A possibility of gravitational force shielding by bulk YBCO superconductor
Podkletnov · Nieminen
Summary and citation · read the original at the source
In one page
In 1992 Eugene Podkletnov and Risto Nieminen published a short paper in Physica C reporting something no established theory allows. Above a large disc of the high-temperature superconductor YBCO — 14.5 centimetres across, six millimetres thick, floating by Meissner repulsion over an electromagnet immersed in liquid helium — they hung a small non-conducting, non-magnetic sample weighing 5.48 grams from an analytical balance. When the disc was driven by high-frequency fields and set spinning, the sample became lighter. The reported loss runs from 0.05 percent up to about 0.3 percent, and it varies with how fast the disc turns. The authors' own wording is deliberately careful: a possibility of gravitational force shielding. This short paper is the peer-reviewed origin of every later claim about weight loss over a spinning superconductor, and the whole of chapter 11's contested territory grows out of it.
Why it matters hereChapter 11 is built on this paper and on what happened next. It is the published starting point, and the measurement that would settle it is named by the experiment itself: a replication with the same disc formulation, the same high-frequency fields and the same large disc spun at low temperature. The attempts made so far have used smaller and simpler apparatus, and Gravity Probe B fixes how large a real gravitomagnetic effect is — which is why this stays on the site as something to watch rather than as a result.
What it claims
01A small non-conducting and non-magnetic sample weighing 5.48 grams, suspended from an analytical balance above a levitating bulk YBCO superconducting disc, was found to lose from 0.05 to 0.3 percent of its weight depending on the rotation speed of the disc.Abstract; results
What to watch02The largest stable weight loss, around 0.3 percent, required the peripheral electromagnets to be driven at high frequency and the disc to be turning at several thousand revolutions per minute — so the reported effect depends on rotation and on the driving fields, not on the superconducting state alone.Experimental section; conditions for maximum effect
What to watch03The disc is a sintered bulk YBa2Cu3O7−x ceramic, 14.5 centimetres in diameter and 6 millimetres thick, levitated by Meissner repulsion above a support electromagnet in liquid-helium vapour driven from 50 hertz up to the megahertz range, with two smaller electromagnets at the rim used to spin it.Experimental arrangement; apparatus figure
Settled physics04Podkletnov and Nieminen present the result as a possibility of gravitational force shielding — a superconductor partially screening a body above it from the Earth's gravitational field, which no established theory of gravity permits.Title; discussion
What to watch
The way in
https://doi.org/10.1016/0921-4534(92)90055-HPublished by Elsevier as Physica C 203, 441–444 (1992); the full text is behind the publisher's paywall and the abstract is free at ScienceDirect. The record is also listed by the Tampere University research portal. The experiment is described in detail in the Defense Intelligence Agency's own reference document The Role of Superconductors in Gravity Research, released under FOIA.
How to cite it
Podkletnov, Nieminen (1992) A possibility of gravitational force shielding by bulk YBCO superconductor. doi:10.1016/0921-4534(92)90055-H
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