Elastic knots are really mind bending

[@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

[@BlameAmes]

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”

[@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.

[@snowjix]

@@Kufunninapuh The people selling the tents should have gone out, collected them all, cleaned them and sold them again next year. Now that would have been a great idea.

[@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

[@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.

[@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

[@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. 😂

[@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? 🤭

[@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.

[@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

[@williamsharkey]

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

[@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 ❤

[@PanthereaLeonis]

@@maynardtrendle820 But it does fit the criteria as well! It doesn't touch itself in its relaxed state. It feels a bit like prooving that 1=1 or 0=0, in that it's fairly obvious that a circle doesn't touch itself. But this might also end up in the territory of arguing if 1 is a prime number. The unknot is the simplest form a knot can be in, but it's not *really* a knot like the others, when all the others intersect themselves at some point.

[@bilboswaggings]

Help my Marvin the Martian is self touching

[@tired3726]

XD

[@MttGaming904]

Must be long...

[@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.

[@alexposada2288]

I used to have a small folding tent that had a frame that was the exact same as the puzzle!

[@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

[@JamesMoris283]

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

[@Artaxo]

​@@JamesMoris283 omg Nintendo, stop trying to confuse Steve Mould

[@baronofclubs]

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

[@solanumtuberosa]

​@@JamesMoris283yuzu did nothing wrong

[@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.

[@MttGaming904]

i have a sunglass

[@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.

[@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.

[@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.

[@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

[@Tsaoted]

Fire in the hole!

[@amichai345]

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

[@tonyjohnson8929]

Two weeks top.

[@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!

[@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]

😂😂😂

[@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!

[@shammer86]

Thanks!

[@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.

[@CaptainMarci104]

It's not a puzzle, it's just a small pop up tent without fabric. ^^

[@octoBadger]

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

[@MttGaming904]

59 liks

[@manbearcow]

I got a tent that works off this concept one time, and it took me a week to put it back in the bag the first time.

[@thenatron6136]

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

[@deltaradiation]

interesting

[@intangible9838]

🤨 I know what you are

[@robertschnobert9090]

I don't understand! ​@@intangible9838

[@TheKhalamar]

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

[@IAmPattycakes]

In every moderately popular KZbin video mentioning knots, there must be at least one thread like this. We all know why.

[@odd4824]

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

[@cookesam6]

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

[@s.domain]

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.

[@2manyinterests2count]

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

[@groovefunkel]

My vacuum cord creates knots that should be studied at MIT.

[@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!

[@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!

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

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

[@franzpattison]

These knots and I have one thing in common: we can't remain stable without touching ourselves.

[@vlvchii]

I never thought knot theory would be so amazing

[@Zippsterman]

The solution is at 0:04 if the video is good enough to catch it

[@voodoobram]

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

[@FourthRoot]

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

[@thetruthexperiment]

There need not be any further comments.

[@nyxa8734]

when you said "i wish it were true, but it's not" i wish you followed up with "or rather, it's not a knot" my sense of humor is in the gutter

[@Dan-vq4pz]

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

[@cadneemountai2791]

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

[@cact0s_ulion405]

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

[@Goatman_Gamer]

I was thinking Marvin The Martian too, glad I wasn’t the only one.

[@zzzaphod8507]

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

[@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.

[@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

[@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!

[@RicardoScattini]

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

[@dennywest1353]

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

[@atgosh]

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

[@mishli7670]

6:35 We know how many knots have how many crossings Now we need a table of knots that have Marvin the Martian!

[@mrpid87]

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

[@SteveMould]

Algodoo

[@mrpid87]

Much appreciated, sir! @@SteveMould

[@cmel7841]

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

[@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"

[@user-wm9qx4km1i]

marvin the martian 👀

[@brycedaugherty9211]

This was stimulating and fascinating. Thanks!

[@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.

[@clairekholin6935]

3:35, that is presumably excluding the un-knot? A single loop is an exception to this rule.

[@mikkolukas]

9:16 "..but it's knot" 😂

[@JonnyMack33]

Ground News is brilliant! 👌🏼

[@miriamrobarts]

2:48 Or you could call it a butterfly.

[@ADBBuild]

3:37 "It's not stable and ends up touching itself." Sounds like your average teenager.

[@vimalk78]

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

[@holvingar4375]

Great spot dude!

[@mathieubtn3789]

where is it possible to find the 12a1019 ?

[@siv9129]

I sure love how they behave is that way 😂

[@johnchessant3012]

2:26 Marvin the Martian

[@7sevin7]

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

[@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.

[@professormarvel4229]

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

[@Dee-Eddy]

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

[@simeonspottswood8932]

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

[@YourComputerExpert]

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

[@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.

[@KeithSkates]

3:43 these knots have a lot in common with me. 😂

[@Thermodynamicool]

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

[@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.

[@pasta0328]

Hey that thing looks just like my Marvin the Martian!

[@insu_na]

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

[@Vok250]

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

[@lassikinnunen]

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

[@paulfoss5385]

2:40 The Klein 4 (C2xC2) subgroup of the alternating group on 4 letters (A4) which is isomorphic to the rotational symmetry group of the tetrahedron, which has 12 elements (there are four positions a face of a tetrahedron can be rotated to, and there are three orientations it can be in 4*3=12). For the C2xC2 subgroup, the black edges could be left in place (the identity action), given a 180 degree rotation onto themselves, or you could swap the two edges, or you could do a 180 degree rotation and a swap. This subgroup is normal, which basically means you can forget it and still have some information about where you were in the original group. This would be visible if he had painted another pair of opposite edges a third color, then the C2xC2 rotations would leave every edge color in place, while the eight 120 degree rotations about each vertex would cycle the colors in any of three positions. A4/(C2xC2)=C3

[@tipsofsmyth]

02:26, that's a classic

[@RangeGleasry]

Marvin the Martian 😂 whatever you say Steve

[@stevewalston7089]

Has anyone found that puzzle for sale anywhere? The first one shown that has to be solved to "fit back in the bag"?

[@Matlauk]

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

[@jeremymcadam7400]

Everyone that's done fencing understands this well

[@LetsGetIntoItMedia]

Looks like Marvin the Martian indeed 😅😅😅

[@learnaticszu4996]

I had that exact as a pop up tent, goddaamn what a hassel it was to get it back in it's bag AKA round form

[@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.

[@irismuddyhehe]

love this! thank you for sharing interesting things always

[@DaffaBun]

3:37 Relatable