Wobbly Earth - Sixty Symbols

[@The4fourEver]

Acoustic levitation can be practiced using frequencies that can't be heard by the human ear. It isn't necessarily loud. Electromagnetic levitation requires that the object be a magnetic, or at least have a magnet on it. The benefit of acoustic levitation is that the objects don't have to meet these requirements.

[@viveksoley]

It was really a clever idea to observe the position of stars during the lunar eclipse..

[@acs197]

By far, the best explanation of axial precession that I have heard thus far! Very well done!

[@deadmansouls]

I love that each of your videos gives me a little bit more knowledge in understanding our universe. Thank you for putting an effort into making these videos. Too bad not to many people are looking into this kind of stuff. Again I thank you!

[@whatsarobut]

I sincerely wish more educational shows were like this. They always seem to stifle the actual science content in favor of being "entertaining"- not realizing talented people can make science entertaining without compromising content. :) Thanks so much for all the videos!

[@MartinB_Art_Design]

I want that floaty earth thingy...

[@mohammedshoaib9008]

you're living in one

[@Metaldetectiontubeworldwide]

Me to associated links plzzz

[@kcsunnyone]

@@Metaldetectiontubeworldwide it is an Earth Globe

[@chrisbailey7384]

@@kcsunnyone The floaty earth thing is controlled by electromagnetism that holds the earth in place by chance if you ever visited Exploratorium in San Francisco, you may have come across a steel ball "locked" in mid air that is controlled by electro magnets.

[@sixtysymbols]

@whatsarobut you're welcome... thanks for the nice comment!

[@mrh3h]

Please make more videos. They are short and a little bit nerdy (it's physics after all), but contain so much useful information about the world. Thank you for your effort!

[@Stormrunner0002]

So the melting ice of the poles, and the resultant water moving to the equator region, would enhance the effect even more, causing the polar regions to get even longer sunlight through the year, which melts even more ice and so on. How long would you figure it would take for a great tilt, and plate shift to occur. I know that there are stones found in Petoski, MI, USA that suggest that that region was once a tropic region. These stones are called Petoski stones and are fosselized coral.

[@DoctorDARKSIDE]

Subscribed... This channel is one of the very best on the tube!!! Thanks for the time you guys spend making these great videos!

[@jeebersjumpincryst]

Good explanation especially using the gyro! I have to say.... Im SO SO SO happy to still be seeing "MrOldProf" at the start, making a cameo. Happy retirement MrOldProf; you have become my fav on SixtySymbols and Im glad you are still helping with Brady's project and keeping us crazy interwebz characters happy, entertained and edu-ma-cated! :) Best Regards, J :)

[@hhnfaa16]

Yes, I know, that's what I've been describing. The point I'm making is that centrifugal and centripetal are the equal and opposite parts of the same force. In your string and tension example, the centripetal force is experienced by the object (the tension from the string.) The centrifugal force is the force experienced by the string pulling outwards, keeping it taught. These are both just the tension in the string. One is from the object's POV, the other is from the string's.

[@DualsOnly]

Sixty Symbols needs to win some sort of award for most informative public video service... or something along those lines.

[@sixtysymbols]

@wvb93 a bit of both I think...

[@tylershepard4269]

Centrifugal force is just the analogue for the change in linear momentum of an object spinning in a circle. It is the opposite of the centripetal force which is actually a force. Centrifugal force is just a more generalized term.

[@gaeel330]

They sell them in a shop in France called "Nature et Découvertes" for about 30€ if my memory is correct. They have a permenant magnet and an electromagnet, I'm not sure of the actual mechanism, but when you move the planet into position, you feel the electromagnet kick in as it starts pulsing on and off, as if the planet was vibrating slightly, if you let go at this point, the planet is held in place. There's very little friction on the planet so it spins for quite a while with a simple rub.

[@hhnfaa16]

If you are in a car, travelling in a circle, your momentum means your mass will move in a straight line if no force acts on it. The force that acts on you is inward, perpendicular to your velocity (applied by the car door). That is centripetal force. The force needed to accelerate you by changing the direction of your velocity without needing to change its magnitude. Centrifugal force is the same force, as viewed fro a rotating reference frame (the car). That clear things up for you?

[@sixtysymbols]

@CRISNCHIPS12398 he's still going to do Sixty Symbols vids... I thought we made that quite clear... well, maybe we didn't! :)

[@bananafoneable]

WOW this pulls so many questions! I think of how this affects "ice ages", "global warmings", magnetic pole flips. so many planetary phenomenon!

