He is so engaged in his explanation about the mechanics of the pendulum, he forgets whish direction the Earth rotates , reminds me of my Professor. I love this channel.

4:49 "And I can't remember which way it [the earth] rotates." The humility of a true scientist!

okay I have an important question here. point at which the pendulum is connected ...is it not rotating along with the earth? did they use some kind of ball bearing or similar so that the plan of pendulum stays constant while the earth rotates? if the pendulum is connected to a ceiling of a building i expect pendulums plane to move along with the rarths rotation since the whole structure/building is moving as well. how did they make pendulum swing independently.

"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 pi, that number which, however irrational to sublunar minds, through a higher rationality binds the circumference and diameter of all possible circles. The time it took the sphere to swing from end to end was determined by an arcane conspiracy between the most timeless of measures: the singularity of the point of suspension, the duality of the plane's dimensions, the triadic beginning of pi, the secret quadratic nature of the root, and the unnumbered perfection of the circle itself." Rest in peace Umberto Eco.

Love the Foucault pendulum and love the way this professor (most physicists) explain it with body movement. Going as far as showing their backside 01:17 and tickling the North Pole 04:50 Don't know why we do it, but probably is related to our enthousiasm of physics. You may also notice the effect when watching timelaps movies of the interiour of large cathedrals with chandeliers hanging from long suspensions. Although the chandeliers (usually) don't swing you'll see them rotate around their axis until the counter torc of the suspension compensates for the Coriolis force and they jump back to their original orientation. Love physics, and love this channel. Always entertaining and educational!

Thank you for making this understandable. I always have difficulty understanding what other people are saying, even if the concept is simple, but I was able to follow you the entire time. You have an excellent way with words!

If the pendulum is attached to a foundation that's attached to the Earth. How is this experiment accurate considering the foundation is attached to the spinning Earth?

isn't the support with which pendulum is connected rotating along with the earth? it's really astonishing to observe rotation of earth being in the same frame of reference with the earth itself. thanks to foucault

I’m going to build one of these in an old building. It will have a vertical shaft where the line attaches. Once per cycle it will oscillate up and down a small distance, giving it the energy to run continuously, without introducing any lateral error. Also a ball bearing where the line attaches.

what kind of boggles my mind is that if the pendulum is not suspended in the air (say with a stationary balloon or something) wouldn't the structure its suspended on move with the earth as well cancelling out the effect. It obviously dosent, but.... why not

When the pendulum is at the equator, would it also be possible for the pendulum to slowly stop oscillating and then be sort of fixed hanging towards the west- because the earth is rotating towards the east Or would it just keep oscillating in the same plane (neglecting any sort of resistance).

wow, awesome video. got one at uni and very really understood what it was about... cheers

Excellent explanation. Amazing experiment.

@Jeeve79 The pendulum is not affected by the rotation of the Earth. As shown in the video, the plane of the oscillation of the pendulum is constant and so the pendulum is moving in an inertial reference frame.

It's also an interesting novel by Umberto Eco.

I like simple experiments that reveal something we can't sense. Nice job :)

Thinking back to prof B on a swing moving his weight up and down (nearer and further from the fulcrum), couldn' t you put a battery powered device on the big weight which moves a smaller weight in this way? Could keep going until the battery is flat. Not as elegant as the original, though.

So, how long does a pendulum take to loose all of it's energy? Is there an easy (or hard) way to calculate that? I imagine that a couple coefficients of fricative force apply, but please enlighten me.

In the video there was no mention of the pivot being free to rotate. I'm not sure if it makes a difference in a real situation but wouldn't the pivot rotate with the Earth if it was fixed, in turn making the string rotate. Wouldn't that cause the plane of oscillation to rotate too?

This is my favorite Professor by far. Always has a witty comment in explanations. Where is he? Hope hes well, would love to hear more from him.

Very cool. There is one of these at the Maryland Science Center. I remember it as a child...now I want to go back and see it again, understanding what it actually is.

We have a big one at the university of Salamanca in Spain

My physics teacher linked our class here, it's a funny feeling to know your teachers like he same youtubers as you.

Very well explained thank you i subscribed

Do a video on the various periods of rotation of the Foucalt pendulum and relate it to conservation of angular momentum. It would be a great video!

I still remember when I first saw this thing vividly in London Scientific museum. I was shocked. We now could think of many crazy ways of demonstrating the Earth's rotation, but who can imagine someone did this long before space age, in such an elegant way? If I saw this when I was much younger and somehow understood it, I would have become a scientist.

What a lovely explanation 😊

Awesome video. I was interested in the last point though (the relationship of the plane of oscillation with respect to Sun and distant stars etc). I watched that segment (towards the end) again and still am not sure what exactly is the conclusion. Is the plane actually constant with respect to the distant stars, or not?

