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Levitating Magnets: Newsletter Challenge (12/12/06)

Posted December 10, 2006 5:01 PM
Pathfinder Tags: challenge questions

The question as it appears in the 12/12 edition of Specs & Techs from GlobalSpec:

You're having a discussion at lunch with your friend, and she tells you that she can make one magnet levitate in free-space above another magnet. You tell her that's impossible, citing Earnshaw's Theorem as your proof. Who's right?

Update (01/02/07 9:12 AM): And the Answer is....
Unfortunately, you lose this one, as your friend demonstrates the next day when you walk into her office and she shows you a small top, spinning happily in midair about two inches above a circular base.

Relax. There's no need to lose faith in your college E&M professor. Earnshaw's Theorem states that there is no static configuration of permanent magnets that allows levitation. The operative word in this case is static. The system your friend has just demonstrated for you is dynamic, because one of the magnets is spinning, so Earnshaw doesn't apply to this system. The stability region is bounded by a pretty narrow range of spin speeds, height, weight of the top, and the slightly off-vertical alignment of the base magnet's field. With some careful adjustment the top will levitate for several minutes, until its rotation slows enough that there is no longer enough gyroscopic action to keep it stable. At that point Earnshaw takes over and the top falls.

Spin stabilized levitation was first demonstrated by inventor Roy Harrigan. More in-depth information (including the mathematical explanation) is available at:

"Spin Stabilized Magnetic Levitation" (Martin D. Simon)
http://www.physics.ucla.edu/marty/levitron/

"A Toy Story - The Chemical Relevance of Earnshaw's Theorem, and How the Levitron® Circumvents It" (J. M. McBride)
http://www.chem.yale.edu/~chem125/levitron/levitron.html

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#1

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/11/2006 5:41 PM

A normal magnet with two poles floating freely cannot be made to levitate above another for the simple reason it will always flip over until the opossite pole is facing the lower magnet and then be attracted down to it.

A monopole magnet if such a thing existed could be levitated but apparently they do not exist.

A magnet can be levitated above a superconductive sheet where the magnet field induces currents in the sheet that produce an opposing field.

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#3
In reply to #1

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 12:10 AM

"A magnet can be levitated above a superconductive sheet where the magnet field induces currents in the sheet that produce an opposing field."

------

The Meisner effect.

------

"A monopole magnet if such a thing existed could be levitated but apparently they do not exist."

Grand Unified Theories (GUTs) and certain String theories predict the existence of magnetic monopoles (the ground state of a hypothetical particle called a dyon). Maxwell's equations are asymmetric, in fact, because of the absence of magnetic monopoles, and does not actually exclude their existence. "Classical" GUTs predict magnetic monopole production as a result of symmetry breaking in the Early Universe, but these same GUTs also predict proton decay, which has never been observed. Even without direct observational evidence, if protons decayed as predicted, the Universe today would be a very different place. The apparent absence of MMs and the problems with proton decay have led many to abandon GUTs in favor of more exotic theories.

Too bad, too. With a few magnetic monopoles I could build myself a DC transformer.

-e

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#2

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 12:04 AM

This sounds very much like a parlor trick - i.e. the catch is in the use of the words levitate and magnet, implying but not stating that magnetic repulsion will do the lifting, and also implying there will only be two magnets present.

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Anonymous Poster
#62
In reply to #2

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/17/2006 9:14 AM

it is a good news

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Anonymous Poster
#168
In reply to #62

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/25/2007 10:10 PM

THE LEVITATION IS MIGHT BE GOOD FOR ENTERTAINERS,MAGICIANS AND ILLUSTIONIST AS WELL AS DIFFERENT TYPES OF GUNS AND THE MAKING OF DIFFENT TYPES OF POWER. ENGINE POWER FOR EARTH SAFENESS AND HOUSEHOULD ELECTRIC POWER. NOT ALL PEOPLE KNOW OR UNDERSTAND THE TECHNOLOGY SO IT WOULD HAVE TO BE SIMPLE.,PEOPLE WOULD EVEN INSTALL FOR THEM AN THE INSTALLERS CAN BE GETTING EDUCATION AS WELL SO THATS GOOD TO ..

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#4

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 12:13 AM

Earnshaw be damned. I'm wrong; she's right. My Levitron toy proves it can be done. The gyroscopic action of the spinning top keeps it from flipping over. Once the top spins down enough, Earnshaw takes over and spoils the fun.

-e

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#35
In reply to #4

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 3:10 PM

The Levitron might be the correct answer, but, I don't think there is only one magnet in the base. I believe it is a series of magnets set in the shape of a donut. I could be wrong. The question specified "one magnet levitate in free-space above another magnet" (not magnets).

Speaking of the Levitron, we are playing with one right now at work. Using the Perpetuator, we were able to get it to levitate for 2 hours and 15 minutes!

--Ariel

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#36
In reply to #35

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 3:28 PM

The levitron does have a single (donut-shaped) magnet in the base. The physical analysis behind the levitron is actually quite complicated. Here are a couple of papers. Warning - they get pretty deep into Hamiltonian and Lagrangian mechanics.

Berry M.V., "The Levitron - An Adiabatic Trap for Spins," Proc. R. Soc. Lond. A 452 (1996) 1207-1220.

Dullin H.R. and Easton R.W., "Stability of the Levitron," 1998.

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#37
In reply to #36

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 1:51 AM

Very nice. Thanks for posting these.

I have a very early Levitron whose magnet is square and has no central hole.

-e

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#42
In reply to #35

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 10:14 AM

There are several ways to find out if the base magnet is a composite of magnets. Firmly grasp a small magnet (size of an aspirin or smaller) between your fingertips and slowly move it over and around the base magnet. Hold it fairly close to the base while you do this. If the base is a single magnet, the torque exerted on your "probe" will vary smoothly. If the base is a composite magnet (presumably to create multiple pole pairs) the torque's "ride" will be bumpy and the probe will occasionally try to do a 180.

-e

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#5

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 12:16 AM

Habach's mag bearings are another exception provided the term "one magnet" can consist of an assembly of magnets each of which is oriented in a specific direction.

-e

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#6
In reply to #5

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 4:36 AM

I think this scheme would comply with the specification laid done, one long magnet is setup with say a north pole facing up, the magnet to be levitated (north pole down) is fitted with a cone of none magnetic material that overlaps the lower magnet so that the centre of gravity of the structure is below the point where the repulsion occurs.

the field of the lower magnet should be shaped so that the strength is weaker in the centre, we have now constructed a single ended magnetic bearing!

