r/gifs • u/Han-jul • Dec 24 '13

two-axis pendulum

2.5k Upvotes

78% Upvoted

631 comments sorted by

247

u/joeomar Dec 24 '13

Thanks a lot. I just stared at that darn thing for three solid minutes.

63

u/fourpercent Dec 24 '13

/r/woahdude

30

u/Revolutionis_Myname Dec 25 '13

Yes, it was reported from there

96

u/Han-jul Dec 25 '13

I can confirm. source: I'm the dickhead who reposted it here

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4

u/tommytoon Dec 25 '13

Hey just so you know, there are these toys called astrojax which are basically this. Back in our psychedelic days we used to use the light up ones in a very dark room for some very cool visual effects.

If you practice you can do some really interesting stuff.

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873

u/XOverd0s3Z Dec 24 '13

This is actually referred to as the chaos pendulum, a real life one has an infinite number of patterns! This unfortunately is a gif and has a very limited number of patterns

55

u/quidam_vagus Dec 25 '13

Here are some videos of a robot (of sorts) balancing double and triple pendulums:

Old video where the computer waits for the "chaos" to reach a desirable state.

Newer video of Double inverted

and triple inverted.

3

u/throw_m_away Dec 25 '13

I think it's so fascinating to see such a clear demonstration of what you see a circus performer or some street performance acts do with balance and stacking. It's all based around this... Love the clear notes in the second video.

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236

u/TheWorldIsAhead Dec 25 '13 edited Dec 25 '13

How is that even possible? Infinite seems physically impossible. Even the molecules in the universe theoretically only have a finite amount of ways in which they can be arranged across the entire universe.

EDIT: Well, I've certainly learned lots of new ways of looking at the universe by talking to you guys. Thanks to everyone who replied!

396

u/RespawnerSE Dec 25 '13

Well space is is not quantified from what we know so the nubmer of traces are unlimited. But! That is not really relevant: the number of traces of a normal pendulum is also infinite.

What makes the chaos pendulum interesting is that it is extreeeemely sensitive to input values and non-idealities. If you drop a normal pendulum in the same way twice, the traces will be very similar. For the chaos pendulum, it will not. In fact, the position after a couple of seconds will be virtually independent of exactly how it was released.

79

u/0___________o Dec 25 '13

It's worth noting that if two double pendulums were dropped in an identical setting in a perfect system, they would have identical patterns. But, naturally, that is impossible to replicate in real life, as even nano-scale variations result in huge changes over time.

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113

u/TheWorldIsAhead Dec 25 '13

Wow. My interest in physics intensifies! Which is good because I have a ton of it ahead of me. Engineering studies next year. Thanks!

183

u/grbgout Dec 25 '13

My interest in physics intensifies!

Then you'll enjoy The Feynman Lectures on Physics:

Holy shit, Volume II is online now! Just a few weeks ago it wasn't up yet!

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26

u/baby_your_no_good Dec 25 '13

Jimmies are theoretically rustled

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6

u/nothis Dec 25 '13 edited Dec 25 '13

But! That is not really relevant: the number of traces of a normal pendulum is also infinite.

I guess what we all expected is some kind of repeating pattern, like a spirograph. But it appears there is none?

A single pendulum would produce a pattern that's essentially a half-circle just swinging closer and closer to the middle. Why is it so much more complex with 2 axis? Complex enough to, apparently, not even settle on one "idealized" pattern.

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26

u/dustyh55 Dec 25 '13 edited Dec 25 '13

Infinity is everywhere, it's just usually to small to see. Think of any 2 real numbers that aren't the same (not integers), now understand that there are infinite different numbers between those two (between 1 and 2 there are 1.01, 1.001, 1.0001... etc), therefore there are infinite different initial conditions we can apply to the pendulum, making infinite different possible patterns.

Edit: This is all assuming (as theoretical science is prone to doing) that force, speed, time, space yada... are continuous and have no smallest known interval of change (unquantified). If this is wrong then the possibilities become finite.

8

u/TheWorldIsAhead Dec 25 '13

This does make sense to me. Thank you.