[@hhnfaa16]

Also, no force is specifically different from any other force. We simply use different terminology in different situations. Tension in ropes, weight as the force due to gravity, friction as either viscous effects or coulomb interactions. All of these are completely interchangeable. If you lubricate a surface to make it nearly frictionless but then attach a damper with the same coef. of friction, a mass will act exactly the same even though the effects are coming from two very different mediums.

[@hhnfaa16]

We simply say centripetal force as the component of force that is exactly perpendicular to the velocity of an object, no matter what is causing that force. in classical mechanics, the equation for acceleration in a polar coordinate system is (r''-r(a')^2) in the radial direction, and 2r'a'+ ra" in the angular direction in which r is the radius and a is the angle. The centripetal force is simply the acceleration in the radial direction times the mass of the object (assuming constant mass).

[@Octanis0]

Since this effect is slow, we add leap days, leap seconds etc. to make our calendar accurate. The other significant thing that will change due to this precession is that Polaris will no longer be the pole star for a while since the axis moves.

[@MagicUserC]

Don't stop making these videos, they are extremly interesting.

[@bluecharger8623]

the reason that centrifugal force is not real is because centripetal force is not its own force but rather another force(or composition of forces) such as tension, friction, or weight that makes an object remain in a circular path. If i were to spin an object with a string in a vertical circular path that is orthogonal to the ground then would there be a 'centrifugal' force at the top of the of the circular path if both tension and weight vector forces point to the center of the path?

[@njimko23]

@ItsNotEvenSunny - ignore centrifugal force and just consider a rock sitting on the equator. At any instant is it moving at 1000 mph towards the horizon. Inertia would cause it to gradually lift off the ground, but gravity pulls it down. The next effect is that it is pushing down more gently than a similar rock on the poles, and so the equator tends to lift away from the Eath's center.

[@feynstein1004]

Hmm but solar eclipses don't tend to occur at the same time of the year, do they? I can't see how Hipparchus could have made reliable comparisons.

[@robinswamidasan]

Hipparchus compared his observations with those recorded by other Greek astronomers over the previous 150 years. Also, we're referring to Lunar eclipses (not Solar eclipses), which tend to occur at around the same time of the year -- advancing by around 10 days per year. Not all are total.

[@jmitterii2]

Found this info: "The axis of the Earth will be tilted TOWARDS the Sun by 23.5 degrees when the Earth is closest to the Sun ( perihelion) in the northern hemisphere in JUNE, and tilted AWAY from the Sun when it is closest to the Sun in December. Each day, our calendar is gradually 'precessing' in time by 0.008 seconds to keep up with the new locations of the equinoxes and solstices so no matter where we are in the precession cycle ,winter will always happen in December, and Summer in June."

[@CathySander]

@McC1oudv2: No. What happens is that, as a consequence, the dates for the equioxes and solstices will shift around a 13 000 year cycle.

[@StereoSpace]

Sure is nice to have a bunch of smart, well educated folks around to explain these complicated to us.

[@ashwith]

Does the tiny change in the orientation of the axis affect the weather significantly, say one year's change?

[@Pulsar77]

@McC1oudv2 No, the seasons won't shift, because our calendar is based on a tropical year, which is defined as the time from vernal equinox to vernal equinox, and this takes precession into account. By contrast, a sidereal year is the time taken by the Earth to orbit the Sun once with respect to the fixed stars. Google "tropical year" and "sidereal year".

[@stevenvh17]

The earth's axis is at an angle with respect to the ecliptical plane it moves in. Due to the same gyroscopic effect as talked about the axis always points in the same direction. That's why it's summer in the northern hemisphere when the north pole points somewhat towards the sun. Without the precession the axis would ALWAYS point in the same direction. It's the bulging at the equator which causes the axis to rotate very slowly instead of being fixed.

[@teavea10]

What kind of experiments did the expeditions to Peru and near north pole do for ten years that allowed them to figure the shape of the Earth? Can you provide a reference? That could be a video in itself.

[@ZiqqiPH]

@MrDeanage Notice that he said it would take several thousands of years (I'm not sure if it was 8.000 or 23.000), it doesn't change in one year. If it did, then yes one side of the earth would always be in sunlight OR the days/nights would last half as long incase it spinned in the other direction. But yeah it would be interesting to know if this actually caused a switch of seasons.

[@Nilguiri]

The seasons are not caused by precession, but simply by the 23.5º tilt of the earth from its orbital plane, so as it orbits the sun the N/S hemispheres tilt towards/away from the sun as you mentioned. The axial precession is a very gradual wobble of the direction of the axis over thousands of years, having negligible effect on the seasons apart from gradually shifting the solstices and equinoxes earlier & later. It is caused by the gravity of the sun (and moon) on the rotating oblate earth, btw.

