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Levitron

The Levitron is a magnetic levitation toy invented in the mid-1970s, consisting of a small spinning top embedded with a permanent magnet that stably levitates several inches above a larger base magnet without physical contact, defying classical expectations of magnetic instability.^[1]^[2] Developed by Vermont inventor Roy M. Harrigan, a high-school graduate with multiple patents to his name, the device was first conceptualized around 1976 through Harrigan's experiments with spinning magnets and patented in the United States on May 3, 1983, under U.S. Patent No. 4,382,245 for a "levitation device."^[1] The Levitron's operation relies on spin-stabilized magnetic levitation, where the top's rapid rotation—typically around 1,000 to 2,000 revolutions per minute—induces gyroscopic precession that counters the inherent instability predicted by Earnshaw's theorem of 1842, which states that static magnetic fields alone cannot achieve stable levitation of a permanent magnet.^[2] This stability requires precise adjustments, including the top's mass (fine-tuned with washers to within 0.1 grams) and the base's level orientation, allowing the top to hover and precess for over two minutes before gradually descending.^[1] Commercially, the Levitron gained popularity in the 1990s after Seattle entrepreneur Bill Hones discovered Harrigan's patent in 1993 and, with his brother Ed Hones, refined and marketed the toy under the Levitron brand through their company, Creative Gifts Inc.^[1] Over 500,000 units were sold worldwide, captivating audiences with its mesmerizing display of physics in action, though the Hones brothers' marketing initially omitted Harrigan's role, leading to controversy over invention credit.^[1] The device's success has inspired scientific research into magnetic stability, including studies on spin rate limits and adiabatic invariance, highlighting its role as both an educational tool and a demonstration of counterintuitive electromagnetic principles.^[2]

Device Description

Components

The Levitron toy consists of a spinning top and a magnetic base, both utilizing permanent magnets to enable levitation through repulsion. The top is a lightweight assembly designed for manual spinning, typically weighing around 22 grams in commercial versions, with its mass-to-magnetic-moment ratio carefully calibrated for stability at approximately 30.4 A m²/kg.^[3] The core of the spinning top is a ring-shaped permanent magnet, often constructed from strong rare-earth materials such as neodymium-iron-boron (NdFeB) in modern iterations, providing a high magnetic field strength essential for repulsion against the base. This magnet, with typical dimensions of about 3/4 inch outer diameter, 9/32 inch inner diameter, and 1/4 inch thickness in early designs, forms the levitating element and is axially magnetized such that one face exhibits north polarity and the opposite south. Attached to the magnet is a non-magnetic plastic or wooden stem, approximately 5 grams, which serves as the handle for imparting spin via finger-twisting, while an optional annular brass or plastic weight ring ensures balanced weight distribution to prevent wobbling during rotation. The top's overall diameter, including the encasing plastic and brass components, measures roughly 2-3 inches to facilitate easy handling and gyroscopic stability.^[4]^[5]^[6]^[3] The base is a circular or square platform housing a larger permanent magnet assembly, also typically neodymium-based for enhanced field intensity, configured to produce a repulsive magnetic field with a weaker or null central region to allow precise positioning of the top. In original patent specifications, this base features a dish-shaped concave upper surface formed by stacking multiple thin, flexible magnetic sheets—such as six 0.060-inch-thick, 3-inch-square laminar members with north poles aligned upward—deformed to create a conical field gradient supporting levitation at about 1.5 inches height. Commercial bases often employ a ring magnet or an array of disc magnets in a geometric pattern, encased in non-magnetic plastic housing measuring approximately 4-5 inches in diameter to shield external interference and maintain field uniformity.^[4]^[3]^[5] Additional components include a thin plastic lift plate placed atop the base during setup, which allows the top to be spun without direct magnetic contact and then raised to the levitation height of around 3.2 cm, and adjustment tools such as leveling shims for fine-tuning the base's orientation to achieve coaxial alignment with the top's axis. These elements, made from non-magnetic materials like acrylic or ABS plastic, prevent unintended field disruptions and aid in calibration without altering the core magnetic interactions.^[3]^[4]

