In theory, is there any reason why this device couldn’t be made , if not infinitely large, at least inconceivably large … like a mile high ?
In practice, it would be an obvious non-starter for many many reasons, but in theory … would a mile high scaled up Chaos Pendulum function in the same way as the one in the video ? … or are there some physical laws which come into play which mean that it couldn’t work ?
A mile-high version would not violate any laws of physics.
If made from known materials, its behavior probably wouldn’t closely match the one in the video due to issues like strength of the bearings, mass and stiffness of the bars, aerodynamic drag, etc.
I believe atmospheric drag is going to be a huge issue if you build one a mile-high on Earth. This drag would make it not work the same as the smaller models. You would have some serious issues with the bottom tip breaking the sound barrier for a mile high model if it tries to spin at proportionate speeds as the smaller model in the video. I don’t know if a model that big would actually break the sound barrier in the lower tip or if the drag would stop it from working very well long before before it approached those speeds.
Are there many varieties of chaos pendula? I can’t view the video on this mochine, but as Google search shows plenty of cites for a “double pendulum” (one pendulum hanging from the end of another pendulum), including the Wiki page with an animated gif.
But I saw some sort of chaotic pendulum system in a museum once that was rather different. (At the Exploratorium in San Francisco some years ago, IIRC.) It had three fixed arms at 120 degrees to one another (that is, the three arms were one single solid piece of hard plastic), with a pendulum hanging at the end of each arm, and the whole thing mounted on an axle at the very center. There was a crank to turn the whole thing to rev it up. Then the three separate pendula would all start swinging highly erratically.
I just wanted to take this opportunity to provide proof that robots will, indeed, one day take over the earth.
I have seen that video before … it is the only video the poster has put up, and I call BS on it … no freaking way is it possible for these three pendulum arms to go into an upward vertical position and remain like that , robot control or no robot control.
The fact that none of the commenters seem able to deduce that the video is fake makes me despair .
I’ve watched it a couple of times, and frame-by-framed it. If it’s fake, it’s an astoundingly good one – the robot always moves (even in a frame-by-frame sense) the direction it should for the corresponding motion that results. It’s an impressive display, and it looks “wrong,” but I think your skepticism is unwarranted.
I am not saying that it is necessarily a video doctored image … it may well be some kind of magnetic on/ off switch thing which enables the pendulums ( sic … I hate the plural “pendula”) to maintain their " upward verticality".
It is just ***so ***obvious to anybody with any practical experience of engineering/mechanics/physics that this video is faked in some respect.
There is another video somewhere on Youtube of a chaos pendulum which keeps oscillating for upwards of ten minutes. I have posted a comment on Youtube about how fake it is … can’t remember the URL right now but I will edit this post if I find it.
There are many Youtube fakesters who derive satisfaction from purporting to portray scientific truth when in fact they are deliberately perpetrating a con.
A cool simulator for chaotic pendulums.
That’s not true. There’s also this one, which shows some other advanced algorithms.
I see no reason to believe this. Balancing a single pendulum is fairly easy for humans. Backing up a double trailer is a similar challenge and highly skilled people can do it at low speeds. A triple pendulum is more difficult yet but I see no reason to believe it’s impossible.
Here’s a list of the guy’s publications, in case you’re interested. If it’s a hoax, it’s an unbelievably sophisticated one.
The problem is that the bearings and materials will have to endure stresses many orders of magnitude higher than the small pendulum in the video.
How do you build a steel bar a mile long? How do you build low-friction rotating bearings that can support thousands of tons of weight?
When you double the height of the pendulum it will weigh 8 times as much, but the cross-sectional area of each member is only 4 times as great. Pretty soon you reach sizes where steel beams and titanium bearings are like cotton candy. The structures fail by bending and breaking.
The pendulum in the video is made out of solid metal arms, which means it is really heavy relative to its size. A giant one couldn’t be made of solid metal because it would rip itself apart. But that means an equivalent scaled-down version of it would be a light framework pendulum, which wouldn’t store very much energy.
Good points, and ones which I had pretty well taken into account when I said in the OP “In practice, it would be an obvious non-starter for many many reasons,”… you have listed some of these reasons.
However, the objective of the question was to ascertain whether in theory if such a device were constructed, what, if any, would be the physical laws making it unfeasible. It is perfectly simple to envisage such a structure, and although it would be a monumental , nay superhuman task in practice, in theory it ***could ***be constructed . But whether it could or could not be constructed is not relevant to the query.
So far, the observations about atmospheric drag, and the very good point about the tip of the pendulum breaking the sound barrier are the most interesting responses .
To reduce atmosphere drag, could it be built in a vacuum, on earth? Or in space, but close to a source of gravity equal to being on earth?
Agreed. Given the things computerized control systems can do like fly insanely unstable aircraft I don’t see this as beyond plausibility.
If it’s a fake, it seems like it would be pretty easy just to film the robot moving and dropping the pendulum and just playing it back in reverse.
If it’s not, could the robot move quickly enough that the centrifugal force straightens it out?
Some applications don’t scale up well.
https://www.youtube.com/results?search_query=mythbusters+newton’s+cradle