[@kindlylove400]

I think the manufacturer stopped making them. I've seen this in vat19, but they said it's discontiued. Vat19 does have a levitron revolution which allows you to magnetically levitate anything under 12 ounces, which isn't discontiued and hopefully won't be for a long time.

[@MrOldprof]

@lpasepok No. It was led by Maupertius who was a bit premature in announcing that Newton was correct and Descartes was wrong. Maupertius became a French national hero because he went so for North and did experiments in terrible conditions.

[@Kurtlane]

I wonder, does axial procession have any effects on climate on the earth in general or in specific areas of the earth?

[@aaronoyler6830]

I see nobody ever answered you. But I have always thought so. It seems to be a better explanation than anything else.

[@mysecretadd]

Does that mean the substances (rocks, minerals, etc) around the equator are heavier in density?

[@noname_atall]

centrifugal forces, like centripetal froces and shear forces are not forces by themselves, but are rather a interpretation of other forces in a system. for example the gravitational atraction between the sun and the earth is a centripetal force in the reference frame where the sun is static, but this force is still a gravitational force. centrifugal forces can be seen the same way, i just can't think how to exemplify this.

[@alcapwned86]

No, because centrifugal forces do exist, depending on your frame of reference. Centrifugal literally means center-fleeing, which is the more intuitive choice in this case because we're talking about the sides of the Earth moving out from the center. There's also the "reactive centrifugal force" which exists in *all* reference frames, and is sometimes simply referred to as centrifugal force. Since I only have 500 chars, google "When I say centrifugal, I mean centrifugal!" or wiki centrifugal.

[@queeniekaz]

@SuperCorey95 Its called a levitating Globe or levitating Earth, you can buy them on amazon!

[@plasmaballin]

It's amazing that ancient Greek astronomers were so accurate that they could see the effects of axial precession.

[@danieldurham2075]

even more amazing that the Egyptians had measured it long before + and that precessional numbers have been imbedded in myth and ancient sites all over the world since antiquity.

[@imitatioDei]

@@danieldurham2075 and the hindus

[@KP_Oz]

@@imitatioDei that's correct. Detailed calculations are embedded in Hindu Jyotish (Ayanamsha) and the Vedas with calculations for cycles (Yugas) all based on precessional movement. This knowledge is scripted for at least 9,000 years, and no one knows how long it's been known for. I'd say that to discover a precession cycle that takes 25,920 years, you'd need at least one cycle to observe and document it, and another one to confirm it. That's assuming we've never had any superior intelligence handed from outside!😅

[@hhnfaa16]

They are the same force, just viewed from different reference frames. If you are in a car, and you get pushed to the outside, you feel the door push inwards on you. This is centripetal force. However, the door, if it could feel, would feel you pushing out on it. This is centrifugal force. They are the equal and opposite components of the exact same force. It just depends on your frame of reference.

[@mysecretadd]

@ItsNotEvenSunny Sure, things would get lighter as gravity gets weaker when farther away from the core. But does the centrifugal force of the earth pull materials with higher density towards the equater due to their higher inertia?

[@Dextomus]

How does this wobbling work on uranus wich is tilted almost 90 degrees?

[@emptychicken]

would the rate of precession increase slightly over massive amounts if time as the earth begins to bulge more and more at the equator?

[@sixtysymbols]

@mrh3h we've got more coming

[@CRISNCHIPS12398]

@sixtysymbols I mustn't have paid attention, but I am glad that he will continue with series :)

[@Nilguiri]

Precession is caused because of the torque produced by the sun's (and the moon, etc) gravity, which is pulling harder on the half of the plant closer to the sun. I'm guessing that the mountains will produce an "additional" effect, but it will average out to zero over a day/year. An enormous mountain Antarctica would produce additional torque during the southern summer but 6 months later it will reduce the torque, cancelling out the average yearly effect, right?

[@Pulsar77]

@teavea10 It's called the French Geodesic Mission. There's a wiki article about it.

[@mickenoss]

So with something like a Powerball, are you basically pushing against the axial progression and reversing the process??

[@lurkern]

Sooo well presented! thank you Brady, brilliant as always :)

[@jeffhx]

does the earth inherit its non spherical shape due to its spinning or did it develop it from some other source? that is to say if the earth did stop spinning would it be a perfect sphere?

[@einsteiner900]

Centrifigual force is a very useful simplification of a complicated effect. If the professional physicists at Nottingham University want to use it to explain something they will do so.

[@Sockheadableful]

Wait... I thought he was retired? Good for you professor!! Coming back and explaining the wondrous of nature.