Operation

To operate the Levitron, begin by placing the magnetic base on a flat, stable surface to ensure a level setup, which is essential for stable levitation.^[7] Use shims or adjustable legs under the base edges to fine-tune the magnetic field's vertical alignment if the top drifts consistently to one side; small adjustments, such as half-turns on leveling pegs, can correct imbalances.^[8] Next, position the lift plate (a non-magnetic plastic disc) directly over the center of the base magnet, as this facilitates precise height adjustment without direct contact.^[9] The setup relies on basic magnetic repulsion between the base and the top's magnet to create the initial lifting force.^[10] With the base prepared, place the magnetic top onto the lift plate and spin it manually by flicking the stem to achieve an initial rotation speed of approximately 1500 to 3000 RPM, though stable levitation often requires sustaining 1000 to 2000 RPM during flight.^[11] Once spinning, slowly raise the lift plate to about 1 to 3.2 cm above the base; if the speed and height are correct, the top will detach and hover steadily due to the balanced forces.^[8]^[9] The user experience demands patience and practice, as minor variations in launch technique can determine success. Under ideal conditions, the levitated top maintains its position for a typical duration of 2 to 5 minutes before air resistance gradually slows the spin below the stability threshold, causing it to descend.^[11]^[9] Stability can be disrupted by external factors such as air currents from nearby fans or drafts, surface vibrations from uneven tables, or temperature fluctuations that slightly alter the magnetic strength (e.g., adding or removing small weights like o-rings to compensate for cooler conditions).^[7]^[10] For troubleshooting, recalibrate the setup by re-leveling the base or adjusting the top's effective weight in increments of 0.1 to 0.2 grams if the top bounces without lifting or flies off immediately.^[7]^[11] Avoid operating near metal objects or ferromagnetic materials, as they can distort the magnetic field and prevent levitation; perform the demonstration in a clear, non-interfering space.^[10] If environmental changes like humidity or room temperature shift occur, repeat the height adjustment with the lift plate to restore the capture volume.^[9]

Physics of Levitation

Magnetic Fundamentals

Earnshaw's theorem, established by British mathematician Samuel Earnshaw in 1842, demonstrates that stable static levitation is impossible in a system composed solely of permanent magnets interacting through electrostatic or magnetostatic forces.^[12] This result arises because the magnetic field of permanent magnets satisfies Laplace's equation (∇²B = 0) in charge-free regions, implying that no local minima or maxima exist in the potential, leading to inherent instability where any perturbation causes the levitated object to move away from equilibrium.^[12] Consequently, pure static magnetic levitation configurations for permanent magnets cannot achieve stability without additional mechanisms.^[13] In the Levitron, magnetic levitation relies on the repulsive interactions between like magnetic poles of the permanent ring magnets in the top and base components. The base magnet is oriented with its north pole facing upward, while the top magnet is aligned with its north pole facing downward, resulting in a north-north repulsive force that counters gravity.^[14] This configuration exploits the dipole nature of the magnets, where the magnetic moment \mathbf{\mu} of the top interacts with the inhomogeneous field \mathbf{B} produced by the base. The magnetic field geometry near the axis of the Levitron can be approximated using a dipole model for the ring-shaped base magnet, creating a vertical gradient in the axial field component B_z. In this approximation, the field expands as a Taylor series along the symmetry axis, with B_z(z) \approx B_0 + B_z' z + \frac{1}{2} B_z'' z^2, where the linear gradient B_z' provides the restoring force.^[13] An equilibrium height z_0 is achieved where the upward magnetic force balances the weight of the top, satisfying F_z = \mu_0 \mu \frac{\partial H_z}{\partial z} = mg, with \mu_0 the permeability of free space, \mu the dipole moment magnitude, H_z the magnetic field strength, m the mass, and g gravitational acceleration.^[13] The basic force equation governing this balance derives from the interaction of the magnetic dipole with the field gradient, given by \mathbf{F} = \mu_0 (\mathbf{\mu} \cdot \nabla) \mathbf{H}, where the vertical component opposes gravity at equilibrium.^[13] This force can also be interpreted as arising from magnetic pressure differences across the top magnet, though the dipole formulation captures the essential physics for the ring geometry.^[14] For typical Levitron parameters, this equilibrium occurs at heights around 3-5 cm above the base.^[13]^[9]