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#34
In reply to #5

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 11:25 AM

Actually they're not an "exception," because they're physically constrained. The challenge was to have one magnet levitate "in free space" above another one. Magnetic bearings work because mechanical constraints force them to be stable.

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#51
In reply to #5

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 11:56 AM

I thought Earnshaw stated that no combination of stationary forces that obey an inverse-square-law relation could result in a stable configuration. That is to say monopoles and complex static arrangements (including magnets with holes) cannot help. Halbach bearings are, to the best of my knowledge, only stable when there is motion - i.e. they use the same principles as the Levitron, but control the positions more positively.

So we have just two options so far - keep the lower magnet spinning, so the upper one can be otherwise unconstrained, or use a diamagnetic material (or superconductor) somewhere in the arrangement to provide the stability.

Fyz

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#7

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 5:07 AM

Without reading other posts....I am just about to, I will be very disappointed if there is no mention of 'Magnetic Cup Cone Bearings. Which are FACTUAL levitating magnets. It's a bit like saying a cup will not hold water because of the 'Balderdash Law'

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#8
In reply to #7

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 5:22 AM

Postscript:- For those unfamiliar with 'The Balderdash Law' it is an extension of the 'Bunkum Theory' ....Namely, that as the Bunkum Theory postulates that liquids flow through all holes, The 'Balderdash Law' states that 'a receptacle with a hole will inevitably leak' and as a 'cup' has a hole in the top, clearly it will not hold water. (Quad Est Demonstrandum.)

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Anonymous Poster
#81
In reply to #8

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 11:31 AM

Alastair Carnegie strikes me as a trifle too arch regarding the merits of Balderdash and Bunkum, which in truth are among life's great verities. Of course a cup won't hold water -- over time. Evaporation will inexorably drain it -- through that hole in the cup's top. B & B triumph again!

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#96
In reply to #81

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/26/2006 2:23 PM

General Sir Peter de la Billière KCB CBE DSO MC MSc DL, one of our most decorated British Officers, will have to name a pair of Billy Goats 'Bunkum' & 'Balderdash' in your honour for the best proof of this law. See "Farm Africa" for details. The General is a 'Patron' aforesaid.

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#93
In reply to #8

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/25/2006 5:19 AM

(O/T!!!) Ancient Latins would say: Quod erat demonstrandum = What was to be demonstrated. Syntactically, idiom "Quod est demonstrandum" is correct (= What is to be demonstrated) but would rather stand at the beginning of a deduction.

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Anonymous Poster
#94
In reply to #93

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/26/2006 9:59 AM

If we're going to be pedantic, ancient Latins wouldn't say anything, because they are all dead. And, although Quad erat demonstrandum" = "that which was to be shown" is traditional, I'd be interested to see a reference that dates before the middle ages (this being a translation of Euclid's Greek version into mediaeval [or dog] Latin)

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#97
In reply to #93

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/26/2006 2:37 PM

Michael Edward Palin CBE, Oxford Scholar and celebrity comic, may have to name a few 'Nanny Goats' in your honour, (magnetisme = Animal Magnetism, I have seen them levitate as kids jumping for joy) you must contribute some good Latin Names 'kalaci' for us. Michael is also a 'Patron' of Farm Africa.

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Anonymous Poster
#9

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 5:41 AM

The levitron works because one magnet is spinning. Contrary to popular belief, it's not because the spinning magnet cannot flip over. Even if its orientation is constrained, it would not be stable. It's a dynamic phenomenon, the math of which is very complicated. It will not be stable if it is spinning too fast or too slow. See this web site: http://www.physics.ucla.edu/marty/levitron/

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#15
In reply to #9

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 7:27 AM

I am new to the Levitron but two points interest me what would be the effect if the top was only used as a flip over restraint and the magnet was mounted on a very low friction jewel bearing top and bottom (such as are used in watches) so that it acquires very little rotation.

Secondly if the magnet is rotating I take it its field is rotating with it hence it must be losing energy by inducing currents in nearby condutors which in turn will produce a magnetic field, will this help or hinder the operation?

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#22
In reply to #15

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 3:49 PM

As for the induction of electric currents in nearby conductors, the levitating magnet rotates around the axis of magnetic flux, causing not appriciable change in magnetic field. I would account for wind losses 10x more than the wobble.

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#23
In reply to #22

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 6:40 PM

halcyon m, your response to syphrum brings to mind a 'Professor Caracticus Pots' type over-unity concept all that is missing is the 'vital' chymestrical ingredient. Quentin Wallop (Earl of Portsmouth) & custodian of the Chymestry Collection of Sir Isaac Newton, would I am sure permit interested academic researchers, access to his extensive muniments not in the Cambridge Library "Portsmouth Collection"

Check out :- http://webapp1.dlib.indiana.edu/newton/index.jsp

Hold on a tick.....I hear a shrill whistle blowing,....time to infuse the folium in balneo aquae ebullentis......back in a mo.....

Readers may like to contemplate the 'Evolute' & ' Involute' of Descartes' folium equation X^3 + y^3 = 3 a.x.y or Parametrically x = 3 at(1 + l^3) = 3 at^2 / (1 + t^3) the 'folium asymptote' x + y + a = 0

I need to find/locate the Lucasian Chair's/Wheelchair's last correspondence to me on this particular cartesian equation and it's profound implications.

Also check out:- http://webapp1.dlib.indiana.edu/newton/mss/dipl/ALCH00109

'Normalised' translation MS :- http://webapp1.dlib.indiana.edu/newton/mss/norm/ALCH00109

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#24
In reply to #23

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 6:47 PM

Transfusion of Folium Minor Camellia Sinesis in balneo aquae ebulenttis complete.

We are searching for a 'Magnetic Shielding Alloy' that is both effective and resistant to induced eddy currents. An Apple Tokamak style transformer with rotating dual-vane alternately shielded permanent magnetic inserts....

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#30
In reply to #22

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 2:43 AM

It has been established that levitation only occurs over a limited range of rotation speeds, I wondered what would be the effect of preventing the magnet from rotating.

