The magnet is stopping due to Lenz's law. Basically, the moving magnet is creating a magnetic flux. The law states that any change in flux (in this case, it's creation through spinning) will work to counteract the change. So, the spinning magnet is creating Eddy currents which cause the magnet to stop spinning.
SixThough, That's a great idea. A spherical or cylindrical magnet should work better. SquidCaps, The north and south poles of the magnet are at the top and bottom, so aliment wouldn't make sense.
hkcute; Flux isn't the issue. Its the second time and spatial derivatives of the magnetic vector potential which induces an opposite (eddy) current density. And yes, if it was perfectly homogenious a spinning cyllinder wouldn't induce any eddy currents in a plane purpendicular to its axis, but you won't find any sufficiently perfect magnet for that to actually work. Zigi Samblak; At the (pretty bad) level of vacuum that he could generate, air resistance would be orders of magnitude weaker than the electro-magnetic losses. In other words, it would stay spinning for literally hundreds of minutes if air resistance were the ONLY loss mechanism.
My hypotheses for why it stopped (in order of likelihood) are: 1) Eddy currents and magnetic resistance 3) Earth's magnetic field 2) Earth's gravity 4) Not a perfect vacuum The solution: Use superconducting magnets in a perfect vacuum, in intergalactic space.
Has basicallybeen done, in the Gravity Probe B - Mission. Except they did it in an orbit around the earth, because gravity causes no friction, this difference does not matter. They levitated spheres coated in a superconductor cooled to 2K in a vacuum surrounded by superfluid helium, surrounded by a superconductor.
Cody'sLab; It does increase the circularly induced eddy currents (kind of like a magnetic stirrer works). Asymmatry in the same plane as the conductor is bad news, but since you have a pretty substantial conductor in all 3 dimentions (and the entire vacuum chamber would also have a BIG effect, even though it is relatively far away - see Gauss' Law for charge screening), ANY deviation in the up-down direction would also cause quite a lot of enegy loss in those modes.
A round/disc magnet will have a axially symmetry magnetic field, if you rotate about the axis of symmetry the magnetic field doesn't change and so you can eliminate the eddy currents. To reduce the faraday disc effect you'd need to use only diamangetic levitation but i'm not sure of the relative strength of these effects. A square magnet doesn't have a axially symmetrical magnetic field. Also you could just use polycardon which has a larger diamagnetic effect than bismuth but might be difficult to get a large enough sample.
MrEvilchickens the problem I see is finding a round magnet that is accurately symmetric enough. Without that, it will spin slanted (as the square magnet in the video) and have symmetry defects, which will end up with the same result (albeit maybe a slightly longer spin duration)
Why not just hook up that little glass pipe to atmospheric pressure and have a 'vent' valve to push it? I think you could get better spinning with that.
Christopher Nah it didn't work, it wasn't strong enough as he said. I really like seeing how he sets stuff off with the laser though. I don't know what he could do without that thing.
sandqwert the correct answer is nothing, it will outlast anything, the problem nothing is the concept of the lack of anything, this concept could better be described but human intelligence can only go thus far, nothing was before the universe nothing will be after the universe, thus nothing lasts forever
you demonstrated why it won't spin forever, when you attempted to move the magnet to start it spinning. Although, there is no force of friction due to air, the bismuth's irregular shape experiences the magnetic field differently as it spins. this still acts as a type of drag. perhaps if you levitate a more perfect sphere you might see more noticeable effects.
Wait...that makes so much sense. And even if he had a perfect magnet and a non conductive magnetic material, it would still stop because of the earth's magnetic poles.
Not sure if it is the earths magnetic field doing this or not. The question I have is why it unwinds when it stops, then rotates the opposite direction, and continues oscillating until it stops completely. Need to mark the spinning magnet and see if it stops every time in the same position relative the the earths magnetic field to be sure! Or it could be the orientation of the supporting magnetic fields. More testing needs to be done.
External magnetic field applies torque to the magnet, trying to align it's magnetic field. But there is no feedback according to magnet's spin speed, if magnet is not perfectly aligned it just always aplies some torque, until magnet crosses balance point at which torque changes direction. But magnet already got some momentum, it can't instantly stop. So it's continues to rotate after balance point until rotational force accumulates enough and it starts to spin other way. I dont think it's only earth's mangetic field, huge magnet on top must add to it. Maybe, quite a lot. So it will be resultant force.
I really LOVE these electro-magnetic experiments! You could maybe try casting the bismuth into a circular mould with many thin pieces of plastic acting as insulators (like in transformer laminations). Also, perhaps you could try a non conductive ceramic magnet (AlNiCo and Samarium Cobalt are about equally conductive, with ferrites being MUCH less conductive) as levitation device? You could theoretically even use many small pieces of Neodymium magnets (without the nickel coating of cource) and have them pin a thin insulator between themselves (mica perhaps?).
Eddy currents in bismuth are probably quite low, since it his high electrical resistance for a metal. Copper Electrical resistivity is 16.78 nΩ·m (at 20 °C) or 0.00000001676 Ω·m bismuth Electrical resistivity is 1.29 µΩ·m (at 20 °C) or 0.00000129 Ω·m So if I did my math right bismuth has 76.8 times higher resistance then copper. I'm thinking about making a bismuth tube to drop my 3/4" neodymium magnet through, so i can see how much the eddy currents slow it down compared to dropping it into a copper tube.
There is not much inertia going on in this magnet. By the way, one comment out there pointed out, that if magnetic field would be very axial with center of mass, there would be no change of magnetic field in any point around magnet spinning on same axis. So, +Cody'sLab, could you please check same with spheroidal or, may be, cylindrical magnet, and, may be, huge chunk of copper above it?
Basically it wants to line up with the Earths magnetic field like a compass. I'm wondering what if you had a magnetic track and a superconductor that you pushed around the track, that will eliminate the magnetic flux, You would then have the issue of keeping the superconductor cold but if it was in a vacuum and levitating then it should stay cold.
Cody, I think the magnet won’t spin forever because it will always point at magnetic north. Correct me if I’m wrong but that’s also why the magnet was favoring facing one side and than swinging back and forth as earths magnetic pull eventually brings it to a stop always facing the same direction.. go get a compass and see if I’m right Cody.
Great video, you actually got your answer as to whether or not it would spin forever at 3;00 you can see the magnet oscillating back and forth. Which means there's some kinda force on it.
