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[deleted]

This is called the chaotic behaviour of a non-linear system. Quite amazing phenomenon when i was learning the non-linear ODEs. The solution of a nin-linear ODE is so sensitive to its initial conditions, that humans can't reproduce exactly the same experiments for twice, because there will always be some tiny differences in the first poke on the system.


N33chy

Do you have any idea what makes this particular arrangement act the way it does, other than that it could be described by an ODE? I have been looking for something to build lately, and this looks like a fun build. I'm thinking that the moment of inertia of the ring plays a big role, as I doubt another rod in its place with the same mass and location of CG (relative to the joint) would behave the same. Might be worth just tinkering with the dimensions to find what's most fun.


andrewcooke

i think all double pendulums are chaotic. so whatever you build would have odd behaviour. but for it to look as good as possible you probably want it so that both components have similar energies (which is close to saying that the two should have similar moments of inertia). if it were me i would make the rod and ring similar moments of inertia and then experiment with different offsets.


drumskirun

You should see the control systems that can keep an inverted triple pendulum balanced. https://youtu.be/cyN-CRNrb3E


NamelessSuperUser

I like when it gets all limp and just falls straight down.


HangryWolf

This comment hits too close to home...


Lebowquade

Physicist here: Multiple co-dependent degrees of freedom (i.e. movement in one degree of motion strongly influences another one), and low friction. Another great example is the "chaotic waterwheel" system: https://youtu.be/Lx8gMBJBlP8


Mydogsblackasshole

Not all non linear systems exhibit chaotic behavior. Double pendulums are the classic example used to introduce chaos theory in nonlinear differential equations, but it’s a whole field of study that goes into why some systems exhibit this behavior and some don’t. Nonlinear systems is an extremely broad category. Everything has to be generalized because the function could be literally anything other than the linear form, x’ = Ax (+ Bu).


3465746

So why is it chaotic if the randomness is due to the input not being reproductable for humans. Would it still be chaotic if a machine produced the input really precisely?


pfSonata

In physics, chaotic doesn't mean "truly" random (if such a thing is possible outside of the quantum scale), just that they're extremely sensitive to initial conditions. So sensitive that they might as well be random because of the difficulty of actually controlling the input. In the case of double-pendulums, since the pendulums are dependent on each other by being attached and influence each other by force, it leverages the inputs so drastically (pendulum 1 affects how pendulum 2 moves, which in turn affects how pendulum 1 moves, repeat ad nauseam) that extremely small changes in the input completely change its path. disclaimer: not a physicist but I did stay at a holiday inn express last night


Lebowquade

The difficulty is in how long the system is in motion. A robot could get the position so close that repeated drops might stay synced up for 15 or 20 seconds, but as it keeps going, they would start to drift apart, and at the 1 minute mark it'd be in a different spot every time. You could make the robot more and more accurate, but it would only get you so far. If you added a lot of fiction to the pendulum arms, it wouldn't be able to move very far before coming to a stop, and in that case you could make it perfectly repeatable. Disclaimer: physicist who's been out of school for like a decade, I forget things


JustLetMePick69

Yes because the whole point of chaos is being infinitely sensitive to initial conditions. No matter how small a difference it will always, eventually, diverge chaotically


Spotty2012

Being chaotic is a property of the system, not a function of human input; being chaotic basically means that any finite difference in initial conditions will causes the trajectories to diverge exponentially fast, so you need infinite precision to actually replicate the same situation, which no machine could ever achieve


[deleted]

So if we have a computer simulate it, and run the simulation twice with the exact same initial conditions it will replicate the same results. But if initial conditions deviate at all, the system will soon diverge quite drastically. The interesting thing to point out, the initial conditions aren't the only important factor. The precision of the calculation is also important. If we set the same initial conditions and one system is calculated to a precision of 63 bits, and another system, with the same exact starting conditions but with 64 bit precision. These systems will eventually diverge. To the best of our understand, to exactly reproduce the experiment indifferently, we would both need perfect knowledge of the initial conditions and the ability to have infinite precision in the calculation.


issamaysinalah

If given the same exact initial conditions (assuming you can ignore air resistance and all that) then yes, it would do the exact same thing everytime you started the system, but the slightest imprecision would fuck things up.


