Quote from: Rodal on 07/05/2015 04:18 PMQuote from: deltaMass on 07/05/2015 04:13 PM....Incorrect if you are disputing the units of the Poynting vector as I described them. Are you?For non-elementary problems in Physics the fundamental quantity to derive forces is the stress. The equations of equilibrium for non-uniform stress are formulated in terms of stress and not forces. I don't care. I described the units of the Poynting vector and you replied with "incorrect". You either need to say why I'm incorrect or retract your statement.

Quote from: deltaMass on 07/05/2015 04:13 PM....Incorrect if you are disputing the units of the Poynting vector as I described them. Are you?For non-elementary problems in Physics the fundamental quantity to derive forces is the stress. The equations of equilibrium for non-uniform stress are formulated in terms of stress and not forces.

....Incorrect if you are disputing the units of the Poynting vector as I described them. Are you?

Quote from: wallofwolfstreet on 07/05/2015 03:47 PM...Maybe I misunderstand you, but I'm going to keep saying it for good measure: The Poynting vector, S, is NOT a force. Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. An constant unbalanced force could only be generated if you saw that Poynting vector continuously and endlessly growing. This is the link to my previous comment on this issue. Correct, as a cursory glance at the units of the Poynting vector will show. It has units of power per unit area, whereby the area refers to the plane orthogonal to the direction of the power flux

...Maybe I misunderstand you, but I'm going to keep saying it for good measure: The Poynting vector, S, is NOT a force. Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. An constant unbalanced force could only be generated if you saw that Poynting vector continuously and endlessly growing. This is the link to my previous comment on this issue.

Quote from: deltaMass on 07/05/2015 04:20 PMQuote from: Rodal on 07/05/2015 04:18 PMQuote from: deltaMass on 07/05/2015 04:13 PM....Incorrect if you are disputing the units of the Poynting vector as I described them. Are you?For non-elementary problems in Physics the fundamental quantity to derive forces is the stress. The equations of equilibrium for non-uniform stress are formulated in terms of stress and not forces. I don't care. I described the units of the Poynting vector and you replied with "incorrect". You either need to say why I'm incorrect or retract your statement.The statement << Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. >> in Quote from: deltaMass on 07/05/2015 04:03 PMQuote from: wallofwolfstreet on 07/05/2015 03:47 PM...Maybe I misunderstand you, but I'm going to keep saying it for good measure: The Poynting vector, S, is NOT a force. Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. An constant unbalanced force could only be generated if you saw that Poynting vector continuously and endlessly growing. This is the link to my previous comment on this issue. Correct, as a cursory glance at the units of the Poynting vector will show. It has units of power per unit area, whereby the area refers to the plane orthogonal to the direction of the power fluxis an over-statement, as the time-averaged (over an integer number of periods) of the Poynting vector divided by the speed of light in free space is the radiation pressure exerted by an electromagnetic wave on the surface of a target, if the wave is completely absorbed by the target .Stress = <Poynting vector averaged over integer number of periods> / c this formula has been verified experimentally multiple times since 1900 when the wave is absorbed by the target

...Completely disagree. My statement << Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. >> is exactly correct. In specific instances, can a poynting vector be used in an equation to derive force? Yes. As you yourself say, its's elementary. The photon rocket and solar sail are both instances where the poynting vector clearly has a relation with force.In general however, you can never conclude force from a Poynting vector alone. Look at the attached figure. There is a "time-averaged (over an integer number of periods)" net Poynting vector. NO force. Put a piece of metal sheet between the battery and the resistor. Is there radiation pressure acting there? No, obviously there isn't. Poynting vectors and radiation pressure don't have a 1-1 correspondence.That figure alone should be enough to convince you that in general, the Poynting vector can not be reduced to a force. Clearly there is some difference between a solar sail being "pushed" by the poynting flux from the sun, and the lack of force on a metal sheet caught in the poynting flux of a simple DC circuit.

