I have a couple questions about this solution. I have not gotten around to studying general relativity in detail, so I can't directly critique the calculations, but there are a few implications this brings up.Are these calculations based on general relativity as it is generally known, or are there some tweaks/ additional assumptions?As I understand it, the explanation for energy/momentum balance is remote interaction with the other objects in the universe. There are 2 ways I can understand this:1. Instantaneous interaction with remote objects - this would cause problems with causality.2. Gravitational waves, which as I understand them have the same Energy/momentum constraints as photon thrusters.I could see the energy/momentum ratio for gravity waves being modified if you don't take the weak-field limit, but that brings up how any non-planet sized device could be outside the weak field limit.On a related note, considering the size of the constant G, even if the device was only as efficient for propulsion as a photon thruster, being able control and put significant energy energy into gravitational waves could open up all sorts of interesting applications.Does the theory really predict meaningful magnitude of the forces, or is it just far enough to say that there is a force in a given direction? From what you said I believe it is the former, but I want to check since I know this could be a very hard calculation to do.

...As of the papers that came out last year. They have rederived the mach effect equations for at least the first term (the space drive). I would need to re read to see if the term, dubbed the worm hole term. Is still there....

Woodward's derivation of an equation for mach's principle has two components: a part that is similar to the EM Drive but different in operating detail; and a second part that leads to navigable wormholes. While currently mucking about with wormholes experimentally is beyond the capabilities of anyone on earth- Woodward (rightly, I think) says that if the first half of his equation is supported by experiment then the wormhole bit must be correct as well....

...Are these calculations based on general relativity as it is generally known, or are there some tweaks/ additional assumptions?...

...As I understand it, the explanation for energy/momentum balance is remote interaction with the other objects in the universe. There are 2 ways I can understand this:1. Instantaneous interaction with remote objects - this would cause problems with causality.2. Gravitational waves, which as I understand them have the same Energy/momentum constraints as photon thrusters.....

Thank you for this information. My first question wasn't stated rigorously because I do not know enough about the details of general relativity to ask it properly, but you provided the information I was interested in.I think I would want to pick up a general relativity textbook and get more comfortable with the basics before I jump into the papers you mentioned, but once I find the time to do so, I will come back to this and study the implications in more detail. I have the math background where I could probably read them now, but I wouldn't understand what it means physically. (at least to my satisfaction, since I can be picky, I want to understand things inside and out)

...could we, in the EM drive and Mach Effect Thruster, potentially be looking at two unrelated mechanisms that might both eventually prove to have value in the area of thrust generation?I would find this a rather remarkable development, if so.

...Woodward does not think his Mach drive and the EM drive operate on the same principle. As of the 1st edition of his book he was skeptical of the EM drive as being anything other than experimental error of some sort. Of course with the cross fertilization that has happened since then (E.G; the SSI conference) he may have changed his opinion on that point. The conference attendees would know if that is still the case or not.

Quote from: M.E.T. on 09/26/2016 08:39 AM...could we, in the EM drive and Mach Effect Thruster, potentially be looking at two unrelated mechanisms that might both eventually prove to have value in the area of thrust generation?I would find this a rather remarkable development, if so.Perhaps the same mechanism is responsible for both the EM Drive and the piezoelectric/electrostrictive stacks tested by Woodward/Fearn: seehttps://forum.nasaspaceflight.com/index.php?topic=40959.msg1588165#msg1588165https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214for Dr. Montillet's paper explaining the EM Drive's acceleration as being due to the Mach/Sciama/Woodward gravitational effect.Quote from: Stormbringer on 09/25/2016 05:55 PM...Woodward does not think his Mach drive and the EM drive operate on the same principle. As of the 1st edition of his book he was skeptical of the EM drive as being anything other than experimental error of some sort. Of course with the cross fertilization that has happened since then (E.G; the SSI conference) he may have changed his opinion on that point. The conference attendees would know if that is still the case or not.I don't know what was his opinion previously, but the above statement is incorrect as of the Estes Park Breakthrough Workshop, as Prof. Woodward was agreeable to Dr. Montillet's explanation of the EM Drive as being due to the Mach effect. Actually Prof. Woodward proposed an experiment (that a superconducting EM Drive's performance will be less than expected because of the much reduced skin depth) to test this idea.