Thank you for the video.

This is some amazing quality content

Treaty states no fire in Antarctica? I couldn’t find anything on this; anybody have any info?

So is it really only air friction that stops the pendulum in time? Are there other effects at a smaller scale that dumps energy out of the system (friction at the point where string is attached to the system for example?)- my point is, what if you did that experiment in a relatively vacuumed chamber? Modern vacuum chambers go down to ~1e-8 bar perhaps?

@physicsbugga wind is a factor to include on this myth something of larger scale like a hurricane vortex do they form in different direction depending side of equator they begin ?

Really enjoyed this clip. I am not at all mathematical but this made perfect sense to me. My son would really connect with this. Any tips on setting up a suitable experiment for a nine year old would be appreciated. Well done!

but does the roation or earth first rotate the string and then this string rotation is moved to the pendulum at the bottom and that is the whole causal link that changes the orientation of the pendulum ? nobody doesn't explain that if you have something on the string hanging then when you rotate the string it will rotate back to it's "zero" position.

That magnetic globe is the coolest lamp in the universe

Every physicist has their experiment that they get excited about when they hear about it. THIS IS MINE! How simple an experiment can one person do to explain so much. Greatest showcase of science ever.

so with a pendulum you can measure where north and south, east and west are, cool and also at which latitude you are

But the support for the pendulum is also rotating....so its the relative rotation that the pendulul swing captures ? or please clarify even at the North and South Pole the Pendulum is attached to the earth and is not floating in space

Would it be possible to cut down the friction of the air in a vacuum to keep the pendulum moving for a longer period of time?

@mvszao as far as I can tell it uses a 1 magnet in the stand, the top of the globe has some type of metal probably steel or iron and a electric force which i assume flips the fields so quickly that it repels and attracts so that it can not move.

can you make it in a vaccum chamber? Remove the air resistance, will it make go for 24 hours?

If the suspension point of the pendulum is fixed, doesn't it acquire a torque as the Earth rotates, or is it the torque that causes the pendulum to change the direction of its swing? What if it was suspended on a frictionless, torqueless mount?

What if you make the Pendulum swing in the North South plane at the equator?

@mrblisterfist counterclockwise is used for 2D but what's used for 3D? if the earth rotates counterclockwise from the north pole, it is the opposite direction from the south pole.

@eltotoX Because the stars experience such a small acceleration as they orbit the galaxy, using them as a reference is a very good approximation to an inertial reference frame (non-accelerating, non-rotating). The stars aren't special, they just make a useful reference. Hope that helps.

6:13 - I like the way he's standing

when the earth rotates, does air rotate with it? I have seen little toys and such (kind of like the globe in the video) that can levitate, if someone was to up a mark on the levitating toy, after 24 hours would the mark be pointing in a different direction?

As much as I love the quantum mechanics/quantum field theory videos, I still find the classical mechanics videos just as interesting.

For the direction of the tangential velocity you can use a right-hand-grip-rule... if you imagine your thumb is in the same direction as the vector of the connection of the geografical southpole to the geografical northpole your fingers show in the same direction as the tangential velocity of the earth...

this professor is so awesome.

Then influenced by centrifugal forces? If so, how does this differ from gravity?

@techdawg667 yes! anyone know where i could buy one?

I want that globe

if they made the pendulum outof a denser material (ie: depleted uranium), it would have less air-drag and would swing for longer. Is it possible to design a more aerodynamic pendulum? perhaps a disc instead of a sphere.

Maybe the apparent motion of the swinging pendulum does not change, it stays the same, but the earth is moving under it, giving the impression that the pendulum is exhibiting precessinon.

Now I believe when Leonard said "I can feel the earth moving!!"

I've just seen this pendulum being demonstrated by James Burke (connections 3). I totally remember learning about it at school but I'd forgotten that the point of it is that that the pendulum is independent to the rotation of the Earth. Amazing! (when I forget which way the Earth rotates I simply remember that the sun rises in the east... so the Earth rotates towards the east... the other way to this video:D)

Can I ask where the levitating globe was bought? @sixtysymbols

I've just searched through the full text of the antarctic treaty and I can't find any reference to the prohibition of open flames. I have read Allan Baker's website about the experience/experiment and he does indeed state that it is against the treaty. Anyone have anymore information about this? Seems strange to forbid the use of fire in this manner when the second article of the treaty supports 'freedom of scientific investigation'. That is all.

Good explanation. :)

Loved it ...

So if you set a good pendulum system into motion with great care and no jostling, the pendulum will not make those patterns you see in people's sand pendulums? Those oscillating patterns happen only because the pendulum is started off with some 'non-planar' or irregular motion to start with? Is that basically correct? I'm very curious about this; it's very interesting.

