A report from two European scientists commissioned by the European Space Agency to investigate antigravity is now available in pre-print form at the ArXiv Web site. “Hypothecial Gravity Control and Possible Influence on Space Propulsion will eventually appear in the AIAA Journal of Propulsion and Power. The authors are Martin Tajmar of the Austrian aerospace firm ARC Seibersdorf and Orfeu Bertolami, of the Instituto Superior Técnico in Lisbon.

(Note: The word ‘hypothecial’ in the paper title is surely a mistake; I’m sure the authors mean ‘hypothetical.’ In any case, the word ‘hypothecial’ doesn’t show up even in dictionaries as huge as Webster’s 3rd Unabridged).

ESA’s original charter to the scientists had been to study the concept of gravity control, and secondly to examine the credibility of previous claims of anomalous gravitational phenomena. From the study:

“…current experimental knowledge and bounds on the fundamental underlying principles of General Relativity and of the Standard Model of the Fundamental Interactions leave little room for the gravity control proposals that were analysed. Among these we could mention exotic concepts such as theories where gravitiy is due to interactions with the Zero-Point-Energy field, warp-drive mechanisms or propulsion concepts based on Mach’s principle. None of the approaches examined proved fruitful. However, the second part of the study has turned out to be rather rich in new findings. Our main conclusion was that even if gravity could be controlled or modified, influence on spacecraft propulsion would be quite modest and would not lead to breakthroughs in the conceptual framework of presently known propulsion principles within the studied manipulation schemes.”

NASA has studied the claims of Russian physicist Eugene Podkletnov that gravity can be manipulated by placing objects over a spinning superconductor, but the effect Podkletnov claims is tiny (about 2 percent) and in any case has not been repeated by subsequent investigators. Tajmar and Bertolami studied other proposed methods of weakening gravity and described them this way: “Experimentally and theoretically they do not seem to meet a standard we could qualify as scientific.” Nor are they impressed by attempts to toy with inertia, such as those advanced by the University of California at Fullerton’s James Woodward. For his part, Woodward dismissed the report, saying “”I regard the conclusion, even if correct, as uninteresting and, frankly, irrelevant.”

The Tajmar/Bertolami paper can be found here (PDF warning). You can read a report on the study in Nature’s online journal here.

Centauri Dreams‘ take: Neither the study’s authors or its critics believe the last word has been said about possible manipulation of gravity or inertia. The fact that earlier attempts have failed leads only to this conclusion: we are not likely to achieve a breakthrough in antigravity any time soon, and while study should continue, the balance of our attention should be directed to propulsion schemes with a higher possibility of success. There are no shortage of candidates, as recent work ranging from ion drives to inertial confinement fusion in its various modes has amply demonstrated. Meanwhile, the attempt to understand how gravity works at the quantum level — with possible propulsion implications — can and should continue.

For a glimpse at the possibilities in inertial research (and its relation to Mach’s principle) see this overview by James Woodward.