dimensional Archimedian solids?
As someone who doesn't understand group theory at all, I love the idea that group theory links so many totally disparate concepts. Does this mean you can create a knot that retains the symmetry operations of each of the 219 space groups for 3d crystals?
A super high mathematician playing with yarn: "Yo man... what if the knots were like.. infinite? That would be WILD"
After a point it all started to go over my head, but this was still a super interesting video. My non-mathematician brain enjoyed the 3D models and the colours 😁👌
The thumbnail looks like a weird daisy chain.
I'm guessing they say "zero" at your lab and not "naught"? knot.
This is such a lovely and concise video. Thank you! :D
Robin Houston saw this video and thought, "I could do better."
I'm fairly sure that almost no mathematics is done by dead white men. Well, who knows, maybe there is an afterlife where mathematicians carry on their research for eternity. But they don't tend to share their results with the living.
does that mean that crocheted items are wild knots? have i been working with wild knots?
00:11 that was the most seamless transition to animation ever seen.
5:32 Quite remarkable/mind blowing
math is diabolical lmao
Is it possible to construct an infinite slipknot of finite length? Perhaps if each cell was half the length of string compared to the previous, for example. Then isn't there an analog to Zeno's paradox wherein pulling on the string at a fixed rate for a finite amount of time will undo each successive cell in half the time of the previous, untying the knot in finite time?
Yes, it is possible to construct an infinite slipknot of finite length. (The example in the video has this property, but that is not emphasised here.) No, it is not possible to perform a "ambient" isotopy, even by undoing the next cell in half the time of the previous. This is because the fundamental group of the wild knot's complement is not the same as the fundamental group of the unknot's complement. EDIT: Here is another answer. Look at the string held by Henry at timestamp 8:47. Pretend that it is made of rubber and can stretch. He holds on to the string and you preform the supertask - you undo the k^th "bite" of the slipknot in time interval [1/2^{k+1}, 1/2^k]. If you draw the pictures, you'll find that there are 2^k points of the rubbery string that are now distance 1/2^k (say) from the wild point. So, in the limit, there are infinitely many points of the rubbery string in contact with the wild point. But an ambient isotopy can't do that...
Wild knots uwu
Funny thing being "Dehn" is German for stretchinf. So "Dehn invariance" sounds like invariance under stretching
Woof, so sorry I missed this video until Matt Parker's video today!