Quote from: X_RaY on 07/30/2015 08:29 PMThats why it is a little bit freaky to me opinion. That can only be true for modes with p value equal to zero, and only if the diameter fits frequency. The angle alone tells nothing. again IMHOWell, the formula also contains Q and if you derive it from the cavity's size ultimately it will contain the length. But if you're supplied with a Q and the dimension then the formula works even if all the dimensions are cut by the same factor.Ultimately it doesn't matter IMHO because it predicts the thrust should start immediately after turning the magnetron, it should be proportional to the power and it should end as soon the magnetron is turned off. Since none of those are true, so either the results come from experimental error and they are useless, or they disprove the theory. Time to go back to lurking.

Thats why it is a little bit freaky to me opinion. That can only be true for modes with p value equal to zero, and only if the diameter fits frequency. The angle alone tells nothing. again IMHO

Quote from: SeeShells on 07/30/2015 05:20 PM...Interestingly enough Doc it doesn't agree with the data published about thrusts. Is the data from the Yang tests totally bogus? Or we don't have the matter of the RF injection correct yet?I'd be wondering what your stress / poynting vector analysis is really showing? As of now it is only showing a asymetrical differential of stress levels from one end vs the other. What are you looking for your asymmetrical stress figures to do I guess would be the question? Right now I can take a enclosed can of air, put a air pump in it blowing at one end and the can sits still, but the pressure is higher at one end vs the other. If your saying that the increased stress in one end compresses and acts like a gravity induced gradient at that end and that causes the can to "squirt" along in it's own micro gravity well trying to equalize itself than that's a gravity warp drive.shellThese are my views on the subject, submitted for whatever little (or nothing ) they may be worth. I submit them now, since you still have time to change the geometry of what you are going to test, and you may want to consider the following points in selecting your geometry.<<Interestingly enough Doc it doesn't agree with the data published about thrusts. Is the data from the Yang tests totally bogus?>>1) My statement above that the net force is zero for Yang/Shell is based on a completely different program using the energy-momentum covariant tensor in General Relativity. This program is NOT the program that processes the Meep output to come up with the stress tensor and forces. Not based on the Meep runs2) The Yang-Shell geometry should not be assumed to be the geometry used by Yang in her tests I should know, since I was the one that calculated the Yang/Shell geometry as the best estimate of her dimensions based on her early theoretical paper, and then placed those dimensions in the EM Drive wiki (explaining where they came from). Those dimensions were a best effort at inferring what the geometry was in one of her earlier papers:a) Yang has several papers, the geometry for which Yang/Shell is based on is from a different paper where she reports the highest forces reported. The assumption that the geometry applies to both is just an assumption.b) Yang does not explicitly give all the dimensions of her frustum. Tajmar gave the dimensions for his EM Drive and it turns out that they were off by a factor of 2. It is quite possible that something was lost in translation and the dimensions of her frustrum are different. The geometry in her drawings looks quite different than the geometry assumed in Yang/Shell. Her drawings show shorter length and a much larger cone angle than the cone angle in Yang/Shell.c) IMO I think that conducting experiments based on the Yang/Shell geometry is more risky because:c1) The Yang/Shell geometry was not provided by Yang. Better to use a geometry provided by one of the researchers. For example the geometry provided by NASA, which we know 100% as to being the true geometry being tested.c2) The Yang/Shell geometry is the closest to a cylinder, having the smallest cone-angle and the largest distance between the small base and the apex of the cone. I would use a geometry having the small base much closer to the apex: the NASA geometry or the Shawyer Demonstratorc3) the Meep runs and my separate runs show the NSF-1701 geometry as more sensitive to test than the Yang/Shell geometry. The Meep runs show NSF-1701 to be much more sensitive to antenna placement: very different behavior of NSF-1701, force orientation when antenna is placed at one end vs the other end. My separate computations of Yang/Shell show it to be very close to a cylinder in its behavior, self-balanced force distribution.c4) Based on the following formulas, the Yang/Shell geometry should be the one producing lowest thrust because:c4A) Marco Frasca General Relativity derivation: the closest to the vertex the better. Yang/Shell is the geometry furthest away from vertex of the conec4B) Todd "WarpTech" Zang and Fan paper: critical parameter is kr. Yang/Shell has highest kr, which is worse, according to the theoryc4C) McCulloch and Notsosureofit thrust is highly dependent on the difference between the radii of the bases. Yang/Shell is the closest to a cylinder: should generate the least thrust.<<I'd be wondering what your stress / poynting vector analysis is really showing? As of now it is only showing a asymetrical differential of stress levels from one end vs the other. What are you looking for your asymmetrical stress figures to do I guess would be the question? >>The stress analysis based on the Meep runs is completely independent of the Poynting vector analysis. The stress analysis is not at all based on the Poynting vector. What is more intuitive to look at are the forces calculated and displayed. The forces are the integral of the normal stress over the cross-sectional areas. Forces is what people talk about when discussing the EM Drive. It is most important to understand what the forces are, how they behave vs. time and how they confirm or nullify the very simplified theories that are being thrown around.<<Right now I can take a enclosed can of air, put a air pump in it blowing at one end and the can sits still, but the pressure is higher at one end vs the other>>The air pressure should not be higher at one end than the other (at least in steady state, which I expect to be rapidly reached). The equilibirum pressure should be uniformly distributed inside, no matter what the shape. PV = nRT. I don't understand the thought-experiment as to why the air pressure varies on the inner surface of the air can.I can show that if one has uniform pressure inside an EM Drive, the normal stress (which is the same thing as pressure) being constant on the inner surfaces, translates to a balanced zero net force. This is NOT what the Maxwell's equations solutions show. The electromagnetic fields do NOT result in a uniform pressure on the inside.IMHO based on the analysis, and as discussed above the NSF-1701 geometry is the one I would test because it has the same diameters as the NASA frustum and the one tested by Iulian Berca, and because the Meep analysis shows it to be more sensitive, while the Yang/Shell geometry is unknown whether it is representative of any EM Drive tested by Yang, and the computer results shows it to be much less sensitive, and its geometry is much closer to a cylinder, and has the small base very distant from the vertex.Since rfmwguy is testing a geometry close to NASA, to be complementary, and since we don't quite know the Yang geometry, but we seem to have a better fix on the Shawyer geometry (from TheTraveller's communication with Shawyer) I would probably choose Shawyer's Demonstrator as the geometry, based on present information, IMHO. SeeShell, I think you have a fabulous testing set-up and testing approach, that's why I spent this time in giving you this lengthy opinion.