[@SamiMechkor00]

@chrisofnottingham i think you are right so it don't matter if we were travelling at the speed of light It would feel the same as if we were still..

[@jordanmccallum1234]

we only have 4 fundamental forces, but there are many, many more forces than just 4. without going into a fundamental level, how would you explain tension? Tension is the pulling force exerted by a string, cable, chain, or similar solid object on another object. note: pulling FORCE. Please dont go on about the electrostatic attraction between the particles because by no physics description, does a force have to be fundamental for it to be a force.

[@bobleclair5665]

Can you correlate the Milankovitch cycles with the earths magnetic poles,the turbulent effects of the inner liquids of the earth and the Coriolis effect on the lava as it erupts from volcanoes ,,I’m having doubts about magnetic pole reversal,thank you

[@chrisofnottingham]

@sonic003573 "Why cant we feel the earth spinning?" What would you expect to feel? Serious question. This was actually a standard SAT question in a primary school near me and the answer given to the teachers was "because it is so big". At work, after discussing it with half a dozen or so engineers for about 20 minutes the only thing we were sure of was that the answer wasn't "because it is so big". Mostly we were trying to figure out what the questioner thought they "should" be feeling.

[@seanoceallachain]

What is the gadget that has the model earth hovering and where can I buy one ??

[@yngmalm]

Whats the link between this effect and climate.

[@mrrig91]

@sonic003573 I don't actually know the answer but I have a rough idea, so anybody correct me if I'm wrong. But I think its something to do with the earth spinning at a constant speed, its the same when your in a car travelling at a constant speed, you can't feel your moving forward, you can only see it.

[@busanoarmy]

@arife06 He said it took 26000 years for the earth to precess one lap. Lets guess he means astronomical years, time for the earth to orbit around the sun relative to the stars. Then as many as 26001 tropical years would have elapsed. In tropical years the seasons are always at the same time since tropical years are determined by the sun relative position to the horizon. The sun would be highest at midsummer and lowest at midwinter for example. Calendars are usually based on tropical years.

[@MultiPaulinator]

Soo... the path of the Earth's axial precision would look something akin to r=5+sin(25theta)... right?

[@ClipsByMiles]

No, since centrifugal force is the correct phrase in this case. The equator feels centrifugal force flinging it outwards, away from the centre of the Earth, however gravity exerts centripetal force on the matter comprising the equator, preventing it from flinging off into space. Centrifugal force is the force felt away from the centre of rotation, centripetal force is the opposing force acting towards the centre of rotation.

[@nickashton3584]

Where do I get that wonderful floating earth?

[@hhnfaa16]

And notice that acceleration in a polar system doesn't care about where the changes in the radius and angle are coming from. The forces causing the acceleration may be tension, weight, a lever, pneumatic or hydraulic forces, air resistance, friction, etc. There is no "type" of force in dynamics of a system. As far as the math and reactions are concerned, every piece of a system is just a mass, spring, and damper, and makes no distinction between tension and any other force.

[@jordanmccallum1234]

honestly I have only ever heard it called the Coriolis effect, so the "Coriolis force" is new for me. complex numbers are a somewhat bad example of these forces; Imaginary numbers are numbers we use in conjunction with real numbers for equations or expressions, where "Centrifugal force" and the "Coriolis force" are simply bad names for effects due to other present forces. Call it the Centrifugal effect, and you would be correct.

[@cristianfcao]

@RAV3xBinG3 I don't know of a single ancient building related to the PRECESSION of the equinoxes. There are of course many related to solstices (the shortest and longest day of the year) and there may be some related to equinoxes (the days that have the same length than their nights). However, I doubt there may be too many buildings related to the precession of the equinoxes. Being a cycle of 26000 years, I doubt many ancient civs would have understood it, really.

[@izzzzzz6]

Is it possible that some of the main processional cycles are longer or shorter than others? Does anyone know what actually causes it?

[@sixtysymbols]

@davedupplaw it's never too late!

[@ndrthrdr1]

This video will make my university course in solar system Astronomy a little easier to understand. Thank you.

[@lovingboarding]

I have a question. Does this axial precession mean that in about 13000 years winter will be warm and summer will be cold?

[@jessegarcia121]

I love all of these videos! These videos got me interested in science and physics! Sixty symbols

[@aer9998]

I think that centrifugal force is a "virtual" force, that only exists if you take a point on earth, for example, to be an inertial frame of reference, which it is not.

