Magnetically levitating graphite can be moved with laser

Dec 27, 2012 by Lisa Zyga feature
(A) Experimental set-up of a 3-mm-diameter graphite disk levitating on NdFeB magnets arranged to face in alternate directions. (B) A laser moves the disk in the direction of the light beam (photographic frames from the video below). Reprinted with permission from Kobayashi, et al. ©2012 American Chemical Society

(Phys.org)—Magnetic levitation has been demonstrated for a variety of objects, from trains to frogs, but so far no one has developed a practical maglev-based actuator that converts some external source of energy into motion. Now in a new study, researchers for the first time have used a laser to control the motion of a magnetically levitating graphite disk. By changing the disk's temperature, the laser can change the disk's levitation height and move it in a controlled direction, which has the potential to be scaled up and used as a light-driven human transportation system. Laser light or sunlight can also cause the levitating disk to rotate at over 200 rpm, which could lead to a new type of light energy conversion system.

The researchers, Dr. Masayuki Kobayashi and Professor Jiro Abe of Aoyama Gakuin University in Kanagawa, Japan (Abe is also at CREST, Japan Science and Technology Agency in Tokyo), have published their study on optically controlling the motion of maglev graphite in a recent issue of the .

"The most important point in this work is the achievement for a real-time motion control technique which can move a magnetically levitating diamagnetic material without contact for the first time in the world," Abe told Phys.org. "Because this technique is very simple and fundamental, it is expected to apply to various daily living techniques, such as transportation systems and amusement, as well as photo-actuators and conversion systems."

(A) A laser causes a magnetically levitating graphite disk to rotate (photographic frames from video). (B) The laser causes temperature changes in the graphite, as measured by infrared images of the disk when under laser irradiation (top) and after the termination of irradiation (bottom). Reprinted with permission from Kobayashi, et al. ©2012 American Chemical Society

As the researchers explain, occurs due to an object's diamagnetism, which repels magnetic fields. Although all materials have some diamagnetism, it is usually too weak to allow them to magnetically levitate. Magnetic levitation only occurs when a material's diamagnetic properties are stronger than its ferromagnetic and paramagnetic properties (which attract magnetic fields). One of the strongest diamagnetic materials is graphite.

In order to magnetically levitate, an object's total magnetic force must not only be repulsive, but the repulsion must also be stronger than the force of gravity. The height at which a diamagnetic material levitates can be controlled by two factors: the applied magnetic field and the material's own diamagnetic properties. The levitation position of diamagnetic materials has previously been controlled by changing the applied magnetic field, but so far no one has successfully controlled maglev motion in the second way, by changing the material's diamagnetic properties with an external stimulus such as temperature, light, or sound.

Here, the researchers did just that by using a laser to reversibly control the temperature of a graphite disk levitating over a block of permanent magnets. They demonstrated that, as the graphite's temperature increases, its levitation height decreases, and vice versa. The researchers explain that the change in temperature causes a change in the graphite's magnetic susceptibility, or the degree to which its magnetization reacts to an applied magnetic field. On an atomic level, the laser increases the number of thermally excited electrons in the graphite due to the photothermal effect. The more of these electrons, the weaker the graphite's diamagnetic properties and the lower its levitation height.

This video is not supported by your browser at this time.
Demonstrations of a diamagnetic graphite disk being moved in a linear direction and rotated by a laser, and rotated by sunlight. A large enough graphite disk could potentially be used as a new type of light-driven human transportation system. Video credit: Masayuki Kobayashi and Jiro Abe

In addition to controlling the height of maglev graphite, the researchers found that they could also make the graphite move in any direction and rotate it by changing the site of irradiation. Whereas the laser was aimed right in the center of the graphite disk when controlling its height, aiming it at the edge of the disk changes the temperature distribution, and thus magnetic susceptibility distribution, in such a way that the repulsion force becomes unbalanced and the graphite moves in the same direction as the light beam.

