2924: Pendulum Types

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Pendulum Types

Title text: The creepy fingers that grow from a vibrating cornstarch-water mix can be modeled as a chain of inverted vertical pendulums (DOI:10.1039/c4sm00265b) and are believed to be the fingers of Maxwell's Demon trying to push through into our universe.

Explanation

This explanation may be incomplete or incorrect: Created by CREEPING TENDRILS OF STARCH - Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks.

This comic shows and describes several pendulums. The first three are actual physics models, while the last one is made up for the comic.

The simple pendulum consists of a joint, rod, and weight, and when released, it swings in a regular fashion. These were used commonly in pendulum clocks to keep time.

The double pendulum consists of 2 joints, 2 rods, and a weight, and when released, it swings in a chaotic fashion. Interestingly, this follows by the mathematical definition of chaotic, being that small changes result in vast differences. This pendulum is thus nearly unpredictable. It does not have any real life applications.

The inverted pendulum consists of a simple pendulum that is placed upside down, with some apparatus underneath moving it side to side to keep it upwards. If left unpowered, it will fall, hence the "unstable" part.

Transcript

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Discussion

Example of the creepy fingers: https://youtu.be/3zoTKXXNQIU?si=MgZgSRFFyxrNGhw3 172.70.175.25 12:58, 24 April 2024 (UTC)

If that's as creepy as Maxwell's Demon gets, you have to wonder if he's related to Gachnar: https://www.facebook.com/watch/?v=3090746901188850 172.70.91.12 14:47, 24 April 2024 (UTC)

Fortunately, Maxwell's Demon can be banished with a silver hammer. 172.69.246.151 15:08, 24 April 2024 (UTC)

Is this a Dungeons and Discourse reference? Psychoticpotato (talk) 18:23, 24 April 2024 (UTC)

Ultimately that'd be from The Beatles... (Don't know that particular D'n'D thing, if that's a thing. Bet that's also a reference of its own.) 172.71.242.70 18:46, 24 April 2024 (UTC)

If by "Dungeons and Discourse", the webcomic from Dresden Codak is meant (two one-offs), it's not mentioned in those two strips (just Laplace's Demon). (Edit: I found Maxwell's demon (summonable, even), but not silver hammer, in this unofficial implementation of the game being played: https://web.archive.org/web/20220928185446/https://slatestarcodex.com/Stuff/DDThird_Edition.pdf) If, instead, the YouTube channel is meant, it doesn't seem like they review that level of content, based on the titles. 172.70.127.68 14:31, 5 May 2024 (UTC)

Thank you, whoever completed the transcript. I didn't know the bullet tag and the comics are starting to get more complicated to explain and transcribe. So again, my thanks. <3 Z1mp0st0rz (talk) 16:12, 24 April 2024 (UTC)

David Acheson showed that any finite number of inverted pendulum segments can be made stable through vibration. related video here: https://www.youtube.com/watch?v=BJ7_fFABc9s&t=0s 108.162.238.131 17:23, 24 April 2024 (UTC)

Considering that Maxwell's demon can reverse entropy, I welcome our new demon overlord. We must all put more starch onto speakers! Fabian42 (talk) 18:10, 24 April 2024 (UTC)

Summon Ba'al the Soul-Eater to rule beside Maxwell's Demon!!!!!!!!!!!!!!!! Z1mp0st0rz (talk) 19:22, 24 April 2024 (UTC)

Should we use "pendula" as the plural to "pendulum"? 172.70.110.47 (talk) 21:38, 24 April 2024 (please sign your comments with ~~~~)

The plural of pendulum would be penduli, as it is Latin second declension.172.70.42.128 13:31, 26 April 2024 (UTC)

Would it not still be pendula, because it is of the neutral gender?

I apologize. You are correct. I was thinking of the male gender. 172.70.135.51 13:11, 1 May 2024 (UTC)

Should we mention that Netflix's airing of 3-body problem means people are probably more interested in chaotic systems right now?--172.70.39.36 03:01, 25 April 2024 (UTC)

Plus there's the US elections coming up...162.158.95.97 09:09, 25 April 2024 (UTC)

A double pendulum requires 2 weights, and additional one at the center joint. Surprisingly Randal has that wrong. 172.69.60.177 00:25, 26 April 2024 (UTC)

Traditionally, I've seen that fudged by a massive 'link'. In fact, the two pendulum lengths can be dense bars, without even a terminating weight.

This obviously changes the dynamics, as the idealised pendulum has all its mass in the swinging weight at its end (the CoG in its centre), a swinging bar is 'twice as long as its swing-factor' (CoG is half way along). So a two-bar double-pendulum (assuming negligable weight bonus/deficit in the mid-joint mechanism) is a half-length-effect secondary pendulum sat at the end of an extended primary.

As if •-O-•-O-, •=joint (zero mass, zero size), -=extension (zero mass, zero flexibility), O=mass (zero size, zero flexibility)...). This is obviously differently 'tuned' to •—©—O (©=weight+joint, at a point).

...or else the inter-length joint, though not obviously so, is suitably overwhelmingly massive to do weight+jointing. 172.69.43.185 02:25, 26 April 2024 (UTC)

Two weights needed for a double pendulum [1]. As drawn, assuming a spherical cow in a vacuum, it's a simple pendulum, with two lightweight bars joined by a lightweight hinge, supporting one weight at a constant distance (as the hinge never bends) from the top support. -- Neil UK (talk) 16:53, 26 April 2024 (please sign your comments with ~~~~)

I wonder if Randall was playing Don’t Starve whose main antagonist is Maxwell, described as demonic, whose world is filled with nightmare themed contraptions, and which feature an entity called night hands that are creepy long fingers that come out at night to snatch your light. 162.158.158.234 (talk) 01:55, 26 April 2024 (please sign your comments with ~~~~)

Maxwell's Demon ultimately refers to a though experiment about entropy, and may very well be the inspiration for the Don't Starve character. However, here, it is most likely that he is referring to the thought experiment.172.70.42.129 13:40, 26 April 2024 (UTC)

There are white dots on the frame of the top piece of the Nightmare pendulum, but they aren't evenly spaced, which is indicative of ... something, maybe. Perhaps they are balls moving around a channel in the frame, to add to the chaos? 172.70.126.167 16:38, 26 April 2024 (UTC)

I would ALMOST take 5hem as markings, like a clock, but the gaps and the two close together at 4:30 makes me think you're right, they're balls rolling around further messing with the balance and adding to the chaos. NiceGuy1 (talk) 05:34, 28 April 2024 (UTC)

Maxwell's demon would indeed violate the laws of thermodynamics. If he was a real demon, i.e. was able to do the task effortless. --172.71.246.39 20:06, 1 May 2024 (UTC)