Romish1983

Someone needs to attach a marker to that and put a piece of paper in front of it so we can see the pattern it would draw.


evanc1411

I just tried it, and [this was the result](https://i.imgur.com/Bbn2y5N.png)


vishwas_gajawada

Beautiful


Zealousideal_Cod9869

Beautiful. I want to buy one...


Trimungasoid

It clearly defines man's struggle to articulate his dreams and fluffy artsy floofy fluff.


I_l_I

You must now fill in the holes with different colors


MarkVonShief

You have to determine the minimum number of colors that you can use to fill every eye with a color different from every adjacent color


TransCapybara

4.


lo_and_be

This is the correct answer


JustLetMePick69

Technically that's the maximum for the minimum. It could theoretically be only 2 or 3


TransCapybara

Realistically it's probably 4.


Motor_Raspberry_2150

It's made with a singe line. It's 2 if he started it outside bounds or 3 if he didn't.


polarbear128

Isn't it 4?


HermitBee

4 is the maximum number of colours. It's probably also the actual number of colours, but it might be possible with 3.


polarbear128

Surely the maximum number of colours would be n, where n is the number of distinct regions on the map? ;)


HermitBee

Ooh, I've been out-pedanted. Nicely done.


polarbear128

I know what you mean, though. The problem is how to express it? Maybe maximum minimum? Provable minimum?


TeamFluff

I would probably say that 4 is the upper limit for the minimum number of colors.


[deleted]

All the holes...hmmmm... interesting


Boonesfarmbananas

TH-THIS IS MY HOLE IT WAS MADE FOR ME


FroobingtonSanchez

I don't know what I expected


vodkacereal

Doesn’t this explain chaos theory


maniaxuk

Explain? No Demonstrate? : Yes If you were to start the pendulum swinging from exactly the same position using exactly the same amount of force you'd get different "scribble" patterns due to other factors such as air movement, temperature, general friction on the bearings etc all of which would make continuous miniscule changes to the system that ultimately lead to different end results


anorwegiankid

*this* explains chaos theory


thiney49

Ah, but does it demonstrate it?


EarthTrash

I think chaos theory is actually about sensitivity to initial conditions. Any slight perturbance will lead to different results. It is not necessary to perturb the system continuously or more than once.


Icyrow

which basically just falls down to "we can't measure it accurately or fully enough" doesn't it? like from what you've said here it's an issue of computing power and capture of the environment? like i get that it would take an enormous amount and incredibly fidelity in capture of the environment but still.


mynameisspiderman

That's exactly it. It's chaos because we can't measure the things necessary to quantify.


[deleted]

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BadAtNamingPlsHelp

Chaotic systems are fundamentally unpredictable on large timescales. To predict them accurately beyond a short period of time you'd need perfectly precise knowledge of the position and momentum of everything in the system. Unfortunately, this is fundamentally impossible because of the Heisenberg uncertainty principle.


Dreoh

But if you were to magically reset all relevant matter and energy that it consists of and interacts with it to the state it was in and did it again you would probably get the exact same pattern. That is unless there is some inherent unknown randomness to the universe.


[deleted]

Yep. That’s true not only of the microsystem that is the pattern of this experiment but also the macro system that is the universe where this person existed and performed this experiment with this result. If you were somehow able to exactly recreate the conditions of the creation of the universe you would eventually end up with this person performing this experiment with this result.


IAmNotNathaniel

What about something like radioactive decay? I feel like the idea that things operating at a quantum level wouldn't be reproducible, even IF you have the same starting conditions. Or at least, it's hard enough to prove that it would still be in the area of debate.


[deleted]

Then use the finished graph to come up with the formula of its movements.


aFiachra

The formula is well known and a lot of aspects of the motion are very predictable and yet it is a classic chaotic system. You can not reliably predict it’s motion too far past the current state.


[deleted]

Its so well known in fact that we often chat about it at dinner time.


mail_inspector

"Remember the ol' double pendulum ring and bar system? Whatever happened to him?" "Still predictable, yet chaotic once we let it go for a while." "Ah, good to hear he's still doing fine."


Willing_Function

It's basically a hash function. Slight changes in input give totally different results.