Replace the air with a superfluid, maybe depending on your temperature. A fundamental experiment here, I love it! Analogues of this are still "spinning" with superconducting loops.
i'll risk making this comment before watching to the end of the video, but at 5:30 you can see there is some asymmetry in the magnetic field from the way the magnet seems to ever so slightly lurch into a "stable spot" before climbing back out again and continuing to rotate with slightly less speed.
really ? seems like a good explanation, but i wouldnt have thought the effects of earth's magnetic field would contribute significantly enough to this system, given the much higher field strength of the magnets and bismuth Cody has set up here. Or is that still possible given that the forces from said magnets are mostly cancelled out ? Basically it seems intuitive to me that this would spin a lot smoother and lose much less energy to this fabled stable spot, if the magnet was perfectly balanced and not sagging on one side. Or would it still get stuck on magnetic north in this "perfect" case ?
I think gravity as well as earth magnetic field is just adding sinusoidal wobble to speed. It does slow magnet down half way, but also do speed it up other half.
posysajrazdwatrzy No, the earth's field is at basically 90 degrees to the rotating magnet's field. It's pulling the magnet to flip on its side, not rotate on axis.
Hi, Cody. You need to use a spherical magnet instead of a cube. The magnetic field of a cube shaped magnet has components that vary with rotation angle. Rotation of the cube magnet then generates a time-varying magnetic field and this will always induce eddy currents in any metals near the magnet. These eddy currents dissipate energy thermally. This is the energy loss that is damping the rotation of the cube magnet. Since the field of a spherical magnet is unchanging with respect to rotation on its dipole axis, it eliminates the time-varying field components and thereby eliminates the eddy current losses that are damping the rotation of your cube magnet. When using a spherical magnet, the only remaining source of eddy current induction will be due to imperfections in the magnets field due to material defects, but these will be very small effects.
Please bear in mind that even the small oscillations of the magnet will cause a change in magnetic flux on the NeFeB magnet on which it levitates. As a result, eddy currents will be created to counteract this. Since these cube magnets ARE NOT perfect in the alignment of the "net magnetic dipoles", this will have a dampening effect not only on the linear oscillations, but also reducing the angular momentum. @Cody'sLab
I'm wondering if there is a different factor here: Earth's magnetic field. That would explain a force that causes it to "rock" left and right at the end of the spin.
You could apply an electric field to the magnet above to get the magnet inside the chamber to spin. Eddy currents would slow the magnet eventually, however. It would spin longer than under atmospheric pressure.
Since liquid oxygen is being attracted to a magnet and is not metallic, would it be possible to contain the oxygen in some form of container (like your glas tubes) to get rid of eddy currents and stuff? Or would you need a ridiculously huge magnet to lift the oxigen together wit its container?
If I understand this correctly, if there is a little enough amount of radiation then items in a vacuum will just get colder and colder to a certain point (I may have misunderstood), so to that end if the oxygen is frozen and placed in a vacuum then it will stay cold enough to stay solid. Alternatively you can always seal the container and if you keep it cold enough to not expand then you should be good.
Zeibentaul Unless the oxygen gave off a form of radiation, I don’t think it would decrease in temperature in the vacuum chamber. That said, it would expand into a gas, and the atoms might transfer their energy to the container walls (say, a sealed glass tube, not the walls of the vacuum chamber). So the gaseous oxygen may decrease in temperature relative to the increase in temperature of the container. Since all the energy would still be conserved within the system.
powdered iron is used with a binder in RF inductors for exactly the reason you need: minimize eddy currents. It won't be zero but alot better than what you've got now. Also ferrites are used. Google powdered iron toroid or ferrite toroid for example.
The magnet induces electricity in all the metal parts around it, which generates an electromagnetic field which counteracts the spin that created it. It's very much like the magnet in a copper tube experiment. Of course, with such a small magnet and such far away and not aligned metal parts the effect is nearly nonexistent, but it does waste some energy, which means that even if all forms of friction were removed the magnet will still eventually stop. Also, generally acquiring perfect steady motion (including rotation) with anything that is magnetic is impossible because of the natural electromagnetic background of the Universe which will always slightly influence it. EDIT: Oh, you've mentioned it. Well, leaving the comment for reference.
Cody when you put a microwave in your vacuum chamber it seemed to draw more power. If you put a microwave in a pressure chamber would it use less power ?
Thank you for performing this experiment. I suggested it to another youtuber who plays with vacuum chambers but he totally butchered it in my eyes. This is pretty much exactly what I would have done, provided I had the stuff to try it.
There are a number of forces I can think of that may be causing the magnet to stop: - Air flowing in slowly when the pump is turned off - Vertical magnetic currents from the larger magnet, orthogonal to the rotation plane, causing alignment (like the moon has one face locked in position) - The Earth's magnetic field, like in a compass - Hysteresis currents
If you cool the entire apparatus down to the point at which materials become superconductive, you could replace the top magnet with a strong electromagnet. You would have to raise the stand inside the vacuum chamber to reduce the gap between the electromagnet and the Bismuth sample. If you could make the electromagnet oscillate at controllable frequencies, you could use that to spin the metal sample (bismuth). After gaining enough speed, switch the electromagnet to a regular state with only enough power output to levitate the metal. At a high enough velocity the sample would spin for a much longer duration...Just a thought...
I'm so happy you did this because during my physics class in last year we were talking about efficiency of motors due to friction and it got me thinking about this exact situation, I just never had the opportunity to look into this.
Before and during the experiment when it stopped it would then rotated a little in the opposite direction. I also noticed that the speed once it was in a vacuum varied depending on which side it was facing. That tells me that it isn't balanced. Even though it's being levitated it is still subject to the force of gravity. I think the heavy side is a force of friction.
I'd say that it's possible, but I doubt that it's the only reason. Earth's Magnetic field surely interracts with it, but I also think there's more factors than just that.
The spinning magnet is creating small electrical currents in the metal below it and these currents are causing their own magnetic fields that are counter to the small magnet and thereby slowing it's spin. Similar to dropping a magnet down the middle of a copper pipe and watching it's rate of fall slow.
Get you an MKS SRG, The MKS Spinning Rotor Gauge (SRG) line is a high-vacuum gauge that operates by measuring the amount of viscous drag on a magnetically-levitated spinning ball, which is directly related to the number of molecules in the chamber (i.e. pressure).
Wood doesnt burn in vaccum, and probably there would be induction on the bismuth because it isn't a superconductor replicating identically the magnetic field lines. And the superior magnet would induce a current on the bottom one due to magnetic field flux be changing. Thanks Cody, I aways wanted to see if it worked out, if I had condition I could do the same experimento that you did.