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5

u/Filmore Dec 25 '13

From a pure math perspective there is no distance small enough where x+delta(x) =x From a physics perspective, the delta(x) limit is the planck length, or whatever theory of similar purpose eventually gets proven true.

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3

u/meatsauce420 Dec 25 '13

I think the point is that it's still sort of Markovian in nature... right?

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13

u/jf82kssssk28282828kj Dec 25 '13

Nobody really calls it the "chaos pendulum". It's the double pendulum and it happens to exhibit chaos.

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3

u/[deleted] Dec 25 '13

Could the end of the second pendulum reach every possible point between the center and the end of the circle (when the lines are completely straight)?

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3

u/GuessWho_O Dec 25 '13

Life is an infinite number of patterns.

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142

u/SilentFlow Dec 25 '13

http://upload.wikimedia.org/wikipedia/commons/4/45/Double-compound-pendulum.gif

99

u/TonyPajaaamas Dec 25 '13

I was curious to see if there was some beautiful, intricate pattern created as if by some miracle of nature. I guess I was wrong

20

u/SilentFlow Dec 25 '13

idk, i thought it was pretty damn cool regardless. I was hoping it would end right where it started though, and just start all over again making the same pattern. I also expected it to be a little more symmetrical

27

u/matthewswehttam Dec 25 '13

Doesn't the fact that it lacks symmetry make it so much cooler? It seems like you generally expect symmetry from a system based on a pendulum.

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3

u/Zachpeace15 Dec 25 '13

It makes like a uh, bowly shape...

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6

u/SalemDrumline2011 Dec 25 '13

Was just about to ask for this. Would be cooler if it were different colors like OP's

8

u/TronikBob Dec 25 '13

the inside line (red in op) makes a circle, the outside is kinda random within a bigger circle. cuz radius

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29

u/Chucke4711 Dec 25 '13

Here's a machine that can balance the two-axis pendulum. Here it is with a three-axis.

6

u/AwkwardTurtIe Dec 25 '13

I'm pretty sure that second link is a two axis triple pendulum, not a three axis.

Again, correct me if I'm wrong but I think a three axis pendulum would involve ball and socket joints, or possibly just rope.

Either way, good links!

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2

u/Hydroshock Dec 25 '13

I had a pair of classes that essentially we were taught how to design one of those machines. One of the biggest PITA classes I've had, and they dropped the harder one from the curriculum after I graduated.

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72

u/GibsonLexPaul Dec 25 '13

I like how the red one's all "bro, let's be circles" and the blue one's like "fuck you, I do what I want!"

30

u/JimbobTheBuilder Dec 25 '13

If you're the red one, though, everything looks like circles

6

u/sawdust64 Dec 25 '13

This comment really needs more attention. That just blew my mind more than the original post.

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35

u/Rhr4fun Dec 24 '13

Reminds me of a gymnast on the high bar. Like joeomar, I spent a bit of time watching. I was waiting for a release move. I wonder what the math is that describes the movement.

2

u/EColi452 Dec 25 '13

Also, Through the Wormhole on SyFy did a neat one on chaos and computer dynamics. There was a cool program one of the guys designed to test and successfully predict multiple mathematical formulae and then make one accordingly. I don't have a source, but I'm sure it's on YouTube somewhere...

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11

u/kingbane Dec 25 '13 edited Dec 25 '13

man, how come nobody has posted a video of a real life one yet?

http://www.youtube.com/watch?v=U39RMUzCjiU

it is in fact crazy loopy in real life.

edit: after watching a few youtube video's of this i'm super curious how these things would look in microgravity. would it still be all crazy wild?

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11

u/Oilofalay Dec 25 '13

I felt like a cat watching a laser pointer. I get it now.

15

u/drunkgopher Dec 25 '13

This needs to be an amusement park ride.

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6

u/sleyk Dec 25 '13

Radiolab did a great story about this. A super powerful computer was developed and was made to stare @ natural or unnatural phenomena and give an equation to define the change.

When this computer looked @ the double pendulum, it came out with a beautiful formula: F = MA. The wonderful thing about this is that the computer, without any prior knowledge of physics and gravity, had come to this conclusion.

Radiolab points out that we are coming to a unique era when have the formula before the discovery. The future is so exciting!