I understand that air resistance is the main source of loss but was interested in the secondary effect of induced magnetic fields

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#38
In reply to #15

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 4:04 AM

I note that Berry addresses the matter of currents induced in nearby conducters and agrees that these would occur and increase the rate of spin loss but I do not think anyone has yet considered how the Levitron would behave if the magnet was contrained from spinning as I have suggested.

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#48
In reply to #38

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 2:30 AM

Separated since birth, mirror-image twins Syhprum and Murphys have finally found each other - on the same engineering forum, on the same thread! Twins do indeed tend toward the same things.

So which one of you is the real Evil Twin?

-e

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#49
In reply to #48

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 4:56 AM

I got black listed because I broached the subject that darest not speak its name, so I got my doppleganger to register via my alternative ISP.

I (syhprum) have now been allowed back but like Mr Hyde my alto ego sometimes sneaks back in and I do not know how to destroy him.

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#54
In reply to #49

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/16/2006 12:46 AM

I have no idea what that unprintable subject might be. Perhaps you might tell me privately lest I make the same mistake? I'm good at things like that.

Thankfully you didn't choose a palindrome for you nom de plume when you first signed on. Like "Bob."

So, if you two shake hands, do you both disappear in a cataclysmic burst of gamma rays? Btw, I understand the "Hyde" part; Penning traps do have a tendency to leak sometimes.

-e

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#50
In reply to #38

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 7:16 AM

If the magnet is constrained from rotating Earnshaw's theorem kicks in and there is no stable configuration that allows levitation.

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#52
In reply to #50

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 4:00 PM

The linked Wikipedia article says there are "no local maxima or minima, only saddle points" for the field potentials in free space. When I was a child, I had a set of magnetic discs named "Thinky Winkies" or something like that. I used to try for what seemed like hours at a time to set one disc above the other in "perfect" alignment so the upper disc would be levitated, but it would always slip off to the side. I didn't know any physics or Hamiltonians then, but I remember the distinct feeling that some undefined force was working against my efforts.

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#16
In reply to #9

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 8:04 AM

Thanks, Guest.

I had been in email contact with the physicist (mentioned by name in early Levitron literature) who evaluated the device when it first came out. I suggested several experiments to ascertain the actual cause of the levitation, to which he replied, "I'm a Theorist, not an Experimentalist!" Hmmm.....

Perhaps he should read Thorstein Veblen's "The Leisure of the Theory Class."

-e

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#17
In reply to #16

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 8:25 AM

europium, Science, I was taught, was a combination of Theory and Experiment,

I have plenty of Fridge Magnets, with a small weak magnet disk insert, I have chewing gum and a box of assorted brass screws I also have an assortment of loudspeaker magnets. Theorising....If I stick a brass screw to the fridge magnet disc insert with a bit of chewing gum.....Visualising he magnetic field of the L/S ring magnet, I can see a 'well' in the center, will I be able? to suspend the disc/brass screw in this well? .....I reckon it might work. I will do the Experiment and invite readers to guess/experiment for themselves as to what might happen.

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Anonymous Poster
#10

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 5:51 AM

Another trick is suspending a magnet below another magnet. This point is normally unstable, but can be stabilized by using a diamagnetic substance such as Bismuth or pyrolytic graphite. See:

http://www.physics.ucla.edu/marty/diamag/

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#11
In reply to #10

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 6:11 AM

Thank you Guest, I have saved those links to my 'Art Stuff' File....An honoured place.

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Anonymous Poster
#19
In reply to #11

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 11:46 AM

Interesting video. One way it could be done is to have pickup coils underneath the brass base underneath the three pendulums. There are a lot of toys around that use that technique. A simple transistor circuit provides positive feedback, and the battery lasts a long time.

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#20
In reply to #19

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 3:13 PM

Guest, without wishing to pour cold water on a lovely piece of sculpture, I took note when I first viewed the video a few weeks ago, that one camera shot showed a mysterious arrangement just proud of the circular ball-race track. each time the big bal-bearing circulated, this bent tube affair was pressed down, There are quite small mercury tilt switches that would fit inside that tube. When I see a perpetual motion machine with full construction drawings and plans. with an invitation to examine and dismantle the working? machine, then and only then, will I blow the last trumpet on the First Law of Thermodynamics. The Philadelphia Scandal had an Old Pensioner imprisoned in an adjoining room perpetually turning a handle. The cad who charged people to view his 'wonder' fed this poor old man on stale bread from the garbage cans.

It was a young boy who first raised suspicions, his father was a clock-smith, and he pointed out that the teeth had worn (were polished and shiny) on the wrong side of a cog. He made no mention of it till he got home. He told his father who then arranged for a friend he knew who could fix clocks and machinery by ear. When he visited the showcase this 'perfect pitch' mechanic noticed immediately the method of the concealed drive mechanism....a fine fishing gut thread pulled through a supporting leg. he proceeded to dismantle the machine there and then, against the protests of the cad....."I will pay for the damage sir, and you can sue me if I am wrong" he of course was right and the poor old man was rescued from his imposed hellish torment.

The angry mob smashed up the exhibit and the cad took flight as soon as the thread was discovered.

A conjecture as to the origin ow World War One, i.e. both sides racing to build warships to be driven by an amazing air compressor perpetual over-unity boiler is too long a tale for this thread, suffice to say both Germany and Britain thought the other side had the amazing secret..... "The 39 Steps" of Book & Film... the dreadful secret of the actual event? quite possibly.

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#66
In reply to #10

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 7:13 PM

The bismuth "floating magnet" as found at sci-toys.com, is a truely permanently self-levitating magnet, and though the toy as shown "suspends" the target magnet totally unfettered from above, the same setup should work in an inverted design, with the larger magnet (the stack) below as easily as from above.

The diamagnetic blocks do actually result in a perpetually suspended magnet above/below another, requiring no dynamics nor power source, nor constraints on the free floating magnet, merely altering the field effect to bypass it's standard inverse square function. That's not cheating, it's using the exception

There is more to be gained from the exception than from the rule. It's the why of the rule one needs to understand.

Let's all keep playing with toys.


NoSciFi

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#12

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 6:16 AM

What would happen if both magnets were inserted into a tube? Would this still be considered "free space".

