Elastic knots are really mind bending

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When you make a mathematical knot using elastic material you get jumping loops and challenging puzzles.
Here's my video about pop-up tents: • Pop-up tents are weird...
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[@SteveMould]

I forgot to say, the puzzle knot by Langer is 9_46 (9 underscore 46). The sponsor is Ground News - give it a try at ground.news/SteveMould. If you sign up through my link you’ll get 40% off the Vantage plan which gives you unlimited access to every Ground News feature. Your subscription directly supports Ground News on their mission to make the media landscape more transparent.

[@jaspyjiindust.9227]

lol your comment was written 18 hours ago according to youtube. but nice video

[@stevendavis3872]

Okay, normally I don't really pay attention to the sponsors, but this one actually has got my attention.

[@conorstewart2214]

@@miil558 what do you even mean by this?

[@jaxelt1]

Interested in how Ground News decides what "factuality" is.

[@zachhoy]

I'm looking for a Langer puzzle knot to buy somewhere online and cannot find one, any tips?

[@Joulespersecond]

"But it's not stable, and if I let it go it ends up touching itself again" feeling personally attacked by this

[@amytysoe2292]

we're right back to matt parker's 'you can't just show up and start cranking it'

[@MacroAggressor]

Marvin the Martian strikes again!

[@TazwaarAhmed09]

i was about to comment the same 💀

[@aalhard]

Remember Marvin!

[@v_lad8559]

“Marvin the Marion”

[@SamuelLewis-wf7uf]

"Marvin the Martian" LOL

[@mblend27]

But with 3 feet 😜

[@JackFate76]

That’s what I’m calling it from now on.

[@dr.kraemer]

@@mblend27 "It does still have a Marvin, though." (6:35)

[@dr.kraemer]

@@JackFate76 that's one way to preserve a single lifestyle.

[@fxbear]

It’s a testament to my mind that I saw something else

[@Bagpipebrad]

9:15 "... but it's knot."

[@pier-lucgaranddion1527]

Look at his eyes. He knew lol.

[@no0ne000]

But are quarks?

[@Propherex]

I wanted to write this!

[@jonslg240]

When you study things like knot theory too long you end up looking like the "cat guy" ("Jizzlord" 😂) from Extraordinary

[@clnrrr]

I was always fascinated by these when trying to pack my "2 seconds" tent at the end of a festival. Turns out, the time you save when it "assembles itself", you really invest at the end, learning how it will go back in its bag

[@engrenage]

did you know there are actually a different number of "modes" (somehow like a vibrating spring in an instrument) to fold them? I found it by "mistake" the first time I folded my tent, finding out it was much smaller than expected.

[@Kufunninapuh]

In 2010 (if memory serves me right) there was a sale on these kind of tents just before a festival in Sweden called Emmaboda. They were one person tents roughly the cost of a fast food meal or ten of the cheaper available cans of beer at the time. I wish this was a story about how an alternative economy emerged now that I expressed it that way but the point is they were so cheap that there were littery thousands left behind the last day of the festival. It looked a little bit like the aftermath of a hostile alien invasion.

[@engrenage]

@@Kufunninapuh unfortunately, a lot of people who buy this sort of tent (and leave them there) don't even know how to setup a normal tent, let alone pack a 2-second tent. maybe there should be some sort of permit to buy stuff like that.

[@mmilerngruppe]

I am ending up with buying a new one every time.

[@UncleKennysPlace]

Reminds me of how I unwrap new bandsaw blades, which come in overlapping loops: I remove the ties, and toss is across the shop.

[@VinayVarsani]

The only safe way to unpack it is to yeet it😂

[@Vmarracing]

The fun part is wrapping up the old ones in the same overlapping loops. Pretty terrifying, but ultimately satisfying.

[@merendell]

Thats because if you dont yeet the blade across the shop it will yeet your fingers across the shop.

[@ramonhamm3885]

Spring loaded loops with teeth are scary!