Stability and Spin Effects

The stability of the Levitron relies on the gyroscopic effects induced by the rapid spin of the magnetic top, which circumvents the instability inherent in static magnetic levitation as predicted by Earnshaw's theorem.^[3] In a static configuration, the top would experience unbalanced torques from the nonuniform magnetic field, leading to exponential divergence from equilibrium. However, when spinning, the top's angular momentum \mathbf{L} = I \omega \hat{\mathbf{n}}, where I is the moment of inertia, \omega is the spin angular velocity, and \hat{\mathbf{n}} is the unit vector along the symmetry axis, generates gyroscopic precession. This precession arises from the torque \boldsymbol{\tau} = \boldsymbol{\mu} \times \mathbf{B} exerted by the magnetic field \mathbf{B} on the dipole moment \boldsymbol{\mu} of the top, causing the axis to nutate (wobble) rather than flip outright. The high spin rate ensures that the nutation frequency is much faster than the precession, allowing the average orientation to follow the local field direction adiabatically.^[15]^[3] The precession manifests as a slow rotation of the top's axis around the vertical direction, stabilizing the orbit at a specific height where the magnetic repulsion balances gravity. The precession angular frequency is given by

\Omega = \frac{\mu B}{I \omega},

where \mu is the magnetic moment magnitude, B is the local magnetic field strength, I is the moment of inertia, and \omega is the spin angular velocity.^[3]^[15] For stability, the adiabatic invariant—the magnetic flux linked by the precessing dipole—remains conserved. This invariance requires a precise balance of parameters: a spin rate \omega typically in the range of 100–300 rad/s (corresponding to 900–2800 rpm), a levitation height h \approx 3–5 cm above the base, and a vertical field gradient dB_z/dz such that the effective potential forms a shallow minimum.^[15] If \omega is too low, precession slows and the top cannot track field variations, leading to instability; if too high, nutation damps insufficiently, causing divergence.^[3] Experimental observations confirm this mechanism, with the visible wobble of the levitating top interpreted as damped nutation superimposed on steady precession. In Michael Berry's 1996 analysis, the top's motion was modeled as an adiabatic trap, where the averaged magnetic energy over rapid nutation creates a stable radial potential well, validated by measurements of levitation durations exceeding 2 minutes at optimal spin rates.^[15] Further validations in inclined Levitron setups show that stability persists for tilt angles up to steep inclinations.^[16] These effects highlight the Levitron as a macroscopic analog of spin traps in atomic physics, where rotation imparts dynamic stability absent in non-spinning configurations.^[15]

