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#520 by frobnicat on 22 Dec, 2015 00:33
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......
I think I can follow the reasoning, but allow me to turn it 180° around...
A device with a constant thrust to power ratio, and a thrust to power ratio higher than a theoretically perfect photon emitter, has a critical velocity that can be reached by a real system. It can therefore be used to violate CoE. Even these lab-scale result are much greater than the thrust of a photon drive, and so if it's a genuine propellantless/reactionless effect, such devices can violate CoE.
[frobnicat covered it better, of course.]
The only way for the device to comply to CoE, would be NOT to have a constant thrust to power ratio ?
... would be NOT to have a constant thrust to power ratio at any vector velocity relative to some local reference frame defined by a medium or field support. For instance a solar sail has a "constant" infinite thrust to power ratio (non 0 thrust with 0 spent power) but the thrust depends on the relative velocity with solar wind (average momentum vector of local flow of solar particles). The spacecraft is actually just "putting on the brakes" as rfmwguy says (bold below added for emphasis)..../...
Sooo, consider the possibility that it is manipulating/focusing/expelling/attracting/interacting with XEM...a natural condition of the universe, perhaps part of the theory of an ever-expanding universe...a driving force...lets even say it could be the new LHC particle, call it unicorn dust...doesn't matter for this thought experiment.
Suppose a natural condition, a zero frame of reference, of which we are never a part of (as we fly thru the cosmos) does exist and somehow we are putting on the brakes, attaching to it/countering it/repelling it, whatever...
Are we really at an over-unity, CoM/E violating condition? I am tending to believe it is not and something hasn't been fully understood by our ancestral scientist friends and their legions of followers.
.../...
Scientist are (more often than not) not the intellectual ayatollahs you apparently think they are. They are trained to jump from one framework to another, so adding another framework is not something I would believe they are afraid of... Anyway :
Let's no longer call that over-unity but above a "break-even" point. This is indeed not necessarily violating CoE to thrust "propellantlessly" at φ=thrust/power>3.33ľN/kW, provided the dot product of thrust (vector) with the velocity (vector) of the thruster relative to the support "zero frame of reference" is below power. Even though this would appear above "break-even" in another frame of reference, call it ground, that happen to have a relative velocity (wrt the zero frame) such that the thruster has a speed>1/φ wrt. the ground (hope you follow me, we have 2 frames + a moving craft now).
In fact we would just be harvesting the energy that exists in a system composed of 2 massive "frames" that happen to have a relative velocity between them, by exchanging momentum between them, i.e. putting on the brakes, that will have a tendency to slow down the relative velocity between the 2 massive frames, hence to lower the mutual kinetic energy of the system, and as a consequence release the same amount of energy (part of which can be harvested, the rest being released as waste heat). Most mundane example is mass of moving air above ground (aka. wind !). Let a kite go with the wind and use the unrolling of string to power a winch generator : net power source.
Assuming such aether, to respect CoE while being able to thrust in arbitrary directions, Emdrive would have to be like a "motorized kite". For instance a φ=thrust/power=0.1 N/kW means a (CoE respecting) maximum velocity of 1/φ=10km/s relative to "zero frame of reference", i.e. the mass of "air", or rather "aether". Now that means that, if some people do succeed in measuring thrusts at 0.1 N/kW and this thrust can be oriented in all directions, then the absolute limit on the aether "wind" relative to ground is 10km/s. I let you ponder the likelihood of an aether just happening to cross by our labs at less than 10km/s when the earth orbit around the sun makes it 30km/s and the solar system circles the galaxy at around 250km/s. Unless such hypothetical "aether" is "frame dragged" locally by planets (in which case expect the behavior of a φ=0.1N/kW emdrive to depart significantly from ideal when entering deep space) I personally find that natural consequence (of a ground level "synchronized" cosmological aether) hard to swallow. To my knowledge no proponent (Shawyer, Yang, White...) ever published sidereal times and orientation wrt. stars of the experiment runs, this is an indication that no one takes this hypothesis seriously, even while it could save the emdrive "would be phenomenology" from the immediate CoE issues. Higher than φ=0.1N/kW makes it even worse, for instance φ=1N/kW would limit the "velocity window" to less than 1km/s, making such figure of merit incompatible with any space mission.