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#13
In reply to #12

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 6:44 AM

I think that would be a cheat mongoose, as the tube would confine the magnet, it would not be 'free' to flip over. If one has two large ring magnets salvaged from a loudspeaker, I am sure it is possible to levitate one above the other in a cup cone arrangement with the floating magnet the truncated cone prevented from flipping over with a suitable weight. This may not qualify as 'free' space either. I have levitated a ball with multiple magnets cut from 10mm x 5mm flexible magnetic strip, suspended over an old L/S magnet. but multiple magnets again might be 'cheating' The Levirtron link our Guest gave was amazing for the height of the levitation.

Now anybody out there wanting to make a floating 'Mirror Tile Glitter Ball' It could be a marketable novelty?

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#14
In reply to #13

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 7:02 AM

Postscript.:- If any interested CR4 hobbyists do make a 'Floating Glitter Ball' I think it would look great as a 'table-center' feature in a Bar or Club. I think a lot of customers would be waiting i.e. Philippe Starke and Jade Jagger of YOO Ltd. might even be interested? send a digital photo in.

A spot light, or several above each table.......mmmm? Flexible Magnetic Strip is easy to cut into squares with a knife, and small square mirror tiles are readily available with self adhesive backing....Project for a Christmas Party perhaps? Not much time left.

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#27
In reply to #14

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 8:27 PM

I think a floating Death Star would sell better...

-T-Rex
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#28
In reply to #27

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 11:10 PM

As it happens I was acquainted with some of the TRex band members, ..an off thread discussion......Sir Isaac Newton most certainly was aware of what we now refer to as Dark Energy or purists refer to as Zero Point Energy. There was a scruffy little teenager named 'Adrian' who won an exhibition to London University. on his first day he kept putting his hand up. The head of the maths dept. asked him if he wanted to go to the lavatory. "No" said the young Adrian, " I want to ask a question" ..."There will be an opportunity to ask questions after I have finished my viva voce lecture"

Adrian waited patiently.

"Now young master Adrian, what was that question"

Adrian proceeded to the blackboard, and without saying a word, demolished the professor's theorem.

Bored to tears with the imbecility of his so-called Professors, Adrian decided to crack Sir Isaac Newton's Cypher....successfully. That was well over 30 years ago.

The Dark Star may yet materialise.....who knows. The information that Adrian begged stay secret for eternity has regrettably been allowed out. Pandora's Box has been opened wide. Never to be closed ever again.

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#29
In reply to #28

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 11:46 PM

An example:- Assume a that by Chimaerical investigations....unlikely....a magnetic shielding alloy of exceptionally high resistance was obtained. Say a Cold Cast Epoxy + Alloy Flake Compound....Whatever. A Transformer is designed...looking much like the 'apple' from the tree at Sir Isaac's home Woolsthrop Manor. A nice big Cooking Bramly I think. lovely baked with lashings of cream and caramelized honey. yum yum.

Well four segments of this big apple need removing. and the core wound as the secondary power output. four strong neodymium magnets are placed in suitable gaps in the four branch manifold of the 'Transformer Steel' core. North South ,East West, so to speak. Four low power synchronous motors each individually drive a pair of vanes made from this Alchemical 'Magnetic Shielding Alloy/Compound?????.... this is the season of Panto and Fairy Tales...please allow it dear reader. It is clear to most, that two magnets will be in North/South polarity and two South/North. The shielding vanes alternately shield either the East-West pair of magnets or the North-South magnets. The winding at the center should theoretically have an induced Alternating Current resultant with the constantly alternating influence of each opposite polarity permanent magnet.....alternatly shielded by the four double-vanes.

Over-Unity? only Puss In Boots Knows for sure. But the Big Ogre from Jack's Beanstalk has put poor Puss in Boots into a box containing a Schwarzchild radius singularity that can be triggered by a mischievous timing device that counts radio active emissions. The decision is entirely remote. Puss in Boots either vanishes into a singularity or survives to let us know the secret. one 'meow' for 'Yes' two 'miaows' for 'No'.

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#31
In reply to #27

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 6:37 AM

MAY THE FORCE BE WITH YOU, LUKE.......TREX..........oh heck whatever...May the floating glitterball/ Death star show you the WAY!!!!

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#45
In reply to #31

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 11:12 PM

"Fe Fi Schroedinger Fum, I smell the blood of a Southafrican" says the Giant Ogre. The levitating glitter-ball is the only escape. Climb back down the beanstalk quick. The Ogre goes into a stupefied trance when he sees it spinning.

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#40
In reply to #27

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 9:19 AM

Check out sci-fi author H. Beam Piper's Little Fuzzy story for a description of a planet model hovering in the corner of the manager's office, illuminated with a sun-simulating spotlight and turning in sync with the planet's rotation so that time could be read directly off the globe. Such a gadget could put the geochron clock people out of business.

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#18

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 9:35 AM

She is right, of course, though I would not told her that it was impossible in the first place.

There have been several different methods shown to succeed in this. One solution is even being marketed as a cheap toy that you can buy from the "Discovery" store.

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#33
In reply to #18

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 8:09 AM

I second the motion, to tell a woman anything is impossible is tantamount to certain death!!! Long, slow angonisingly painful horrific etc etc etc death. Could you possibly supply further details on said toys! Thanks

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#41
In reply to #33

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 10:03 AM

I have a bumper sticker that reads "Marriage Is A Voluntary Misfortune."

(The other ones are geeky: "Bush > /dev/null" "Got Root?" "I Can Read Your Email" and "Keep Austin Weird").

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#21

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 3:45 PM

Actually the magnet can be made stable with the use of electronic stabilization or certain diamagnetic materials.

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#25

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 7:04 PM

The Midnight hour approaches, Woden's Day is upon us. A wee dram of Special Reserve in the 'Camellia Sinesis' in honour of Woden and the Cardinal Number of the occasion. A perfect nest of Balls. adding if made of clay and rolled in the hand to a perfect spherical Dodecahedron.....mmmmm

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#26
In reply to #25

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/12/2006 7:15 PM

1.08 precisely GMtT....Woden...likened by the Romans to Mercury the messenger. His Magic Square that of 64 or 8 x 8,....The $64 dollar question for the Norse God.

The 'Evolute' of Descartes' Folium is a 'DECUS ET TUTAMEN' meaning 'An Ornament and a Safeguard'

The 'Involute' is where the Guard-Safe needs posting. It is a Serpent.