...Interestingly enough Doc it doesn't agree with the data published about thrusts. Is the data from the Yang tests totally bogus? Or we don't have the matter of the RF injection correct yet?I'd be wondering what your stress / poynting vector analysis is really showing? As of now it is only showing a asymetrical differential of stress levels from one end vs the other. What are you looking for your asymmetrical stress figures to do I guess would be the question? Right now I can take a enclosed can of air, put a air pump in it blowing at one end and the can sits still, but the pressure is higher at one end vs the other. If your saying that the increased stress in one end compresses and acts like a gravity induced gradient at that end and that causes the can to "squirt" along in it's own micro gravity well trying to equalize itself than that's a gravity warp drive.shell

2) Explaining what is the "acceleration" (and corresponding inertia modification) of photons inside the EM Drive. What is accelerated? If photon travels at c, nothing is accelerated. Is he using the group velocity? the phase velocity? why?

Post-Marital Stress Field is my favorite that would be a great title for a paper

Wouldn't any theory of EM drive that involves a fourth spatial dimension — one that's not infinitesimal – necessarily place us in ultrahyperbolic spacetime? Which I've always thought was a rather bad spot for physical constructs dependent on consistent laws. That was always my understanding going back to Klein. No extra spatial dimensions for you! Not unless those dimensions are bound in a compact manifold making them about as easy to access as other parts of the multiverse.But hey, I've got my own heresies. I'm still a fan of the idea that dark matter is just probabilistic gravity leakage across branes rather than some invisible stuff in own universe. It notonly seems neater that way, it blows open fun doors in information theory.(Note: this from a guy whose degrees are biology and geology. No one should allow this post to sway their physics opinions one Planck length.)