Glass is diamagnetic. Not as much as Bismuth...but when the well the magnet floats within is self-centering, the last few spins remind me of torque translation, or putting square wheels on a vehicle over flat ground. At one face especially, it looks like it's climbing a hill, then falling down the opposite side. If I look really carefully, it appears that to be pistoning (up and down) against gravity; spinning in this well looks like work.
If I remember correctly to limit eddy currents constructors of engines divide the magnet with several thin non conductor slices reducing a lot the area of the circles the current follow so limiting its effect substantially. I may confusing it with some other dissipative effect though.
it's pulling in one side, you can see it choosing a fixed position, going back and forward until it finds it. so the magnet is not positioned correctly, it's pulling in several directions at the same time
I think you would need a perfectly ballanced cube or disk to let it turn longer, because the cube doesn't look's like that. If the cube is nearly at the end of the applied force, it swing's back and forth. Which means that there is a point on the cube lower than all other on the downside, which is affected by gravity.
Ferrite cores used in high frequency switching transformers have magnetic properties but have low electrical conductivity, the core material is designed specifically to reduce eddy currents, not sure how well the material would work but it would be interesting to try.
The field of the magnet extends throughout all space. It is necessarily going to interact with every conductor in the universe, creating eddy currents. Those conductors in general are not superconductors so have electrical resistance. That leads to heating and energy loss. So the answer is no it won't. No matter what you do eventually it will stop. (Well, down to the quantum limit of zero-point motion that is)
Apparently these magnets (assuming you're using a neodymium magnet) are usually coated with nickel having a 1.4*10^7 S/m conductivity but the neodymium iron boride, despite being a ceramic, has a conductivity of about 1*10^6 S/m. So, probably some of the effects of the eddy currents, which would indeed be on the surface of the magnet, would be somewhat lessened if you removed that coat.
pressurise that little bulb with the wood in it seal it with wax then melt the wax under vacuum. The Coriolis effect will influence the spin of the magnet. also it doesn't look level. and to a much smaller degree than the Coriolis effect light hitting the magnet will influence it. (Radiometer) BUT they don't work by light bouncing off them as I once though it is actually heat and pressure. Which is why they spin towards the foil part and not towards the black. Balance of the magnet will also effect it.
if im not wrong a magnetic field has magnetic friction acting on the bismuth , still doesnt defy the law of thermodynamics , its just losing lesser energy over a period of time as it is harder for it to disperse energy which can be seen as the most efficient way we have found to sustain motion
it still react or lines up into the direction of magnetic poles of the earth like a compass that's why i think it will not really spin forever even if there is no air resistance.
Thank you so much for this video Cody. Back in highschool I wanted to research this for my "thesis" but my teacher thought I wouldn't be able to finish it. Now I finally know the outcome!
Non conductive magnetic , Yes, ferrite. According to this brochure, Ferrite-NiZn has a resistivity of 10^4 Ohm·m. This is better than damp wood, at least. You can trade magnetic properties for resistivity by coating and embedding ferrite pellets in an insulator, as suggested in the comment above, but fashioning your own metamaterial will probably involve quite a bit of research and experimentation.
That it's rocking back and forth after the first attempt shows that it isn't just air resisting it spinning. Weight distribution or something else, there's a "hump" there that it has to overcome.
The Earth's magnetic field will also be absorbing energy from the system. Magnetic remanence is another source of loss. Then there's still a little bit of air still inside the chamber. Thanks Cody. Interesting,as always.
i think it will rotate much longer with a round magnetic form like a like a zylinder or a ball. Because the cube had a resistance to the magnetic field.
The reason of the stop is lenz lawa, the magnet is inducing a current on the opposite direction hence creating a force to the other, this makes sense because if it where to go on forever you would be essentially making infinite energy
The magnetic force between the magnets making the levitation makes it slow down like friction. Even if it didn't unless you had a complete vacuum air would slow it down eventually
you know those hand crank flashlights? You feel more resistance the faster you crank them. That resistance is a rotating magnetic field cutting a conductor and inducing current into something. This is the force that stops this magnet
If I recall, the viscosity of air is constant down to about a torr, which is what you pumped down to, so you're probably still seeing significant air resistance effects. You might try with a lower vacuum pressure if your system can do that.
you should pressurize a fluid then bring it room temp. so that, when it depressurizes it will be about 40 F or "ice cold". in my ap chem class we thought of a soft drink that when you open it, it will depressurize and chill the drink inside so you don't have to chill your drinks.
My best guess is that this is caused by electromagnetic resistance. The best example i can think of when you crank a hand generator no matter how hard you push it ramps up slowly because of the resistance of the fields interacting with eachother. Basically an electromagnetic form of friction
Hey Cody I was about to dive into this. Check this out. Pipe an air compressor into the glass to push the magnet. It has to be a very small amount of air pressure. And your decompresor would have to constantly run. But just for proof of concept in space. This could be it.
I think it is the magnet's "compass" behaviour that is slowing it down. As the magnet wants to point north it is periodically accelerating towards it and slowing away from it. Thats why when it is slowing down it will slow and then speed up before slowing again. I imagine doing this experiment a considerable distance away from an active planet's core would work.
Or it just migt try to orient itself along the Earth's magnetic lines. Sure, it's facing up/down direction. But the Earth's field is not exactly paralel to the surface either. I mean, I can stick two small magnets together with a thread in between and it readily orients itself in North/South direction. So hanging in vacuume with all the forces being equilized all it takes is a bit of extra magnetic field to stop it. The fact that it's tilted could make extra tendency to orient along the lines as well as being a consequence of that tendency.
Maybe its because the magnet is not directly straight up and down. I noticed this because the magnet increased in speed when the lower part of the magnet is closer to the magnet on the bottom but also slowed back down a bit when it turned around. maybe this causes gravity to pull at one side more than the other while its turning because the lower magnet is not extremely level or even more interesting the lower magnet doesn't have the same magnetic push throughout the whole thing and it may be effecting the floating magnet on the right half only maybe causing some extra magnetic friction if that's what you call it.
Forever is such a strong word... Even in a perfect vacuum (and not just 1/800 of normal air pressure) it would still slow down. Even if you would remove everything you possibly could that interacts with the magnet it would slow down. Very, very slowly but it would still stop eventually. There is always something that will interact with this system. If we assume that the universe will exist for all eternity in some fashion without ever stopping to exist and if we assume that this system can exist in this configuration for all eternity as well, even the tiniest possible influence on it will eventually make it stop spinning. I guess it depends on how you define "forever" :) If you define it as "until no one exists anymore to witness it stop spinning" then I could get behind it. If no one exists anymore to care whether it's spinning anymore or not, I guess then we can say that it did spin forever ;)
Surely it's the rotation of the magnetic flux which provides the resistance and slows rotation? The rotation will causes an Electoral field and that uses energy from the momentum of the rotating magnet?
it doesn't really matter what you use, so long as you use a diamagnetic material, as it will form resistance moving so close to the material in question, and eventually sacrifice its momentum for a proportional electric field
The fact that the magnet is slowly oscillating back and forth when it should be at rest, indicates to me that it's not going to spin forever. There appears to be some resistance in the magnetic field itself that the object is "bouncing" off of. It will probably sit there and oscillate for a long time but eventually stop doing that as well.
the magnetic field itself will act as a breaking force. if you spin your pice of iron inside it, the electrons in it will react to the field and orientate accordingly. this will convert the movement energy to heat energy, ultimately converting it to em radiation.