Quote from: Rodal on 09/26/2016 01:10 PMQuote from: M.E.T. on 09/26/2016 08:39 AM...could we, in the EM drive and Mach Effect Thruster, potentially be looking at two unrelated mechanisms that might both eventually prove to have value in the area of thrust generation?I would find this a rather remarkable development, if so.Perhaps the same mechanism is responsible for both the EM Drive and the piezoelectric/electrostrictive stacks tested by Woodward/Fearn: seehttps://forum.nasaspaceflight.com/index.php?topic=40959.msg1588165#msg1588165https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214for Dr. Montillet's paper explaining the EM Drive's acceleration as being due to the Mach/Sciama/Woodward gravitational effect.Quote from: Stormbringer on 09/25/2016 05:55 PM...Woodward does not think his Mach drive and the EM drive operate on the same principle. As of the 1st edition of his book he was skeptical of the EM drive as being anything other than experimental error of some sort. Of course with the cross fertilization that has happened since then (E.G; the SSI conference) he may have changed his opinion on that point. The conference attendees would know if that is still the case or not.I don't know what was his opinion previously, but the above statement is incorrect as of the Estes Park Breakthrough Workshop, as Prof. Woodward was agreeable to Dr. Montillet's explanation of the EM Drive as being due to the Mach effect. Actually Prof. Woodward proposed an experiment (that a superconducting EM Drive's performance will be less than expected because of the much reduced skin depth) to test this idea. Am I interpreting the above correctly? Is the suggestion that the Mach Effect was the underlying cause of the thrust signatures all along, and that the EMdrive theorists' search for alternative explanations might merely lead them back to the Mach Effect in the end?If so, I believe this is something Prof. Woodward alluded to some years ago. Rather than saying that the EMdrive results were completely flawed, I seem to recall him suggesting originally that if there is any thrust there, it might be due to accidental Mach Effects being generated.Are we approaching some kind of consensus among those involved in studying both phenomena that this might indeed be the case?

Quote from: M.E.T. on 09/26/2016 01:26 PMQuote from: Rodal on 09/26/2016 01:10 PMQuote from: M.E.T. on 09/26/2016 08:39 AM...could we, in the EM drive and Mach Effect Thruster, potentially be looking at two unrelated mechanisms that might both eventually prove to have value in the area of thrust generation?I would find this a rather remarkable development, if so.Perhaps the same mechanism is responsible for both the EM Drive and the piezoelectric/electrostrictive stacks tested by Woodward/Fearn: seehttps://forum.nasaspaceflight.com/index.php?topic=40959.msg1588165#msg1588165https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214for Dr. Montillet's paper explaining the EM Drive's acceleration as being due to the Mach/Sciama/Woodward gravitational effect.Quote from: Stormbringer on 09/25/2016 05:55 PM...Woodward does not think his Mach drive and the EM drive operate on the same principle. As of the 1st edition of his book he was skeptical of the EM drive as being anything other than experimental error of some sort. Of course with the cross fertilization that has happened since then (E.G; the SSI conference) he may have changed his opinion on that point. The conference attendees would know if that is still the case or not.I don't know what was his opinion previously, but the above statement is incorrect as of the Estes Park Breakthrough Workshop, as Prof. Woodward was agreeable to Dr. Montillet's explanation of the EM Drive as being due to the Mach effect. Actually Prof. Woodward proposed an experiment (that a superconducting EM Drive's performance will be less than expected because of the much reduced skin depth) to test this idea. Am I interpreting the above correctly? Is the suggestion that the Mach Effect was the underlying cause of the thrust signatures all along, and that the EMdrive theorists' search for alternative explanations might merely lead them back to the Mach Effect in the end?If so, I believe this is something Prof. Woodward alluded to some years ago. Rather than saying that the EMdrive results were completely flawed, I seem to recall him suggesting originally that if there is any thrust there, it might be due to accidental Mach Effects being generated.Are we approaching some kind of consensus among those involved in studying both phenomena that this might indeed be the case?your recollection is correct. I remember the same comment. However, Woodward was never actually against the EmDrive. He was just against the theory, Dr. White's i believe, that was being used to explain it. I would have to troll through the em drive thread but I believe this was relayed to us by Paul March in one of his ghostly appearances on the forum.