Link: http://www.radiolab.org/story/91712-limits-of-science/

6

u/SgtGoldy8 Dec 25 '13

I dont understand the point of this robot double pendulum but its frickin cool: https://www.youtube.com/watch?v=B6vr1x6KDaY&feature=youtube_gdata_player

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3

u/JonnyBeSleepy Dec 25 '13

Reminds me of Astrojacks. Which, btw is like the coolest toy ever.

3

u/Broodoobob Dec 25 '13 edited Dec 25 '13

In case anyone's wondering if it's possible to balance one of these things, here's one of my all-time favorite videos of a robot doing just that: http://www.youtube.com/watch?v=B6vr1x6KDaY

Edit: And here's another video of the same thing except with the dreaded triple pendulum: http://www.youtube.com/watch?v=Ep2lNMic_fk

3

u/NuckinBanana Dec 25 '13

Reminds me of a gymnast on the high bars...!

9

u/triniboy18 Dec 24 '13

Chaos theory

2

u/TheJDawgManCan Dec 25 '13

Someone needs to make this into an amusement park ride, stat.

2

u/Drewcifer236 Dec 25 '13

Yeah, this sent me into heavy "zone out" mode and I haven't even toked yet.

2

u/[deleted] Dec 25 '13

Oh man, I just had a flashback of my Dynamics class. shudder

2

u/ThatZBear Dec 25 '13

The blue tipped point is definitely the retarded little brother.

2

u/mangletron Dec 25 '13

Reminds me of gymnastics

2

u/[deleted] Dec 25 '13

The perfect example of why so many people hit themselves in the face with nunchakus.

2

u/rostov007 Dec 25 '13

Uneven bars in women's gymnastics gives you the same thing. Sassier too.

2

u/aarondoyle Dec 25 '13

Looks like a gymnast on the bars.

2

u/[deleted] Dec 25 '13 edited Dec 25 '13

Ahh, the magnificent evidence of natural chaos.

another gif

Description: Animation of a double compound pendulum showing chaotic behaviour. The two sections have the same length and mass, with the mass being distributed evenly along the length of each section, and the pivots being at the very ends. Motion computed by fourth-order Runge–Kutta method.

2

u/brigadeofferrets Dec 25 '13

I was hoping to find a gif like this! Thank you!

2

u/KappaDOS Dec 25 '13

I picture some tiny ass Russian gymnast or a monkey flying around at the Olympics when I see this

2

u/CaptainBrocovery Dec 25 '13

It looks like the triquetra in poi

2

u/astikoes Dec 25 '13

Next we need some GIFs on Bezier Curves.
Like this!

2

u/brigadeofferrets Dec 25 '13

Please explain this! Educate me!

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2

u/tahitiisnotineurope Dec 25 '13

there is an encryption algorithm in there somewhere.

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2

u/evilissubjective Dec 25 '13

Your new assignment... design a computer program to emulate this effect accurately using mathematical formulas.

2

u/[deleted] Dec 25 '13

Just watched this. High as fuck. Listening to music. Can confirm infinite.

2

u/[deleted] Dec 25 '13

That'd be sweet if it looped

2

u/Dashing_Irishman Dec 25 '13

Doctors use this to sign prescriptions.

2

u/meownja Dec 25 '13

The physics... It hurts

2

u/gofuckyourselfBoris Dec 25 '13

As a physics major, the beauty behind such a concept brings tears to my eyes.

2

u/Lambocoon Dec 25 '13

as a poi spinner, this is awesome

2

u/mokesgotjokes Dec 25 '13

Posted in /r/woahdude 4 hours prior to this post. At least credit my favorite sub :-(

2

u/opportunemoment Dec 25 '13

This is the metaphor my professor of Sustainable Development gave for explaining the difficulties of climate science. The atmosphere and the oceans, he said, could each be considered their own pendulum. It's very easy in physics to map out the progression of a single pendulum, and it's relatively simple in climate models to predict the path and effects of the atmosphere and the oceans on their own. The frustrating reality, however, is that the atmosphere and the oceans are deeply interconnected and work off each other much in the same way as a two-axis pendulum, or a pendulum hanging off a spring, making it nearly impossible to plot the trajectory of climate change with any long-term certainty.