G.K. Chesterton :-

Gilbert Keith Chesterton's "Utopia Of Userers And Other Essays" www.kessinger.net Millionaires Gilbert writes in the essay entitled "Unbusinesslike Business" :- The fairy tales we were all taught did not..........consist entirely of lies......" "......For instance "Puss in Boots" and "Jack and the Beanstalk" if I remember aright, the ogre was not only an ogre but also a magician.........." "....Bad government, like good government, is a spiritual thing. Even the tyrant never rules by force alone; but mostly by fairy tales......." ".....The sight of a millionaire is seldom,.....he is a fascinating personality. So is snake. At least he is fascinating to rabbits; and so is the millionaire to rabbit-witted sort of people...." ".....He has truly turned men into sheep, as Circe turned them into swine." IT CONTINUES.... ENJOY, IT IS THE SEASON OF PANTO-MIME. Puss in Boots? or Jack in the Beanstalk?

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#32

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/13/2006 7:14 AM

I suppose looking at Wikipedia is probably cheating but it seems from this article that the friend is right so long as she is not talking about "classical" magnets. I have not really grasped the whole concept but very light "diamagnets" can be made to do this.

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#39
In reply to #32

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 6:54 AM

Thanks 'zarboki' I guess the princess that kissed the levitating frog in that fantastic video, would soon have a 'Leaping Lord' or even a handsome 'Leaping Prince' plighting his troth...... "On the first day of Christmas my true-love said to me.....tra la laa"

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#44
In reply to #39

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 5:54 PM

Alastair -

Your posts have spiraled from the slyly obscure through the delightfully daffy to the wildly wacked-out. Whatever that is you're slipping into the chamomile, can I have some??


- AstroNut

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#70
In reply to #44

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 10:17 PM

Camellia Sinesis, Well now, That's a tough one, and by the way this is bog standard Yorkshire Tea 'Camellia Sinesis' is the stuff in regular tea bags, A week ago we purchased three fine bottles of Whisky, one Irish and Two Scottish, for a whisky blending party. the girls chose a 50/50 Jameson/ 18year old single malt. (Top Secret) naturally how it mixes with tea is a vital consideration. We are talking of an unusual marriage, perhaps next year we will have a better idea. ab Irish & Scottish blend, may need a while to settle in. the girls liked the 18year old best for the oak/peaty aftertaste, the lads liked the smoothness of the Jameson. They work me so hard. decisions decisions. ..... I shall need to consult with my Priest, Father Tubman. This job is far too hard for a 'Minorite'. R.M.P.T.A. semi-retired reserve Military Chaplain.

Ah yes, levitation, The Olympics from Beijing will soon be upon us. James Carnegie, His Grace the Duke of Fife is U.K. Olympic Sponsor. We are a bit concerned the Tibet/China team might run off with all the high jump medals. Levitation being a Tibetan speciality. China with Tibet may have an unfair advantage. more research work needed. Magnetic levitation now that I have seen a 'frog' do it, might be a solution, if those monks try it on? Check out 'Pravda' on the subject, I suspect our Soviet friends are equally concerned.

http://english.pravda.ru/society/anomal/09-11-2005/9197-levitation-0

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#47
In reply to #39

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 2:22 AM

Alastair, methinks you missed your calling. Just look at Jim Carey. As long as they regulate his Ritalin, he does fine.

Btw, would you like to try some of my Adderall? Just in case you'd like to chill for awhile...

-e

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#43

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/14/2006 4:56 PM

I think she's right. Some methods have already been mentioned (including control systems to move the lower magnets, spinning magnets...). She can also do it with 'conventional' magnets and without spinning anything if she places a superconducting plate between the magnets.

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#46
In reply to #43

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 2:11 AM

Years ago I was given a disk of high-temp superconductor as a gift along with a couple of aspirin-sized rare-earth magnets. The disk was of one of the ceramic SCs nicknamed "1 2 3," and it would superconduct somewhat above LN2's boiling point (77° K). The Meisner effect (the basis of your suggestion to interpose an SC plate between the two magnets, which definitely would work) was really something to actually see up close and personal. Thankfully my employer had plenty of LN2 on hand. I like to eat my Reese's Cups frozen.

-e

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#53

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/15/2006 10:27 PM

You can produce and effect not unlike the reflected magnetic filed in a superconductor by rotating a sheet of conductive material at high speed below the magnet.

The movement of the sheet of conductive material causes induced currents in it that result in a magnetic field in the opposite direction of the magnets field. The only problem with this technique is that it will impart a considerable torque on the magnet thus causing it to rotate. Once the magnet begins to rotate the relative motion between the magnet and plate reduces and the opposing magnetic field decays.

It is however possible that, if you used both magnets arranged so that the induced torque on each cancelled that of the other magnet's, it might just work.

That gives us three possible solutions but unfortunately they all require some sort of active intervention and since the question states;

"make one magnet levitate in free-space above another magnet"

it would clearly preclude the superconductor and rotating conductor as the levitating magnet or magnets would clearly be not be levitating above another magnet.

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#55
In reply to #53

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/16/2006 11:47 AM

I think that, so long as the lower magnet is vertically below a successfully levitated magnet, the lady wins* - whatever she places in between the magnets, and whether or not the presence of the lower magnet has any relevance to the levitation of the upper.
*(I certainly wouldn't expect to win against that)

Aside from that, are you certain that the rotating plate works when the magnet is aligned above the centre of rotation with North-South vertical? (I think the potential gradient becomes radial, so no eddy currents are possible).

Fyz

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#56
In reply to #55

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/16/2006 3:03 PM

When the lower magnet is rotating it will of course drag the upper one round but could it not be restrained by a horizontal magnetic field or are we defying both Earnshaw and the young ladies again

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#57
In reply to #56

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/16/2006 4:31 PM

I was writing here about rotating a non-magnetic conductive plate, as described by masu, rather than about rotating lower magnet or magnets. The problem I was trying to describe was that, even if the basis of the rotating plate could work as described, the 'levitated' magnet would naturally rotate to the position where it could fall. Actually, I don't believe that it works at all - I'll concoct an explanation of the flaw when I have more time.

Back to the basics: in the absence of unquenched conduction (or diamagnetism), I believe that it is momentum that is the final parameter that 'breaks' Earnshaw's inverse square law constraint. I believe that, if we use lower magnets that are not rigidly constrained, their momentum could be made to serve the same purpose as moving the upper ones; however, to the best of my knowledge this has yet to be demonstrated. In any event, recent enhancements to the Levitron have demonstrated that the momentum of the levitated magnet can be maintained indefinitely via magnetic drive.