[@j.szelecz2530]

BONZAI ! the shopping cry of the workshop ---- WELL SAID ! ---- from Canada J.

[@cherrypie9566]

3:38 no self control 😔

[@CDCI3]

Knots are teenage boys.

[@justinklenk]

Please do knot encourage those of us with naturally knotty minds.

[@Nickakanugboy]

I literally came here to point this out

[@jin_cotl]

@@CDCI3🤨

[@junovzla]

@@Nickakanugboy you did... what? 🤭

[@Mike__B]

The beginning of the video I start feeling the cold sweats, and I'm instantly reminded of those window shades for cars or those quick pop up tents/sunshades that I can never figure out how to rebend to fit in the same size area.

[@estherstreet4582]

I just remembered that nitinol wire is also used in dental braces and my teeth hurt...

[@fluffycritter]

I've gotten pretty good at twisting those things back into shape.

[@alankasjan6488]

I just close my eyes and apply pressure. Just like magic, they fold up as they should.

[@SchoolhouseTechno]

Probably got really satisfied at 8:00

[@djmintyfreshful]

I have one of those shades for my car. I have no idea how I know how to put it back in the bag, but if I question it it will become impossible. 😂

[@fragglet]

Polite request that it would be good if you could put things a bit higher up in the frame so that they don't get covered by the subtitles ❤

[@SteveMould]

Noted!

[@abacabdk3490]

You can also move the subtitles out of the way by dragging them, I just noticed

[@meazle]

@@abacabdk3490Now, that's a handy tip. Thank you

[@fragglet]

@@abacabdk3490 this is what I did, yes

[@magnusmedivh6555]

​@@abacabdk3490not at the mobile app

[@yawnberg]

Lord Kelvin's attempts to make mechanical models of elementary particles is one of the coolest failures in history. Also kinda tragic because he was so convinced that he could apply his engineering genius to the atomic scale that, late in life, he got a bit obsessed with trying to model the aether and refused to accept other theories. Shouldn't overshadow his many MANY other accomplishments though. Biographies of Thompson are always a good read, much recommend.

[@TheAgamemnon911]

Yeah... it's always tragic when being validated becomes more important than being correct.

[@yawnberg]

@@TheAgamemnon911 agree but there's a little more to it in this case. At that point in his life he hardly would have needed validation. Steve pointed out how lovely the idea was, even with the hindsight we're afforded today. I think Thompson was enamored with the idea of demonstrating a unified mechanics of the universe. He wasn't the first to aspire to that and he certainly wasn't the last.

[@dmk_games]

You seem a big fan of the guy. But I've always associated him with absolute zero. 😂

[@peterfitzpatrick7032]

@@dmk_games .... that was cold ... 😏

[@SioxerNikita]

​@@yawnbergThat is more likely than wanting to be validated. Beyond that, during that time there wasn't really a great element understanding in the first place.

[@bilboswaggings]

Help my Marvin the Martian is self touching

[@tired3726]

XD

[@kwhite621]

A non self touching knot is also called a Catholic knot

[@jillianonthehudson1739]

Well played

[@mynt253]

Not to be confused with knots that touch smaller knots

[@stevesmith7839]

Good one.

[@vlvchii]

For some reason I read that as a celtic knot and I was like ok makes sense. But I've never heard of a catholic knot

[@stevesmith7839]

@@vlvchii It's a joke. non Self touching.

[@Dave-rd6sp]

3:38 I can relate.

[@RangeGleasry]

😂

[@jackbuff_I]

Beat me to it! 😂

[@nevinofstedal8679]

That was the smoothest transition to a sponsor I've ever seen. 10/10

[@freescape08]

3:18 I found the non-self-touching relaxed knot you mentioned not existing! I call it - the Un-knot! And there's actually an alphanumeric character for it: "°"

[@wteff8586]

Un-knot, or simply: not

[@maynardtrendle820]

I guess you already know that the "Unknot" is the name of the most trivial knot- the circle. If you didn't know, great job picking the exact terminology!😂

[@nathangamble125]

The coconut knot is not a knot.