Wanting to have the freedom to thrust in arbitrary directions and φ=1N/kW and deltaV missions way above 1km/s, and respecting CoE, I see only one solution, not one "zero frame of reference" aether but a multiplicity of such massive frames to grip (brake) onto :
https://forum.nasaspaceflight.com/index.php?topic=38577.msg1452446#msg1452446
This is actually close to White's take on the problem, so I must say "vacuum plasma" theory makes sense in this respect, also White will never publicly admit that his theory implies tapping into energy of vacuum background, just tapping into momentum of background. As if it was possible to tap into the momentum without tapping into the energy...We have not yet tested a static device yet, let alone one moving at high speeds.
High speed relative to what ?
Relative to a galactocentric frame the device has been tested around + and - 250 km/s (depending on sidereal time and orientation) even while sitting on the bench...QuoteWould/could the relative speed of the cavity itself have an impact on how the force is generated internally?
That would make the EMdrive an "absoluteSpeedOMeter". So far there is no indication (and all indication to the contrary) that there is an embedded absolute reference frame "in the background" (accessible in a closed box). Other things, defining local frames, that might make it into a closed copper box at ground level are gravity, neutrinos, weakly interacting dark matter, a few energetic particles...Quote
What does the velocity of the EMdrive mean for the electromagnetic waves that bounce around and their resonance patterns?
Nothing. Acceleration might blueshift or redshift a little bit here and there, but nothing distinguishes what happens in a box on an inertial trajectory from a similar box on another inertial trajectory. An experience in a box in a spacecraft cruising at 10km/s relative to earth works exactly the same as the same experience freefalling in a 0 g tower on earth (so long as it is free falling). This is precisely the point of special relativity, and that principle (and thought experiments around that) was highly successful (in accordance with what we observe experimentally).QuoteIsn't an electromagnetic wave limited to the speed of light, regardless the reference frame it bounces in?
so if the cavity moves, it takes light less time to travel the distance in one direction then in the other direction. (Doppler effect?)
Yes, yes. No. Depends on the observer.
Special relativity : time and distance are relative, they will not be the same measured from within the box (more strictly, by an observer at rest wrt. box) than from a standing passerby, but both cases distance/time=c, no matter the "direction". Passerby will indeed see redshifted photons from one end mirror and blueshifted photons from the other, but not the "comoving" observer. Maybe people here more at ease with SR than me can elaborate ? Calculations made by both observers should yield the same conclusions...QuoteSo the question is then what effect has that on the possible force generation in the frustum?
Unless we are breaking relativity, and/or emdrive is sailing/dragging on some preferred rest frame aether, "absolute velocity" should have none.
As for GR, I know people here are still trying to put it at work, but while qualitatively interesting things happen in GR we have yet to see quantitative values that are more than about 20 order of magnitude below the ľN/kW we are talking about as a floor case (the photon rocket). Please correct me if it is an overstatement.QuoteI know it doesn't look good on paper,
That's an understatement, it looks horrible.Quotebut... IF the tests show there is some force going on, how on earth is that apparent violation of Energy going to be explained then?
Or do we reside right away that it is "not possible" from start and that all measurements are flawed?
Are you 110% sure we don't take a flawed assumption somewhere that is counter-intuitive?
I am in doubt...seriously...
I can see where it goes wrong. You and frobnicat (and doc Rodal before that) explained it well, but I'm not yet prepared to throw all testing results overboard. Maybe we're overlooking something, made wrong assumptions?
From the apparent violation of CoE there are 2 pathways to go: either dismiss the whole concept as being ridiculous "impossible" or ask yourself where we made a conceptual mistake?
Or ask where the apparent excess power would come from, not shy away from it.
Proponents use a purported φ=thrust/power way above 3.33ľN/kW to project missions implying delta velocities > 1/φ, that is very overtly "overunity". Then they try to hide the fact by saying that other schemes have same problem (implying that everyone is at lost with Newtonian mechanics ?).
