Editing 2201: Foucault Pendulum
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==Explanation== | ==Explanation== | ||
+ | {{incomplete|Created by the International Earth Rotation and Reference Systems Service. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}} | ||
+ | [[Black Hat]] is attending what appears to be a guided tour of a museum with a {{w|Foucault pendulum}}. [[Megan]] is explaining to him, [[Cueball]] and [[Ponytail]] about the device which demonstrates the rotation of the Earth. | ||
− | + | Black Hat, being himself, immediately sees an opportunity to cause chaos and seizes it with both hands, quite literally — as he grabs the pendulum which causes the others to shout after him to stop. At first this would seemingly be for fear of ruining the delicate demonstration. However, in the final panel, the [[:Category:News anchor|news anchor]] [[Blondie]] reveals to us that by arresting the motion of the pendulum, Black Hat has somehow stopped the rotation of the Earth. However, it was only briefly since the local {{w|geophysicists}} managed to wrestle him down, and then it must be assumed they quickly restarted the pendulum and thus the Earths rotation. | |
− | + | This of course is blatantly impossible since the Foucault pendulum's motion is tied to the Earth's rotation, not the other way around (at least in any significant way, see below). A Foucault pendulum is a regular {{w|pendulum}} that swings from a bearing that allows rotation in any direction, like your shoulder joint instead of your elbow. But has been set up to display the Earth is rotating beneath it. If the Earth were stationary, it would continue to swing over the same portion of the Earth as when it was released, but any pendulum will continue to swing in the same plane in space compared to the distant fix stars. So because the Earth moves beneath it (and in comparison to those distant stars), over the course of the day the pendulum's motion gradually changes direction relative to the room. The low-resistance bearing doesn't allow the rotation of the Earth to affect the motion of the pendulum, so it tends to stay aligned to its original inertial reference frame according to the fix star (far away in space) rather than to the rotating surroundings which follow with the Earth's rotation. If the pendulum is at one of the poles, it will take a full day to move one full round. At the equator there is no movement, and in between it will take longer than 24 hours (24 hours divided by the sine of the latitude). | |
− | + | The fact that the Earth's rotation does not influence the motion of the pendulum does NOT mean that other things can't affect it - for example, by running up and manually repositioning the pendulum. Of course, the apparent rotation of the pendulum's plane relative to the Earth is an effect of the planet's motion, rather than the cause of it. Thus, stopping a Foucault pendulum manually does not entail pausing the rotation of the Earth. | |
− | + | If it were somehow possible for a Foucault pendulum to control Earth's rotation (see above), Black Hat would probably not want to alter the momentum of the pendulum if he where not at one of the Earths poles. That is assuming he was told that it was related to Earth's rotation and assuming that he would prefer to preserve his own life over making chaos (unless due to his advanced technology, he can resist being slammed into a nearby wall at the speed of sound). The reason why is because if the rotation of Earth were to be stopped for even very short amounts of time (a few seconds), it would cause everything on Earth that wasn't bolted/fastened to the ground to move eastward compared to the now stationary ground. If they are near the Equator it would be at a speed of 300-360 meters per second, likely causing the death of most lifeforms on Earth beneath a certain latitude almost instantaneously. Those close enough to the poles may survive though. Also this will cause massive windstorms, tsunamis, volcanic and tectonic events on a scale not previously observed on Earth. This would likely cause a mass extinction event and wipe out 99% of humanity in the initial events (which would eventually lead to our extinction). It is possible that Black Hat's grabbing the pendulum would cause a gradual slowing prior to stopping, minimizing the issue (though this doesn't seem to be the case), but the results would still be catastrophic, as the aforementioned events are still likely to occur (specifically the tsunamis and volcanic events). However, as mentioned above, if this pendulum was located at the South pole, then Black Hat and other people around him would not be affected immediately, and he could both do it, survive and be stopped again. The question is if there would be any more news stories to cover this given what would happen to the rest of the world! If there was no-one to readjust the pendulum's rotation, then certain events would happen after the initial damage (see this video [https://www.youtube.com/watch?v=q_T7L8rt1Ec]). [[Randall]] previously covered this scenario in detail in his [[what if?]] book, see [https://io9.gizmodo.com/xkcds-creator-explains-what-would-happen-if-earth-stopp-1625068208 XKCD's Creator Explains What Would Happen If Earth Stopped Spinning]. | |
− | + | To be completely correct, the angular momentum of the Earth+pendulum system is constant, so that when Black Hat "stops" the pendulum rotation with respect to the Earth, he actually transfers to the pendulum some of Earth's angular momentum, thereby ''slightly'' slowing Earth's rotation. But the order of magnitude of that effect is (at most) in proportion of the mass ratio. Earth's mass being ~6.10<sup>24</sup>kg, the effect would be beyond the twentieth decimal place for any practical pendulum, and therefore go totally unnoticed. | |
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− | + | In the title text the [https://www.iers.org/IERS/EN/Home/home_node.html International Earth Rotation and Reference Systems Service] is mentioned. It is an organization providing standards for global time and reference frames; this organization would have a very rough day after the fiasco with Black Hat. The title text refers to a (probably) fictional paramilitary enforcement arm of this organization and the foolishness of tangling with such a force. If Foucault pendulums were somehow able to influence the rotation of the Earth in any measurable way, the IERS enforcers would probably strictly control their installation and monitor their use (and misuse). Black Hat is likely in for a rough day as well. It seems like some on this team are geophysicist since they where the one that took Black Hat down. | |
==Transcript== | ==Transcript== | ||
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:Character off-panel 1: Hey! | :Character off-panel 1: Hey! | ||
:Character off-panel 2: Stop him! | :Character off-panel 2: Stop him! | ||
− | :Sound: ''Grab | + | :Sound:''Grab'' |
:[Blondie as a news anchor uses her held out hand to indicate Black Hat who is shown on a screen next to her. There is a caption in two lines above it. The first line in normal text, the second line in white in a black rectangle. There are further unreadable text below the picture.] | :[Blondie as a news anchor uses her held out hand to indicate Black Hat who is shown on a screen next to her. There is a caption in two lines above it. The first line in normal text, the second line in white in a black rectangle. There are further unreadable text below the picture.] |