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#58
In reply to #57

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/16/2006 11:40 PM

Physicist wrote in post #55

"Aside from that, are you certain that the rotating plate works when the magnet is aligned above the centre of rotation with North-South vertical? (I think the potential gradient becomes radial, so no eddy currents are possible)."

I don't know as I have never played with it myself, I have only seen it demonstrated at a distance. The strength of the induced currents is proportional to the velocity of the conductor and the strength of the magnetic field that it is moving through so the effect would decrease as you approached the center.

If the magnet had one pole directly over the center of the disk the induced currents would be radial in nature and tend to cancel out. However if the disc ware fairly thick the strength of the induced current would decrease as you got further away from the magnet. That would tend to indicate that a radial current at the surface of the disc would then flow down through the disk and return to the center as you get further from the magnet. These currents however would be small compared to those induced at or near the edge of the disc.

In any case it's not the answer to the question as it clearly states the objective is to;

"make one magnet levitate in free-space above another magnet"

Which would preclude the super conductor and rotating plate solutions.

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#59
In reply to #58

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/17/2006 1:48 AM

Hi Masu,

How are you enjoying your new scope? Did it arrive intact?

-----

"make one magnet levitate in free-space above another magnet"

Which would preclude the super conductor and rotating plate solutions.

+++++

I wouldn't be too sure the superconductor is out of the race. While a magnet is suspended above a superconductor (a particular manifestation of the Meisner effect), the superconductor is indeed a magnet; an electromagnet whose surface currents produce a magnetic field that precisely counters the suspended magnet's field. Any attempt by the suspended magnet to change position is immediately checked, no matter how small the attempt (limited only by quantum effects), by concommitant changes in the currents. A superconductor may not be an intrinsic magnet, but under these conditions it is every bit an electromagnet as one wound from conventional wire.

The Challenge speaks of the relationship between the magnets, but nowhere does it say anything about the magnets themselves. All we are told is that they're magnets. I'm taking that more or less as a carte blanche as far as magnets are concerned.

----

Where are the best 'seeing' conditions in your "neck of the woods?" I'm guessing maybe somewhere outside of Adelaide?

Take care, and remember to bring a red torch/flashlight with you when you go stargazing. I nearly broke my neck once because I forgot to bring mine and couldn't find my way in the darkness. Most of all, have fun!

See ya,
-e

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#60
In reply to #59

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/17/2006 3:49 AM

The scope arrived on Thursday and it's taken me a bit to translate the manual for the automated tracking and star finder from English into something that resembles English. I finally managed to get a grasp of how to drive the thing and guess what, yep it started raining and didn't stop till about 01:00am this morning. I couldn't get the thing to align and it took a while and a GPS to figure out that the co-ordinates that were supposedly preset to my location were wrong. When I entered the real co-ordinates it worked like a charm. Saturn shows up brilliantly and the moon is crystal clear even with the 25mm eyepiece that comes with it.

Now all I need to do is convince the better half to let me spend money on accessories like extra eyepieces, barlow, dew shield, camera mount etc…

There are plenty of good places to observe the southern sky in Aus, nearly everybody lives in the eight capital cities so there is plenty of empty space without lights. Where we live in Adelaide we are actually on the very outskirts of the city, in a wine producing region, so the night sky is quiet spectacular. Don't know when we will be back there though and it could be several months. Probably the best know place for observation is Mt Stromlo which is about a 4 hour drive from Sydney. Unfortunately a bush fire went through the area a couple of years back destroying some of the observatories and telescopes so there is a fair amount of construction going on there at the moment. When you get out in the middle of the continent with no center of population for hundred of kilometers the sky is probably unbeaten anywhere else on earth.

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#61
In reply to #58

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/17/2006 5:21 AM

Hi Masu - the objective says nothing about cause and effect - merely that the magnet should levitate in free space, and that it should be above another magnet. Therefore, so long as there is a magnet underneath the levitated magnet, the lady wins - and unless you yourself are a lady, you should know better than to argue that point with her. (BTW, I seem to remember similar semantic considerations coming to the fore in my school playground - don't they play these semantic games in school playgrounds in Australia?)

While I'm in contradictory mood: you say that "You can produce and effect not unlike the reflected magnetic filed in a superconductor by rotating a sheet of conductive material at high speed below the magnet". On the basis that the conductor is essentially linear, this must be incorrect. The effect of the falling and of the rotation add linearly - so we can consider the effect of rotation independently of the falling of the magnet. It then becomes obvious that, if one direction of rotation serves to support the magnet, the reverse direction will pull it downwards. This clearly suggests that the only possible effect of rotating the sheet would be to apply forces to the magnet that are (on average through a cycle) parallel to the plane of the magnet's rotation.

This could be a method for maintaining the rotation of the upper magnet for the Levitron, however.

Fyz

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#63

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 1:58 PM

I wonder if it would be possible to place a small magnet on the table, to put a large curved magent above it, and have it levitate in free space. My thinking is this: a large magnet would have a moment of inertia such that the magnetic field would not be able to tip it over (much like how a tightrope walker uses a long pole to keep themselves upright), and a curved surface would keep the upper magnet centered. The upper magnet would be sitting on a "cushion" of repelling magnetic forces much like a hovercraft sits on a cusion of air.

I know it is possible to magnetically hold a sphere stationary in free space, because that is how ultra precise vacuum gauges are calibrated. A sphere is colored on one side, and held in magnetic levitation. It is then magnetically coupled to "spin" in a vacuum. the coupling is turned off, and by shining a laser at the sphere and picking up on the reflection from the uncoated side, the vacuum pressure can be obtained based on the decay of the the rotational rate due to molecular drag. It is concievable that given enough time that the sphere may itself become magnetic, but its rate of spin keeps it in check with only small purturbations.

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#64

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 5:22 PM

Levitating magnets is no secret any more, the Germans are constructing trains with magnets under the train structure and also along the tracks, the magnets are of opposite polarity so they not only make the train levitate but also are used to impulse the train and achieve velocities of more than 100 miles an hour. This subject is nothing new and the only problem in the past was to have the technology to achieve it ... now is question of the past.

Robert Murillo Garcia

Electrical Engineer.