[@ignorancja]

​@@nathangamble125 i see you ❤

[@reiserlein]

Popup tents are working like that puzzle. Love it❤

[@steamer2k319]

Yeah--kinda laughing that people would pay just to experience the frustration of trying to put one of those away. It's all about framing I guess 🤭.

[@parmsib]

Heads up: There's a typo in the title. "is" should be "in"

[@SteveMould]

Thanks! Fixed now

[@NlNTENDOJAPAN]

@@SteveMouldheads up: there’s a type in the title. “In” should be “is”

[@Artaxo]

​@@NlNTENDOJAPAN omg Nintendo, stop trying to confuse Steve Mould

[@baronofclubs]

Heads up: There's a typo in the title. "Behave" should be "Beehive"

[@solanumtuberosa]

​@@NlNTENDOJAPANyuzu did nothing wrong

[@kinexkid]

That windows pipe screensaver just gave me a flashback. About 15 years ago i had a really nasty case of the flu, and had a fever of a little over 104 degrees and i woke up in the middle of the night. I was so out of it, that i was hallucinating that those giant blobs of pipes were coming out of my mouth and floating arou d the room while shape-shifting into different configurations

[@Irondragon1945]

hell yeah pipe related fever dreams relateable

[@TheRip72]

It reminded me of the opening sequence for series 3 of Monty Python's Flying Circus.

[@acherongoon]

With the Arizona (?) Teapot randomly.

[@kinexkid]

The second time I was hallucinating against my will was much more enjoyable, but more painful. A couple years after that I was traveling from Central CA to northern AZ to look at a potential college. I took a flight down to LA, then a flight to Pheonix, followed by a 7000 foot elevation drive. During it all, as soon as we took off on the first flight, my ears wouldn't pop and the pressure in my head was getting excruciating. We got to the city that the college was in and I immediately went to the hospital. I had a double ear infection, sinus infection, and an upper respiratory infection. They gave me some really good meds and some steroids for my asthma. That night, while in the hotel bed, I hallucinated a full orchestra performing a double concerto with violin and clarinet soloists. It was so beautiful and clear and lasted about 15 minutes. I received a $40,000 per semester scholarship there for music and astronomy, basically a full ride, but all that pain and discomfort I experienced was probably the main reason I didn't end up going there

[@m.i.c.h.o]

@@Irondragon1945you could almost call them… pipe dreams.

[@octoBadger]

I'm enjoying the idea that in 100 years people will be using the euphemism "Marvin" but no-one can remember why.

[@KarstenJohansson]

I have a fishing hat with mosquito net that uses one of these configurations. When not worn, it packs flat in an envelope. When you pull it out, it springs to life as a full-size hat.

[@MMTMacroTrader]

Looks like Marvin the Martian you say?

[@ccoder4953]

Definitely a very strong, efficient shape.

[@mme725]

​@@ccoder4953RCE, is that you? 😂

[@faramoftae]

My Marvin looks nothing like that 😔

[@andymouse]

LMFAO!@@faramoftae

[@Rthomas176]

😂😂😂

[@cookesam6]

3:38 I think we all end up touching ourselves if we've ever been let go 💔

[@williamsharkey]

Casual exposition style belies mastery of conveying so many beautiful concepts with ease. Thanks for putting in the effort Steve!

[@kmill31415]

The observation that the figure eight looks sort of like a tetrahedron is a good one. The topologist Bill Thurston noticed that there's a way to glue together two tetrahedra with all the vertices collapsed to a single vertex, and then edges-to-edges and faces-to-faces, such that if you remove a small neighborhood of the vertex in the resulting topological space, what you get is a space related to the figure eight knot: it's the same topological space as the space consisting of everything *outside* a figure eight knot. (It's very mind-bending to try to perceive this...) He used this to show that the space outside of a figure eight knot can be given a hyperbolic geometry, and it was a key insight that eventually led him to his Geometrization Conjecture, one part of which was Perelman's resolution of the Poincaré Conjecture. Topologists still call it the "Geometrization Conjecture", but it's a theorem as of about ten years ago.