To rotate the levitating graphite disk, the researchers replaced the rectangular prism-shaped magnets beneath the disk with a stack of cylindrical-shaped magnets, and again aimed the laser at the disk's edge. The distorted temperature distribution causes the levitating graphite disk to rotate, with the direction and rotational speed depending on the irradiation site. Rotation also occurs when the set-up is exposed to sunlight. By converting solar energy into rotational energy, the disk can reach a rotational speed of more than 200 rpm, which could make it useful for applications such as optically driven turbines.

The researchers predict that the ability to control maglev-based motion with a laser could lead to the development of maglev-based actuators and photothermal solar energy conversion systems. Applications could include a low-cost, environmentally friendly power generation system and a new type of light-driven transportation system.

"At this moment, we are planning to develop a maglev turbine blade suitable for this system," Abe said. "In this case, it is predicted that friction disrupts the rotation of the maglev turbine. Therefore, we would like to develop a light energy conversion system with a high efficiency with reference to the so-called MEMS (Microelectromechanical Systems) technique.

"As for the actuator, the maglev graphite can convey anything that has almost the same weight as the levitating graphite disk. So, if the scale expansion of the photo-actuator system is achieved, it is not a dream that a human on the maglev can drive himself."

Explore further: Team finds electricity can be generated by dragging saltwater over graphene

More information: Masayuki Kobayashi and Jiro Abe. "Optical Motion Control of Maglev Graphite." Journal of the American Chemical Society. DOI: 10.1021/ja310365k

Journal reference: Journal of the American Chemical Society search and more info website

5 /5 (41 votes)

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antialias_physorg
5 / 5 (1) Dec 27, 2012
"At this moment, we are planning to develop a maglev turbine blade suitable for this system," Abe said. "In this case, it is predicted that friction disrupts the rotation of the maglev turbine. Therefore, we would like to develop a light energy conversion system with a high energy conversion efficiency with reference to the so-called MEMS (Microelectromechanical Systems) technique."


Put it in a vacuum?
I'm seriously curious what kind of conversion efficiency one could achieve if one were to not only use the infrared spectrum of sunlight but also downshift the visisble and UV frequencies into the IR range and focus it on such a generator.
Lurker2358
2.6 / 5 (5) Dec 27, 2012
Did they try Concentrated solar?

Just make sure you don't burn or melt the target.

Applications could include a low-cost, environmentally friendly power generation system and a new type of light-driven transportation system.


A rail road that uses permanent magnets, a graphite sheet, and a flashlight...yay...

It could be even better than that. You could have "Back to the Future" style hover boards which could have a rail, so that people can get on and off with their board and just go where they want, like the side walk is now. Since you wouldn't be pushing an entire train, this would be much more efficient than a train. Since it appears the technology is almost entirely passive, there's nothing to break down.
Matthewwa25
2.7 / 5 (7) Dec 27, 2012
Could this make "back to the future havor boards" real.
Jeddy_Mctedder
1 / 5 (4) Dec 27, 2012
Levitation relies on quantum efeects induced by cold temperatures (superconducting fields)

It is fruitless to add heat to levitating system to do USEABLE WORK unless you have a system for cooling the system that requires economically less costly energy than the economic benefit amount of work you are getting out of the system
antialias_physorg
5 / 5 (4) Dec 27, 2012
Levitation relies on quantum efeects induced by cold temperatures (superconducting fields)

I'm not sure what you are commenting on, here. This technology has nothing to do with superconductors.
El_Nose
5 / 5 (1) Dec 27, 2012
@Jeddy

Levitation relies on quantum efeects induced by cold temperatures (superconducting fields)


that is simply not true -- levitation is cause by magnetic field repulsion. You can use a superconductor to create tat field or a simple electromagnet will do.

It is fruitless to add heat to levitating system to do USEABLE WORK unless you have a system for cooling the system that requires economically less costly energy than the economic benefit amount of work you are getting out of the system


But they are using pyrolytic graphite which should be obvious from the fact that you saw no condensation clouds in the video and when talking about magnets and graphite, pyrolytic graphite is assumed.