Hello Professor! I love your video's so much, thank you endlessly for sharing your knowledge! I'm hoping to come study at your university soon after doing an access course at college this year. I did a years foundation course for engineering at London South Bank University but didn't finish for health reasons.My question is about the Precession of Earth as discovered by Hipparchus in 130BC and the alignment of Polaris as a marker for our rotational axis.. Apparently this cycle is renewed every 26,000 years. Does this tie into our Julian calendar or even the fact that we measure time from 0AD? Christianity seems to cloud my sensible reasoning, although I do not deny that such events did indeed happen.. To some extent!Thank you very much,Darren Herbert, aspiring student! :)

if you can no longer question what you have learned, how would you describe this being?

Does the toilet swirl opposite in the northern and souther hemisphere?

It would swing for much longer but it still loses energy in the bending of the string! I wonder if you could measure how much energy it takes to bend a string on each swing of the pendulum.

What is it gonna do relative to the sun?

I don't understand one thing about this pendulum, since we are all moving with the earth rotation and i don't affect us how come the pendulums swing is, how can it not move with the earths rotation?

@wesmatron Do you think the Allais effect is a myth? It certainly seems ridiculous, but has it been definitively ruled out?

@8DX As well as obvious gravity but wind / pressure is a factor on the pool of water surface weather it is high or low i think it is part of coriolis effect isnt it ! quaternion

just asking but would it go clockwise or anti clockwise?

what was the device at 4:38? i've only ever seen them in science fiction films :P

Whoooaaa, that's a very cool globe! Where can I get one?

Do they have an episode that talks about the "natural" reference frame in which the CMB is (more or less) isotropic? Also proper distance vs. comoving distance. And the size of the universe (i.e. I know the observable universe is finite, but is the entire universe infinite? I mean, there can't be some wall somewhere, so if you were to travel in one direction forever you would never hit "the edge" of the universe, but is that due to expansion, or because the universe is truly infinite?)

@carlsontechnology I would say it depends on the toilet not on which hemisphere it's located. A toilet wouldn't swirl at all if it wasn't designed to.

Super1Champ The helicopter is still being affected by gravity. So it'll still move with the earth. Just because something is not physically touching the ground doesn't mean it's not affected by the earth's gravity.

"Excuse me Brady I am showing my backside" XDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

Hey, my college has a huge version of one of these installed our library. Come to think of it, I have no idea if it was put in by the physics department or the psychology department, because only a very small percentage of students (now including myself) know what it is, which makes for a great opportunity to watch confused freshmen question their sanity when they emerge after a long study session to find that the pendulum is moving in a direction completely different from when they came in.

the one at work (radboud university of nijmegen) is driven by a clever magnet setup and during the day you can see the effect which is very cool indeed

Brilliant!

I think I read Foucault had a magnet under the floor that kept his pendulum going.

No, When you turn off an a electromagnet the ball will still remain magnetized for a short time and unevenly release from the magnet. sort of like a "stickiness". this would interfere with the initial swing of the ball.

But isn't the ceiling that the pendulum is attached to also moving along with the floor? Or is the pendulum attached to outer space?

professor, isn't the room moving in comparising with the plain and not the other way around?

Would this explanation be the same example for the coriolis effect at the equator? They give a demonstration there of water in their pan circling in one direction, then take a few steps to see it circle in the other direction trying to prove that the equatorial line separates the two spins.

I really could listen to Professor Bowley speak all day long.

Thank you sir

At the south/north poles couldn't this system (given energy) be used as a clock?

Anyone know what a "Foucault Gyroscope" would do? (btw.... the sun sets in the west, so viewed from above the north pole, the earth rotates counter-clockwise.)

@Kargoneth Try to imagine it with Vector Forces, If at the poles the Force acts directly perpendicular on the pendulum making it rotate, and at the equator it acts parallel to the pendulum motion, in between both of them, the force should be on an angle which still causes it to rotate around.

@puretroubleman Why not have the top of the globe and holder be north poles and the bottoms the south poles?

What's with the advert at the begining of the clip?

Ha I've seen this before, never knew what it was called or who was behind it!

I would have very much liked this man as my professor.

@MrOldprof My deepest apologies sir. I seriously respect your knowledge and absolutely love watching you on Sixty Symbols. It was my error to point out such a simple mistake that anyone could make.

Would the experiment show the same results in a vacuum?

can we do this, but instead of measuring effects by rotation, measure effects by orbit of the sun?

The Treaty of the Antarctic forbids matches? Please cite your source. I don't think that's correct.

So interesting!