History and Development

Invention

Roy M. Harrigan, a Vermont-based inventor from Manchester with a high school education and over a year of college, developed the Levitron in the late 1970s amid his extensive experimentation with permanent magnets, having conceived thousands of inventions including 16 patented ones.^[17]^[4] Harrigan's breakthrough occurred serendipitously through persistent lab tests spanning over two decades, starting from childhood attempts at magnetic levitation; after roughly 1,000 trials with a smaller spinning magnet, he observed its unexpected stability above a base magnet, thereby circumventing Earnshaw's theorem via gyroscopic rotation without prior knowledge of the theoretical barrier.^[17]^[18] He filed a patent application for the device on February 17, 1976, which was granted as U.S. Patent No. 4,382,245 on May 3, 1983.^[4] Early prototypes were crafted by hand using ferrite or similar permanent magnets, with the base formed into a dish shape from thin laminations and the top consisting of a spinning magnetic assembly balanced on a non-magnetic sheet such as aluminum before being positioned for levitation.^[4] These initial models grappled with limitations of weak magnetic fields and imprecise balancing, yielding brief levitation periods of mere seconds, though iterative adjustments in magnet strength, top mass, and spin rate extended durations to up to five minutes in refined versions.^[4] Harrigan personally financed the development and showcased working prototypes through private demonstrations and video recordings, yet faced skepticism from experts and achieved no immediate commercial viability, stalling broader adoption for years.^[17]

Commercialization and Patents

Roy M. Harrigan filed for and was granted U.S. Patent No. 4,382,245 in 1983 for a "Levitation device" that described a spin-stabilized magnetic top levitating above a base magnet, though the patent's explanation of the underlying physics was later noted as incomplete.^[4] The device utilized ferrite magnets and achieved brief levitation periods, but Harrigan's invention remained largely dormant as a prototype without commercial pursuit. In 1993, Seattle entrepreneur Bill Hones discovered Harrigan's patent while researching permanent magnet levitation and contacted him to learn the technique, leading to a collaboration with Hones, who commercialized the device through his company, Fascinations Toys & Gifts.^[19] Hones prototyped an improved version using stronger neodymium magnets, which enhanced magnetic field strength and enabled more stable levitation. The Levitron debuted commercially in 1994 at toy fairs, with refinements allowing the top to levitate for 3 to 5 minutes per spin before slowing due to air resistance.^[9] Distribution was handled by Creative Gifts Inc., which held the Levitron trademark, and Fascinations Toys & Gifts, Hones' company, targeting science and educational markets. Subsequent patent filings in the 1990s included U.S. Patent No. 5,404,062, granted to Bill Hones and Edward W. Hones in 1995 for a modified magnetic levitation device featuring a square base magnet to improve stability.^[20] These adjustments addressed limitations in Harrigan's original design, though physicists such as Michael V. Berry provided corrections to the patent's claims by elucidating the adiabatic and geometric phase mechanisms enabling long-term stability, as detailed in theoretical analyses published in the late 1990s.^[15]