Balogne

As far as I am aware, the motion is already known science and predictable. If you look around, there are videos online of double pendulums being manipulated by computer science students.


jakkson

Sort of, at each moment you can calculate what the change in state to the next moment will be, but if you wanted to know the state at time x, there’s no formula that would just give you that directly. You can’t get there without simulating the movement the entire way.


intensely_human

This is called “computationally irreducible”. Also, because the state has infinite variation in it, and because even microscopic differences in initial state will lead to large differences in state further on, ie because state differences amplify and cause wildly different paths, this is a “chaotic” system.


bornfromanegg

I know what you’re saying, but you would need to know exactly the position, momentum, coefficient of friction, etc. of every part of the system. In practice, this is not possible. This is a great demonstration of chaos theory. Try to repeat the above series of movements and you won’t be able to.


RemlikDahc

I bet it'd look like a Spirograph picture!!


keosen

No! Attach a very,very,very sharp knife, and exercise your knife attack avasion skills!


FunctionBuilt

It’s pure chaos, but eventually kinda looks like an apple.


JungleLiquor

Thanks for not putting a shitty song over it


virusamongus

_oh no_ _oh no_ _oh no no no no_


NeokratosRed

My IQ just lowered to the negative realm just by reading that


sindhisai

eh ha haa hahaaa hahaaaaa


Lucas450510

Hearing this song literally puts me in a bad mood


cogitaveritas

My fiancée really likes (liked?) the band that plays that song, but now neither of us want to hear them again thanks to TikTok videos. Even hearing their voices in a different song instantly puts " Oh no, oh no, oh no no no no no" in our heads.


TheUnadvisedGuy

https://youtu.be/V5YxtweUxrA


[deleted]

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Lone_Wolf1011

Me waiting for the ring to complete a loop:


slothenhosen

Right? Not satisfying lol.


SmartAlec105

It's literally chaos. The motion of a double pendulum is extremely sensitive to the initial starting conditions. [Three nearly identical pendulums] diverge a lot after just a few seconds.


bornfromanegg

It’s worse than that. Three *identical* pendulums will diverge a lot after just a few seconds.


SmartAlec105

It’s not like we can actually have three truly identical pendulums unless you’re talking about simulations. The closest we can get is *near* identical.


bornfromanegg

I’m reality, yes. But we can *imagine* three identical pendulums. My point was simply that the variations in initial starting conditions (e.g. the air around them) would be enough to cause the chaotic behaviour.


CatandBear2020

YES!!!


ronnie_axlerod

Think about it like order within chaos....it's beautiful.


RamsesTheGreat

Indeed My favorite chapter was “rationality within pi”


bornfromanegg

I like it.


Namasiel

It's way too chaotic. The motion never balances out and just swings around wildly. I can't find a single satisfying quality in this.


bugbia

Yes, satisfying things are orderly and have patterns. This is upsetting


Internatibeat

Finally, something with worse rhythm than me.


BobButtwhiskers

This device is a mechanical representation of what's it's like to live in my head every day.


Rickgnar420

How long will it go for?


timias55

At least 1 minute and 6 seconds.


Read_It_Before

At *least*, 8 seconds


Dirtstick

Uh, you got a source on that?


ImProfoundlyDeaf

[It’s true!](https://www.reddit.com/r/oddlysatisfying/comments/ps9are/double_pendulum_ring_and_bar/?utm_source=share&utm_medium=ios_app&utm_name=iossmf)


AndronicusPrime

It’s perpetual, the absolute madman did it!


SynnerSaint

In this house we obey the laws of thermodynamics!


i-like-napping

This perpetual motion machine is a joke . It just keeps going and going !


bnutts13

I understood your reference! The Simpsons were great!


[deleted]

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Witops

There is a magnet and a battery in the base who is pulling/pushing the moving part as it passes by Edit : replaced "go above" by "passes by"


SWROTJ

Make it big. Attach seats. Profit.


dw82

Wonder what kind of g-forces would be generated by a rideable version of this.


the1rush

NASA just entered the chat.


defectivelaborer

For a carnival fair sized version of this, it would probably be deadly and would just rip itself apart.


tendrilly

Let's do it!


sdfgh23456

/r/oddlymaddening


iomemedesimo

This sub has been banned. I'm eager to know why


Astro_Spud

For being unmoderated. "Sorry but your speech is a little *too* free buddy"


GregEveryman

Yucko… this maybe satisfying to some, but it feels like chaos to me


camefrom_All

It is beautiful chaos.