There is nothing fundamentally wrong with apparent overunity, for instance probes trajectories to outer planets "routinely" use gravity assist (slingshot) effect and that subtracts a lot to the required energy to reach a destination out sun's gravity well at a given velocity. I don't know the precise numbers (curious to learn if anyone has a clue) but wouldn't be surprised that the final acquired kinetic + potential energy > onboard energy at start of journey. That's alright as we know at what's expense (planets orbits) this energy was gained.QuoteUntil the experiments can clearly identify the EMdrive as a measurement mistake, I'm inclined to question our understanding about whats happening, rather then to dismiss it as impossible...
Mmm, until the experimenters can clearly identify a reproducible design and do a lot (a lot more) of clean parametric studies involving the frustum and the immediate vicinity of the frustum, I'm inclined to question the validity of the effect (as purported of being of use in deep space as a mean of thrusting).
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#521 by SeeShells on 22 Dec, 2015 00:35
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So one large error is being overlooked here. That is the difference between power input, resonance density, and force output. Even if we don't assume that resonance creates thrust this is still just as relevant because resonance is an easy way to measure accumulated power.
How would you design an experiment to test for this?
What do we know about the elasticity of a linear function? That it is nonlinearly varying over the course of a straight line.
That is to say that if thrust power output is a linear function of resonance power, this still wouldn't make thrust a linear function of power input. If you have 1000 photons bouncing in a cavity (let's assume perfect reflectors, and that we aren't even extracting work from their momenta), it takes 100 photons to scale the power of resonance up by 10%. To scale resonance power up another 10% will require 110 photons, which is nonconstant returns to thrust from input power.
Because other forms of thrust do not work by accumulating resonance of thrust energy, I think some of the calculations being done here are mistaken. Note again, this should be true even if resonance is not the creator of thrust but an indicator of energy density.
I plan a series of tests at incremental power levels (
into the Frustum.
This will be done with the drive in resonance mode and shifted out to each 3db point to 15db down from the center Fo (Frequency Operation)on each side of the Fo.
I'll be varying the plate width to set the tune out from the calculated center Fo using the digital scales to determine cavity plate distances.
Record and monitor the Spectrum Analyzer the 3db point power runs. Since I have a set incoming frequency 2.47GHz I have to work with that instead of varying the RF frequency.
I'll monitor and record the VSWR and the record the Spectrum, as well as the heat and thermals on the frustum. Power in to the inverter will be noted for the beginning of each test and in the middle of each run.
All of this while monitoring the digital scales through the some +80 runs of 1 minute each with 5 minutes between each test run.
I hope this will give us a power/thrust/tune/Q profile and should tell us when the thrusts occur.
Shell
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#522 by rfmwguy on 22 Dec, 2015 00:59
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Frobnicat, I can follow your synopsis a bit, then I go into theory tilt mode. Frame dragging/reference is a bit hard to visualize but thanks for your efforts and detailed reply. Hardware and software design...I can do. Theoretical physics, uhhhh, best left to braintrusts like yourself.
In a sentence or two, assuming the emdrive force is real, what is it? -
#523 by A_M_Swallow on 22 Dec, 2015 01:04
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I plan a series of tests at incremental power levels ( into the Frustum.
This will be done with the drive in resonance mode and shifted out to each 3db point to 15db down from the center Fo (Frequency Operation)on each side of the Fo.
I'll be varying the plate width to set the tune out from the calculated center Fo using the digital scales to determine cavity plate distances.
Record and monitor the Spectrum Analyzer the 3db point power runs. Since I have a set incoming frequency 2.47GHz I have to work with that instead of varying the RF frequency.
{snip}
If the same energy is going into the cavity then the same thermals should come out. Although varying the plate width may cause the heat to exit at different places. -
#524 by TheTraveller on 22 Dec, 2015 01:07
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I plan a series of tests at incremental power levels (8) into the Frustum.
This will be done with the drive in resonance mode and shifted out to each 3db point to 15db down from the center Fo (Frequency Operation)on each side of the Fo.
I'll be varying the plate width to set the tune out from the calculated center Fo using the digital scales to determine cavity plate distances.