It is is a synthetic material, that is more diamagnetic than bismuth at room temperature, at least in one direction.

heating/cooling does not matter as long as you don't melt it
Lurker2358
1.8 / 5 (4) Dec 27, 2012
Jeddy:

This system is using normal permanent magnets at room temperature.

Presumably, the energy from the light is doing two things:

1, Temporarily weakening the magnetism of the target on one side, causing it to be slightly unbalanced.

2, The thermal energy is converted to "work" to accelerate the magnet, which dissipates the heat.

The magnet spinning 200 RPM in sunlight is proof that the cooling isn't an issue. Well, 200 RPM is probably a limit caused by the setup, similar to "Terminal velocity," where it can't dissipate the heat fast enough to spin more quickly, but it doesn't necessarily need to spin 200 RPM to do useful, macroscopic work.

I'm interested in seeing if there is a way to get more out than you put in, over the short term.

Think about it, the "momentum" of the light which was shown on the magnet is nowhere nearly as high as the "momentum" the magnet has when it is moving at maximum velocity in that demonstration. What this suggests to me is energy transformation
Lurker2358
1.3 / 5 (6) Dec 27, 2012
What interests me is the opening part of the video, since we must (supposedly) conserve linear and angular momentum.

I can't imagine that the "momentum" of the photons in the laser are enough to explain the motion of the magnet (solar sails take a lot longer than that to work in vacuum,) so where is the "momentum" coming from? Gravity, I think.

I like AP's suggestion of trying this in vacuum to see how it changes limits and such. Make sure this isn't some sort of convection-induced effect masquerading as a magnetic effect.
Lurker2358
1.5 / 5 (4) Dec 27, 2012
Oh yeah, I forgot to mention.

They need to experiment with larger targets (but same laser input,) to see how the size of the target changes the effects.

I believe a larger target should have more thermodynamic efficiency because of the larger distance between the opposing sides of the target (allows higher heat differences therefore potentially amplifying the effect, I think,) however a larger target should require more work to move, but I think in a vacuum a larger target should have a higher maximum efficiency and possibly a higher maximum RPM, contrary to normal intuition of larger objects being harder to move. Which is to say it will take longer to accelerate because it is more massive, but it should have a higher maximum velocity.

The next thing I'd do if I were them, is try scaling the radius for both the laser and sunlight, and see what the results are, and quantify changes for both max RPM and changes in light input.

Meh, a mouth full I guess.
Lurker2358
1 / 5 (3) Dec 27, 2012
Just imagine what you could do in controlled environments like production facilities and automated warehouses.

You could make lifters and movers which use almost no energy due to nearly zero friction and off-board power supply of lasers.

I guess it would depend on the product, because you wouldn't want electronics near magnets, but most of what we use warehouses for are container production and food production, storage, and transport. Those things wouldn't be hurt by magnetism at all.
Husky
not rated yet Dec 27, 2012
well, if you need to make pure laserlight from solar first, then its no good use because of the initial conversion losses, maybe if it works with solar concentrators and lenses then it might be usefull on a larger scale.
wheelnut
3.3 / 5 (3) Dec 27, 2012
Have these guys never heard of the Crookes radiometer?
antialias_physorg
not rated yet Dec 27, 2012
well, if you need to make pure laserlight from solar first, then its no good use because of the initial conversion losses,

Watch the video (especially the last part). It works with ordinary light, too.

You could make lifters and movers which use almost no energy

Lifters would not benefit at all. Movers for heavy stuff would benefit only minimally (the energy needed for acceleration and decelartion accounts for the overwhelming part of energy used - not the "constant speed" part in between. And the energy for those is determined by the mass - which is unaffected by this technology)
sirchick
1 / 5 (1) Dec 27, 2012
Levitation relies on quantum efeects induced by cold temperatures (superconducting fields)

It is fruitless to add heat to levitating system to do USEABLE WORK unless you have a system for cooling the system that requires economically less costly energy than the economic benefit amount of work you are getting out of the system


