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bitstream [soylentnews.org] writes:

The proposed radio frequency (RF) resonant cavity thruster [wikipedia.org] that unlike conventional ones uses no reaction mass and emits no directional radiation. Designed using principles that are not supported by prevailing scientific theories, apparently violating the law of conservation of momentum. The EmDrive [emdrive.com], has roiled the aerospace world for the several years now [examiner.com], ever since it was proposed by British aerospace engineer Robert Shawyer. The essence of the claim [arxiv.org] is that bouncing microwaves in a truncated cone, thrust will be produced out the open end. Most scientists have snorted at the idea, noting correctly that such a thing would violate physical laws. However, prestigious organizations like NASA have replicated the results showing thrusts. MIT Technology Review has some reasoning on the subject, [technologyreview.com] with a picture of the device [technologyreview.com]. It's supposedly the so called unruh effect [wikipedia.org] at play. When NASA tested the device they measured with input of 17 W an average thrust of 91 µN (5.4 µN/W). A Chinese team used 2500 W and measured a thrust of 720 mN (288 µN/W). The expected radiation pressure is closer to 0.003 µN/W.

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