Record and monitor the Spectrum Analyzer the 3db point power runs. Since I have a set incoming frequency 2.47GHz I have to work with that instead of varying the RF frequency.
I'll monitor and record the VSWR and the record the Spectrum, as well as the heat and thermals on the frustum. Power in to the inverter will be noted for the beginning of each test and in the middle of each run.
All of this while monitoring the digital scales through the some +80 runs of 1 minute each with 5 minutes between each test run.
I hope this will give us a power/thrust/tune/Q profile and should tell us when the thrusts occur.
Shell
I'm sure Roger is proud of your results to date and of your future plans:
His 2002 results:
http://emdrive.com/feasibilitystudy.htmlQuoteA 160 mm diameter experimental thruster, operating at 2450 MHz was designed and built. (see fig 2)
The design factor, calculated from as-built measurements of the thruster geometry was 0.497.
An unloaded Q of 5,900 was measured.
The maximum thrust, measured using a precision balance was 16mN for an input power of 850W, which is very close to the thrust of 16.6mN predicted from equation 1.
The thrust could be varied from zero to maximum by varying the input power, or by varying the resonant frequency of the thruster.
Considerable efforts were made to test for possible thermal and electromagnetic spurious effects.
The primary method was to carry out all tests in both nominal and inverted orientations, and to take the mean of the results.
The thruster was also sealed into a hermetic enclosure to eliminate buoyancy effects of the cooling air.
Three different types of test rig were used, two using 1 mg resolution balances in a counterbalance test rig and one using a 100 mg resolution balance in a direct measurement of thruster weight.
Comparison of the rates of increase of thrust for the different spring constants, using pulsed input power, gave a clear proof that the thrust was produced by momentum transfer and was not due to any undefined spurious effect.
The total test programme encompassed 450 test runs of periods up to 50 seconds, using 5 different magnetrons. -
#525 by SeeShells on 22 Dec, 2015 01:10
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I'll be recording the thermal camera and it will show what is happening in the frustum. Here is where all the speculation on what's happening in the frustum is defined and I hope some answers come out of it.
I plan a series of tests at incremental power levels ( into the Frustum.
This will be done with the drive in resonance mode and shifted out to each 3db point to 15db down from the center Fo (Frequency Operation)on each side of the Fo.
I'll be varying the plate width to set the tune out from the calculated center Fo using the digital scales to determine cavity plate distances.
Record and monitor the Spectrum Analyzer the 3db point power runs. Since I have a set incoming frequency 2.47GHz I have to work with that instead of varying the RF frequency.
{snip}
If the same energy is going into the cavity then the same thermals should come out. Although varying the plate width may cause the heat to exit at different places.
Shell
PS: I have a whole series of other tests to run as well. -
#526 by A_M_Swallow on 22 Dec, 2015 01:39
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I'll be recording the thermal camera and it will show what is happening in the frustum. Here is where all the speculation on what's happening in the frustum is defined and I hope some answers come out of it.
If the same energy is going into the cavity then the same thermals should come out. Although varying the plate width may cause the heat to exit at different places.
Shell
PS: I have a whole series of other tests to run as well.
Good.
A side effect of being able to buy working EMDrives is that physics, mechanical engineering and electronic engineering professors will be telling their research students to investigate the true nature of the device and its properties.
I hope they cite this tread as background information. -
#527 by Notsosureofit on 22 Dec, 2015 01:46
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As for GR, I know people here are still trying to put it at work, but while qualitatively interesting things happen in GR we have yet to see quantitative values that are more than about 20 order of magnitude below the ľN/kW we are talking about as a floor case (the photon rocket). Please correct me if it is an overstatement.
Are you referring to theory or experiment ?
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#528 by mwvp on 22 Dec, 2015 02:12
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...
Would/could the relative speed of the cavity itself have an impact on how the force is generated internally?.
How about the acceleration of the cavity? Fresh energy is coupled to the cavity at its present velocity. Stale energy is circulating in the cavity at Q times the intensity of new energy.What does the velocity of the EMdrive mean for the electromagnetic waves that bounce around and their resonance patterns?