Legal Disputes

In the mid-1990s, tensions arose between inventor Roy M. Harrigan and entrepreneur William G. "Bill" Hones over the development and commercialization of the Levitron. Harrigan, who held the original U.S. Patent No. 4,382,245 issued in 1983, collaborated briefly with Hones starting in 1993 after Hones discovered the patent and borrowed Harrigan's prototype. Hones promised Harrigan 5% royalties and public credit as the inventor, but after Hones and his father Edward E. Hones secured their own U.S. Patent No. 5,404,062 in 1995—despite similarities to Harrigan's design—Hones proceeded to market the product through Fascinations Toys & Gifts Inc. without fulfilling these commitments or acknowledging Harrigan's role. This led to disputes over inventorship, royalty payments, and usage of the "Levitron" name, with Harrigan alleging misappropriation while Hones claimed independent refinement of the concept.^[19] The conflicts escalated into litigation in 1997 when former distributors Michael and Karen Sherlock, operating as UFO, published an exposé on levitron.com accusing Hones of stealing Harrigan's invention and revealing videotaped evidence from 1993 meetings. Hones, along with affiliated companies Creative Gifts Inc. and Fascinations Toys & Gifts Inc., filed suit in the U.S. District Court for the District of New Mexico (No. CV-97-1266-LH/WWD) against the Sherlocks for trademark infringement under the Lanham Act, defamation, and unauthorized use of the "Levitron" mark (U.S. Trademark Reg. No. 1,896,265, registered in 1995) and domain name. The Sherlocks counterclaimed, arguing the mark was generic and raising defenses like acquiescence and naked licensing, while highlighting the prior Harrigan patent. The district court rejected the defenses, found infringement, and imposed sanctions dismissing the counterclaims for discovery violations; it also ordered transfer of levitron.com to the plaintiffs. The U.S. Court of Appeals for the Tenth Circuit affirmed the ruling in 2000 (235 F.3d 540), solidifying Hones' control over the trademark. The defamation claim was dropped in April 1999, allowing continued sales under Hones' entities.^[21]^[19] A related patent dispute between Harrigan and Hones centered on claims of invalidity due to technical inaccuracies in the filings. Harrigan's 1983 patent and the Hones 1995 patent both contained erroneous explanations of the levitation mechanism, incorrectly attributing stability to magnetic field tailoring rather than spin-induced gyroscopic precession—a misunderstanding later clarified in scientific analyses. Although Harrigan's patent expired unenforced in May 2000, the similarities prompted a legal challenge where Hones' company prevailed, retaining exclusive commercialization rights and resolving royalty claims in Hones' favor without public disclosure of settlement terms.^[22]^[3] Broader intellectual property issues emerged with unauthorized copycat products, particularly as manufacturing shifted to Asia in the late 1990s. Fascinations Toys & Gifts Inc., under Hones, enforced its patents and trademark against competitors, including a 2008 patent infringement suit in the U.S. District Court for the Western District of Washington (No. 2:08-cv-00028) against Levitation Arts Inc. for producing similar levitating devices, which underscored efforts to maintain market exclusivity amid rising imitations. A parallel 2007 declaratory judgment action by Levitation Arts in Texas (No. 1:07-cv-00990) was resolved in Fascinations' favor, preventing further unauthorized sales. These actions highlighted challenges in protecting novelty toys from overseas replication, where low-cost production fueled knockoffs but enforcement preserved the original brand's dominance.^[23]^[24] Ultimately, the disputes resulted in Fascinations Toys & Gifts Inc. retaining the "Levitron" brand and intellectual property rights, enabling ongoing sales of over 500,000 units by 1999 through licensees like Creative Gifts in Japan. As of 2025, Fascinations Toys & Gifts continues to sell Levitron products without further reported disputes over the original invention rights.^[25] The episode underscored lessons for patenting scientific toys, including the risks of incomplete enforcement, the need for accurate technical disclosures to withstand validity challenges, and the importance of clear agreements in inventor-licensee relationships to avoid protracted conflicts over royalties and attribution.^[21]^[19]