Why are you commenting before looking at the video...? Use intelligence in future. This is a science website after all.
packrat
1 / 5 (1) Dec 27, 2012
Since it's using magnets as a base anyway, I'm wondering how much torque a disk could put out if it was a couple of feet in diameter. I can think of a few things where it would be very useful to just need sunlight shining on it to make it turn even if it didn't put out but just a couple of lbs worth of torque.
carrotSnack
3 / 5 (3) Dec 27, 2012
I have owned this diamagnetic pyrolytic graphite for the past year and its fun to play with. Using the same arrangement of magnets used in the the superconducting maglev tracks, I've made my own tracks that the graphite will levitate over and follow. I've never thought of pointing a laser as it, my own research/playing with it has been the use of magnets/electromagnets external to the track to alter the track's magnetic field whenever the graphite comes close. By increasing the field behind the graphite it will be pushed forward etc.
From my own experience though, it's a mere novelty, the pyrolytic graphite itself is expensive and the rare earth magnets you need are also expensive, the graphite cannot carry much load. The largest load I could get it to carry was a sail made of paper that could be blown on the provide locomotion on the maglev track. In my own experience with it, it has few large scale applications where superconductors or electrodynamic suspension is more suitable.
sirchick
not rated yet Dec 27, 2012
Was the 200RPM in a vacuum ? Less air resistance would give its true max RPM.
superheromail
1 / 5 (3) Dec 28, 2012
This is so cool perhaps one day it will be used for skateboards like the one in back to the future.

superheromail.com
ValeriaT
2 / 5 (4) Dec 28, 2012
Was the 200RPM in a vacuum ? Less air resistance would give its true max RPM.

IMO this speed is driven with speed of heat convection (you need to cool the graphite fast for fast rotation, not just to heat it). The vacuum would rather slow down the revolutions.
Osiris1
not rated yet Dec 28, 2012
Question: Just how 'high' can one lift the system above any surface.Given enough power, could an internally powered device generate the magnetic field necessary to levitate itaelf any arbitrary height using the fields and the laser also carried inboard. Fusion powered flying saucers anyone?
antialias_physorg
5 / 5 (1) Dec 28, 2012
Just how 'high' can one lift the system above any surface.

There's a couple of other factors involved. The higher you go the less stable your machine (it would want to flip over at the slightest imbalance). Only at very small distances (less than the radius of the disc) do you get a stable miniumum.

The vacuum would rather slow down the revolutions.

Well color me pink and call me Howard. After several years here Zephyr actually makes a first post that is technically correct.
Must be the end times.
ValeriaT
1 / 5 (3) Dec 28, 2012
I just don't want to waste time with questions, which don't require the AWT for answering or with problems, where the prediction of AWT doesn't differ from those of mainstream physics.
Lurker2358
1 / 5 (2) Dec 29, 2012
Movers for heavy stuff would benefit only minimally (the energy needed for acceleration and decelartion accounts for the overwhelming part of energy used - not the "constant speed" part in between. And the energy for those is determined by the mass - which is unaffected by this technology)


Um. No friction with the ground has got to be worth something like 20% to 30% of net energy use.
Lurker2358
1 / 5 (3) Dec 29, 2012
IMO this speed is driven with speed of heat convection (you need to cool the graphite fast for fast rotation, not just to heat it). The vacuum would rather slow down the revolutions.


Heat still escapes by infrared radiation.
Lurker2358
1 / 5 (2) Dec 29, 2012
They never explained where the ANGULAR MOMENTUM came from to spin the disk. The sunlight and laser light are striking the disk orthogonal to it's own plane, so why is the disk spinning?

Is this literally the spin of the photons?

But if that's the case, why are the photons "chiral"? If they had random distribution you would expect left and right spin, (or up/down depending on how you look at it,) to be in equal amounts.

Maybe the angular momentum is coming from the photon's wave form, as I've seen some models suggest that photons may have spiral waves, rotating in a 4th dimension as they move through 3d space. Otherwise, I still don't know quite where the angular momentum is coming from.

Linear momentum is what is supposed to make a solar sail work, but that pushes the sail in the direction of the original photon's movement.

This effect causes rotation orthogonal to the photon's movement, which must be coming from some sort of rotation or orbit of the photon itself...
antialias_physorg
5 / 5 (1) Dec 29, 2012
Heat still escapes by infrared radiation.