Nothing, according to Relativity. Acceleration, however...Isn't an electromagnetic wave limited to the speed of light, regardless the reference frame it bounces in?
EM energy propagates at the speed of light in a vacuum. Your inertial frame determines the frequency and electric or magnetic fields you will measure, but according to relativity, C is always C for light propagating in the vacuum.so if the cavity moves, it takes light less time to travel the distance in one direction then in the other direction. (Doppler effect?)
I would say as the cavity accelerates, light is red/blue shifted from the bottom and top (to a lesser degree the angled sidewalls), respectively, and the monochromatic injected energy is split into upper and lower doppler sidebands.So the question is then what effect has that on the possible force generation in the frustum?
Ah, yes! Now that is The question!
Now we know the vacuum is lossless, and the metallic frustrum has copper/skin effect/I^2*R losses. And the bottom area is >> top area, and consequent losses are concentrated in the bottom. That asymmetric dissipation is enough to generate asymmetric thrust in itself by absorbing and radiating as heat the radiation that would otherwise balance thrust and reaction forces.
I find it intuitively obvious that the blue-shifted upper-sideband will reside in the frustrum top, and the red-shifted lower-sideband the frustrum bottom, and consequently the lower sideband will experience much greater attenuation and be dissipated as heat. Leading to asymmetrical radiation pressure.
The dispersion curve of the frustrum is also asymmetrical, with the top having a much greater phase shift than the bottom. Hence the near/at cutoff operating point. Much more to say and think about that.Maybe we're overlooking something, made wrong assumptions?
Yes, indeed. Maybe something obvious, conventional, insipid and banal. Like it's a conventional freakin heat-engine, entirely explainable with decades old, tried & true, conventional physics.
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#529 by Rodal on 22 Dec, 2015 02:20
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As for GR, I know people here are still trying to put it at work, but while qualitatively interesting things happen in GR we have yet to see quantitative values that are more than about 20 order of magnitude below the ľN/kW we are talking about as a floor case (the photon rocket). Please correct me if it is an overstatement.
Are you referring to theory or experiment ?
The theoretical analysis of NASA's Eagleworks frustum of a cone by physicist Dr. Marco Frasca (@StrongGR) we discussed at length with Frasca in previous threads: the General Relativity effect would have been present mainly at the singularity of the apex or the cone. The design by Shawyer, and tested by NASA, Yang, RFMWGUY, etc., is way off because it truncates the cone so prematurely, way short of the apex of the cone, so such GR effect is extremely negligible (> 20 orders of magnitude smaller than even a meek photon rocket). -
#530 by mwvp on 22 Dec, 2015 02:25
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So the question is then what effect has that on the possible force generation in the frustum?
Unless we are breaking relativity, and/or emdrive is sailing/dragging on some preferred rest frame aether, "absolute velocity" should have none.
But what effect will acceleration have on an asymmetric, dissipative and dispersive high-Q energized cavity near cutoff? -
#531 by ThinkerX on 22 Dec, 2015 02:38
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Ok, stupid question time:
Is it possible to violate Conservation of Energy for a short period of time?
That is, have an output far above the CoE limit for a short while, which is then 'balanced' (?) by a serious reduction in output?
I am thinking of the MEEP runs from last spring/summer (which possibly implied something like this) and Shell's report of how her exceptional thrust cratered. -
#532 by SeeShells on 22 Dec, 2015 02:44
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Ok, stupid question time:
Is it possible to violate Conservation of Energy for a short period of time?
That is, have an output far above the CoE limit for a short while, which is then 'balanced' (?) by a serious reduction in output?
I am thinking of the MEEP runs from last spring/summer (which possibly implied something like this) and Shell's report of how her exceptional thrust cratered.
I've wondered about that as well but wouldn't you see a "rebound" in the other direction, like the data from EagleWorks?
