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This Defense Intelligence Reference Document, dated 29 March 2010 and prepared by the Defense Intelligence Agency, is one of a series of advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It uses a metric tensor approach from general relativity to catalog the physical effects of engineering spacetime, such as altered time, mass, light speed and antigravity. It concludes that such concepts, including warp drives, are consistent with physics, but that the energy requirements remain daunting.
“The Advance”10 pages
UNCLASSIFIED//F9A: 9FFI~II k YE'lii 911k>C GRAVITY/ ANTIGRAVITY /PROPULSION EFFECTS In the GR ansatz gravitational-type forces derive from the spacetime metric, whether determined by natural sources (for example, planetary or stellar masses) or by advanced metric engineering. Fortunately for our consideration of this topic, discussion can be carried out solely based on the form of the metric, independent of the specific mechanisms or dynamics that determine the metric. As one exemplar, consider Alcubierre's formulation of a "warp drive," a spacetime metric solution of Einstein's GR field equation (References 2, 22). Alcubierre derived a spacetime metric motivated by cosmological inflation that would allow arbitrarily short travel times between two distant points in space. The behavior of the warp drive metric provides for the simultaneous expansion of space behind the spacecraft and a corresponding contraction of space in front of the spacecraft (see Figure 3). The warp drive spacecraft would thus appear to be "surfing on a wave" of spacetime geometry. By appropriate structuring of the metric, the spacecraft can be made to exhibit an arbitrarily large apparent faster-than-light speed as viewed by external observers without violating the local speed-of-light constraint within the spacetime-altered region. Furthermore, the Alcubierre solution showed that the proper ( experienced) acceleration along the spaceship's path would be zero, and that the spaceship would suffer no time dilation-highly desirable features for interstellar travel. In order to implement a warp drive, one would have to construct a "warp bubble" that surrounded the spacecraft by generating a thin shell or surface layer of exotic matter-that is, a quantum field having negative energy and/or negative pressure. Although the technical requirements for such are unlikely to be met in the foreseeable future (Reference 22), the exercise nonetheless serves as a good example for showcasing attributes associated with manipulation of the spacetime metric at will. The entire discussion of the possibility of generating a spacetime structure like that of the Alcubierre warp drive is based simply on assuming the form of a metric (that is, g ;,.,) that exhibits desired characteristics. In like manner, arbitrary spacetime metrics to provide gravity/antigravity/propulsion characteristics can in principle be postulated. What is required for implementation is to determine appropriate sources for their generation, a requirement that must be met before advanced spaceship technology based on vacuum engineering can be realized in practice. The difficulties, challenges, and options for meeting such requirements can be found in the relevant literature (Reference 22). 10 UNCLASSIFIED/ ,'P8"1 8PPll!l"'I! l!l!il! 8111!¥
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 17 pages are in the text index: search them above, or from the library's search.