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This Defense Intelligence Reference Document from the Defense Intelligence Agency is dated 23 March 2010. It was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program and surveys the history of attempts to use superconductors to manipulate gravity in the laboratory. It reviews theoretical work by Li and Torr, Podkletnov's disputed gravity shielding experiments, NASA replication attempts and Tajmar's results. It concludes that no repeatable effect has been verified and that research in this area remains fraught with experimental difficulty.
“Cooper”5 pages
UNCLASSIFIED/ ;raA 8FFIQIIP 1!55 0111 Y The "attraction" of modifying gravity-whether your own, your spacecraft's, or that of a nearby large mass-for propulsive purposes lies in two general categories of effect: • The modifying, neutralizing, or negating of the gravitational attraction of a nearby body, typically Earth. • The provision of propulsive force or impulse to a spacecraft based on manipulation of the same underlying physical phenomenon that forms the basis of gravity. The theoretical and experimental attempts outlined in this paper deal with both these possibilities. In experiments designed to produce a gravity-like force or to interact directly with a local gravity field, the researcher has to be looking for extremely small deviations from a null result. Observations to date demonstrate that interactions between gravity and electromagnetic fields, given the field densities and strengths available to even the most well-equipped laboratory, are many orders of magnitude smaller than those required to begin to see such forces. Braginski et al. (Reference 8) showed that ordinary matter cannot be used to generate measurable gravitational fields in the laboratory. The standard edict against such things as gravity shields can be summed up by noting the absence of negative gravitational mass, at least in this sector of the universe, resulting in the relative "gravitational permittivity/permeability" being unity in normal matter. Therefore, demonstrating that a new force, whether gravitational or not, has been discovered in the laboratory will require an intense effort to provide proof. This implies being able to distinguish between true gravity-like forces and gravity interactions and a host of prosaic effects masquerading as these forces. A list of potential artifacts attendant on such experiments can be found in Reference 9. General relativity introduces a metric tensor theory of gravity, and while it does not explain the fundamental physical basis of the gravitational attraction between two bodies, it does allow the prediction of a large range of interactions between bodies. Similarly, Maxwell's vector equations do not explain the fundamental basis for electromagnetic interactions but do allow us to predict the outcomes of such interactions. It is possible to reformulate the tensor format of GR into a simple vector format that is valid only for a subset of GR conditions, namely in the weak field approximation and for nonrelativistic velocities. Using perturbation theory, for example, to compute the equations of motion in the simplified GR equations results in terms that have direct analogs in Maxwell equations where electrical current flow is replaced by mass flow, for example. Forward (Reference 10, 11) was among the first to investigate this analog. One term is analogous to the Biot-Savart-like magnetic field and is generally referred to as the "gravitomagnetic field" (and also sometimes as "gravitational frame dragging" or the "Lense-Thirring Effect") and has the dimensions of s- 1 . Another term is analogous to the electrostatic coulomb field and is referred to as the "gravitoelectric field." Essentially, the gravitomagnetic field produces a force between currents of flowing matter, while the gravitoelectric field produces a force between masses themselves (the Newtonian gravitational field). Sometimes the term "gravitoelectromagnetic field" is used to refer to both the gravitoelectric and gravitomagnetic fields. Gravity is thus composed of a (Newtonian) velocity-independent field and a (gravitomagnetic) velocity-dependent field analogous to the electric and magnetic fields 2 UNCLASSIFIED//F8A 8FFI&l11J.k WliS SU.kif
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 16 pages are in the text index: search them above, or from the library's search.