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#533 by ThereIWas3 on 22 Dec, 2015 02:58
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Just some accidental artwork. I have been working on the meep model for multiple side-entering signals and did a test run after putting in just one. This is a quarter-wave stub antenna mounted a quarter wavelength down from the small end, using Shell's frustrum measurements. Meep was not able to discover any resonances (I beleive this had been established before - a single extreme off-center feed does not seem to resonate.) However, I went ahead and made all the pictures anyway - All six field, each seen along all three axes. There were some surprises. I have no idea what any of this means, but it sure looks interesting. The label under each image, like HYX, means which field component (Hy in this case) and which direction of view (X). The X dimension is the long axis of the frustrum.
Update: I discovered that the __Y and __Z views are looking at the outside of the frustrum, which explains their lack of a trapezoid shape. These have now been redone and a new montage created. The __X views are looking at the Big end.
I have played with movies that sweep through the frustrum from end to end, and that is interesting too.
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#534 by Bob Woods on 22 Dec, 2015 04:19
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Suggestions from the non-scientist. It's winter so wherever Shell and Dave do test runs it's going to be in a room that needs to be heated, not cooled. That takes out one ambient temp management factor.
1. Choose a room temperature and hold it there. Pick something comfortable, like 72 degrees, but keep it there.
2. Use graph paper for your laser target so you have a good, fixed measure for your target, not just a slit, so you can repeatedly center and measure any displacement during testing on a consistent measure.
3. Run some tests to choose the magnetron cycle time for your "best" guess on a measured effect.
4) Allow 1 hour between tests to stabilize room temp, frustum temp, and air currents
5) Run the real experimental test based on the "best" cycle time a minimum of 36 times, changing the orientation of the small end to up/down/sideways (13 each) which gives you a preferred axis for any final measurable test.
6) Drink lots of coffee or Mountain Dew to stay awake.
7) After you have verified a a preferred axis (I will assume small end down) run an additional 36 tests with 1 hour time delays as before and measure your results. This will give you statistically significant measures.
If you get repeated positive results, pass Go, collect $200, and drink lots of champagne. I'll buy. -
#535 by SteveD on 22 Dec, 2015 04:23
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So one large error is being overlooked here. That is the difference between power input, resonance density, and force output. Even if we don't assume that resonance creates thrust this is still just as relevant because resonance is an easy way to measure accumulated power.
How would you design an experiment to test for this?
What do we know about the elasticity of a linear function? That it is nonlinearly varying over the course of a straight line.
That is to say that if thrust power output is a linear function of resonance power, this still wouldn't make thrust a linear function of power input. If you have 1000 photons bouncing in a cavity (let's assume perfect reflectors, and that we aren't even extracting work from their momenta), it takes 100 photons to scale the power of resonance up by 10%. To scale resonance power up another 10% will require 110 photons, which is nonconstant returns to thrust from input power.
Because other forms of thrust do not work by accumulating resonance of thrust energy, I think some of the calculations being done here are mistaken. Note again, this should be true even if resonance is not the creator of thrust but an indicator of energy density.
If he's saying what I think he's saying, apply power at different frequencies. The lower the frequency the more photons. I've got a spreadsheet that can suggest some frequencies that might have better results than others. -
#536 by SeeShells on 22 Dec, 2015 04:53
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rfmwguy... You still have that picture of the maggie that you modified for your VNA scan, could you post it again?
Thanks,
Shell -
#537 by SeeShells on 22 Dec, 2015 04:59
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Suggestions from the non-scientist. It's winter so wherever Shell and Dave do test runs it's going to be in a room that needs to be heated, not cooled. That takes out one ambient temp management factor.
I'll try to do that but you better buy Red Bull instead of Champagne, gonna need it.
1. Choose a room temperature and hold it there. Pick something comfortable, like 72 degrees, but keep it there.
2. Use graph paper for your laser target so you have a good, fixed measure for your target, not just a slit, so you can repeatedly center and measure any displacement during testing on a consistent measure.
3. Run some tests to choose the magnetron cycle time for your "best" guess on a measured effect.
4) Allow 1 hour between tests to stabilize room temp, frustum temp, and air currents
5) Run the real experimental test based on the "best" cycle time a minimum of 36 times, changing the orientation of the small end to up/down/sideways (13 each) which gives you a preferred axis for any final measurable test.