Somebody asked if anyone could cite a device that accelerates propellantlessly, and of course the answer was given (to precis and generalise the answer) that an external field often does the trick. Let me riff off that observation in the context of the Lorentz force.The scalar expression (I won't bother with cool vector notation because it's Thursday) is simplyF = B*I*Lwhere F=force (N), B=magnetic field (T), I=current (A), L=conductor length (m). We use the right-hand rule to deduce the direction of F given (B, I along L). For max effect, B is at right angles to I,L (it's a cross-product I L^B).So that's all just a backgrounder for interested neophytes, and very cursory.It can be easily shown that, for any closed system of conductors looping current in an external B-field, the net Lorentz force in any direction is identically zero. Were that not the case, I hazard a guess that our current transportation tech would look very different (and doubtless much cooler). But alas 'tis not thus.Not one single EmDrive experiment to date is fully self-contained. There are wires entering and exiting the apparatus in all cases. So when you draw your virtual "force integration box" around such apparatuses, you will get a net force (however large or small) because the current source at the other end of those wires isn't in your box. This is standard physics and should come as no surprise. It is also why any EmDrive you test should be fully boxed, should run on batteries inside that box, and have no trailing wires outside that box. Yes, I'm a broken record Let's run a sample calculation for order-of-magnitude purposes. The Earth's field is on order 5*10^{-5} TLet's peg the sort of forces being reported as on order 50 uN = 5*10^{-5} NIf this force is all due to the experimental artifact of a Lorentz force, thenF/B = I*L = 1 Amp-metreThat's not a lot, is it, considering the sort of dimensions and currents we're talking about re. EmDrives?And it's easy to ask that this figure be a lot lower when the value of B is jacked up to represent an ambient magnetic field due to other current-carrying conductors in the vicinity. So we see thatIt's quite easy to get Lorentz forces comparable to the measured thrusts.Cannae is the oddball here. Fetta's simulator, an expensive professional piece of kit (whose name currently escapes me) calculates a net Lorentz force inside his cavity that is non-zero. This is a rather mysterious result, since we are talking about a closed system of currents. Last I checked, he didn't understand it, the simulator bods didn't understand it, and I for sure don't understand it.It might be instructive for the MEEPers to take a look at this domain of behaviour.Lastly, I have not studied how the Lorentz force transforms under SR and GR. I will leave that as an open question.

It is also why any EmDrive you test should be fully boxed, should run on batteries inside that box, and have no trailing wires outside that box. Yes, I'm a broken record

NSF-1701 - 245x261x261 This is the final summary output from the log file.run 0 finished at t = 13.054 (6527 timesteps)Total number of slices 14, the last 14 of 32 full cycles, or periods at 0.1 period intervals. That is, at 30.7, 30.8 and so forth to 32.0 periods of the drive center frequency.Number of time steps, 6527 and total meep time = 13.054 time units.

Same antenna, 58 mm in the y direction, Ez excitation.(set! antlongx 0) ; direction vector of dipole antenna SI units(set! antlongy 0.058) ; = 58 mm(set! antlongz 0)

Quote from: Devilstower on 07/30/2015 09:55 PMWouldn't any theory of EM drive that involves a fourth spatial dimension — one that's not infinitesimal – necessarily place us in ultrahyperbolic spacetime? Which I've always thought was a rather bad spot for physical constructs dependent on consistent laws. That was always my understanding going back to Klein. No extra spatial dimensions for you! Not unless those dimensions are bound in a compact manifold making them about as easy to access as other parts of the multiverse.But hey, I've got my own heresies. I'm still a fan of the idea that dark matter is just probabilistic gravity leakage across branes rather than some invisible stuff in own universe. It notonly seems neater that way, it blows open fun doors in information theory.(Note: this from a guy whose degrees are biology and geology. No one should allow this post to sway their physics opinions one Planck length.)Read up on the Randall/Sundrum theory that places a short finite length dimension between our brane and a gravity brane, attempting to explain why gravity is so relatively weak.

@Rodal:Clearly your net force over time has a DC component, which means a time-averaged measurement would return a nonzero reading. Thus a suggestion: plot the time average instead, cycle by cycle. That's a useful distillation of your data.

Oh, and make sure us non-MEEPers can read off Newtons and seconds!

Quote from: SeeShells on 07/30/2015 05:20 PMRight now I can take a enclosed can of air, put a air pump in it blowing at one end and the can sits still, but the pressure is higher at one end vs the other. If your saying that the increased stress in one end compresses and acts like a gravity induced gradient at that end and that causes the can to "squirt" along in it's own micro gravity well trying to equalize itself then that's a gravity warp drive.shellWhich is a hypothesis that's been covered several times in these threads....

Right now I can take a enclosed can of air, put a air pump in it blowing at one end and the can sits still, but the pressure is higher at one end vs the other. If your saying that the increased stress in one end compresses and acts like a gravity induced gradient at that end and that causes the can to "squirt" along in it's own micro gravity well trying to equalize itself then that's a gravity warp drive.shell