Quote from: birchoff on 09/26/2016 01:42 PMQuote from: M.E.T. on 09/26/2016 01:26 PMQuote from: Rodal on 09/26/2016 01:10 PMQuote from: M.E.T. on 09/26/2016 08:39 AM...could we, in the EM drive and Mach Effect Thruster, potentially be looking at two unrelated mechanisms that might both eventually prove to have value in the area of thrust generation?I would find this a rather remarkable development, if so.Perhaps the same mechanism is responsible for both the EM Drive and the piezoelectric/electrostrictive stacks tested by Woodward/Fearn: seehttps://forum.nasaspaceflight.com/index.php?topic=40959.msg1588165#msg1588165https://forum.nasaspaceflight.com/index.php?topic=40959.msg1588214#msg1588214for Dr. Montillet's paper explaining the EM Drive's acceleration as being due to the Mach/Sciama/Woodward gravitational effect.Quote from: Stormbringer on 09/25/2016 05:55 PM...Woodward does not think his Mach drive and the EM drive operate on the same principle. As of the 1st edition of his book he was skeptical of the EM drive as being anything other than experimental error of some sort. Of course with the cross fertilization that has happened since then (E.G; the SSI conference) he may have changed his opinion on that point. The conference attendees would know if that is still the case or not.I don't know what was his opinion previously, but the above statement is incorrect as of the Estes Park Breakthrough Workshop, as Prof. Woodward was agreeable to Dr. Montillet's explanation of the EM Drive as being due to the Mach effect. Actually Prof. Woodward proposed an experiment (that a superconducting EM Drive's performance will be less than expected because of the much reduced skin depth) to test this idea. Am I interpreting the above correctly? Is the suggestion that the Mach Effect was the underlying cause of the thrust signatures all along, and that the EMdrive theorists' search for alternative explanations might merely lead them back to the Mach Effect in the end?If so, I believe this is something Prof. Woodward alluded to some years ago. Rather than saying that the EMdrive results were completely flawed, I seem to recall him suggesting originally that if there is any thrust there, it might be due to accidental Mach Effects being generated.Are we approaching some kind of consensus among those involved in studying both phenomena that this might indeed be the case?your recollection is correct. I remember the same comment. However, Woodward was never actually against the EmDrive. He was just against the theory, Dr. White's i believe, that was being used to explain it. I would have to troll through the em drive thread but I believe this was relayed to us by Paul March in one of his ghostly appearances on the forum.Yes, the Quantum Vacuum Fluctuation theory in particular was the one he disagreed with I believe. Also, in his audio interview on the Space Show about a year or so ago, which I listened to, he was quite clear in his disagreement with the above. I just find it exciting that after all of the focus on the EMDrive, and the apparent disregard for Woodward's work during this time (this thread received almost no updates for months on end compared to the multitude of EMDrive threads), things seem to be going full circle, back to his Mach Effect theories once more.What I'm trying to ascertain is whether this is indeed the case, or whether I am misinterpreting the latest developments.

...Yes, the Quantum Vacuum Fluctuation theory in particular was the one he disagreed with I believe. Also, in his audio interview on the Space Show about a year or so ago, which I listened to, he was quite clear in his disagreement with the above. I just find it exciting that after all of the focus on the EMDrive, and the apparent disregard for Woodward's work during this time (this thread received almost no updates for months on end compared to the multitude of EMDrive threads), things seem to be going full circle, back to his Mach Effect theories once more.What I'm trying to ascertain is whether this is indeed the case, or whether I am misinterpreting the latest developments.

...That said, I really really want to see this linearized GR version of Mach Effects. Mainly becasue I have been operating under the assumption that the only reason Headi adopted HN Theory was because it already had Gravitational absorber theory integrated into it. So if there is a linearized GR version of Mach Effects, one has to wonder if the absorber theory is really neccessary. Would love to hear Dr. Rodals take.

