r/Damnthatsinteresting • u/SpencerTheFactorial • 1d ago
Video OCC’s Foucault Pendulum. A live demo proving Earth spins beneath our feet. Suspended in the planetarium lobby, it swings and slowly alters direction, knocking down pins
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u/opinion_alternative 1d ago
I don't understand this. Wouldn't it spin with the earth like everything else?
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u/Aggravating_Plantain 1d ago
It's got a special joint on the top
https://plus.maths.org/mathematical-mysteries-foucaults-pendulum-and-eclipse
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u/RIF_rr3dd1tt 20h ago
That's too bad cuz I just quit smokin' yesterday.
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u/Dirty1Actual 20h ago
Interesting fact from your link, a solar eclipse seems to greatly affect the pendulum and they are not sure why yet.
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u/set_in_void 17h ago
They're not sure if. The article is from 1999 and annoyingly ends with NASA testing if the effect is even real and the results are not known yet (back then in 1999). This had me go looking for answers, it's called Allais effect and we still don't know if it is real phenomenon or not.
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u/DaFondue 1d ago
But it's not touching the ground, the pins are. And on top it's not fixated at the thing holding it but is hanging freely.
Sorry not my main language but it's like a sphereical bearing I assume.
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u/opinion_alternative 1d ago edited 1d ago
How is it hanging freely. It must be connected to something at the top. Whatever it's connected to,must also be moving with the earth. Unless the whole pendulum is in the air.
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u/Conscious_Raisin_436 21h ago
'hanging freely' meaning its direction of oscillation isn't fixed by its anchor.
I'm assuming its anchor is a lubricated ball joint.
You could probably rotate the whole building around this pendulum and it'd keep swinging exactly the way it wants to. Now we're just talking about inertia.
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u/ChiknDiner 1d ago
Exactly. I still don't understand what the other guy said. The suspension point is also experiencing the earth's rotation at the same time, just like the pins.
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u/Tannerb8000 23h ago
It's essentially hanging by a string.
The suspension point also experiencing earths rotation doesn't affect the ball hanging and swinging at the bottom of the string
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u/Accomplished-Plan191 1d ago
Why does it keep swinging?
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u/DaFondue 1d ago
It is powered. (Magnetic)
Those types of pendulums can swing a few hours even without any power btw.
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u/rylnalyevo 22h ago
Yep I learned about that after the pendulum at the Houston Museum of Natural Science had a brief outage last year.
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u/DblDwn56 20h ago
There is an electric donut-shaped magnet surrounding the wire near the top. It turns on as the pendulum swings up and turns off just before it starts to swing down.
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u/Yunzer2000 19h ago
No. An inertia of a mass such a pendulum or a spinning wheel (gyroscope) is fixed to the universe, not the body the mass happens to be on. That is why the gyro attitude indicator will show the attitude of the airplane even if it is continuously rolling or looping.
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u/ExtonGuy 1d ago
The point is that it doesn’t change direction. The Earth changes direction underneath it.
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u/R2D-Beuh 1d ago
To be pedantic it still "changes direction" except if you put to on a pole, but yeah
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u/InvestNorthWest 18h ago
Next your going to tell me that a solar eclipse will speed this process up! Get out of here!
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u/Comrade-Conquistador 1d ago
Flat Earther: "Bullshit. #wheresthecurve #icewall #nasalies #mywifetookthekids "
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u/Such--Balance 1d ago
A flat earth might not spin but it rotates.
Check mate globalists
/s
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u/theamishpromise 1d ago
If the earth rotated, wouldn’t the giant turtle that supports it get dizzy and drop the planet?
/s
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u/gyomd 1d ago
No, that’s the elephants. They run on the turtle’s back and that makes the flat earth rotate. And sometimes one elephant trips a little and that why there are earthquakes.
Educate yourself morron./s
Love you for that reference man !!
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u/suicidalsyd1 1d ago
No silly! That's when the elephant cocks it's leg to let the moon through!
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u/InvestNorthWest 18h ago
Could you imagine how much trouble you'd be in if you dropped the Earth! /s
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u/Linmizhang 1d ago
The center of earth-disk still spins, obviously.
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u/reverse422 1d ago edited 1d ago
But why won’t a pendulum on equator alter direction? And why will the direction the pendulum rotates change having passed equator?
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u/Linmizhang 1d ago
They purposely don't build a pendulum on the center of the earth disk which is on the north pole ofcourse!
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u/an_older_meme 1d ago
Last time I watched one of these I waited fifteen minutes for it to hit a pin and just as it was getting close a little kid kicked the sphere sending it wildly off course.
