That is true but that is not what I mean. Imagine you are the ball and you are resting wrt to the table and the earth. A cue or another ball hits you so you move at 1 m/s wrt to the table. Would you be so self-centred as to claim you are still resting, and that the table and the earth are now moving under you at 1 m/s?
If such a conceit were true the pool players standing around the table would have been flung off their feet as the earth abruptly accelerated under them from 0 m/s to 1 m/s. Harry ----- Original Message ----- From: leaking pen <[EMAIL PROTECTED]> Date: Thursday, September 25, 2008 12:43 pm Subject: Re: [Vo]:Chinese building "space drive" unit > Yes. It is more the opposite, but every step you take, you push the > Earth, and she pushes back at you. The Earth pushes a hell of a lot > harder, but you DO have an effect on the motion of the Earth, however > infintesimal, with each step. > > On Thu, Sep 25, 2008 at 9:38 AM, Harry Veeder <[EMAIL PROTECTED]> wrote: > > > > > > ----- 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 > > > > > >