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#65

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 5:49 PM

She is, this is done with a small round magnet set up like a top and a larger round magnet as a base, place the smaller one in the center of the larger base and give it a spin, it takes a few trys ... if done right the spinning magnet will rise a few inches above the larger one and hover there untill it wabbles out of balance and falls to the side.

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#67

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 7:41 PM

it is true if the magnets are strong very strong and big you can set on the top on and it will hold you up. I used to make rare earth magnets until the fourn market back to strong and i started lousing money. my phone number is 9894270011 if you would like to chat.

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#68
In reply to #67

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 8:55 PM

With all of this chat about magnets, I would like to make an observation!

Having played with magnets since a small child, and always being fasinated by them, I just wonder WHY someone hasn't made something useful out of all that energy!!

I mean like a small opposing magnet motor/generator that could at least power some very low voltage LED bulbs....

Please comment

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#75
In reply to #68

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 6:03 AM

Hi, Campbell Lighting Here at Red Scar Industrial Coatings Ltd. where a lot of steel components are shot-blasted, one problem is 'airborne dust' A sort of solution to this is to ensure magnetic door seals etc. It helps to cut down a lot of the dust. Even 'rust' is attracted to very strong magnets.

The local firm that supply us, told me in confidence that he never discourages inventors with a new magnetic perpetual motion device. He would lose far too much business. Sadly so far, no client has succeeded to date.

Now I have this wacky idea, a core from a 'Toroidal' transformer, cut a gap, and insert two opposite polarity ultra-strong neodymium magnets. Naturally reverse polarity, & side by side. Then arrange for a magnetic shielding alloy to alternately shield either one magnet or the other. This shielding alloy, must not itself be either conductive(eddy currents) or magnetic,......we are working on the problem. I figure the conduction problem can be sorted by deploying a resin cold-cast technique. grains of alloy held together by an insulating adhesive like epoxy. sort of cold sistering.(You can buy cheap neodymium magnets used to pick up tools, fixed to a telescopic rod/pen from hardware shops. Drop one of those down a long length of copper pipe, 'rattle-fit,' and wait a long time for it to emerge from the end. It fall through like it was going through treacle,)

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#106
In reply to #68

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/02/2007 12:17 AM

Someone has. Check out Glacier Bay, they offer PM gensets.

A friend designed and built one that delivered about 12kW. Bigger models are now available.

Elnav

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#118
In reply to #106

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/04/2007 11:57 AM

I seem to remember I had one on my bicycle over 40 years ago. It powered the front and back lights. But I think the idea post 68 was drawing attention to, was an over-unity generator. The stuff of endless inexhaustible pipe dreams.

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#69

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 9:42 PM

This is the 12/19 edition, where is the answer?

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#71
In reply to #69

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/19/2006 11:25 PM

In response to the question;

"This is the 12/19 edition, where is the answer?"

I will quote from the 19/12 Specs & Techs bulletin

"The Challenge is currently on holiday break."

So I guess that we are just going to have to wait till after the holiday season.

One possible answer is along the lines of the suggestion by a Guest in post #64 of an arrangement of magnets along the lines of those used in a maglev train, as in Fig. 1.

However NoSciFi in post #66 might be onto something here. With an appropriately shaped diamagnetic material placed above the magnet it might just be possible to use the repulsive force to stabilize the levitating magnet, as in Fig. 2. This however whilst possible would be very tricky to achieve.

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#88
In reply to #71

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 8:45 PM

Your levitating magnet design appears to require constraint in order to keep repulsive pairs aligned. The use of the bismuth dielectrics allowa for attractive fields to align, while the pinching of the field away from the dielectrics requires no external constraint, no dynamics, no revolution, and will levitate for eons, even with small attempts to dilodge, the levitatee self-centers. The field external to the levitation chamber cannot (at least predominantly) pass THROUGH the bismuth, and is forced around from all directions. The resulting attractive field creates a virtual magnet in the same place as the floater. Away from center is always a weaker field, thus the self-stabilized levitation.

NoSciFi

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#89
In reply to #88

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 11:09 PM

NoSciFi you stated;

"Your levitating magnet design appears to require constraint in order to keep repulsive pairs aligned. The use of the bismuth dielectrics allowa for attractive fields to align"

Bismuth is a diamagnetic material not a dielectric material. A diamagnetic material will be repelled from a magnet the same way a magnetic material is attracted. The only problem is that the diamagnetic effect is miniscule compared to the magnetic effect and hence it would be impractical to use it to perform the levitating. It can however be used to stabilize the levitated magnet.

In the diagram the levitated magnet would try and drift away from the magnet that is lifting it but as it approaches the bismuth the repulsive diamagnetic force increased pushing it back into the centre. The trick is getting the levitated magnet in a position such that the lifting magnets field is just enough to lift the magnet but not strong enough to overwhelm the diamagnetic repulsive force.

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#90
In reply to #89

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 11:59 PM

True. No external constraints, no power source, no rotation required, no dynamics. A statically stable and generally perpetual (life of the magnets) levitated magnet, and it can sit on a glass coffee table. Has anyone tried with the field magnets below? It is easier to build above, but if you have the glass coffee table....

The field between the diaMAGNETIC guides is the same whether the field is applied from above or below. I built one 20 years ago, and for 10 years, it was beautifully stable. I hope the new owner is enjoying it.

Anyhow, the concept of the freely levitating magnet above another can be accomplished, without chicanery of any kind. It just uses the exception to the rule. Now that you've bent the fields to make it work, how do you bend the rule to make it reflect the real world?

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#72

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 12:54 AM

ANSWER:

This one is easy to answer. because Earnshaw's Theorem simply requires one revolving idea. The magnet that is being levitated is spinning at an RPM that places its "flipping" force less than the calculated mass to maintain its upright position.

This is similar to a front tire of a 27" bicycle wheel rotating from a rope or chain hanging from the ceiling....try to change its axis while the wheel is rotating at 170 RPM, and you will agree, it won't begin to change its horizontal axis until the RPMs are reduced significantly.

Now, you are ready to perform the experiment with magnets. The smaller the diameter of the levitating magnet, the higher the RPMs must be. Also, the lighter the (mass) or weight of the magnet, will also require higher RPMs.

When you are done...let me know how surprised you become.

...then, you will know why I am the "AnswerMan".