Yes. But in a non-vacuum environment you have radiation AND convection - so it cools off quicker. (Radiation alone is also not particularly effective at cooling stuff down. That is why vacuum sealed flasks keep their stuff at temperature for so long - and also why one of the biggest problems on the ISS is getting rid of excess heat even though it is located in the ultra-cold of space)
They never explained where the ANGULAR MOMENTUM came from to spin the disk

Look at the way the magnets are arranged below the disc (and where it moves when the light is shone upon it). Also note that in the 'stack of magnets' configuration they have a central pillar of magnets with oppositte magnetic field.

...looking at the video closely is probably better than making up far fetched 4th dimension stuff.
ValeriaT
1 / 5 (2) Dec 31, 2012
I've seen some models suggest that photons may have spiral waves, rotating in a 4th dimension as they move through 3d space

I do agree with it, IMO the polarization of light is the tangible evidence of extra-dimensions in the same way, like the refractive phenomena. But the polarization of sun light is quite weak, this effect cannot be responsible for the momentum of graphite plate. After all, it could be tested rather easily with polarizer - or not?
antialias_physorg
5 / 5 (1) Dec 31, 2012
Erm.
Have you guys ever heard of something called an "electric motor"? If you understand why an electric motor can rotate then you will understand why these graphite sheets rotate/move. It has nothing to do with extra dimensions, polarization or other gobbeldygook whatsoever.
packrat
1 / 5 (2) Dec 31, 2012
Hmmm.... according to the explanation in the article all it should really do is drop somewhat on the side the light is shining on closer to the magnet. It shouldn't really generate any field itself that might make it turn until it was already turning from what I understand about the operation of motors. There is something missing from the explanation unless it's turning due to the same reason the a radiometer works I.E. air molecules moving away from the hot spot to the other side of the disk. That doesn't make much sense in this case either since it would push it to the side versus turning. I don't see how killing the diamagnetic field in one spot would cause rotation as the magnet fields below are stationary. It obviously does but there has to be some better explanation for it.
antialias_physorg
not rated yet Dec 31, 2012
. It shouldn't really generate any field itself that might make it turn

It says in the article the disc is diamagnetic. The light (more precisely the increase in temperature) lessens the diamagnetism and hence you get an uneven field which causes the disc to move/rotate.

That doesn't make much sense in this case either since it would push it to the side versus turning.

Look at the arrangement of the magnets, where the light shines on it, and how the disc moves a bit to the side the moment the laser/light hits it before starting to rotate.
packrat
1 / 5 (2) Dec 31, 2012
Ok, I see what you mean about the slight bump before it starts going. That small movement probably does create just enough field to get it moving and is probably why it doesn't spin all that fast even once it gets going. That's got to be a very tiny field difference. Neat trick!
ValeriaT
1 / 5 (3) Jan 01, 2013
If you understand why an electric motor can rotate then you will understand why these graphite sheets rotate/move.
Such a post just illustrates, you didn't understand both electric motors, both the diamagnetic levitation movement, because these phenomena are both based on different principles. The rotation of electric motor has it's orientation well defined with Lenz force. But what defines the orientation of rotation in diamagnetic levitation experiment?

This is typical arrangement of diamagnetic levitation (it's sliced for to see the orientation of magnets in it). Can you predict with your understanding of electrical motor, if this device will rotate along green (A) or violet (B) arrow? I seriously doubt it. Your post is typical RTFM answer of arrogant nerds, who are just pretending, they do understand everything when they refer to Wikipedia.
Kafpauzo
not rated yet Jan 01, 2013
About the rotation, I think you people are misunderstanding each other here.

Here's another way to ask the same question (at least I think it's essentially the same question):

Why is it that the disk turns counterclockwise when illuminated at the right side, as seen from the camera? Why not clockwise? What prompts one specific direction over the other? What special relationship ties the camera's right side with the counterclockwise direction?

And of course the converse for the left side and the clockwise direction.