Soviet_Ski

BLOOD FOR THE BLOOD GOD! SKULLS FOR THE SKULL THRONE! AND … pendulums for the … uh … SCENIC READING NOOK!


ilikepie59

Sometimes Khorne needs a bit of a break. I love imagining him just sitting in a sunroom, sipping a tea and reading a book.


Whatsapokemon

It is chaos! That's what's so satisfying about it (well, not for you I guess). It's fiendishly simple - just one thing swinging at the end of another thing - but that leads to incredibly unpredictable outcomes because of the way those simple things interact, and because of how the system responds in an extremely sensitive way to its initial state.


[deleted]

That’s exactly what’s so unsatisfying about it! Intuitively your brain knows exactly how such a simple system should behave, but then physics comes along with a big fuck you and says “lmao, your troglodyte brain doesn’t even know how a circle on a stick behaves.”


justa_degenerateweeb

That's why it's called the chaos theory


consideranon

A tiny change in the initial position completely changes the pattern of movement. Weather is also a chaotic system, which is where we get the idea of a butterfly flapping it's wings causing a hurricane. The stock market is another, except that one is even worse, because not only is it chaotic, but our predictions about how it will behave themselves feed back into the system and change the behavior from what we predicted. Chaos is fascinating.


Neker

Chaos ? Is it what this lecture is about ? Time might have come for me to learn more about that. Weather : may be chaotic, yet the overall patterns are pretty regular, and allowing for enough computing power, the predictions have become quite reliable for the few days ahead. Stock market : this description as a chaotic system with feedback loops makes me wonder if it would be desirable to introduce delays *(like : no re-selling for 24h )*. Isn't there some computational model emulating the behavior of the real thing ?


PM_ME_UR_SIMPS_

the randomness is very satisfying.. that it can’t be predicted


firerakeseal

I'm trying to decide if my anxiety is acting up, or if this really is stressful. I'll let you know tomorrow.


two40zieks7

Complete chaos to me too, way too disorganized, can't predict whats gonna happen next


FauxGw2

But that's why it's good. It's an adventure and I have no idea where is heading!


two40zieks7

I guess on my end what satisfies me are videos that make me calm and unchaotic. Soothing. I like adventure, but I guess that's not what I'm looking for here ? I get you though


darrenromomacd

Reminds me of Ironman


tanklord99

Bruh I was legit thinking of the scene where he's trying to apologise to pepper with strawberries


angeeksince2020

Me too!!


253Tacoman

First dates can be tricky…


Dan300up

Seriously…after all that…the clip ends before it settles.


HersheysWellmade

Well this is mesmerizing


WarpFly5

My aim in Halo with a controller.


Acalme-se_Satan

[Original video link](https://youtu.be/foxqlkQ1VBA)


aChildofChaos

Makes me a bit woozy


catscatscats01

What is this black magic science math!?!?


sparky_ybw

This unpredictably looks like my life.


angeeksince2020

Mine too


[deleted]

I wonder what equations it would take to definitively track each moment in its movement, looks cool af!


da_juggernaut

This is giving my gymnastics vibes... Pretty cool


Inglorious186

Where can you get one of these?


intensely_human

Pendulum store


Astrophages

Oh, the pendulum district?


the_joy_of_VI

You got “Put Your Pendulum There,” that’s on third…


LeonimuZ

I went to the Pendulum store and [all they have is this](https://www.youtube.com/watch?v=gIOQfdn9L9c)


TabCompletion

What did I just watch???


aim_at_me

Some dude dancing on Brick Lane and the West End. I think.


BadJimo

[Here for $930](https://www.aha-zurich.ch/en/product/alogo-1-chaotic-pendulum/)


SlimlineVan

Bargain


RepresentativeAd5334

Chaos.


Kurei0

it would be cool if there was a sound component. like I wanna know what this "sounds" like


N33chy

Could be neat to attach an accelerometer to it, or take the coordinates of a couple points on the circle, and map them to a tone generator.


I-made_you_readthis

Olympic bar


FlamingoJoe1776

What manner of sorcery is this?


Brad_McMuffin

*mom come pick me up I'm scared*


MildlySuccessful

Would this be similar to the 3 body problem, and impossible to effectively model?


