Can spinning a heavy wheel change how fast it falls? Standard physics says no: the equivalence principle holds that every body falls with the same acceleration in a given gravitational field, whatever it is made of and however it moves internally. A short paper by A. L. Dmitriev, E. M. Nikushchenko and S. A. Bulgakova of St-Petersburg State University of Information Technologies, Mechanics and Optics, posted to arXiv as 0907.2790, reports the opposite. A sealed container holding gyroscope rotors spinning about a horizontal axis is said to have fallen measurably faster than the same container with the rotors at rest.
The paper matters to this dossier because it shows how the idea of anomalous gravity from rotation, which Nikolai Kozyrev pursued with gyroscopes on balances from the 1950s onward (see Gyroscope Time-Pattern Experiment), carries on in later laboratory claims. It needs care, though. The paper does not cite Kozyrev, does not use his causal mechanics, and puts its result in terms of gravitation and inertia, not the properties of time. It belongs here as a parallel, not as a confirmation.
What the authors claim
The headline claim is an increase in free-fall acceleration of Δg = 10 ± 2 cm/s² when the rotors spin at up to about 20 000 rpm. That is roughly one per cent of ordinary gravitational acceleration. The authors say the increase appeared regularly when the rotors went from rest to spinning. They also say it shrank as the rotors coasted down and disappeared when the rotors stopped. Their summary calls the increase "essentially exceeding errors of measurements".
Several further observations are reported:
- In the main runs both rotors turned the same way, giving a total angular momentum of about J_Σ ≈ 0.2 kg·m²/s. When the rotors turned in opposite directions, so that J_Σ ≈ 0, the authors report a small reduction in g instead. They give no number for it.
- Pointing the spin axis north–south or west–east made no difference to Δg, according to the paper.
- The authors looked for a daily cycle in Δg and found none.
How the measurement was made
The approach differs from most earlier tests of spinning bodies, which weighed a rotor on a balance. Here the whole container is dropped and its motion is timed optically. A compact, highly stable pulse generator mounted on the container drives two light-emitting diodes of different colours. Each diode sits behind an aperture, and the hole centres are l = 76.25 mm apart. The diodes flash at F = 56.25 Hz with pulses lasting 0.13 ms. A digital camera with a long exposure of 0.6–0.8 s photographs the fall, so each frame records a trail of dots marking the container's position at equal time intervals.
The dot coordinates were digitised by computer. Acceleration was worked out from the difference in length between neighbouring stretches of the trail, each containing the same number of marks, scaled by the pulse frequency. The known diode spacing set the image scale. To reduce lens distortion, the scale was averaged over readings at the top, middle and bottom of the trajectory. Each reported value of g is the mean of the two trails, one per colour. The rotor assembly itself (two coaxial rotors) is described in an earlier paper by Dmitriev and V. S. Snegov in Measuring Techniques (2001), not in this one.
The schedule is given as follows. After spin-up, the rotors keep turning for 14–15 minutes. One measuring cycle of 4–5 photographs takes about two minutes. More than 200 photographs were processed in total. The single published figure shows 17 measurements plotted as (g − 970) cm/s²: numbers 1–4 with the rotors at rest, 6–10 with them spinning, and 12–16 at rest again after the spin ended.
Why the authors think free fall is the better test
The authors explain why they changed method. Their earlier work weighed two coaxial rotors with a horizontal axis and zero total angular momentum, and found small weight changes that depended on rotation speed. They concede that those readings may have been confused by gyroscopic precession driven by the Earth's rotation, because J_Σ = 0 could not be achieved exactly. In their view, precession affects a freely falling rotor much less, and a falling rotor interacts with the Earth's gravity under quite different conditions from one sitting on a balance.
Their proposed explanation is brief. With the axis horizontal, each particle of the rotor oscillates both horizontally and vertically. The vertical motion involves an unlimited series of time derivatives of displacement. Citing their own earlier papers and D. I. Mendeleev, the authors suggest such motion might reveal "nonclassical" properties of gravitation. They argue that the result does not conflict with precise measurements of gyroscope precession in Earth orbit, because falling while oscillating vertically is physically different from orbital motion. The paper offers no quantitative theory that predicts the size of Δg.