This indicates that there's some asymmetry in the setup. Where's the asymmetry?

(I absolutely refuse to speculate about subatomic chirality, much less additional dimensions. Why not look for evidence-based explanations first, before rocketing off into wildly fantastic guesswork? It seems far more meaningful to at least try to look for some explanation with some basis in some kind of controllable empirical evidence.)
Kafpauzo
not rated yet Jan 01, 2013
Lurker2358:

You could have "Back to the Future" style hover boards which could have a rail, so that people can get on and off with their board and just go where they want, like the side walk is now.


Sorry, no hoverboards that you could easily carry around under your arm. From the article:

the maglev graphite can convey anything that has almost the same weight as the levitating graphite disk.


Your hoverboard would weigh more than you.
ValeriaT
1 / 5 (3) Jan 01, 2013
The polarization of light IS extradimensional effect, as the 4D space-time doesn't allow such a thing during light propagation. You needn't to speculate about it, this is a fact. This is just a difference between string theorists, who are looking for extra-dimensions and real physicists, who already know about it.

But I don't think, the direction of rotation of graphite is driven with polarization of light, as the graphite rotates even at the sunlight, which isn't polarized too much.
Kafpauzo
not rated yet Jan 01, 2013
OK, maybe I wasn't saying it clearly enough. Maybe I should have expressed myself more exactly and completely. Here's a more detailed version:

(I absolutely refuse to speculate about (the asymmetry that I just described being caused by) subatomic chirality, much less additional dimensions. Why not first look for evidence-based explanations (for the asymmetry that is the point of this entire comment), before rocketing off into wildly fantastic guesswork (about what causes the asymmetry being discussed here)? It seems far more meaningful to at least try to look for some explanation (for the asymmetry under discussion) with some basis in some kind of controllable empirical evidence.)
antialias_physorg
not rated yet Jan 01, 2013
The initial asymmetry you get because the disc isn't perfect (as can be seen with the naked eye). From then on you get asymmetry because heatup is much faster at the part hit by the light than cooldown is in the part that isn't hit by the light.

If you wanted to plot the diamagnetic field of the rotating disc (with x axis being along the circumference and y axis being the strength of the field) you'd NOT get an inverted symmetrical gaussian curve at the point of the light shining on it - but a heavytailed curve.
The higher the speed the less the decrease of the minimum from the steady state value between revolutions.

Also note the properties of pyrolytic carbon
http://en.wikiped...c_carbon
Kafpauzo
not rated yet Jan 01, 2013
Thanks for the interesting explanation. If I understand you correctly, when the disc isn't moving, and the light is turned on, the disc's state becomes unstable, and it will turn in any direction. Somewhat like a plank that you balance perfectly on its short edge. Some random influence will move the plank / the disk in any direction, and then the movement gets enforced and accelerates from there.

I find this very surprising, because the greatest irregularity is the white line across the disc. Under the light, the black carbon should be warmed a little more than the white line. This influence seems strong enough to dominate over other influences.

And yet, on the first rotation, counterclockwise, the white line is initially pushed away from the light, and on the second rotation, clockwise, the white line is initially pulled into the light.

Am I wrong? Is the heating influence of dark vs light color much less than I thought?
ValeriaT
1 / 5 (2) Jan 01, 2013
This question is the example of physical problem where the knowledge of formal math cannot help you in its understanding - you should understand the subject at its intuitive level. And its solving has nothing to do with electromagnetic motor too.
The magnetic field intensity is not homogeneous - it's profile at the graphite plate level is similar to this curve. This gradient is actually the reason, why the diamagnetic plate will not fall from magnets - it's attracted to the center of the device. After then the direction of graphite rotation will depend on the side of gradient, from which the light is shinning (two possible directions are denoted with green and violet arrows).
antialias_physorg
not rated yet Jan 01, 2013
Am I wrong? Is the heating influence of dark vs light color much less than I thought?

Can't really tell you that, since I don't have access to the paper.
If you're really interested in this I'd suggest you just send an email to the authors (which can be gotten from the link to the abstract in the article).