Hey Cody, if you're looking for a magnetic material that's non-conductive, you should check out some ferrites. They're good insulators and they're ferrimagnetic, so if you put a piece in a strong magnetic field you can permanently magnetize it. If you get a hard ferrite (high coercivity) it might work in this experiment, though it won't be nearly as strong as the neodymium magnet you've got so I'm not entirely sure it would hover above the bismuth as well.
You didn't need the blower. It started spinning because it's lob-sided (more mass on one side) so you can create a circular motion of the top magnet and induce a spin in the bottom one.
its going to slow down because magnetism is as much a physical force as actually touching something. its 'friction' because just like the surface of two objects rubbing together isnt perfect and so the forces of those imperfect ridges and valleys at a microscopic scale slamming into each other causes heat, the magnetic field - thogh invisible - also has imperfections when sliding against another field that is going to cause minut changes in the action leading up to a slowdown.
I noticed that the magnet is a little low on one corner. So it is not balanced. It will stop due to gravity if for no other reason. You can see that at one point in the video, as it is swinging back and forth , only to settle in one specific orientation.
If you could replace the bismuth with a superconductor you might get further. The trick is getting a high-temperature superconductor ($$$, if you even can) and cooling it down evenly with liquid nitrogen without damaging the vacuum chamber.
Cody, you might want to try electrostatic levitation, if you really like challenges. All you need is HV generator, concave base and very lightweight and thin insulator. Levitating disk will have some charge so it will not be perpetual motion, but charge count compared to metal will be very small. Actually base can be insulator as well, conductors might be arranged in it radially from the center, so Eddy currents will not be induced.
You could try embedding a superconductor in solid nitrogen using evaporative cooling. The vacuum would freeze the nitrogen and would simultaneously isolate the whole thing so as long as you keep intense light from it, it would levitate.
If you balanced the field above and below where the bearing would most likely be in the middle it should spin longer. The reason to balance is that at your current position you are still creating an artificial gravity field from the closest object. Balance and you should neutralize the pull.
its also constantly having to use energy to remain in the upright position bouncing occasionally off a confining magnetic field creating an additional loss of energy
The rotating magnet is almost certainly generating eddy currents in the bismuth as well. Perhaps bismuth powder mixed in epoxy would produce lower losses (due to lower conductivity/smaller loop area)?
Take the bismuth levitating device and move your finger tip through the field between levitating magnet and carrier magnet. It's one of the most funky ways to realize that your body is diamagnetic...
If a magnetic field interacts with any other object, that magnetic field will progressively get weaker until it is no longer magnetic. Even though that can be a very long time no magnet can last forever unless it is remagnetized by a separate, very strong magnet. :)
Nothing can be known to spin forever, once you make a medition its because, in some sort of way, you've generated a change on it, by looking at it you need to shot photons to it, and such has some kind of knetic energy, and perhaps mesuring it gravitational field would alterate the same or influence it gravitationally with the mesuring mechanism.
It'd stop eventually. Eddy currents and material imperfections will provide slight coupling to its surroundings resulting in mechanical friction and electrical heat.
At 1:01 it's already clear it won't spin forever, because when it's levitated it rotates, but then rotates back a bit. Something makes it prefer a direction... even possibly Earth's magnetic field.
The magnet is stopping due to Lenz's law. Basically, the moving magnet is creating a magnetic flux. The law states that any change in flux (in this case, it's creation through spinning) will work to counteract the change.
So, the spinning magnet is creating Eddy currents which cause the magnet to stop spinning.
RE exactly what I was thinking.I wonder if a circular magnet would spin longer as the circumference will just be moving over the same area
I can bet that the objects ends up aligned north south on earth's magnetic field and that is enough to stop it. It oscillates in the end.
SixThough, That's a great idea. A spherical or cylindrical magnet should work better.
SquidCaps, The north and south poles of the magnet are at the top and bottom, so aliment wouldn't make sense.
Besides that, a perfect vacuum doesn't exist so it would be impossible to completely remove all resistances.
hkcute; Flux isn't the issue. Its the second time and spatial derivatives of the magnetic vector potential which induces an opposite (eddy) current density.
And yes, if it was perfectly homogenious a spinning cyllinder wouldn't induce any eddy currents in a plane purpendicular to its axis, but you won't find any sufficiently perfect magnet for that to actually work.
Zigi Samblak; At the (pretty bad) level of vacuum that he could generate, air resistance would be orders of magnitude weaker than the electro-magnetic losses.
In other words, it would stay spinning for literally hundreds of minutes if air resistance were the ONLY loss mechanism.
My hypotheses for why it stopped (in order of likelihood) are:
1) Eddy currents and magnetic resistance
3) Earth's magnetic field
2) Earth's gravity
4) Not a perfect vacuum
The solution: Use superconducting magnets in a perfect vacuum, in intergalactic space.
AFastidiousCuber it would already spin forever in space
Knuckles
Unless something gets in da wae
Has basicallybeen done, in the Gravity Probe B - Mission. Except they did it in an orbit around the earth, because gravity causes no friction, this difference does not matter. They levitated spheres coated in a superconductor cooled to 2K in a vacuum surrounded by superfluid helium, surrounded by a superconductor.
Basically, that’s planets and stars
The earth's magnetic field can be reduced by several magnitudes inside a Mu-Metal chamber
try using a round magnet, ball bearing type would be best. the square shape changes the magnetic fields and slow it down.
I might try it at some point but I dont see any reason that would make a huge difference.
Cody'sLab; It does increase the circularly induced eddy currents (kind of like a magnetic stirrer works). Asymmatry in the same plane as the conductor is bad news, but since you have a pretty substantial conductor in all 3 dimentions (and the entire vacuum chamber would also have a BIG effect, even though it is relatively far away - see Gauss' Law for charge screening), ANY deviation in the up-down direction would also cause quite a lot of enegy loss in those modes.