[@AndrewYarmola]

The tetrahedral symmetry is not too surprising if you know that the complement of the figure-8 knot is the gluing of two truncated tetrahedra. The edge colorings also match.

[@columbus8myhw]

To explain somewhat, for those who are not familiar: take two tetrahedra, and cut off the corners (revealing several new faces, which I'll call truncation faces). If you allow yourself to deform these shapes like play-dough, and glue the non-truncation faces together in a certain way, the result will be essentially a doughnut with a knotted hole. If done correctly, that hole will be the figure-eight knot.

[@amichai345]

So a non self touching knot is a master of it's own domain?

[@tonyjohnson8929]

Two weeks top.

[@werlmb]

I don't know if you'll see this Steve but I appreciate Algodoo is still used today! I'll recognise that cursor and UI anywhere! It was a great learning tool for much younger me.

[@mrhanlon]

This is uncannily similar to my graduate thesis, except there we were exploring optimization algorithms and applying them to untying knots. In one part of the research we used prime knots as input for our knot modeling software and randomly cut the knots so that they would then be "untie-able". Then we used an optimization algorithm to "shake" the knot until it was untied. I'm not sure if the clips shown starting at 4:58 are from something the authors provided or something else, but it looks so similar to what we built I gasped!

[@thenatron6136]

Thank you, Steve, I love big knots 2:26 A knot shaped knot lol

[@orangejuliaa]

interesting

[@intangible9838]

🤨 I know what you are

[@MrCrackbear]

rather peculiar

[@robertschnobert9090]

I don't understand! ​@@intangible9838

[@TheKhalamar]

I was looking for a comment about 2:26. Especially during the self-touching part. Thank you.

[@richieh2006]

I love your videos, Steve. I'm going through a bit of a hard time in my life at the moment and have felt sad. But your videos always enlighten me and cheer me up.

[@FourthRoot]

I bet that marvin the martian knot is the hardest knot to prevent self-touching.

[@thetruthexperiment]

There need not be any further comments.

[@scottmasson3336]

Try opening a bandsaw blade when it comes coiled.

[@WillBinge]

Oh Christ that sounds like it would end badly

[@BWWWAAALORDOFDUCKS]

Or closing it back up for disposal.

[@octoBadger]

Safety glasses on 😊

[@GingerGigantus]

Amen, keep your gloves on

[@AnthonyHowellII]

Fire in the hole!

[@Mosenhosen]

Topic suggestion for Steve: Somehow this video reminded me of four bar linkages. One day I had an apparently small hobby engineering problem to solve and ended up deep down in a rabbit hole. Four bar linkages are so easy to describe and have so few parameters and yet such complex kinematics emerge from it... And: they are everywhere!

[@2manyinterests2count]

Steve, you should heat set the nitonol into the 'solved' position and see if it will solve itself when dropped into warm water.

[@vlvchii]

I never thought knot theory would be so amazing

[@odd4824]

Always a pleasure to watch you work through the difficulties of a problem!

[@cact0s_ulion405]

That reminds me of the video you made about how pup-up tents work!

[@mikkolukas]

9:16 "..but it's knot" 😂

[@cadneemountai2791]

I had a little folding tent like the first puzzle when I was a kid.

[@dennywest1353]

This guy is a awesome and informative teacher ty for your videos bro

[@YannChemineau]

Rabbit : Tie them together, Piglet! Can you tie a knot? Piglet : I cannot Rabbit : Ah, so you can knot Piglet : No, I cannot knot Rabbit : Not knot? Pooh : Who's there? Rabbit : Pooh! Pooh : Pooh who? Rabbit : No! Pooh... Piglet, you'll need more than two knots Piglet : Not possible Owl : Ah, so it is possible to knot those pieces Piglet : Not these pieces! Pooh : Yes. Knot those pieces Piglet : Why not? Eeyore : 'Cause it's all for naught

[@96thelycan]

i can't retain information that well, but mathematical knots sure create a lot of pee pees

[@d0pomein]

Moooooom! The Nitinol knot is touching itself again!