I'm very sure they will answer any specific questions you have.
Scientists are pretty friendly/forthcoming when you question them about their work (even if you sometimes feel that the questions are 'simple').
carrotSnack
1 / 5 (1) Jan 01, 2013
I made a comment earlier about my own experience with pyrolytic graphite. As I don't have a laser pointer I've been waiting for a sunny day to try moving the graphite on a maglev track with focused sunlight, here's the results /watch?v=aoyUWFb-m2o (can't post links yet). Sorry for the bad quality, but you can see that it worked, though its not strong enough to get the graphite out of the centre junction where the field is slightly weaker, you can clearly see it following the focused sunlight.
I don't have the magnets to do the rotating demonstration, but I do have lots small square ones to try the 2D plane one and maglev track one I just showed.
sirchick
not rated yet Jan 02, 2013
. This is just a difference between string theorists, who are looking for extra-dimensions and real physicists, who already know about it.


Who knows it and when did they win the nobel prize?
ValeriaT
1 / 5 (2) Jan 02, 2013
I made a comment earlier about my own experience with pyrolytic graphite.
Great private re-search, your http://www.youtub...UWFb-m2o]link is here[/url]. Syntax is [ url = http://www.youtub...UWFb-m2o ]link[ / url ], just without spaces.
Who knows it and when did they win the Nobel prize?
Do you think, that all physicists must win the Nobel price?
Kafpauzo
not rated yet Jan 02, 2013
Antialias, thanks for the information about scientists often being very willing to answer questions. I'll keep that in mind in the future.

However in this case it's just curiosity. It piqued my interest, that's all. I won't bother them for the sole purpose of satisfying some curiosity.

But it's good to know in the future.
Kafpauzo
not rated yet Jan 02, 2013
ValeriaT, thanks for taking the effort to make that graphic, just to explain to me. A nice touch.

Unfortunately, I tend to be quite wary of your explanations, since you often present highly unconventional theories, different from physics as known to science. But at other times you seem to explain ordinary physics. In this particular case I'm left guessing whether you're explaining ordinary physics or personal ideas.

Since Antialias sticks to ordinary science, I tend to consider his explanations likely to conform with ordinary science (but not guaranteed, of course). With your explanations, I always remember that they may be something highly speculative, just some guy's personal speculations.

From the information in the article, I get the impression that the magnets under the rotating disk are circular, and thus don't look like they do on your graph.

So, thanks a lot for the nice effort, but unfortunately it isn't all that convincing.
antialias_physorg
not rated yet Jan 02, 2013
Antialias, thanks for the information about scientists often being very willing to answer questions. I'll keep that in mind in the future.

Well, in this case I wanted info from the source, too. So I fired off an email to him this morning. No reply, yet - but I'll post it if one arrives (or PM you directly if the topic has disappeared from the front page by then)
Kafpauzo
not rated yet Jan 02, 2013
Thanks, Antialias! This should be interesting.
packrat
1 / 5 (2) Jan 02, 2013
Antialias, thanks for the information about scientists often being very willing to answer questions. I'll keep that in mind in the future.

Well, in this case I wanted info from the source, too. So I fired off an email to him this morning. No reply, yet - but I'll post it if one arrives (or PM you directly if the topic has disappeared from the front page by then)


Please post any reply. I'm rather curious about it now too.
antialias_physorg
not rated yet Jan 03, 2013
OK: Here's the answer from the author (Jiro Abe). I kept my questions short - didn't want to bother him too much. But he was kind enough to also attach the full paper. If anyone wants it send me your email address as a PM.

-------------------------------
Dear Peter



Thank you very much for your interest to our study. Please find the attached JACS paper.



Question: What determines which way the disc will start rotating?

This may be due to the ununiformity of the magnetic field.



Question: What determines the maximum speed at which the disc will rotate?

We are now investigating the effect of the light intensity on the rotation speed. In near future, I will publish the more detailed data for the system.

Best regards
---------------------

The diamagnetic field seems to look almost the way I envisioned it in an earlier post. Also the stack setup seems to be in line with what we had surmised (including the initial 'bump' move).

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