================================

The question as it appears in the 12/12 edition of Specs & Techs from GlobalSpec:

You're having a discussion at lunch with your friend, and she tells you that she can make one magnet levitate in free-space above another magnet. You tell her that's impossible, citing Earnshaw's Theorem as your proof. Who's right?

The answer to this questions will be revealed in the 12/19 edition of Techs

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#74
In reply to #72

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 3:19 AM

I am inclined to agree with Answerman that the most likely answer is to have the levitating magnet spinning fast enough so that the gyroscopic effect is sufficient to stop the magnet from flipping over.

This solution would however require either multiple magnets or a single toroidal magnet arranged in such a way that there was a weaker magnetic filed at the center than at the edge. Without such an arrangement there would be nothing to stop the spinning magnet from being pushed laterally and ultimately falling to the ground.

This of course is the mechanism behind the levitron as posted by europium in post #4 and was discussed in some detail but to date we still havn't seen anything that strictly answers the challenge to;

"make one magnet levitate in free-space above another magnet"

It all depends on how strictly you interpret the challenge and going on past challenge question answers I just don't know which is the correct response.

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#73

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 2:52 AM

This sounds like a trick comment. She did not specify the type of magnet used. I too can make a magnet float above another.I'll tell you all how later!

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#76

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 7:48 AM

Everyone is right but at the same time wrong. Anything is possible, Theory.

When a magnet is used in combination of a super-conductive plate the plate in its self become a monopole magnet. The resistive (suspension) lines of flux are reversals (bounce back) of the same field. While the side opposite of the magnet will exhibit a magnetic field is caused by pass through/around lines. Even though a magnet is needed to make the superconductor work the superconductor does not magnetize.

Ernshaw - Two forces of equal but opposite poles will expel each other. But when centrifugal force is applied to both "it" will over ride the natural force to reach a neutral point or flip over and attract. One magnet must be in a stabilized fixture and both must have a means of maintaining their respective positioning.

Maybe, just maybe the more interesting of possibility is held in "Black Matter".

Just some thoughts,

mudhawaii@sbcglobal.net

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#78
In reply to #76

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 8:33 AM

Hi Mudhawaii

I rather think that what you say (rather than what you probably mean) is even more "right and wrong" than many of the rest of us. For example, the reflected flux from the super-conductive plate does not look like a monopole. For an infinite super-conductive plate, it would be just the same as placing a reversed dipole (or multi-pole) on the other side of the plate; for a finite plate, the field is somewhat more complex.

Returning to others' descriptions: A perfect superconductor would behave here exactly as an ideal diamagnet. Based on the principle that "if it walks like a duck, quacks like a duck, etc. then it is a duck", the contributors are perfectly correct in calling the super-conductive plate a diamagnet (this is not the same as a conventional magnet). Incidentally, in case this is not already clear, much of the "stability" using a diamagnet can be regarded as a result of the magnetic image moving with the original magnet.

BTW, as I recollect Earnshaw relates exclusively to forces that obey the inverse square law, and simply states that no static combination of inverse-square-law effects can result in a stable equilibrium - the 'best' that can possibly be achieved is a saddle-equilibrium, i.e. one that is stable against movements along one axis, but unstable along another. This is why a combination of (non-diamagnetic) magnetostatics, electrostatics, and gravity can never result in as stable equlibrium - i.e. something has to move. Diamagnetics and conduction "break" this impasse, as they can result in appropriate movement of charges to allow stability.

Fyz

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#91
In reply to #76

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/21/2006 12:08 AM

I thought the only force available was the centripetal, and that no such force as centrifugal existed?

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#77

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 7:48 AM

There have been several propositions put forward that would/could meet the constraints the lady put forth. Many responses include disclaimers stating (basically) that something will happen causing the magnet to slip off-center, skew, slide or fail to hold position. The lady did not state HOW LONG a period of time it must levitate.

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#79

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 9:10 AM

I'm no scientist but I think that you can levitate one magnet over another if you alter the environment, subject the magnets to super low temperatures.

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#80

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 11:02 AM

dispite erhshaws theorem, a repelling magnet may levitate above another larger ring magnet. The levitron magnetic top toyt does it all the time.

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#82

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 11:46 AM

The devil is in the details as usual. Earnshaw's Theorem has the caveat of applying to permanent (stable field) magnets. Now that could be assumed from the statement but this could be one of those "Well, that is what I meant!" deals when she shows up with a set-up other than just two magnetic squares. The base magnet would need to be a variable field magnet or the "floating" magnet would need to be rotating or some variation on that. The other aspect that is not quantified is "how long".

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#83
In reply to #82

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 12:05 PM

I don't know how it is done, but I know it can be done.

You can see it at Floating Magnetically Levitating bed the bed is on sale for 150K


Eli

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#92
In reply to #83

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/21/2006 12:28 AM

I haven't even found a link to the "scale model that was presented" anywhere, much less any sign that it ever did work.

And I thought that the rotors in megawatt power generators ( aren't they really alternators?) were magnetically self-suspending once they were rotating? I had heard that the lower thrust bearing was only good for about 20 cold starts.

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#109
In reply to #83

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/02/2007 4:50 PM

Not so. This bed is tethered by four cables, which is what forces it to be stable. The challenge question was "free floating."

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#111
In reply to #109

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/02/2007 6:00 PM

I've googled that bed, and could not even find the working "model" that was supposed to be presented. A full-size was supposed to be years away. Did the creator of this manage to levitate himself out of sight after a pipe dream?


RichH

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#158
In reply to #83

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

01/12/2007 12:37 PM

I can just see the 'Dolly Bird' tripping up on those guy ropes in the middle of the night. The end of a beautiful relationship......Why not have them anchored from opposite corners....or would that spill the contents? as soon as one person got off the bed. I can see a great romantic comedy sequence here. Hollywood take note.

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#84

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 12:22 PM

Of course it can be done! Each magnet is a ring with a central hole (donut). With a pencil through each hole and the nearest poles in oposition, the top one will levitate just fine. I know, I know - the pencil violates the "free space" condition, but only a little.

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#86
In reply to #84

Re: Levitating Magnets: Newsletter Challenge (12/12/06)

12/20/2006 1:45 PM

The pencil thru the hole violates "free space" a great deal (not just a little). But that is one of the practical benefits of engineering, to give the world what it can afford! Anyone who wants a bed levitated in space using cryogenic technology has way, way, way too much money in their possession.

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