Cody'sLab laminating the metal to reduce eddy currents?
A round/disc magnet will have a axially symmetry magnetic field, if you rotate about the axis of symmetry the magnetic field doesn't change and so you can eliminate the eddy currents. To reduce the faraday disc effect you'd need to use only diamangetic levitation but i'm not sure of the relative strength of these effects. A square magnet doesn't have a axially symmetrical magnetic field.
Also you could just use polycardon which has a larger diamagnetic effect than bismuth but might be difficult to get a large enough sample.
MrEvilchickens the problem I see is finding a round magnet that is accurately symmetric enough. Without that, it will spin slanted (as the square magnet in the video) and have symmetry defects, which will end up with the same result (albeit maybe a slightly longer spin duration)
Why not just hook up that little glass pipe to atmospheric pressure and have a 'vent' valve to push it? I think you could get better spinning with that.
I was thinking that while facepalming rly hard. Or yk he could've idk, remote-controlled a let?
Ugh..
2:17 That's a really clever way of getting it spinning.
Not really clever, since it didn't work
Christopher Nah it didn't work, it wasn't strong enough as he said. I really like seeing how he sets stuff off with the laser though. I don't know what he could do without that thing.
I would have used water instead of wood, It would have boiled off in the vacuum and get the thing spinning i guess :)
water equalizes too much, you'd need to get ALL of the water your trying to heat up to boiling temperature which with a lazer would take ages
Matthew Bevan instead of burning wood, he can burn gunpowder, it would produce more gas.
A perpetual motion machine? In this house we obey the laws of thermodynamics!
chbrules I refuse to
@@vivimannequin REEEEEEEEE YOU CAN'T DON'T CREATE A PARADOX
Kono platelet da! Already got one planned
@@vivimannequin shit now I gotta go back in time before you plan that shit do you know how much ppl died because of you!
I understood that reference
Nothing lasts forever, even cold november rain....
sandqwert the correct answer is nothing, it will outlast anything, the problem nothing is the concept of the lack of anything, this concept could better be described but human intelligence can only go thus far, nothing was before the universe nothing will be after the universe, thus nothing lasts forever
the smell of farts under the duvet
it rains in november?
It's hard to hold a candle In the cold november rain.
But... Diamonds are forever... forevaah foreverahh
you demonstrated why it won't spin forever, when you attempted to move the magnet to start it spinning. Although, there is no force of friction due to air, the bismuth's irregular shape experiences the magnetic field differently as it spins. this still acts as a type of drag. perhaps if you levitate a more perfect sphere you might see more noticeable effects.
You just made a big bulky compass!
Wait...that makes so much sense. And even if he had a perfect magnet and a non conductive magnetic material, it would still stop because of the earth's magnetic poles.
No, it does not.
it's will just add some sinusoidal speed wooble, when rotation slowed down half way, and speed up other half.
Not sure if it is the earths magnetic field doing this or not. The question I have is why it unwinds when it stops, then rotates the opposite direction, and continues oscillating until it stops completely. Need to mark the spinning magnet and see if it stops every time in the same position relative the the earths magnetic field to be sure! Or it could be the orientation of the supporting magnetic fields. More testing needs to be done.
External magnetic field applies torque to the magnet, trying to align it's magnetic field. But there is no feedback according to magnet's spin speed, if magnet is not perfectly aligned it just always aplies some torque, until magnet crosses balance point at which torque changes direction. But magnet already got some momentum, it can't instantly stop. So it's continues to rotate after balance point until rotational force accumulates enough and it starts to spin other way.
I dont think it's only earth's mangetic field, huge magnet on top must add to it. Maybe, quite a lot. So it will be
resultant force.
Apart from the fact it's sitting inside a field made from a giant magnet sitting above it a million times stronger than the Earth's magnetic field.
the lazy nerd in me very much appreciates all the work you put into this channel! thanks cody!
I really LOVE these electro-magnetic experiments!
You could maybe try casting the bismuth into a circular mould with many thin pieces of plastic acting as insulators (like in transformer laminations).
Also, perhaps you could try a non conductive ceramic magnet (AlNiCo and Samarium Cobalt are about equally conductive, with ferrites being MUCH less conductive) as levitation device? You could theoretically even use many small pieces of Neodymium magnets (without the nickel coating of cource) and have them pin a thin insulator between themselves (mica perhaps?).
Hi-ed everyone, welcome back to Cody's Lab
i always assumed it was "alright everyone!" o.o
It is alright everyone...
Be easy on him, dude drinks cyanide and breathes Xenon.
For me it was " I know everyone" with a smiling face always.
Woah Bobby duke wtf are you doing here lmao, I’m subscribed tho😘
I think the magnet probably slow down mainly because of Eddy currents.
Nice experiment though
I do think same way, but could you make that prediction before you seen magnet slowing down? I couldnt.
morpheus ꀊ Yes I agree!!
Eddy currents in bismuth are probably quite low, since it his high electrical resistance for a metal.
Copper Electrical resistivity is 16.78 nΩ·m (at 20 °C) or 0.00000001676 Ω·m
bismuth Electrical resistivity is 1.29 µΩ·m (at 20 °C) or 0.00000129 Ω·m
So if I did my math right bismuth has 76.8 times higher resistance then copper.
I'm thinking about making a bismuth tube to drop my 3/4" neodymium magnet through, so i can see how much the eddy currents slow it down compared to dropping it into a copper tube.
There is not much inertia going on in this magnet.
By the way, one comment out there pointed out, that if magnetic field would be very axial with center of mass, there would be no change of magnetic field in any point around magnet spinning on same axis.
So, +Cody'sLab, could you please check same with spheroidal or, may be, cylindrical magnet, and, may be, huge chunk of copper above it?
Basically it wants to line up with the Earths magnetic field like a compass. I'm wondering what if you had a magnetic track and a superconductor that you pushed around the track, that will eliminate the magnetic flux, You would then have the issue of keeping the superconductor cold but if it was in a vacuum and levitating then it should stay cold.
From what?
Sounds like a pretty good second experiment
Cody, I think the magnet won’t spin forever because it will always point at magnetic north. Correct me if I’m wrong but that’s also why the magnet was favoring facing one side and than swinging back and forth as earths magnetic pull eventually brings it to a stop always facing the same direction.. go get a compass and see if I’m right Cody.
Great video, you actually got your answer as to whether or not it would spin forever at 3;00 you can see the magnet oscillating back and forth. Which means there's some kinda force on it.