6) Drink lots of coffee or Mountain Dew to stay awake.
7) After you have verified a a preferred axis (I will assume small end down) run an additional 36 tests with 1 hour time delays as before and measure your results. This will give you statistically significant measures.
If you get repeated positive results, pass Go, collect $200, and drink lots of champagne. I'll buy.
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#538 by ThinkerX on 22 Dec, 2015 05:00
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Quote
I've wondered about that as well but wouldn't you see a "rebound" in the other direction, like the data from EagleWorks?
Shell, I have a suspicion, nothing more about why we are not seeing a 'rebound in the other direction.'
Has to do with the magnetron cycle. When that changes, the 'downside' curve 'breaks,' and doesn't happen. Then it starts over again with a new 'up' curve, which in turn gets broken before it can get too far down. To this suspicion I add two others:
1 - This device works, in part, precisely because the magnetrons are so dirty. A 'clean' signal might actually reduce or even kill the thrust.
2 - The 'interrupted cycle' is part of a larger curve, one that is inherently unstable. Past a certain point, even with the 'downside' cut out, it will collapse.
Or to put it another way, this thing works because of two accidental (?) design issues with the magnetrons used in microwave ovens: dirtiness, and the cycle.
All of this, of course, is mere unfounded suspicion. -
#539 by OnlyMe on 22 Dec, 2015 05:06
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When thinking about red and blue shifting of the EM radiation inside the frustum there would be no special or general relativistic effects, which would support the issue as it seems to be being discussed.
The distances inside the frustum are very small relative to the speed of light and any acceleration is also very small.., to non existent during testing even where thrust is measured and so once again no measureable affect on frequency or any relative velocity of the EM spectrum.
There may be some shifting that occurs as an artifact of resonance and Maxwell's equations, but that is something others would know more of than I...., and it should not be affected by any velocity or classical accelerations of the frustum.
On a separate note.., when thinking about any transfer of momentum between the resonant microwaves and the frustum walls, there are two aspects of EM radiation that must be considered...
As has been mentioned in the past.., for the most part it is best to think of the microwaves as waves rather than photons, for part of what is happening... But where a transfer of momentum is concerned it is better to think of them as photons, because any transfer of momentum occurs at the first interaction between the microwaves and the atoms in the frustum walls, which is better described as a particle like interaction, while resonance depends more on the wave nature and involves how the wave character interacts with the frustum walls many atoms deep. But even as photons you cannot forget the wave character and frequency. It plays an important role in how efficiently EM radiation transfers momentum to an atom.
Once an initial photon interaction transfers any momentum, the effect rapidly becomes increasingly randomized as it travels through the thickness of the frustum wall, spreading out.., but not to the same extent as any heat spreads and dissipates. Momentum retains a greater memory of the initial interaction which should be generally close to 90 degrees with the surface and roughly conical, with some angular aspects depending on exactly how the photon impacts an atom.... But resonance between the frustum wall and the microwaves is important...
At any location along the frustum walls where the microwave resonance is very concentrated, the atoms in the frustum wall near the surface of the metal will begin to resonate with the microwave frequency. Any microwave interaction with atoms where both the atoms and the microwaves resonate in lock step, should result in an increase in the transfer of momentum and a decrease in further heating, at least as it affects those atoms at the surface of the metal wall where any transfer of momentum must occur.
If thrust is developed directly through a transfer of momentum as long, as the thrust and heat together does not exceed the power in, there will be no violation of CoM. It would just be a new method of converting electrical power into kinetic energy.
If the quantum vacuum is proven to exist whether as an immutable ground state or a dynamically mutable background potential, the issues raised involving constant and uniform acceleration, over extended periods of time, will almost certainly become an issue that must be addressed as how an accelerating object interacts with the vacuum state. I really don't believe that is an issue that can or should be dealt with when testing in a lab frame.
I cannot imagine any way to sample how the atoms of the inside wall of a frustum resonate during operation without affecting operation, but how heat is transferred in different parts of the frustum may useful and is on the ticket for things to be looking at. It would be important to have some way to compare how heat develops in different parts of the frustum.
into the Frustum.