----- Original Message ----- From: "Stephen A. Lawrence" <[EMAIL PROTECTED]> Date: Thursday, September 25, 2008 11:18 am Subject: Re: [Vo]:Chinese building "space drive" unit
> > > OrionWorks wrote: > > I bet this device look familiar to a few vorts! > > > > See: > > > > http://blog.wired.com/defense/2008/09/chinese-buildin.html > > > > > > Uh -- not me; looks sort of like an antique picture tube, maybe, > but I > don't recognize it. > > I notice Emdrive hasn't gotten as far as running a spell checker over > their front page, which doesn't automatically fill one with > confidence. > From the description, it appears to be a microwave oven. Surprising > that they claim it will fly. > > I had one other comment on the website. On the theory page, they say: > > > ... Einstein’s Special Law of Relativity in which separate frames of > > reference have to be applied at velocities approaching the speed > of light. > > This is absolutely false. SR does *not* require that you must apply > "separate frames of reference" when approaching the speed of light. > In > fact any analysis which relies on total momentum or energy *must* be > carried out entirely within a *single* reference frame or else you'll > end up with nonsensical results (just as they have apparently done > here). > In the FAQs they say: > > Thus the system of EM wave and waveguide can be regarded as an open > > system, with the EM wave and the waveguide having separate frames of > > reference. > > This is complete nonsense. The "reference frame" chosen is based on > what makes it easiest to solve a particular problem. There's nothing > magical about relativity theory here, nor is there any mystical > significance to the term "reference frame"; *exactly* the same concept > exists in ordinary Newtonian mechanics. > > When a pool player strikes a ball, in the frame of the table, the cue > and the player's arm have significant momentum just before the ball is > hit. Afterwards, the table, player, and cue have zero momentum in the > *table's* reference frame. And yet, the ball has zero momentum in the > *ball's* reference frame, too! So, where did the momentum go? > Answer: > you need to do the momentum budget using a *single* frame, not a > different frame for each physical object! (But you get to pick which > frame to use.) > I have difficulty even accepting newtonian relativity. Do you think by a flick of the wrist the mass of the table (and the earth!) have gone from being at rest wrt to the cue ball, to being in motion wrt to the cue ball? Harry