Bismuth is cool stuff.
electronicsNmore too bad he hasn't done a video centering around Bismuth
Replace the air with a superfluid, maybe depending on your temperature. A fundamental experiment here, I love it! Analogues of this are still "spinning" with superconducting loops.
i'll risk making this comment before watching to the end of the video, but at 5:30 you can see there is some asymmetry in the magnetic field from the way the magnet seems to ever so slightly lurch into a "stable spot" before climbing back out again and continuing to rotate with slightly less speed.
Dn Fx That stable spot is the earth's magnetic field :^) - it's behaving like any compass and wants to align with the earth's field.
really ? seems like a good explanation, but i wouldnt have thought the effects of earth's magnetic field would contribute significantly enough to this system, given the much higher field strength of the magnets and bismuth Cody has set up here. Or is that still possible given that the forces from said magnets are mostly cancelled out ?
Basically it seems intuitive to me that this would spin a lot smoother and lose much less energy to this fabled stable spot, if the magnet was perfectly balanced and not sagging on one side. Or would it still get stuck on magnetic north in this "perfect" case ?
I think gravity as well as earth magnetic field is just adding sinusoidal wobble to speed. It does slow magnet down half way, but also do speed it up other half.
ah, yes. stopping caused by Foucault/Eddy currents in bismuth plate
posysajrazdwatrzy
No, the earth's field is at basically 90 degrees to the rotating magnet's field. It's pulling the magnet to flip on its side, not rotate on axis.
Hi, Cody. You need to use a spherical magnet instead of a cube.
The magnetic field of a cube shaped magnet has components that vary with rotation angle. Rotation of the cube magnet then generates a time-varying magnetic field and this will always induce eddy currents in any metals near the magnet.
These eddy currents dissipate energy thermally. This is the energy loss that is damping the rotation of the cube magnet.
Since the field of a spherical magnet is unchanging with respect to rotation on its dipole axis, it eliminates the time-varying field components and thereby eliminates the eddy current losses that are damping the rotation of your cube magnet.
When using a spherical magnet, the only remaining source of eddy current induction will be due to imperfections in the magnets field due to material defects, but these will be very small effects.
try doing it with a sphere/ball magnet .
Please bear in mind that even the small oscillations of the magnet will cause a change in magnetic flux on the NeFeB magnet on which it levitates. As a result, eddy currents will be created to counteract this. Since these cube magnets ARE NOT perfect in the alignment of the "net magnetic dipoles", this will have a dampening effect not only on the linear oscillations, but also reducing the angular momentum. @Cody'sLab
The magnetic field itself is resistance. You would need a constant permanent magnet inside the chamber to apply continuous pressure against it.
Interesting to see the experiment, love your creative ways of interacting with objects inside the vacuum chamber. +1 for Lenz's law.
I'm wondering if there is a different factor here: Earth's magnetic field. That would explain a force that causes it to "rock" left and right at the end of the spin.
You could apply an electric field to the magnet above to get the magnet inside the chamber to spin. Eddy currents would slow the magnet eventually, however. It would spin longer than under atmospheric pressure.
Since liquid oxygen is being attracted to a magnet and is not metallic, would it be possible to contain the oxygen in some form of container (like your glas tubes) to get rid of eddy currents and stuff? Or would you need a ridiculously huge magnet to lift the oxigen together wit its container?
Interesting
If I understand this correctly, if there is a little enough amount of radiation then items in a vacuum will just get colder and colder to a certain point (I may have misunderstood), so to that end if the oxygen is frozen and placed in a vacuum then it will stay cold enough to stay solid.
Alternatively you can always seal the container and if you keep it cold enough to not expand then you should be good.
Zeibentaul Unless the oxygen gave off a form of radiation, I don’t think it would decrease in temperature in the vacuum chamber. That said, it would expand into a gas, and the atoms might transfer their energy to the container walls (say, a sealed glass tube, not the walls of the vacuum chamber). So the gaseous oxygen may decrease in temperature relative to the increase in temperature of the container. Since all the energy would still be conserved within the system.
Zeibentaul
powdered iron is used with a binder in RF inductors for exactly the reason you need: minimize eddy currents. It won't be zero but alot better than what you've got now. Also ferrites are used. Google powdered iron toroid or ferrite toroid for example.
Hello Cody would the magnet spin better if it was balanced?
I beleive, it wont. Gravity might slow it down when one part of magnet is going up, but when it rotated 180 degree, same part will go down.
The magnet induces electricity in all the metal parts around it, which generates an electromagnetic field which counteracts the spin that created it. It's very much like the magnet in a copper tube experiment. Of course, with such a small magnet and such far away and not aligned metal parts the effect is nearly nonexistent, but it does waste some energy, which means that even if all forms of friction were removed the magnet will still eventually stop.
Also, generally acquiring perfect steady motion (including rotation) with anything that is magnetic is impossible because of the natural electromagnetic background of the Universe which will always slightly influence it.
EDIT: Oh, you've mentioned it. Well, leaving the comment for reference.
Cody when you put a microwave in your vacuum chamber it seemed to draw more power. If you put a microwave in a pressure chamber would it use less power ?
Gary Roe no, it's "working normally or arcing and consuming more power", so if pressure is not low, power consumption will be the same
Thank you for performing this experiment. I suggested it to another youtuber who plays with vacuum chambers but he totally butchered it in my eyes. This is pretty much exactly what I would have done, provided I had the stuff to try it.
What about Earth's magnetic field??
Does it count?
chetan desai haha 😆 wait seriously 😳
When it started spinning in the opposite direction it was clear there are other forces applied.
Yes, gravity and the not perfectly vertical magnetic field the magnets make is what affects it
the real secret to fidget spinning: vacuum chambers.
There are a number of forces I can think of that may be causing the magnet to stop:
- Air flowing in slowly when the pump is turned off
- Vertical magnetic currents from the larger magnet, orthogonal to the rotation plane, causing alignment (like the moon has one face locked in position)
- The Earth's magnetic field, like in a compass
- Hysteresis currents
Wouldn't a spherical magnet work better?
If you cool the entire apparatus down to the point at which materials become superconductive, you could replace the top magnet with a strong electromagnet. You would have to raise the stand inside the vacuum chamber to reduce the gap between the electromagnet and the Bismuth sample. If you could make the electromagnet oscillate at controllable frequencies, you could use that to spin the metal sample (bismuth). After gaining enough speed, switch the electromagnet to a regular state with only enough power output to levitate the metal. At a high enough velocity the sample would spin for a much longer duration...Just a thought...
When I clicked on the thumbnail I expected to hear "Will it spin forever?" in the Blendtec guy's voice
I'm so happy you did this because during my physics class in last year we were talking about efficiency of motors due to friction and it got me thinking about this exact situation, I just never had the opportunity to look into this.