Quote from: wallofwolfstreet on 07/05/2015 05:34 PM...Completely disagree. My statement << Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. >> is exactly correct. In specific instances, can a poynting vector be used in an equation to derive force? Yes. As you yourself say, its's elementary. The photon rocket and solar sail are both instances where the poynting vector clearly has a relation with force.In general however, you can never conclude force from a Poynting vector alone. Look at the attached figure. There is a "time-averaged (over an integer number of periods)" net Poynting vector. NO force. Put a piece of metal sheet between the battery and the resistor. Is there radiation pressure acting there? No, obviously there isn't. Poynting vectors and radiation pressure don't have a 1-1 correspondence.That figure alone should be enough to convince you that in general, the Poynting vector can not be reduced to a force. Clearly there is some difference between a solar sail being "pushed" by the poynting flux from the sun, and the lack of force on a metal sheet caught in the poynting flux of a simple DC circuit. Yes, we disagree. I would not presume, as you are doing, what other analysts can or cannot conclude from their knowledge of a subject. ___PS: this is a state of non-uniform stress, one of the first steps in analyzing it is to deal with stresses and not forces. Poynting vectors are fluxes: power over surface area, therefore the discussion should be about stresses and not forces.

...What is it that I am "presuming"?

Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces.

Quote from: wallofwolfstreet on 07/05/2015 05:44 PM...What is it that I am "presuming"?Quote from: wallofwolfstreetJust because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces.If that applies to what you can conclude, please don't presume that it applies to what others may conclude (based on their knowledge).

This guys think another wayhttp://arxiv.org/abs/0708.3519

Quote from: Rodal on 07/05/2015 05:46 PMQuote from: wallofwolfstreet on 07/05/2015 05:44 PM...What is it that I am "presuming"?Quote from: wallofwolfstreetJust because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces.If that applies to what you can conclude, please don't presume that it applies to what others may conclude (based on their knowledge).I don't understand. Are you saying that there is a force on a piece of material placed between the battery and resistor in a simple DC circuit?If you answer no to that question, than we must be in agreement. There is a Poynting vector, there isn't a force. QED, my statement << Just because you see a net, time-averaged Poynting vector doesn't mean you can conclude anything about any unbalanced forces. >> is correct. If you answerd yes to the question, well I guess you know something I don't.

Following discussions with Roger Shawyer, I now understand why using a scale to measure EMDrive Force generation is a waste of time.

Following discussions with Roger Shawyer, I now understand why using a scale to measure EMDrive Force generation is a waste of time.1) Basically when you sit the EMDrive on your scale based measurement system, it will be non moving. 2) Once you fill the frustum with microwaves it will be in IDLE mode waiting for some external Force to move/vibrate it slightly big end to small end. 3) Once that happens the EMDrive enters MOTOR mode and starts to build up an external Force. That Force will push against the measurement system and achieve a slight amount of room to slightly accelerate. 4) However soon after what ever compressive movement that was there is now gone, the EMDrive stops moving and flips back into IDLE mode and shutting off Force generation.{snip}

...Are the Meep simulations and Poynting vectors being recorder during the period when the frustrum is fluxing-up, or after several microseconds when an equilibrium between power-input vs. dissipation has been reached?

....

I applaud the NSF people for the work: it's interesting (though they don't give the magnitudes in their plots) but I've been revising Poynting vectors & I don't believe they are going to move the cavity: the consequences still have to obey conservation of momentum as usual (so nothing to do with MiHsC).In general, I'm wary of the tendency in physics to use complex computer models (eg: thermal explanation of Pioneer, dark matter) to explain things, it is so seductive but the details are hidden and it can give the right answer for the wrong reasons. How many free parameters are in the model? Have they tested it on cavity data?

Again...!http://www.nature.com/ncomms/2014/140306/ncomms4300/full/ncomms4300.html"Momentum and spin represent fundamental dynamic properties of quantum particles and fields. In particular, propagating optical waves (photons) carry momentum and longitudinal spin determined by the wave vector and circular polarization, respectively. Here we show that exactly the opposite can be the case for evanescent optical waves. A single evanescent wave possesses a spin component, which is independent of the polarization and is orthogonal to the wave vector. Furthermore, such a wave carries a momentum component, which is determined by the circular polarization and is also orthogonal to the wave vector. We show that these extraordinary properties reveal a fundamental Belinfante’s spin momentum, known in field theory and unobservable in propagating fields. We demonstrate that the transverse momentum and spin push and twist a probe Mie particle in an evanescent field. This allows the observation of ‘impossible’ properties of light and of a fundamental field-theory quantity, which was previously considered as ‘virtual’."