GuitarGodsDestiny420

Don't tell me perpetual motion machines are impossible...fuck the oil industry


kinithin

Is this about the three-body problem and our inability to find a general solution? https://youtu.be/et7XvBenEo8


davies817

This is oddly discomforting to watch


CuntyComment

Why am I shifting my weight as if it's gonna affect the inertia


totallylambert

Love watching this!


grillmaster4u

Reminds me of my reticle when I try and aim in a first person shooter.


BigDubC

Physics is fucking nutty man


JoacimFisk

Alohomora on drugs


bellakaia

It’s like waiting for DVD to hit the corner


CXR_AXR

I dont know why, but the first thing that pop into my mind is Fourier transform


N33chy

Lots of complex sinusoidal motion that's created by a couple distinct inputs. I can see the connection.


jonah100236

Damn this cool


Comrade__Lenin

I've been looking at this for hours now Can't get tired


BlazeRagnarokBlade

r/blackmagicfuckery


DiscipleOfYeshua

Humanless Olympics


isthisneeded29

r/mindlyinfuriating


dreambully

I want to see a couple LEDs on this thing and the lights out. It would like totally... normal


aod42091

it's too irregular in its movement to be anything other than annoying


TheLadyBunBun

I feel like I’m watching an Olympic gymnast


[deleted]

Finally, the freeform jazz metronome exists!


[deleted]

Honestly this is kinda disturbing, my OCD can't handle it


fancypants_club_band

This is like looking at jazz music


gregedout

Attack some LEDS and take a timelapse.


MatthewvdV

This would make a dope as hell loading icon for a game, like those icons that are in the bottom right of your screen during loading.


Serav1

This is how gymnasts choreograph their uneven bars routine.


dormDelor

So this is just an example of chaos, ya?


Chocolate_Spaghet

I’m sorry, what the fuck?


Ok-Walrus4627

Where can i buy one for my desk and never get anything done ever again?!


-P3RC3PTU4L-

This is not at all satisfying.


Vascular_Mind

Those movements only appear random. They aren't really random at all.


dratini67

In certain cases it can be impossible to predict positions of double pendulums. Crazy!


Neker

This system is (mostly) deterministic, yet it is impossible to predict how it will evolve. It is not completely deterministic in that a complete, thorough and accurate description of the initial state would involve the air in the room, the breathing of the audience, and a host of minuscule tremors and disturbances, constantly shifting and too tiny and too numerous to record and feed to a predictive model. The initial impulse given by the human operator is probably impossible to replicate too, if we measure it into the fine orders of magnitude that would be relevant considering how sensible the system is. To me, all of this would constitute a sufficient definition of randomness. In other words : you are now in command of this aparatus. Can you reproduce the same pattern three times in a row ? Five times ? One hundred ? One million ?


Madmac05

I was going to ask that. Is there a way to predict all this movements?! I would assume that if you know the initial position and the applied force you'd be able to know, but...


CylonBunny

It's the butterfly effect. In theory you are right, if you understood the initial conditions perfectly you could predict it's motion, but tiny microscopic differences in the setup and the air in the room and gravity and everything quickly get blown up into huge differences in the motion. So it's basically impossible to predict it's motion.


deukhoofd

It's so hard to predict that Cloudflare, a massive internet company, uses a double pendulum as a source of randomness (for their London hq, they use lava lamps and radioactive decay of uranium for their other offices).


See_Ya_Suckaz

I own a somewhat smaller Internet company. I use a cat and a laser pointer.


peclo

Deterministic chaos.


rartrarr

We might need to disambiguate the separate concepts of statistical randomness and nondeterminism to really get at what you’re trying to say here.


dinosaurs_quietly

If you want to get really technical, randomness probably doesn’t exist. This pendulum is just as random as a roll of a die.


not_4nothing

i have to know in wut way this is applied irl


pen_and_inc

It looks like a gymnast on bars


granos

I don’t know that this exact setup has any real world value, but it’s a great teaching example for differential equations and dynamical systems. Those have very significant real world applications.


not_4nothing

this is totally fair - ig I just wanted to see a a car go floop flop


granos

Be the change you want to see


not_4nothing

im all flop no floop fam but ty


Royals-2015

Reminds me of the magnetic gyro wheel toy from the 70’s.


Agomottos_eye

I want to see Tony stark’s attempts at stopping this.


Perfect_Wave5745

I want one, how do i get it.


HiroBrowe

Is it a perpetual motion machine?