The description of how the EM drive should move makes me think of a movie of a rocket played backwards. The movie-in-reverse-rocket would initially accelerate a lot and then the rate of acceleration would decrease until it stops accelerating and is at rest or coasting. I have also read that the EM drive accelerates in the opposite direction that is normally expected and a movie-in-reverse-rocket would behave similarly. Note: The movie-in-reverse-rocket is a metaphor rather than an analogy since matter is not literally following into the drive.
CoE is preserved through the conversion of energy into mass. The second LoT is broken and so is CoM, but how many laws does the universe need? Or maybe the measured thrust is only artifact. Harry On Mon, Mar 14, 2016 at 2:44 PM, David Roberson <[email protected]> wrote: > Good argument. I just wanted to add one thought. > > From the EM drive's point of view the CoE must be violated because as it > accelerates in space a portion of it's mass must be converted into energy > that is used to power the drive. When it ceases to use the drive it begins > to remain motionless in space from its point of view. Where did that mass > go which was converted into energy that powered the drive? Did it simply > vanish? > > This problem does not exist for normal rocket engines that expel a reaction > mass. In that case, the energy is accounted for by the mass that is > speeding rapidly away from the rocket. > > -----Original Message----- > From: Vibrator ! <[email protected]> > To: vortex-l <[email protected]> > Sent: Mon, Mar 14, 2016 7:03 am > Subject: Re: [Vo]:Re: EM Drive(s) > > Yes, and this is why KE = 1/2 MV^2 - ie., why the acceleration unit cost > escalates; a given force has to be applied over an ever-greater distance as > velocity (time rate of change of position) increases. Alternatively, we > could hold displacement constant and progressively raise the force > magnitude. > > Yet Craig still seems to have a point - without some kind of corporeal > reaction mass, what is an EM drive's velocity actually relative to? What's > its reference frame, if not the thing it's pushing against? > > To illustrate the conundrum, suppose i have an EM drive aboard a train, and > you the observer are standing on the platform as the train passes through > the station: I fire the engine, and it accelerates by 1 meter / sec. > > Suppose the engine weighs 10 kg. From my perspective, its KE has increased > by 5 Joules - ie. it's perrformed 5 J of mechanical work, regardless of how > much more energy may have been wasted to heat. > > But if the train was already travelling at 10 m/s, and the drive accelerated > in the same direction, then from your stationary perspective the drive has > accelerated up from 10 to 11 m/s - and for a 10 kg mass that's a workload of > 105 J - bringing its KE up from 500 J to 605 J. > > So, has the drive burned 5 J or 105 J? > > > If i cheated - the drive doesn't really work, and i just gave it a > surreptitious shove - this same paradox is resolved by a corresponding > deceleration of the train - ie. if i accelerate a small mass against the > inertia of a larger mass, the latter is decelerated and net momentum is > conserved. > > Except here, the drive ISN'T pushing against the train. Yet it still > benefits from its ambient velocity. Net momentum is NOT conserved, and > neither is energy. > > > And so the question arises, how does the EM drive "know" what its reference > frame is? Shawyer claims (or seems to imply) that the unit cost of > acceleration increases as we would normally expect (distance over which a > given force is applied keeps rising) - but how does it measure "distance"? > Relative to what, exactly? Without physical reaction mass, such a system > has its own unique reference frame - from within which, energy may be > conserved, but which from without, cannot be. > > I mean this not as a crtitique against the plausibility of such systems, and > share the prevailing cautious optimism. But if they do work, then we also > have an energy anomaly. > > In the many years i've been researching classical symmetry breaks, one thing > has become clear - the only way to explain away a real symmetry break is to > invoke another somewhere else up or downstream (it's a standard recourse for > pseudoskeptics). As much as i'd welcome free energy, momentum and FTL > travel, and despite Shawyer's assurances everything's classically > consistent, these enigmatic implications remain.. for me, at least. > > On Mon, Mar 14, 2016 at 4:17 AM, <[email protected]> wrote: >> >> In reply to Craig Haynie's message of Sun, 13 Mar 2016 21:08:43 -0400: >> Hi, >> [snip] >> >> Note the use of the word "acceleration". >> >> Acceleration produces a force. Force times distance = energy. >> >> >This doesn't make any sense: >> > >> >"For a given acceleration period, the higher the mean velocity, the >> >longer the distance travelled, hence the higher the energy lost by the >> >engine." >> > >> >Since we're not talking about relativistic speeds, then the idea that a >> >device will consume more energy, over a given period of time, simply >> >because it's moving, would violate Einstein's Special Relativity which >> >says there's no preferred frame of reference. The moving object cannot >> >be said to be moving at all. >> > >> >Craig >> Regards, >> >> Robin van Spaandonk >> >> http://rvanspaa.freehostia.com/project.html >> >