DERIVATION OF THRUST FROM A TAPERED WAVEGUIDE PHOTON ROCKETI updated the equations to make the derivation clearer. In these equations, z is the axis of the cone, theta is the half-angle, E is energy, M and m are mass terms, and the rest is just wave vectors in a waveguide.You can see that if the cone were not tapered there would be no dependence on z, the last term in the force equation would not exist. If it were not starting in a waveguide, the phase velocity would be c. Then we have a "flashlight" photon rocket. This is a different animal. This Force only applies when the big end is OPEN! Closed, all bets are off, but this explains where the tremendous thrust to power ratios are coming from.FYI: This is the foundation of the paper I'm writing. Now you have the "tech" right in front of you while I try to put this in "writing". Have at it! Can't wait to see what sort of designs you come up with. Todd

If you setup a sealed system to give an impulse that would provoke particles to move what would seem faster then the speed of light in classical mechanics, consequential reaction would be smaller then the impulse and a part of the impulse would "externalize". This is just my guess.What happens on the level of quantum physics will probably be the last thing we find out on the topic. If we knew quantum physics this well then we wouldn't even need an experiment. However, empirical is still the primary method and everything more specific is also way more abstract.My working prototype uses a different approach, has better power to weight ratio and will probably be the one to withstand the test of time.

Doctor McCulloch made a comment on the MEEP results:Quote I applaud the NSF people for the work: it's interesting (though they don't give the magnitudes in their plots) but I've been revising Poynting vectors & I don't believe they are going to move the cavity: the consequences still have to obey conservation of momentum as usual (so nothing to do with MiHsC).In general, I'm wary of the tendency in physics to use complex computer models (eg: thermal explanation of Pioneer, dark matter) to explain things, it is so seductive but the details are hidden and it can give the right answer for the wrong reasons. How many free parameters are in the model? Have they tested it on cavity data?

Quote from: Ricvil on 07/05/2015 03:36 PMhttp://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1040027Quote from: WarpTech on 07/05/2015 06:18 AMDERIVATION OF THRUST FROM A TAPERED WAVEGUIDE PHOTON ROCKETI updated the equations to make the derivation clearer. In these equations, z is the axis of the cone, theta is the half-angle, E is energy, M and m are mass terms, and the rest is just wave vectors in a waveguide.You can see that if the cone were not tapered there would be no dependence on z, the last term in the force equation would not exist. If it were not starting in a waveguide, the phase velocity would be c. Then we have a "flashlight" photon rocket. This is a different animal. This Force only applies when the big end is OPEN! Closed, all bets are off, but this explains where the tremendous thrust to power ratios are coming from.FYI: This is the foundation of the paper I'm writing. Now you have the "tech" right in front of you while I try to put this in "writing". Have at it! Can't wait to see what sort of designs you come up with. ToddWhere the first equation comes from, and what is "Xmn" It comes from the circular resonator equation. Where, Xmn denotes the n-th zero of the m-th cylindrical Bessel function, used for TM modes. For TE modes, X'mn denotes the n-th zero of the derivative of the m-th cylindrical Bessel function. Rather than a longitudinal p-mode, I've shown it as k_{z} as a traveling wave.Todd

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1040027Quote from: WarpTech on 07/05/2015 06:18 AMDERIVATION OF THRUST FROM A TAPERED WAVEGUIDE PHOTON ROCKETI updated the equations to make the derivation clearer. In these equations, z is the axis of the cone, theta is the half-angle, E is energy, M and m are mass terms, and the rest is just wave vectors in a waveguide.You can see that if the cone were not tapered there would be no dependence on z, the last term in the force equation would not exist. If it were not starting in a waveguide, the phase velocity would be c. Then we have a "flashlight" photon rocket. This is a different animal. This Force only applies when the big end is OPEN! Closed, all bets are off, but this explains where the tremendous thrust to power ratios are coming from.FYI: This is the foundation of the paper I'm writing. Now you have the "tech" right in front of you while I try to put this in "writing". Have at it! Can't wait to see what sort of designs you come up with. ToddWhere the first equation comes from, and what is "Xmn"