Posted on 10/10/2025 11:44:34 AM PDT by Red Badger
A photograph of a black graphite disk floating above a stack of three, round magnets. (Credit: Adrian Skov (OIST))
Study shows how perfect magnetic symmetry can cancel energy loss. In A Nutshell Researchers at OIST built a 10-millimeter graphite disk that levitates and spins above a magnetic array inside a vacuum chamber. By arranging magnets in perfect circular symmetry, the setup cancels the eddy currents that normally slow conductors moving through magnetic fields. Even at one-billionth of Earth’s air pressure, the disk kept spinning with almost no slowdown; only tiny tilts or material imperfections created measurable friction. This ultra-stable, contact-free rotor could enable new kinds of gyroscopes, vacuum gauges, and precision instruments to study gravity, quantum effects, or “vacuum friction.” OKINAWA, Japan — A small graphite disk floats in midair, spinning freely above a ring of magnets inside a vacuum chamber. There’s no physical contact, no energy being pumped in, yet it keeps rotating with almost no slowdown, behaving in ways that seem to defy everyday friction, but follow precise physical rules.
Researchers at the Okinawa Institute of Science and Technology have achieved what seems almost magical: a conducting rotor that levitates and spins with extraordinarily low energy loss. Published in Communications Physics, the study demonstrates a 10-millimeter disk made of pyrolytic graphite that hovers above permanent neodymium magnets, spinning in near-perfect isolation from the forces that normally bring rotating objects to a halt.
The secret lies in a careful arrangement. By using magnets positioned in a pattern where the magnetic field looks identical from every angle around a central axis, the researchers eliminated a major source of energy loss called eddy damping. When most conductive materials spin in magnetic fields, they generate electrical currents that act like brakes. In this setup, the symmetry means those currents never form.
Graphite That Pushes Back Against Magnets Pyrolytic graphite is a peculiar material. Unlike most substances, it actively repels magnetic fields. Place it above the right arrangement of magnets, and it pushes back hard enough to levitate at room temperature without any active control or power supply.
The research team built a magnetic trap from five layers of ring-shaped magnets surrounding two central cylinders. Each layer alternated north and south poles to create a stable field that held the graphite disk about 0.82 millimeters above the surface.
To track the disk’s rotation, researchers marked its surface with a white dot of ink and filmed it with a specialized camera that detects motion. Even at pressures near 5 × 10⁻⁵ Pascals (roughly a billionth of atmospheric pressure) the disk kept spinning with barely any slowdown.
The black graphite disk floats above a stack of three, round magnets. (Credit: Adrian Skov (OIST))
What Normally Stops a Spinning Object
At normal air pressure, the disk’s rotation slows primarily because air molecules collide with it. Higher pressure means more collisions and faster slowdown.
The researchers measured how quickly the disk’s spin decayed at different pressures, from atmospheric levels down to near-vacuum conditions. At high pressures, gas collisions dominated. In intermediate ranges, the damping rate scaled linearly with pressure, exactly as theory predicted for molecules bouncing off the surface.
At very low pressures though, something else took over. Even when gas molecules became sparse enough that they rarely hit the disk, a small amount of damping persisted below about 0.1 Pascals.
The Surprising Culprit: A Tiny Tilt
That residual damping came from imperfect symmetry. When the experimental platform tilted even slightly, as little as a fraction of a degree, gravity pulled the disk’s center of mass off the magnetic field’s central axis. Once offset, the disk’s rotation did generate small eddy currents because different parts of the disk experienced different magnetic field strengths as they spun past.
To investigate this, the team deliberately tilted their setup at various angles while keeping the pressure constant. The damping rate increased dramatically with tilt, climbing by an order of magnitude within half a degree of offset from perfect level. The researchers confirmed that damping increases roughly with a power law of the disk’s lateral offset from perfect alignment.
Computer simulations confirmed this pattern. The simulations showed that for displacements greater than 0.05 millimeters from the symmetry axis, the damping followed a near-perfect power law relationship. Extrapolating backward, the data pointed strongly to eddy damping vanishing entirely at exactly zero displacement, where perfect symmetry exists.
Mathematical Proof of a Frictionless Spin
To confirm their observations, the researchers proved mathematically that a conductor rotating in a perfectly symmetric magnetic field cannot sustain steady eddy currents, because every point experiences an unchanging magnetic flux.
Without changing magnetic flux, there’s nothing to induce electrical currents. The team also constructed an explicit example with a specific magnetic field geometry where they calculated the currents directly and confirmed they vanished.
Computer simulations alone couldn’t quite reach zero damping because the computational grid inevitably breaks perfect symmetry at microscopic scales. The mathematical work removed any lingering doubt.
The measured minimum damping rate in the experiment was 5.5 × 10⁻⁵ Hz, corresponding to an offset of about 18 micrometers from perfect alignment. That tiny displacement likely arose from slight imperfections in either the graphite disk or the magnets themselves.
VIDEO AT LINK..................
When Symmetry Breaks, Energy Bleeds
When researchers levitated the same disk on a different magnet arrangement — a checkerboard pattern instead of the cylindrical array — the disk’s rotation damped out rapidly even though its shape was equally circular. The checkerboard’s lack of rotational symmetry meant every point on the spinning disk continuously experienced changing magnetic fields, generating energy-sapping eddy currents throughout.
Material inhomogeneities could also break symmetry. Pyrolytic graphite has different properties along different crystal directions, and if the disk’s geometric center doesn’t align perfectly with its material symmetry axis, similar offsets occur.
From Laboratory Curiosity to Real-World Tools
A rotor that spins almost indefinitely without contact has practical applications. Gyroscopes based on this principle could achieve unprecedented sensitivity for detecting rotations, potentially measuring Earth’s spin or tiny angular accelerations in spacecraft navigation.