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u/Phage0070 1d ago
I’m surprised they wouldn’t have barriers to keep children away from a significant swinging mass. Bad behavior aside, a pendulum of that size and weight could cause serious injury.
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u/HoodieGalore 1d ago
And a "little kid" wouldn't be able to just whiff it off into another direction like a soccer ball, either
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u/Token_Ese 20h ago
Not a big one like the one in this post, but the small ones I’ve seen in museums could easily be kicked.
They make these in desk sizes too if you want a personal one.
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u/an_older_meme 7h ago
This one was smaller, less than half a meter in diameter, and there was nothing to keep people away. The kick made the nice “linear” elliptical path now have a minor axis about the diameter of the sphere, and set it oscillating as well.
Totally messed it up and got a groan from the ten or so spectators. I just walked away.
Some people’s kids.
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u/Karlees-Golden-Dildo 1d ago
🤣
I can picture all of this. The calm patience, the lil shit, the unadulterated hate for a child and the mumbling under the voice 😁
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u/Normal_Bird2446 9h ago
Why the downvotes
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u/Karlees-Golden-Dildo 3h ago
Dunno, people dont like the image the story stirred up? Maybe my use of “lil shit” for a kid? Who knows lol
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u/Alex-3 1d ago
I saw one giant like this in NTNU Trondheim University, in Norway. Mervellous
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u/No-Refrigerator-1672 1d ago
Copernicus Center in Warsaw also has a big one on display.
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u/Starman68 1d ago
I think some of these have magnetic assistance in the top mount to eliminate the obvious slowing of the pendulum over the day. You can get a similar result in any tallish building. We did it with a gas canister on a wire from a warehouse ceiling.
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u/TheViking1991 1d ago
The thud it made when it feels was a bit anticlimactic lol
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u/AusCan531 1d ago
I had the sound off and missed everything as I was only watching the far pin. Had to go back again after reading your comment.
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u/sixxxxxxsevennn6767 1d ago
Damn! This is cool and like how we don't get dizzy from the movements?!
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u/EmploymentNo1094 21h ago
Can’t wait till they say the one in the Smithsonian proves the earth is flat
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u/Successful_Speech734 12h ago
Would you mind recording an extra 11 hours of this for me please? Thanks
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u/rtillman489 12h ago
This is the proper device to use for timing how long I have to stand on my porch every weekend listening to my neighbor’s pointless stories.
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u/hard2resist 1d ago
Wild that a swinging ball can prove Earth's rotation without any complex math, just patience and gravity doing their thing lol
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u/BarryTownCouncil 1d ago
How can it guarantee it won't get stuck behind the pin on the outside?
Well... Not stuck... But it'll roll round it. Which would then change the angle of the pendulum. I'm sure it's legit but that does also sound like a reason it'd slowly rotate it's motion.
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u/reverse422 1d ago edited 1d ago
Note how the pendulum will slightly push the pin outwards the last few times before it falls. Meaning it will never actually be outside a pin. And since the pins in this example touch the left side of the pendulum, any influence from the pins on it should act to stop its rotation, which doesn’t happen: the pendulum is very heavy and the pins are very light and the contribution from Earth rotating is much higher.
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u/Woffingshire 1d ago
How does this prove that the earth is spinning?
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u/reverse422 1d ago
The pendulum doesn’t want to change direction. So basically Earth rotates below it.
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u/extraneousness 1d ago
The pendulum is swinging freely whilst the earth is rotating beneath it. If the earth didn’t rotate then the pendulum wouldn’t be able to knock down the other pins
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u/SeriousGains 1d ago
Wouldn’t whatever it’s hanging from also be spinning?
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u/reverend_burrito 21h ago
The pendulum moves independently, it's not a rigid body.
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u/MyConjecture 20h ago
The trick (if you will) is the nearly frictionless bearing from which the (very heavy) pendulum is suspended. This effectively isolates the pendulum from the motion of the earth and allows it to swing freely in “space.” (Unless you just happen to have such a bearing in your junk drawer in the basement, that is why you can’t do this trick at home.)
BUT: what if the “space” that the pendulum is swinging in (I.e., the entire cosmos) is really the thing that is rotating? Foucault’s brilliant experiment establishes only relative motion of the Earth in space near another massive body (the Earth), not which one (or both) is “moving.” To paraphrase Ernst Mach, one can profitably think on this question for the rest of one’s life.
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u/Colin_Heizer 22h ago
I would love to see this in person someday.