[@auchucknorris]

cos gravity pulls it all together into the center, the force of gravity easily stops it all from spreading out from g force, and the reason they dont spin faster is cos they are so big they are still spinning extremely fast compared to any thing your thinking of in terms of how big the diameter is, like the entire surface length of the earth is how much it spins in a day, and that would take alot of energy to get it spinning that fast were as a ball rotates alot in terms of rpm for little energy

[@theAmdisen391]

could the Axial precession have something to do with the different ice ages we have had on the earth ?

[@PooseV2]

Excluding non-related geophysical phenomena, would this precession have an effect on the seasons in temperate regions of the globe?

[@Gribbo9999]

Some very early aircraft had rotary engines which were in effect a large gyroscope. Many new pilots crashed because when they tried to climb or dive the aircraft the aircraft tried to yaw to left or right. If the pilot didn't anticipate this and correct, the results could be catastrophic.

[@whoistavo]

Great Video. Where could I buy a rotating/ hovering globe like the one in this video?

[@rogerwilco2]

I think our calender actually already corrects for that, using leap days and such. What I think it does mean is that over 26,000 years the zodiac and all the other stars would move w.r.t. to in which month the sun transits them.

[@spacedtime6597]

The trip to Peru he talked about where they measured the Equator and the poles for Newton's statistics of Earth's shape was made by Charles la Condamine. An excelled story of science. There is a great story by the History channel you can watch or check the wikipedia entry

[@deeprecce9852]

Question was the bulge at the equator because of centrifuge force from the spinning or it was naturally bulge that way? If CF has anything to do with the bulge than earths rotation is because of procession or CF?

[@BigCrowsVideos]

So, if you want a scale model and can spin a model earth about 36500 rpm (that's not that fast), than that precession will take about 4.3 hours, instead of 26000 years.

[@chrisofnottingham]

@sonic003573 "im not sure just the feel of motion " What is that like? I really can't imagine.what you expect it to feel. Constant linear motion feels identical to being stationary. If you are in, say, a car you get jiggled around by bends and bumps but obviously the Earth's motion is smooth. Any centrifugal force due to the curved path manifests as a constant (tiny) reduction in weight, so you have nothing to compare it to. Do you expect to feel the wind in your face? Genuinely perplexed.

[@ustoledmysammich]

This video is quite dangerous, it nearly hypnotized me at 1:30.

[@stevenvh17]

Hardly. Not only are they much smaller than the equatorial bulge (a few thousand meters compared to a 43 km bulge), the bulge also works over the full 360° circumference, whereas the mountains are just small dots. Their mass is negligible; without the equatorial bulge they might cause a precession period of maybe tens to hundreds of millions of years.

[@solidqadz]

@Imakeplanesboom what is it called?

[@alcapwned86]

Did you read the pages I referenced? 1) Centrifugal forces *do* exist in rotational reference frames. Just like imaginary numbers (which don't exist in the real world at all) and the Coriolis force (also only exists in rotational frames), CF is a useful concept that simplifies the math in certain situations. 2) There is a reactive centrifugal force pulling out on the earth's interior that is 100% real. Together with centripetal force it forms a reaction pair as required by Newton's 3rd law.

[@zaggedout]

@McC1oudv2 no but the pole star changes.

[@jmomm]

I am almost 11 and I hope that you can help me. Why does Venus rotate clock-wise? I thought that is was because an asteriod hit it but after seeing your video I wonder if its weight is off centered to make it go clock-wise...

[@lpasepok]

Do you know if perhaps Carl Linnaeus had something to do with the whole Lappland thing? I'm just guessing and all but that would sound reasonable considering the fact that he did go up there.

[@tribiz6762]

I thought that the reason that the casing for the gyro moves the opposite direction of the gyro bc of conservation of angular momentum

[@DonkiDonkey]

Centrifugal force does not exist in a inertia frame of reference where newton's law of motion is applicable. Centrifugal force is introduced into a non-inertia frame of reference as a fictitious force to apply newton's law of motion in a non-inertia frame of reference. So, no. The physicists are not wrong. And yes, centrifugal force is imaginary but, it exists. Hopes its clear enough.

[@boogeyman2868]

what

[@ataraxic89]

@Jeuhann yes. Yes it will. And only we can choose what kind.

[@stuartlarge9503]

During the last ice age, the mass of ice was not over the pole, but was centered about Hudson Bay, what effect would that have had on Earths precession

[@CMichaelLyle]

Could the Earth's procession have an effect on the weather? Could the angle of the earth relative to the Sun be a degree colder or hotter?

[@NormBaker.]

Answer this. Once the earth processes and the star vega becomes the north star, taking in to account the different angle of the earth. Won't the days and nights in the upper hemisphere be both twelve hours, all year long?

[@resotheque]

@McC1oudv2 I'm curious about this too. I think that this means every 13k years we have an ice age. No?