Quote from: birchoff on 03/29/2016 09:01 PMI have the kindle version. Unfortunately those pages are the book page numbers not the ebook one so I couldnt provide you the information you want.Thanks for the consideration anyway.The reason I am asking origintates in the followng quote from woodward's recent monographQuoteIn the case of a rocket motor, the thing to observe is that there is one invariantvelocity involved: that of the exhaust plume with respect to the motor. All observers,irrespective of their own motions, agree on both the magnitude and direction of thisvelocity. And it is the velocity that yields momentum conservation. An argument basedon an incorrect application of Newton’s second law to METs was advanced as a criticismof Mach Effects by an Oak Ridge scientist many years ago. It is dealt with on pages 77and 127 of Making Starships and Stargates: the Science of Interstellar Propulsion andAbsurdly Benign Wormholes. It will not be discussed further here.As I understand it, the argument advanced by the Oak Ridge scientist was that F=ma is only correct at the system level for systems where the mass of the system is constant in time (which is clearly not true for METs). This is because the more general expression for Force is correctly given by (I leave it to the reader to distinguish vectors from scalars):F_{net}=(d/dt)(p)=d/dt(mv)=(dm/dt)v + m(dv/dt)=(dm/dt)v + ma where:F=external forces (i.e. forces applied across the system boundary)p=momentumm=massv=velocitya=accelerationd/dt= partial derivative with respect to timeObviously we can return to the more familiar F=ma expression by just setting mass constant so that dm/dt=0.To demonstrate that this is the correct expression, consider the case of a rocket expelling exhaust in free space (i.e. no gravity; the only thing in this universe is the rocket and it's exhaust). Now draw a control volume around the rocket plus a portion of the exhaust stream that has been expelled from the rocket. Let this control volume be fixed to the rocket so it moves with it (i.e. a lagrangian control volume). Now as is always the case, internal forces (f) are always equal and opposite to one another, and so they sum to zero. Because the "rocket + some exhaust" system is in free space, it experiences no external forces either, so F=0. Remember that the force applied to the rocket by the exhaust is equal and opposite the force on the exhaust applied by the rocket. Since we have included this portion of the exhaust in our control volume, these forces are themselves internal, and sum to zero (see attached figure). Now if we applied F=ma we would get that 0=ma so a=0. Apparently rockets don't work. But if we apply the correct force derivation, F=d/dt(p) then we get:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma a=((-dm/dt)v)/mwhich is the correct equation of motion for a rocket. Essentially, when we choose a control volume where a portion of the exhaust is in the control volume and that portion has been fully accelerated (such that any particle of exhaust has a=0), then the acceleration of a rocket is NOT in fact from a "force" at all, but from the expulsion of mass across the system boundary that envelops the control volume (at least in the lagrangian interpretation).This preamble has to do with the MET because mass fluctuations only lead to an apparent force within a closed system IF you take the INCORRECT F=ma approach as opposed to the more general F=d/dt(p) approach. If you have a closed system (i.e. nothing transfers across the system boundary) and you apply cyclic mass variations within the system, you would see that:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma (F_{net}=0 because the system is closed)0=0 + ma (since there is no flow of mass across the system boundary)***a=0And so (following this derivation) cyclic mass variation won't actually yield any propulsive benefits.Basically I want to see how Woodward addresses this issue, and whether it is done so in such a way as to make METs viable. I want to see why Woodward finds this argument "incorrect" as he says. Welcome other posters to point out any issues with this derivation as well of course. ***If there is energy flux across the system boundary in the form of gravinertial waves, then those would account for the dm/dt term and presumably gravinertial waves travel at the speed of light, so v=c. However, if that were the case, then the MET would be unable to achieve thrust greater than a perfectly collimated photon rocket, which can be derived as follows:E=mc^{2}m=E/c^{2}(d/dt)m=(d/dt)E/c^{2}dm/dt=P/c^{2}E=energyP=powerc=speed of lightSub this expression for dm/dt into the rocket equation (realizing that we have now replaced the exhaust flow with photons/gluons/W,Z bosons, gravitons, gravienterial waves, magic energy waves - literally anything that has energy but no rest mass) and you get:0=(P/c^{2})c + mama=P/cSo we are back to the thrust of a perfectly collimated photon rocket.

I have the kindle version. Unfortunately those pages are the book page numbers not the ebook one so I couldnt provide you the information you want.

In the case of a rocket motor, the thing to observe is that there is one invariantvelocity involved: that of the exhaust plume with respect to the motor. All observers,irrespective of their own motions, agree on both the magnitude and direction of thisvelocity. And it is the velocity that yields momentum conservation. An argument basedon an incorrect application of Newton’s second law to METs was advanced as a criticismof Mach Effects by an Oak Ridge scientist many years ago. It is dealt with on pages 77and 127 of Making Starships and Stargates: the Science of Interstellar Propulsion andAbsurdly Benign Wormholes. It will not be discussed further here.