Pressure sensors already use spinning rotors to gauge vacuum levels in ultra-high vacuum chambers. Lower damping means better sensitivity to the few remaining gas molecules that cause the slowdown.
The setup could also probe fundamental physics. Researchers have proposed using macroscopic spinning objects to test quantum mechanics at large scales or to search for subtle effects like vacuum friction—the idea that empty space itself might exert a tiny drag on rotating objects.
Getting the symmetry even more perfect would push the boundaries further. The researchers noted that better fabrication techniques like laser cutting or electrical discharge machining could produce more geometrically precise disks, while using materials like bismuth with higher crystalline quality might reduce material-induced asymmetries. With better machining and precise tilt control, they estimate damping could drop to about 10⁻¹¹ Hz, so low the disk might spin for weeks with almost no energy loss.
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Paper Summary
Methodology
The researchers fabricated a 10.02-millimeter diameter, 1.12-millimeter thick disk from pyrolytic graphite using computer numerical control milling followed by diamond polishing to ensure high circularity. They created a magnetic trap using five layers of ring-shaped neodymium magnets surrounding two cylindrical magnets at the center, arranged with alternating vertical magnetization. The graphite disk levitated about 0.82 millimeters above this array inside a vacuum chamber capable of reaching pressures near 5 × 10⁻⁵ Pascals. To measure rotation, they marked the disk’s surface with white ink and tracked it using an event-based camera viewing the disk through a mirror and telescope lens arrangement. They induced rotation through lateral vibrations and measured how the angular velocity decayed over time at different gas pressures. They also systematically varied the platform’s tilt angle using optical table adjustments and screw jacks while measuring the resulting changes in rotational damping.
Results
At atmospheric pressure, rotational damping was dominated by gas friction following laminar flow dynamics, with finite element simulations matching experimental observations. As pressure decreased into the free molecular flow regime (below 100 Pascals), the damping rate scaled linearly with pressure, agreeing with theoretical predictions for ballistic molecule collisions. Below approximately 0.1 Pascals, damping reached a plateau around 10⁻² Hz despite further pressure reductions. Tilt experiments revealed that this residual damping increased dramatically with platform inclination, climbing by an order of magnitude within 0.5 degrees of tilt from the minimum damping orientation. The minimum observed damping rate was 5.5 × 10⁻⁵ Hz, equivalent to an 18-micrometer offset from perfect axial symmetry based on the fitted power law relationship between displacement and damping. Finite element simulations of eddy damping showed near-perfect power law dependence for offsets greater than 0.05 millimeters, with the relationship extrapolating to zero damping at zero displacement. Mathematical proofs demonstrated that the steady-state current density in a uniformly rotating conductor within a perfectly symmetric magnetic field must be exactly zero.
Limitations
The study faced several constraints related to achieving perfect symmetry. The minimum measured damping rate was limited by small geometric or material imperfections in either the pyrolytic graphite disk or the magnet assembly. Slight misalignments between the disk’s geometric center and its material symmetry axes could introduce asymmetry. Finite element simulations became unreliable for displacements below 0.05 millimeters due to mesh-induced asymmetry and numerical errors, preventing direct computational verification of zero damping at perfect alignment. The experimental setup had an initial platform misalignment of approximately 0.5 degrees that had to be corrected. The fabrication process, while precise, may not have achieved perfectly uniform material properties throughout the disk. Environmental vibrations or thermal fluctuations could dynamically displace the disk from the symmetry axis, though calculations showed thermal effects at room temperature would contribute negligible damping (around 10⁻¹⁵ Hz). The study did not test materials with higher crystalline quality than pyrolytic graphite or employ advanced fabrication techniques like laser cutting or electrical discharge machining that might further reduce asymmetries.
Funding and Disclosures
This work was supported by the Okinawa Institute of Science and Technology Graduate University in Japan. The authors acknowledged assistance from the Engineering Section and the Scientific Computing and Data Analysis Section at OIST. The authors declared no competing interests.
Publication Details
Kim, D., Tian, S., Calderoni, B., Sastre Jachimska, C., Downes, J., & Twamley, J. (2025). A magnetically levitated conducting rotor with ultra-low rotational damping circumventing eddy loss. Communications Physics, 8, 381.
DOI: 10.1038/s42005-025-02318-4
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That drinking bird is pretty quiet, too.
I repel people despite my magnetic personality.
No.
True.
It may be sending out emanations that, like dog whistles, cannot be heard by normal humans.
I’ve been waiting for my flying car since watching The Jetsons 60 years ago.
Will it make that sound too?
Soon we will be able to build pyramids with this technology.
Yea, but will it cure ED?
Wow!
Good thing they hadn’t invented this experiment before April 1, 1945...
The consequences might have been even worse than they were...
exactly how much friction is there in a vacuum chamber of one-billionth of Earth’s air pressure? how many gaseous molecules remain in such a vacuum?
grok sez: Approximately 2.33 × 10¹³ molecules remain in a 1-quart vacuum chamber at a pressure of one-billionth of Earth’s atmosphere at sea level, assuming a temperature of 298 K
“ They have to get down to at least 0.05 Pascals and then they’ll really have something.”
I’ll pay three quakloons for it. But only if it’s .005 pascals.
A PORTAL!!
A perpetual almost fidget spinner.
Thanks guys. I see you had time on your hands.
Wow!
Good thing they hadn’t invented this experiment before April 1, 1945...
The consequences might have been even worse than they were...
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And the people selling these in miniature on Amazon are laughing all the way to the bank at this.
Bkmk
Nope it won’t work.
Once you put a load, it will stop turning and then stop levitating.
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