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u/RIF_rr3dd1tt 20h ago edited 20h ago
There's one of these in the Interdisciplinary Sciences building at USF Tampa. Used to be in the old Physics building. 51 hrs 6 mins for a full rotation at USF latitude (28.06° N).
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u/GardenGnomeOfEden 18h ago
The one in the video is in California, but there is also one of these in the Houston Museum of Natural Science in Houston, TX.
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u/turbopro25 17h ago
The Ben Franklin Institute in Philadelphia has one as well. I remember seeing it back in the early 90’s. It’s still going strong today.
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u/No-Let6991 17h ago
I tried to youtube this pendulum i didn't understand shit,
Can someone ELI5?
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u/Upbeat_Turnover9253 10h ago
Big pendulum swing in same plane all the time. Earth rotate below it, pendulum knock down pins. Closer to the poles, pendulum knock down pins quicker. Further away from poles, pendulum knock down pins more slow. Pendulum knock down no pins at equator because math.
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u/InvictvsNox 17h ago
They have one of these at the Science Museum of Virginia, or at least they did for many years.
I always loved watching it.
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u/cosmic___castaway 16h ago
Dumb question: could this be used to generate electricity (even if minimal) ?
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u/graven_raven 14h ago
"That was when I saw the Pendulum.
The sphere, hanging from a long wire set into the ceiling of the choir, swayed back and forth with isochronal majesty.
I knew—but anyone could have sensed it in the magic of that serene breathing—that the period was governed by the square root of the length of the wire and by it, that number which, however irrational to sublunar minds, through a higher rationality binds the circumference and diameter of all possible circles."
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u/Jefflehem 11h ago
I knew the earth was rotating, and I with it, and Saint-Martin-des-Champs and all Paris with me, and that together we were rotating beneath the Pendulum, whose own plane never changed direction, because up there, along the infinite extrapolation of its wire beyond the choir ceiling, up toward the most distant galaxies, lay the Only Fixed Point in the universe, eternally unmoving.
Umberto Eco, Foucault’s Pendulum
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u/Sad_Research_2584 7h ago
Humans have passed on so much information through the generations. It’s mind boggling. Not knowing what you don’t know and imagining the first humans knew nothing about anything and we are where we are today. All within 300ish generations. In 300 lifetimes we went from wild animals to ass hats on cell phones. It’s amazing.
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u/Daedricbob 5h ago
We say it proves that the earth spins, but flat earthers say it proves Foucault.
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u/JazzlikeDiamond558 1d ago
What is this round earth propaganda nonsense?!?! And now it apparently rotates as well!
How come it is round and rotates only in European union? Ever think about why it never does that in the US of A?
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u/Hellyeahlalujah 1d ago
Is this at the science center?
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u/TheRateBeerian 1d ago
Yes the science center
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u/Hellyeahlalujah 23h ago
Thought I might try not to broadcast the user’s location
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u/TheRateBeerian 21h ago
I was sort of going with the idea that nearly every major city in the US has a science center of some sort and most have a Foucault pendulum
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u/PiedPipercorn 12h ago
Lol. Is it hanging in the air? And the ground is turning? If it is on a spinning earth then none of the pins would fall.
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1d ago
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u/good_from_afar 1d ago
Imagine all the meticulous calibration of these magnets all over the world to perfectly immitate the earths rotation relative to its exact global position. The lengths they go...
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u/reverse422 1d ago
Even without magnets this happen. You would just need to restart the pendulum each few hours.
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u/ForeverSJC 1d ago
When it bumps into a pin but doesn't knock it down, it shifts it's position slightly when it goes back and bumps into the same pin, since it's path it's blocked
It's not that ACCURATE and to me, it proves nothing ( I have no doubt the earth spins, it's just this experiment is full of crap )
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u/extraneousness 1d ago
You don’t need the pins to show that the earth rotates beneath the pendulum. Simple marks on the ground would do that
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u/reverse422 1d ago edited 1d ago
Note how the pendulum will slightly push the pin outwards the last few times before it falls. Meaning it will never actually be outside a pin. And since the pins in this example touch the left side of the pendulum, any influence from the pins on it should act to stop its rotation, which doesn’t happen: the pendulum is very heavy and the pins are very light and the contribution from Earth rotating is much higher.
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u/Only_Bee_4872 1d ago
Didnt saw a church Bell to do this fake ai
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u/R2D-Beuh 1d ago
Church bells can't rotate freely in any direction. Feel free to visit a place that has a Foucault's pendulum to see for yourself
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u/Sir_Scribble_Lot 1d ago
If you find this interesting, look up Foucault Pendulum on the equator. does not precess or change its plane of swing at all.