Quote from: wallofwolfstreet on 03/30/2016 01:56 AMQuote from: birchoff on 03/29/2016 09:01 PMI have the kindle version. Unfortunately those pages are the book page numbers not the ebook one so I couldnt provide you the information you want.Thanks for the consideration anyway.The reason I am asking origintates in the followng quote from woodward's recent monographQuoteIn the case of a rocket motor, the thing to observe is that there is one invariantvelocity involved: that of the exhaust plume with respect to the motor. All observers,irrespective of their own motions, agree on both the magnitude and direction of thisvelocity. And it is the velocity that yields momentum conservation. An argument basedon an incorrect application of Newton’s second law to METs was advanced as a criticismof Mach Effects by an Oak Ridge scientist many years ago. It is dealt with on pages 77and 127 of Making Starships and Stargates: the Science of Interstellar Propulsion andAbsurdly Benign Wormholes. It will not be discussed further here.As I understand it, the argument advanced by the Oak Ridge scientist was that F=ma is only correct at the system level for systems where the mass of the system is constant in time (which is clearly not true for METs). This is because the more general expression for Force is correctly given by (I leave it to the reader to distinguish vectors from scalars):F_{net}=(d/dt)(p)=d/dt(mv)=(dm/dt)v + m(dv/dt)=(dm/dt)v + ma where:F=external forces (i.e. forces applied across the system boundary)p=momentumm=massv=velocitya=accelerationd/dt= partial derivative with respect to timeObviously we can return to the more familiar F=ma expression by just setting mass constant so that dm/dt=0.To demonstrate that this is the correct expression, consider the case of a rocket expelling exhaust in free space (i.e. no gravity; the only thing in this universe is the rocket and it's exhaust). Now draw a control volume around the rocket plus a portion of the exhaust stream that has been expelled from the rocket. Let this control volume be fixed to the rocket so it moves with it (i.e. a lagrangian control volume). Now as is always the case, internal forces (f) are always equal and opposite to one another, and so they sum to zero. Because the "rocket + some exhaust" system is in free space, it experiences no external forces either, so F=0. Remember that the force applied to the rocket by the exhaust is equal and opposite the force on the exhaust applied by the rocket. Since we have included this portion of the exhaust in our control volume, these forces are themselves internal, and sum to zero (see attached figure). Now if we applied F=ma we would get that 0=ma so a=0. Apparently rockets don't work. But if we apply the correct force derivation, F=d/dt(p) then we get:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma a=((-dm/dt)v)/mwhich is the correct equation of motion for a rocket. Essentially, when we choose a control volume where a portion of the exhaust is in the control volume and that portion has been fully accelerated (such that any particle of exhaust has a=0), then the acceleration of a rocket is NOT in fact from a "force" at all, but from the expulsion of mass across the system boundary that envelops the control volume (at least in the lagrangian interpretation).This preamble has to do with the MET because mass fluctuations only lead to an apparent force within a closed system IF you take the INCORRECT F=ma approach as opposed to the more general F=d/dt(p) approach. If you have a closed system (i.e. nothing transfers across the system boundary) and you apply cyclic mass variations within the system, you would see that:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma (F_{net}=0 because the system is closed)0=0 + ma (since there is no flow of mass across the system boundary)***a=0And so (following this derivation) cyclic mass variation won't actually yield any propulsive benefits.Basically I want to see how Woodward addresses this issue, and whether it is done so in such a way as to make METs viable. I want to see why Woodward finds this argument "incorrect" as he says. Welcome other posters to point out any issues with this derivation as well of course. ***If there is energy flux across the system boundary in the form of gravinertial waves, then those would account for the dm/dt term and presumably gravinertial waves travel at the speed of light, so v=c. However, if that were the case, then the MET would be unable to achieve thrust greater than a perfectly collimated photon rocket, which can be derived as follows:E=mc^{2}m=E/c^{2}(d/dt)m=(d/dt)E/c^{2}dm/dt=P/c^{2}E=energyP=powerc=speed of lightSub this expression for dm/dt into the rocket equation (realizing that we have now replaced the exhaust flow with photons/gluons/W,Z bosons, gravitons, gravienterial waves, magic energy waves - literally anything that has energy but no rest mass) and you get:0=(P/c^{2})c + mama=P/cSo we are back to the thrust of a perfectly collimated photon rocket.I wrote an analysis to Professor Woodward's monograph linked in your post. I posted it in the EmDrive thread,http://forum.nasaspaceflight.com/index.php?topic=40959.msg1589319#msg1589319(link to pdf available in that post)There I included a section talking about when the equation dp/dt=Mdv/dt vdM/dt holds and when it does not hold. I think it is relevant to your discussion.

...2. Dr. Lance Williams has shown that the Mach effect transient terms can be derived from a linearized GR. That is comforting, certainly. Whether these solutions are present in Nature has to be resolved by experiments. The Hoyle-Narlikar derivation from Heidi Fearn is robust from the point of view that she derives it from the fully nonlinear, covariant formulation. My contribution is to rigorously derive a force from those transient terms. Action at a distance (advanced waves) is needed to justify this mathematical solution as a physical solution: under either derivation.