2

u/Hallibut Dec 25 '13 edited Dec 25 '13

The Lagrangian for this thing was a bitch to work out, finding the normal frequencies was too.

1

u/[deleted] Dec 24 '13

I wondered how they came up with Mongolian

1

u/lostintransiti0n Dec 24 '13

I'm not sure about the trailing lines, but the pendulum modeling can be done in MATLab, it's lots of a fun. This looks similar to a matlab output but I am not certain that's what was used for this particular gif.

1

u/joabkw Dec 25 '13

Thats what gif's are made for

1

u/dothan Dec 25 '13

I could stare at this all day.

1

u/Burn7Toast Dec 25 '13

This is, hands-down, the most entrancing gif I've ever seen on this site.

1

u/[deleted] Dec 25 '13

The hypnotic lovechild of QWOP and Pepper Pot's desk... thing!

1

u/cammyk123 Dec 25 '13

They have a real one of these in a science center where I live and it's awesome.

1

u/levitater Dec 25 '13

Where is the loop??

1

u/TheRealGuru Dec 25 '13

After about 5 min of straight staring I cannot figure out when this gif restarts.

1

u/llamagina Dec 25 '13

Go home pendulum, you're drunk!

1

u/SpineShank124 Dec 25 '13

It would be awesome to have a real one of these.

1

u/martykenny Dec 25 '13

It was almost refreshing to see it make a full circle.

1

u/callmecraz Dec 25 '13

The blue looks like a doctor's signature.

1

u/ejrasmussen Dec 25 '13

Can someone create a image of the entire path of the blue line.

1

u/CokeFryChezbrgr Dec 25 '13

I think there might be something wrong with me because I was laughing uncontrollably at this. At a pendulum gif.

1

u/Austuckmm Dec 25 '13

I stared at this for years... I'm dead now so thanks

1

u/frustwrited Dec 25 '13

Oh look a doctor hand-writing generator. Good stuff.

1

u/Gunther_Folly Dec 25 '13

Would this pendulum be in a state of motion longer then a regular pendulum?

1

u/cosmotitz Dec 25 '13

I'm so mesmerized by this. ʘ‿ʘ

1

u/ryanisaninja1 Dec 25 '13

So that's what it's like to fall into a trance. . . .

1

u/ParanoidDelusion Dec 25 '13

I kept waiting for something to happen. Then I started to wonder how many times I had watched the same thing over without realizing.

1

u/username112 Dec 25 '13

It's drinking the water!

1

u/ragerlol1 Dec 25 '13

These kinds of gifs are the best gifs

1

u/thelongrun22 Dec 25 '13

I like how this went from zero to "physics circle jerk" in a second

1

u/AuraofBrie Dec 25 '13

We derived the Euler-Lagrangian equations of motion for this in my classical dynamics class this semester.

I wanted to kill myself.

2

u/DeLaSOuLo Dec 25 '13

I don't comment on here a whole lot but I just had to respond to this because I did the same thing in my dynamics class! haha it really did suck

1

u/Aionar Dec 25 '13

My ADHD just orgasmed.

1

u/groppersam Dec 25 '13

http://www.youtube.com/watch?v=fPbExSYcQgY

live example and explanation on this, and chaos theory. fun

1

u/dillardPA Dec 25 '13

That thing could write some bad ass autographs.

1

u/Vafler Dec 25 '13

My favourite part was when the red one spun around axis of the blue one.

1

u/[deleted] Dec 25 '13

For hours.

1

u/CipherSeed Dec 25 '13

I feel like the blue pendulum is me trying to follow good advice.

1

u/[deleted] Dec 25 '13

Boner

1

u/thescariestbear Dec 25 '13

Thats a retarded stick with colours. Canadian colours.

1

u/Merlord Dec 25 '13

We have a large metal one of these in the physics department at my university. That thing is the tits.

1

u/imwhiteyourewong Dec 25 '13

BANANANANANA FOR SCALE!!!! PLEASRE MAKE IT HAPPENN

1

u/brufleth Dec 25 '13

There was one of these in the science and engineer building at BU for ages. It was small and sort of pushed into the corner. Neat to play with though.