[@jackbuff_I]

Ground News is brilliant! 👌🏼

[@thactotum]

you reminded me of and obsession with knots I had years ago. and also make me want to know if there's a knot equivalent of platonic solids

[@zzzaphod8507]

I appreciate this work even if it was knot an exhaustive approach.

[@voodoobram]

Never regretted watching one of your videos, about time i subscribe!

[@simeonspottswood8932]

I love this video, I would love more content on this subject

[@RicardoScattini]

3:23 it is like me. When I am feeling unstable, I end up touching myself...

[@flomoose7315]

Man… you’re really intriguing my senses with your videos. They have just the right amount of breaking the information down so an amateur can understand, but still keeping it to a high standard, so that knowledge is transferable. To keep it short: I love your channel! Jep up the great work😍

[@SharpAssKnittingNeedles]

He really is one of the best science/math communicators out there! We are lucky to have him!

[@cmel7841]

your videos are fascinating, been a fan for a long time, thanks for educating us

[@7sevin7]

God I love it when smart people talk about knots. 🥵

[@vimalk78]

1:11 hey that's "Mould Effect" apparatus at the back

[@user-wm9qx4km1i]

marvin the martian 👀

[@brycedaugherty9211]

This was stimulating and fascinating. Thanks!

[@melodyshortsmusic.8]

Very nice 🙂

[@addictedyounoob3164]

I like the video a lot, its very interesting and fun to watch, but directly from the start I had trouble understanding what elastic material exactly meant/means... what does it mean for a material to be elastic???

[@Erhannis]

Depending on the level of detail you want, I think it means "springy". More specifically, that every length of the material "wants" to be straight, that it resists bending, that it exerts a force opposite and proportional to its curvature - something like that.

[@mikayla_collie]

*_my top 3 favorite knots:_* 1: Fox 2: Dog 3: Wolf

[@randomlightstand]

And Marvin the Martian

[@Zippsterman]

9:13 "Part of me wishes it was true, but it's knot"

[@CutesyPie]

This is very cool ❤❤❤❤

[@johnchessant3012]

2:26 Marvin the Martian

[@Dee-Eddy]

Really cool! Dont get your marvin stuck in it though!

[@allisoncooke7405]

This is like the pop up beach tent i bought.

[@StevenHallOfGaming]

Hey Steve thanks for making me a little smarter, always look forward to your next video

[@Dan-vq4pz]

Steve at start of video: Unlike any puzzle *Bandsaw blade has entered the arena*

[@mrpid87]

@SteveMould what do you use for your physics simulations? Another great video by the way

[@SteveMould]

Algodoo

[@mrpid87]

Much appreciated, sir! @@SteveMould

[@stcorbett]

Great video! I was able to connect concepts and get new understanding about knots!

[@dnagpal001]

A beach tent of mine was this shape when open. I really felt like burning it rather than closing and packing it up.

[@siv9129]

I sure love how they behave is that way 😂

[@atgosh]

Petition to edit the subtitles to say 'knot' whenever Steve says 'not' I would settle for a k/not counter

[@Vok250]

I've played this puzzle with extension cables many times. I loathe it!

[@jeremymcadam7400]

Everyone that's done fencing understands this well

[@YourComputerExpert]

09:10 "Part of me wishes it was true, but it's (k)not" lol

[@Elyasafshweka]

This reminds me of how you safely (?) fold a Bandsaw blade. Also folding a car sunshade feels similar.

[@rickclayton1806]

You need to keep clear when you release one from the package. I throw them out on the floor.

[@Thermodynamicool]

Please keep making me curious. Mould my mind. You're such an inspiration.