What the document does and does not establish
The paper describes a real procedure, with the main parameters stated, and the authors suggest repeating it with precision interferometric methods. Still, several features limit what it can show.
- The baseline is off by about as much as the claimed effect. With the rotors at rest the apparatus gave about 990 cm/s², while the standard value at the latitude of Saint Petersburg is about 982 cm/s². The authors put the gap down to errors in the image scale, in the absolute generator frequency, and in small local changes in g. A constant offset would cancel when spinning and resting runs are compared. However, the paper does not show that the same error sources are unaffected by the running rotors.
- Possible effects of the spinning rotors themselves are not ruled out. Vibration, heating, electrical load on the on-board pulse generator, and torques passed to the container at release could all differ between the spinning and resting states. The paper does not report controls for any of them, and it does not describe the drop height, the release mechanism or air drag.
- The statistics are thin. The ±2 cm/s² error bar is stated, but the paper does not show how it was derived, how individual photographs were selected, or the spread of single measurements. The only figure is an example run, not the full data set of over 200 photographs.
- The counter-rotating result is vague. A "small reduction" with no number cannot be tested against the main claim.
- The scale of the claim clashes with precision tests. The authors themselves cite precision weighings of rotors from 1990 (J. E. Faller and colleagues; T. J. Quinn and A. Picard; J. M. Nitschke and P. A. Wilmarth) and a 2002 study by J. Luo and colleagues. They describe these as generally finding no positive effect, mostly with vertical spin axes. A one-per-cent change in g is very large next to those results, and the paper's argument that free fall differs physically from weighing has not been tested independently.
The document reports no independent replication, and none should be inferred from it.
How it connects to the Kozyrev dossier
Kozyrev's reported gyroscope results were weight changes of a few milligrams on lever balances. He linked them to vibration and to the direction of rotation, and read them through his time-pattern constant (see Kozyrev C₂ Constant and Quantized Weight-Change Stages). The Dmitriev group reports a different quantity (free-fall acceleration), a different apparatus, and a result it says does not depend on axis orientation. The two claims should not be combined into one effect.
Their shared context is easier to trace. The Shikhobalov account summarised in Kozyrev Claims vs. Evidence: The Causal Mechanics Capture Without Data lists the same 1990 null results by Faller and colleagues and by Quinn and Picard alongside the reported confirmations of Kozyrev. The persistence of the gyroscope claim therefore looks like a recurring pattern. Small anomalies are reported in modest set-ups; precision experiments come back null; and later groups change the geometry, here from a vertical axis to a horizontal one and from weighing to dropping, while the anomaly is still claimed. Whether any of these anomalies survives a well-controlled, independent repetition is still unresolved.
References
- A. L. Dmitriev, E. M. Nikushchenko, S. A. Bulgakova, "Nonzero Result of Measurement of Acceleration of Free Falling Gyroscope with the Horizontal Axis", arXiv:0907.2790.
- References cited by the paper: J. E. Faller et al., Phys. Rev. Lett. 64, 825 (1990); T. J. Quinn and A. Picard, Nature 343, 732 (1990); J. M. Nitschke and P. A. Wilmarth, Phys. Rev. Lett. 64, 2115 (1990); J. Luo et al., Phys. Rev. D 65, 042005 (2002); A. L. Dmitriev and V. S. Snegov, Measuring Techniques 44, 831 (2001); A. L. Dmitriev, E. M. Nikushchenko, V. S. Snegov, Measurement Techniques 46, 115 (2003); A. L. Dmitriev, AIP Conf. Proc. 969, 1163 (2008); D. I. Mendeleev, Works, vol. 22, AN SSSR (1950).
Source notes & attribution
- https://arxiv.org/pdf/0907.2790