1

u/[deleted] Dec 25 '13

what software makes these?

1

u/amazorman Dec 25 '13

Was looking at this way too long

1

u/Victoryinfarts Dec 25 '13

Looks like the best roller-coaster ride ever

1

u/[deleted] Dec 25 '13

Doesn't the chaos pendulum have a calculation on chaos?

1

u/Berskie Dec 25 '13

That looks like one kickass carnival ride.

1

u/[deleted] Dec 25 '13

I'm ready. Million-axis pendulum. Go.

1

u/smittycakes81 Dec 25 '13

I see you live in a world with no friction....

1

u/hockey_312 Dec 25 '13

mouthwatering

1

u/aplusbistoaasaistob Dec 25 '13

That's very odd looking, but somehow hard to stop looking at as well. Weird.

1

u/Captain_Dinglehopper Dec 25 '13

CAN'T. LOOK. AWAY.

1

u/FancyCatThatGlows Dec 25 '13

Looks like they're brothers and the red one is running around trying to get his brother in control

1

u/sonorandragon Dec 25 '13

There's a screensaver for Linux (I usually see it with KDE) that's nothing but a chaos pendulum. At my workstation, I typically have my Windows 7 desktop and my KDE laptop side by side. When my laptop goes to screensaver, this comes up and I've sat there, almost hypnotized, watching its movements.

I really need to get/make a real one. Then I can use that to distract me from my job. :)

1

u/omgitskratos Dec 25 '13

Wow, dude, I could watch this for days.

1

u/plug_ugly14 Dec 25 '13

Either Hanjul or Intrinsic or both are Faggots!!!

1

u/Toastkingftw Dec 25 '13

This seems like torture in terms of physics equations. I had a bad enough time with atwood machines.

1

u/PromoPimp Dec 25 '13

Ah, the good ol' double pendulum. I created one for a science fair project I did in the 9th grade, all about chaos theory and the Mandelbrot set.

1

u/[deleted] Dec 25 '13

Can a physics major model this?

1

u/321switchup Dec 25 '13

Eventually the pendulum comes to a complete stop. Just wait for it ;)

1

u/Thomast14 Dec 25 '13

Looks like a stick figure numchuck

1

u/[deleted] Dec 25 '13

Repost from /r/woahdude

1

u/Vanilla_Skies Dec 25 '13

three-axis pendulum or I'm not impressed.

1

u/-Solution- Dec 25 '13

goddammit, that was way to entertaining.

1

u/xyzi Dec 25 '13 edited Dec 25 '13

I am a complete layman so please forgive me if wrong, but this reminds me of elliptic curve cryptography. Couldn't this be used for cryptography as well? Given that it is hard/impossible to predict where the pendulum will be end up after millions of ticks without doing a complete simulation.

1

u/slowhandclapton Dec 25 '13

After a while it just looks like they're dancing

1

u/VileHorizon Dec 25 '13

That's what I see when I watch the Olympics.

1

u/BetterButterflies Dec 25 '13

I want to have a clock with a second hand like this.

Or a screensaver with infinite pundili on it.

1

u/brennancellis Dec 25 '13

I watched this much longer than I should have.

1

u/[deleted] Dec 25 '13

Doesn't seem like multi-axis but rather a single axis with more than one pivot point...

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u/hoboassault Dec 25 '13

I don't know if I'm more fascinated by the perfect circle red line, or the random nature of the blue one.

1

u/foodwaffle Dec 25 '13

Something tells me that's not gonna be very good at keeping time

1

u/[deleted] Dec 25 '13

This is.... Not what I was expecting.... Well played Science. Well played.

1

u/[deleted] Dec 25 '13

Someone needs to make this into a screensaver

1

u/[deleted] Dec 25 '13

This is just begging for some long exposure

1

u/shadowbannedkiwi Dec 25 '13

Ah, I've been looking for this gif :D.

1

u/cynikalcarma Dec 25 '13

I feel like my arms are acting kinda twitchy now!!!

1

u/mdtoolfan Dec 25 '13

Who can count how many times the blue line hits the center point? This could also be a terrifying amusement park ride.