[@AngryBuddhistPirate]

Subscribed for the science and then was IMMENSELY impressed by the sponsor. Glad to know you don’t buy into the establishment narrative. I’ll stick around for more.

[@miriamrobarts]

2:48 Or you could call it a butterfly.

[@tipsofsmyth]

02:26, that's a classic

[@RangeGleasry]

Marvin the Martian 😂 whatever you say Steve

[@reddblackjack]

My brother had a pop out tent like this. The base was a big 4 meter diameter ring that when folded correctly fit into a 4 foot round bag. It was a challenge sometimes until we figured out that twisting it two times was the trick. Twist it once and it's a figure eight, twice made a similar shape with three loops and the outsides fold over the center and one hand can keep it folded. Then you slide it into the bag. It was still difficult because of all the tent material on it. You had to mentally ignore it all and envision the loop, twist it two times and stuff all the extra material inside while doing it.

[@lemm9068]

reminds me of a folding tent It's such a puzzle to fold it back into a circle

[@Grayson_Wu]

07:42 Oh, Mark Pauly at EPFL again! I think that's the third time I saw his name on this channel. The previous are Self-assembling material and Caustic lenses.

[@tolgayldz1898]

He has really great works on solid/geometric modeling as well.

[@insu_na]

"Part of me wishes for it to be true, but it's knot." Steve M∞ld, 2024

[@dirxcec7035]

As soon as it came out of the bag, I was like, I have a tent like that! You just twist it down. Neat to see it explained!

[@lillyevergreen9385]

It's so strange to find a really in-depth science on something I was thinking about

[@LetsGetIntoItMedia]

Looks like Marvin the Martian indeed 😅😅😅

[@Matlauk]

It's so crazy how they behave is that way.

[@middenrat1433]

Exactly what I need at 2 am.

[@professormarvel4229]

I love that idea that atoms are knots. So smart really.

[@lassikinnunen]

"I was eventually able to solve this problem thanks to the hydraulic press channel"

[@polyblank73]

I thought of something you might be interested in looking into for your channel. When you aggressively pour a liquid into another liquid, sometimes some liquid will splash up into the air. I've been wondering if that liquid splashing up is the... "analyte" or the "titrant" (didn't know what else to call them lol, but you know what I mean). Is it always only the analyte or the titrant, or is it a mix of both? are the drops pure analyte/titrant, or are they x% of the analyte, and y% of the titrant? I dunno, just a shower thought that I thought you'd find interesting as well.

[@echognomecal6742]

Would watching slo-mo videos of pouring coloured liquids help?

[@polyblank73]

@@echognomecal6742 Yeah, that's what I thought too.

[@chrislewis7811]

I doubt there's a single answer here. Say you're pouring A into B. If A is a solid (eg a marble) and B a liquid, any splash is all B. If A is a liquid and B a solid, it's all A. With both liquids, the situation is somewhere between these two extremes. Factors that will affect the ratio include the rate, height and angle at which A is poured, viscosity, density and surface tension.

[@pasta0328]

Hey that thing looks just like my Marvin the Martian!

[@ThePhoenixSlayer]

Hey Steve. A new video by the Action Lab was just published, showing a cup that can be used while in a "zero-G" environment. The first thing I thought of is, "We need a Steve Mould see-through hydrodynamic system for this one"

[@DaffaBun]

3:37 Relatable

[@MrMediator24]

Marvin the Martian knot definitely fond of self touching

[@_..-.._..-.._]

This is me trying to repackage my springy car windshield shade 😂

[@mohammadsattar5488]

I saw a thing about knots from veritasium and I was amazed at just how many types of knots there actually are and it in the thousands or tens of

[@tahaasabir4090]

Too late people, you missed a rare occasion of a typo by Steve Mould

[@bluenono3821]

to*

[@doctorwhom8881]

is

[@lemonlemonlemonlemonlemonlemo]

this reminds me a little of Outside In

[@jaewok5G]

nitinol?! i had been introduced to nitinol maybe 20 years ago … it's great stuff!!