Hi Cody, are you going to make another Q and A on reddit?
Well then you are two years late because when he had around 9000 subs he responded to me and almost every second comment :D
Adio_ I try clicking ur profile but I no get game
Before and during the experiment when it stopped it would then rotated a little in the opposite direction. I also noticed that the speed once it was in a vacuum varied depending on which side it was facing. That tells me that it isn't balanced. Even though it's being levitated it is still subject to the force of gravity. I think the heavy side is a force of friction.
the earth's magnetinc feild could be messing with the motion of the little magnet.
i'm ignorant in the matter so don't laugh if i'm totally wrong XD
Field*
I'd say that it's possible, but I doubt that it's the only reason. Earth's Magnetic field surely interracts with it, but I also think there's more factors than just that.
The spinning magnet is creating small electrical currents in the metal below it and these currents are causing their own magnetic fields that are counter to the small magnet and thereby slowing it's spin. Similar to dropping a magnet down the middle of a copper pipe and watching it's rate of fall slow.
That would make a good fidget spinner
fidget spinner in a vacuum
great idea
Get you an MKS SRG, The MKS Spinning Rotor Gauge (SRG) line is a high-vacuum gauge that operates by measuring the amount of viscous drag on a magnetically-levitated spinning ball, which is directly related to the number of molecules in the chamber (i.e. pressure).
Cody pls can you do More CODY'S MINE!
#CODY'SMINE
Wood doesnt burn in vaccum, and probably there would be induction on the bismuth because it isn't a superconductor replicating identically the magnetic field lines. And the superior magnet would induce a current on the bottom one due to magnetic field flux be changing.
Thanks Cody, I aways wanted to see if it worked out, if I had condition I could do the same experimento that you did.
only ones up this late love u thow
its 2pm here
its 5 am here
3pm herre
Woke up an hour ago
It's RUclips.
You can literally just wait and watch it later.
That's the entire reason internet video replaced TV for people.
Glass is diamagnetic. Not as much as Bismuth...but when the well the magnet floats within is self-centering, the last few spins remind me of torque translation, or putting square wheels on a vehicle over flat ground. At one face especially, it looks like it's climbing a hill, then falling down the opposite side. If I look really carefully, it appears that to be pistoning (up and down) against gravity; spinning in this well looks like work.
If I remember correctly to limit eddy currents constructors of engines divide the magnet with several thin non conductor slices reducing a lot the area of the circles the current follow so limiting its effect substantially.
I may confusing it with some other dissipative effect though.
it's pulling in one side, you can see it choosing a fixed position, going back and forward until it finds it. so the magnet is not positioned correctly, it's pulling in several directions at the same time
I think you would need a perfectly ballanced cube or disk to let it turn longer, because the cube doesn't look's like that. If the cube is nearly at the end of the applied force, it swing's back and forth. Which means that there is a point on the cube lower than all other on the downside, which is affected by gravity.
Ferrite cores used in high frequency switching transformers have magnetic properties but have low electrical conductivity, the core material is designed specifically to reduce eddy currents, not sure how well the material would work but it would be interesting to try.
The field of the magnet extends throughout all space. It is necessarily going to interact with every conductor in the universe, creating eddy currents. Those conductors in general are not superconductors so have electrical resistance. That leads to heating and energy loss.
So the answer is no it won't. No matter what you do eventually it will stop. (Well, down to the quantum limit of zero-point motion that is)
Apparently these magnets (assuming you're using a neodymium magnet) are usually coated with nickel having a 1.4*10^7 S/m conductivity but the neodymium iron boride, despite being a ceramic, has a conductivity of about 1*10^6 S/m. So, probably some of the effects of the eddy currents, which would indeed be on the surface of the magnet, would be somewhat lessened if you removed that coat.
pressurise that little bulb with the wood in it seal it with wax then melt the wax under vacuum.
The Coriolis effect will influence the spin of the magnet. also it doesn't look level.
and to a much smaller degree than the Coriolis effect light hitting the magnet will influence it. (Radiometer)
BUT they don't work by light bouncing off them as I once though it is actually heat and pressure. Which is why they spin towards the foil part and not towards the black.
Balance of the magnet will also effect it.
if im not wrong a magnetic field has magnetic friction acting on the bismuth , still doesnt defy the law of thermodynamics , its just losing lesser energy over a period of time as it is harder for it to disperse energy which can be seen as the most efficient way we have found to sustain motion
it still react or lines up into the direction of magnetic poles of the earth like a compass that's why i think it will not really spin forever even if there is no air resistance.
Thank you so much for this video Cody. Back in highschool I wanted to research this for my "thesis" but my teacher thought I wouldn't be able to finish it. Now I finally know the outcome!
One of the most impressive things I see from you regularly is how you interact with things while they are in a vacuum chamber. Genius methods.
Non conductive magnetic , Yes, ferrite. According to this brochure, Ferrite-NiZn has a resistivity of 10^4 Ohm·m. This is better than damp wood, at least. You can trade magnetic properties for resistivity by coating and embedding ferrite pellets in an insulator, as suggested in the comment above, but fashioning your own metamaterial will probably involve quite a bit of research and experimentation.
That it's rocking back and forth after the first attempt shows that it isn't just air resisting it spinning. Weight distribution or something else, there's a "hump" there that it has to overcome.
The Earth's magnetic field will also be absorbing energy from the system. Magnetic remanence is another source of loss. Then there's still a little bit of air still inside the chamber. Thanks Cody. Interesting,as always.
i think it will rotate much longer with a round magnetic form like a like a zylinder or a ball. Because the cube had a resistance to the magnetic field.
The reason of the stop is lenz lawa, the magnet is inducing a current on the opposite direction hence creating a force to the other, this makes sense because if it where to go on forever you would be essentially making infinite energy
The magnetic force between the magnets making the levitation makes it slow down like friction. Even if it didn't unless you had a complete vacuum air would slow it down eventually
you know those hand crank flashlights? You feel more resistance the faster you crank them. That resistance is a rotating magnetic field cutting a conductor and inducing current into something. This is the force that stops this magnet
If I recall, the viscosity of air is constant down to about a torr, which is what you pumped down to, so you're probably still seeing significant air resistance effects. You might try with a lower vacuum pressure if your system can do that.
you should pressurize a fluid then bring it room temp. so that, when it depressurizes it will be about 40 F or "ice cold". in my ap chem class we thought of a soft drink that when you open it, it will depressurize and chill the drink inside so you don't have to chill your drinks.
My best guess is that this is caused by electromagnetic resistance. The best example i can think of when you crank a hand generator no matter how hard you push it ramps up slowly because of the resistance of the fields interacting with eachother.