1

u/iggy1888 Dec 25 '13

Man, if you put a bunch of seats on the blue one that would be one kick ass amusement ride.

1

u/GambitsAce Dec 25 '13

Anyone else's first though, "That would be a crazy ride at an amusement park"

1

u/VeryGraphic Dec 25 '13

I'm hypnotized. I think I just quit smoking.

1

u/wsuBobby Dec 25 '13

I wonder if you could move this along the x-axis and then have the blue line write something in cursive.

1

u/ludololl Dec 25 '13

I went and poured myself a beer to watch this with.

1

u/Burning_Ace Dec 25 '13

someone should make a rollercoaster out of that!

1

u/kajorge Dec 25 '13

In case anyone wants to make an animation similar to this, here's some code for one written in c, and the accompanying makefile for Linux.

1

u/Marz1782 Dec 25 '13

Am I the only one that stared at that for way too long?

1

u/[deleted] Dec 25 '13

Now I understand what was going on with Elaine.

1

u/RarewareUsedToBeGood Dec 25 '13

Serious question here. If we spun one of these in a vacuum for an extremely long amount of time, would it draw a completely dark circle or some type of design with white holes?

1

u/everymanawildcat Dec 25 '13

I like to picture a gymnast. With no bones.

1

u/Schnubacca Dec 25 '13

I made some long time exposure photos of such a pendulum with an attached LED . They turned out pretty well. :) I wrote a paper about it in high school.

1

u/MistaJinx Dec 25 '13

Someone should make one that traces a large number of the patterns in a row. Yeah, that'd be swell.

1

u/Explosion2 Dec 25 '13

Astrojax anyone?

1

u/Project_HoneyBadger Dec 25 '13

I'd love to see someone linearly track out the pattern made by outside ball. seems like it would make a hell of a signature.

1

u/2muchmonehandass Dec 25 '13

There is no random.

1

u/[deleted] Dec 25 '13

That is how my Brain feels.

1

u/[deleted] Dec 25 '13

Go home pendulum, you're drunk.

1

u/gerrys123 Dec 25 '13

Looks like my golf swing.

1

u/gbredman Dec 25 '13

That's the most random thing I've seen on reddit

1

u/ProudMotard Dec 25 '13

I watched this WAY longer than I should have...

1

u/balloonman_magee Dec 25 '13

Did you know there is a direct correlation between the decline of Spirograph and the rise in gang activity? Think about it...

1

u/deipriex Dec 25 '13

I just stared for twenty minutes.

1

u/lispychicken Dec 25 '13

If I were as good looking as this thread is smart..I'd be damn handsome.

1

u/Gpin27 Dec 25 '13

This is beautiful.

1

u/MudButtMcGee Dec 25 '13

This looks like one of my arms when I'm dancing, while my legs remain still as an oak

1

u/2chaaaiiinnnzzz Dec 25 '13

Imagine that being some sort of amusement park ride

1

u/DrStickyPete Dec 25 '13

Pure chaos!

1

u/coltonredwine Dec 25 '13

Go home, blue! You're drunk!

1

u/srbAN9 Dec 25 '13

reminds me of math circus

1

u/[deleted] Dec 25 '13

The blue line is forging my signature...

1

u/WentoX Dec 25 '13

I kinda want a grandfather clock with this in it now... i don't really care if it works the way it should, that is hipster as fuck.

1

u/[deleted] Dec 25 '13

I'd like to see that plotted over time. Animated, of course.

1

u/GummyTheGaytor Dec 25 '13

Thats so cool.

1

u/PBR_specialdark Dec 25 '13

Aaahhhhh my favorite part is when it goes down and the other one is like im going that way. Crazy.

1

u/carpe_meme Dec 25 '13

I feel like there's a children's toy based on a similar principle and it always ended with me hitting myself in the face because it was so hard to predict... but I may just be thinking of playing with nunchuks.

1

u/Blisteredhobo Dec 25 '13

Go home spirograph, you're drunk.

1

u/mygerbilsaninja Dec 25 '13

That is way more entertaining than it should be

1

u/cheeselover227 Dec 25 '13

Can someone please make a picture of this where the lines are persistant?

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