References

[1]
An amazing invention, and a patent failure - SCIENCE HOBBYIST
Sep 22, 1999 · IN 1993, Seattle entrepreneur Bill Hones ran across a 10-year-old U.S. patent describing a device for levitating a spinning permanent magnet.
[2]
(PDF) Stability of Levitrons - ResearchGate
Aug 6, 2025 · It was invented by Roy Harrigan, for the history of its invention see [6]. ... magnetic levitation of the Levitron. Symmetric and asymmetric ...
[3]
[PDF] Spin stabilized magnetic levitation - UCLA Physics & Astronomy
The Levitron®1 ~Ref. 1! is a remarkable toy which levi- tates in air a 22-g spinning permanent magnet in the form of a small handspun top. The top is spun ...
[4]
US4382245A - Levitation device - Google Patents
The invention relates to apparatus for creating levitation and more particularly to magnetic or electrostatic field apparatus to achieve levitation.Missing: US3846255A | Show results with:US3846255A
[5]
Levitron - Physics Demos
The spinning top is composed of a disc of strong permanent magnetic material as well as some plastic and brass. There is also a powerful neodymium magnet in ...Missing: components | Show results with:components
[6]
Levitron - Real World Physics Problems
The spinning top of a Levitron is a disk which is made up of strong permanent magnet material, in addition to plastic and brass.Missing: components | Show results with:components
[7]
How to Use the Levitron - MIT
If the top does not lift off the plate, cut the weight in half. If the next time around, the top does not lift off the plate and is not close to lifting off ...
[8]
LEVITRON – Department of Physics | CSU
LEVITRON ; Procedure: Spin the top on the lifter plate over the center of the base magnet. Raise the lifter plate approximately 1” above the surface of the base ...
[9]
Levitron -- Spin stabilized magnetic levitation
Levitron -- Spin stabilized magnetic levitation. ... spinning top to the to the right location. The parameter space for ...
[10]
Levitating Top | K&J Magnetics Blog
### Summary of Levitating Top Instructions (Levitron/DIY)
[11]
[PDF] Spin stabilized magnetic levitation - Páginas de materias
predict that the top will be supported stably up to spin speeds of about 3065 rpm. An upper spin limit of 2779 rpm for this top is observed experimentally ...
[12]
Earnshaw (1805–1888) and Passive Magnetic Levitation
Aug 7, 2025 · The stable levitation of magnets is forbidden by Earnshaw's theorem, which states that no stationary object made of magnets in a fixed ...
[13]
[PDF] Simple theory for the Levitron - Free
Stable levitation is possible because of a unique coupling of the magnetic forces and torques with the gyroscopic action of the top. A simple theory of its ...
[14]
[PDF] The LevitronTM 1 Problem 2 Solution - Kirk T. McDonald
Apr 4, 1997 · For the example of a magnet levitated antiparallel to the field of a loop of radius a that carries a steady current, find the range of ...
[15]
The LevitronTM: an adiabatic trap for spins | Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences
### Summary of Levitron Stability Physics
[16]
Inclined Levitron experiments | American Journal of Physics
Nov 1, 2012 · In this article, I demonstrate and explain how the Levitron can be operated in a visibly precessing or nutating mode or at a constant angle of inclination.
[17]
SCIENCE HOBBYIST: An amazing invention, and a patent failure
Sep 22, 1999 · IN 1993, Seattle entrepreneur Bill Hones ran across a 10-year-old U.S. patent describing a device for levitating a spinning permanent magnet.
[18]
levitron.html - Yale University
Aug 27, 2001 · Roy Harrigan (Manchester, VT) counts the "Levitation Device" as one ... He built it in the late 1970's and received U.S. Patent 4,382,245 on May 3 ...
[19]
The Providence Journal - The patent that failed - Vote Smart
In 1993 Seattle entrepreneur Bill Hones ran across a 10-year-old U.S. patent describing a device for levitating a spinning permanent magnet. Hones contacted Roy ...Missing: components | Show results with:components
[20]
US5404062A - Magnetic levitation device and method
The levitation device comprises a first magnet with a polygonal, preferably square, periphery and a substantially planar upper surface magnetized normal thereto ...
[21]
Creative Gifts, Inc., Fascinations Toys & Gifts, Inc. and William Hones ...
Creative Gifts, Inc., Fascinations Toys & Gifts, Inc. and William Hones ... Levitron trademark for the levitron.com website. Armstrong replied later ...
[22]
[PDF] The Levitron - 3D House
The Levitron R is a toy consisting of a spinning-top magnet levitating over a permanent-magnet base. This seemingly violates Earnshaw's theorem which for-.
[23]
Fascinations Toys & Gifts Inc v. Levitation Arts Inc et al - Justia Dockets
Jan 8, 2008 · Plaintiff: Fascinations Toys & Gifts Inc. Defendant: Levitation Arts Inc. Case Number: 2:2008cv00028. Filed: January 8, 2008.
[24]
1:07-cv-00990 | Levitation Arts Inc v. Fascinations Toys & Gifts Inc
Levitation Arts Inc v. Fascinations Toys & Gifts Inc ; Filed. 12/05/07 ; Cause of ActionPatent Infringement ; SectorComp. Arch. and Software ; Status. Closed (02/22 ...