Basically an electromagnetic form of friction
Hey Cody I was about to dive into this. Check this out. Pipe an air compressor into the glass to push the magnet.
It has to be a very small amount of air pressure. And your decompresor would have to constantly run.
But just for proof of concept in space. This could be it.
I think it is the magnet's "compass" behaviour that is slowing it down. As the magnet wants to point north it is periodically accelerating towards it and slowing away from it. Thats why when it is slowing down it will slow and then speed up before slowing again.
I imagine doing this experiment a considerable distance away from an active planet's core would work.
Or it just migt try to orient itself along the Earth's magnetic lines. Sure, it's facing up/down direction. But the Earth's field is not exactly paralel to the surface either. I mean, I can stick two small magnets together with a thread in between and it readily orients itself in North/South direction. So hanging in vacuume with all the forces being equilized all it takes is a bit of extra magnetic field to stop it. The fact that it's tilted could make extra tendency to orient along the lines as well as being a consequence of that tendency.
Maybe its because the magnet is not directly straight up and down. I noticed this because the magnet increased in speed when the lower part of the magnet is closer to the magnet on the bottom but also slowed back down a bit when it turned around. maybe this causes gravity to pull at one side more than the other while its turning because the lower magnet is not extremely level or even more interesting the lower magnet doesn't have the same magnetic push throughout the whole thing and it may be effecting the floating magnet on the right half only maybe causing some extra magnetic friction if that's what you call it.
Forever is such a strong word...
Even in a perfect vacuum (and not just 1/800 of normal air pressure) it would still slow down. Even if you would remove everything you possibly could that interacts with the magnet it would slow down. Very, very slowly but it would still stop eventually.
There is always something that will interact with this system. If we assume that the universe will exist for all eternity in some fashion without ever stopping to exist and if we assume that this system can exist in this configuration for all eternity as well, even the tiniest possible influence on it will eventually make it stop spinning.
I guess it depends on how you define "forever" :) If you define it as "until no one exists anymore to witness it stop spinning" then I could get behind it. If no one exists anymore to care whether it's spinning anymore or not, I guess then we can say that it did spin forever ;)
The eddy current within your metal is creating a dynamic brake within itself. The field of the magnets induce this (Lenz's Law) and can't be avoided.
Surely it's the rotation of the magnetic flux which provides the resistance and slows rotation? The rotation will causes an Electoral field and that uses energy from the momentum of the rotating magnet?
it doesn't really matter what you use, so long as you use a diamagnetic material, as it will form resistance moving so close to the material in question, and eventually sacrifice its momentum for a proportional electric field
The fact that the magnet is slowly oscillating back and forth when it should be at rest, indicates to me that it's not going to spin forever. There appears to be some resistance in the magnetic field itself that the object is "bouncing" off of. It will probably sit there and oscillate for a long time but eventually stop doing that as well.
the magnetic field itself will act as a breaking force. if you spin your pice of iron inside it, the electrons in it will react to the field and orientate accordingly. this will convert the movement energy to heat energy, ultimately converting it to em radiation.
Hey Cody, if you're looking for a magnetic material that's non-conductive, you should check out some ferrites. They're good insulators and they're ferrimagnetic, so if you put a piece in a strong magnetic field you can permanently magnetize it.
If you get a hard ferrite (high coercivity) it might work in this experiment, though it won't be nearly as strong as the neodymium magnet you've got so I'm not entirely sure it would hover above the bismuth as well.
You didn't need the blower. It started spinning because it's lob-sided (more mass on one side) so you can create a circular motion of the top magnet and induce a spin in the bottom one.
Eddy currents the changing magnetic field induce a current in the bismith. We need a non conductive paramagnetic material
its going to slow down because magnetism is as much a physical force as actually touching something. its 'friction' because just like the surface of two objects rubbing together isnt perfect and so the forces of those imperfect ridges and valleys at a microscopic scale slamming into each other causes heat, the magnetic field - thogh invisible - also has imperfections when sliding against another field that is going to cause minut changes in the action leading up to a slowdown.
I noticed that the magnet is a little low on one corner. So it is not balanced. It will stop due to gravity if for no other reason. You can see that at one point in the video, as it is swinging back and forth , only to settle in one specific orientation.
If you could replace the bismuth with a superconductor you might get further. The trick is getting a high-temperature superconductor ($$$, if you even can) and cooling it down evenly with liquid nitrogen without damaging the vacuum chamber.
Cody, you might want to try electrostatic levitation, if you really like challenges. All you need is HV generator, concave base and very lightweight and thin insulator. Levitating disk will have some charge so it will not be perpetual motion, but charge count compared to metal will be very small. Actually base can be insulator as well, conductors might be arranged in it radially from the center, so Eddy currents will not be induced.
You could try embedding a superconductor in solid nitrogen using evaporative cooling. The vacuum would freeze the nitrogen and would simultaneously isolate the whole thing so as long as you keep intense light from it, it would levitate.
Ferrite core magnets have high electrical resistance, and can be strengthened by passing high current through them. Try that
If you balanced the field above and below where the bearing would most likely be in the middle it should spin longer. The reason to balance is that at your current position you are still creating an artificial gravity field from the closest object. Balance and you should neutralize the pull.
its also constantly having to use energy to remain in the upright position bouncing occasionally off a confining magnetic field creating an additional loss of energy
The rotating magnet is almost certainly generating eddy currents in the bismuth as well. Perhaps bismuth powder mixed in epoxy would produce lower losses (due to lower conductivity/smaller loop area)?
It is oscillating which means there is a force acting on it and it won't spin forever.
Great example of magnetic braking without any outside forces.
Take the bismuth levitating device and move your finger tip through the field between levitating magnet and carrier magnet. It's one of the most funky ways to realize that your body is diamagnetic...
If a magnetic field interacts with any other object, that magnetic field will progressively get weaker until it is no longer magnetic. Even though that can be a very long time no magnet can last forever unless it is remagnetized by a separate, very strong magnet. :)
Nothing can be known to spin forever, once you make a medition its because, in some sort of way, you've generated a change on it, by looking at it you need to shot photons to it, and such has some kind of knetic energy, and perhaps mesuring it gravitational field would alterate the same or influence it gravitationally with the mesuring mechanism.
It'd stop eventually. Eddy currents and material imperfections will provide slight coupling to its surroundings resulting in mechanical friction and electrical heat.
At 1:01 it's already clear it won't spin forever, because when it's levitated it rotates, but then rotates back a bit. Something makes it prefer a direction... even possibly Earth's magnetic field.