英和和英

出典:『Wikipedia』 (2011/06/13 05:50 UTC 版)

英語による解説

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Field propulsion is the concept of spacecraft propulsion where no propellant is necessary but instead momentum of the spacecraft is changed by an interaction of the spacecraft with external force fields. The concepts that have been proposed for such means of propulsion range from schemes using the presently accepted physics paradigm to other more speculative means using "frontier physics" that may or may not be reduced to engineering practice in the future. Schemes for field propulsion that operate within the present engineering paradigm, such as the commonly used gravity assist trajectory, which uses planetary gravity fields and orbital momentum, schemes that use electromagnetic fields such as radiation pressure such as solar sails or photonic drive, and even aerodynamic fields such as solar wind and aerobraking are not controversial. More speculative ideas such as coupling to the momentum flux of the zero-point electromagnetic wave field hypothesized in Stochastic Electrodynamics have a plausible basis for further investigation within the existing theoretical physics paradigm. Examples of proposals for field propulsion that rely on physics outside the present paradigms are various schemes for Faster-than-light, Warp drive and antigravity, and often amount to little more than catchy descriptive phrases, with no known physical basis. Any such schemes worthy of discussion must rely on energy and momentum transfer to the spacecraft from some external source such as a local force field, which in turn must obtain it from still other momentum and/or energy sources in the cosmos in order to satisfy conservation of both energy and momentum.