Quote from: Tellmeagain on 09/28/2016 02:27 PMQuote from: wallofwolfstreet on 03/30/2016 01:56 AMQuote from: birchoff on 03/29/2016 09:01 PMI have the kindle version. Unfortunately those pages are the book page numbers not the ebook one so I couldnt provide you the information you want.Thanks for the consideration anyway.The reason I am asking origintates in the followng quote from woodward's recent monographQuoteIn the case of a rocket motor, the thing to observe is that there is one invariantvelocity involved: that of the exhaust plume with respect to the motor. All observers,irrespective of their own motions, agree on both the magnitude and direction of thisvelocity. And it is the velocity that yields momentum conservation. An argument basedon an incorrect application of Newton’s second law to METs was advanced as a criticismof Mach Effects by an Oak Ridge scientist many years ago. It is dealt with on pages 77and 127 of Making Starships and Stargates: the Science of Interstellar Propulsion andAbsurdly Benign Wormholes. It will not be discussed further here.As I understand it, the argument advanced by the Oak Ridge scientist was that F=ma is only correct at the system level for systems where the mass of the system is constant in time (which is clearly not true for METs). This is because the more general expression for Force is correctly given by (I leave it to the reader to distinguish vectors from scalars):F_{net}=(d/dt)(p)=d/dt(mv)=(dm/dt)v + m(dv/dt)=(dm/dt)v + ma where:F=external forces (i.e. forces applied across the system boundary)p=momentumm=massv=velocitya=accelerationd/dt= partial derivative with respect to timeObviously we can return to the more familiar F=ma expression by just setting mass constant so that dm/dt=0.To demonstrate that this is the correct expression, consider the case of a rocket expelling exhaust in free space (i.e. no gravity; the only thing in this universe is the rocket and it's exhaust). Now draw a control volume around the rocket plus a portion of the exhaust stream that has been expelled from the rocket. Let this control volume be fixed to the rocket so it moves with it (i.e. a lagrangian control volume). Now as is always the case, internal forces (f) are always equal and opposite to one another, and so they sum to zero. Because the "rocket + some exhaust" system is in free space, it experiences no external forces either, so F=0. Remember that the force applied to the rocket by the exhaust is equal and opposite the force on the exhaust applied by the rocket. Since we have included this portion of the exhaust in our control volume, these forces are themselves internal, and sum to zero (see attached figure). Now if we applied F=ma we would get that 0=ma so a=0. Apparently rockets don't work. But if we apply the correct force derivation, F=d/dt(p) then we get:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma a=((-dm/dt)v)/mwhich is the correct equation of motion for a rocket. Essentially, when we choose a control volume where a portion of the exhaust is in the control volume and that portion has been fully accelerated (such that any particle of exhaust has a=0), then the acceleration of a rocket is NOT in fact from a "force" at all, but from the expulsion of mass across the system boundary that envelops the control volume (at least in the lagrangian interpretation).This preamble has to do with the MET because mass fluctuations only lead to an apparent force within a closed system IF you take the INCORRECT F=ma approach as opposed to the more general F=d/dt(p) approach. If you have a closed system (i.e. nothing transfers across the system boundary) and you apply cyclic mass variations within the system, you would see that:F_{net}=(dm/dt)v + ma0=(dm/dt)v + ma (F_{net}=0 because the system is closed)0=0 + ma (since there is no flow of mass across the system boundary)***a=0And so (following this derivation) cyclic mass variation won't actually yield any propulsive benefits.Basically I want to see how Woodward addresses this issue, and whether it is done so in such a way as to make METs viable. I want to see why Woodward finds this argument "incorrect" as he says. Welcome other posters to point out any issues with this derivation as well of course. ***If there is energy flux across the system boundary in the form of gravinertial waves, then those would account for the dm/dt term and presumably gravinertial waves travel at the speed of light, so v=c. However, if that were the case, then the MET would be unable to achieve thrust greater than a perfectly collimated photon rocket, which can be derived as follows:E=mc^{2}m=E/c^{2}(d/dt)m=(d/dt)E/c^{2}dm/dt=P/c^{2}E=energyP=powerc=speed of lightSub this expression for dm/dt into the rocket equation (realizing that we have now replaced the exhaust flow with photons/gluons/W,Z bosons, gravitons, gravienterial waves, magic energy waves - literally anything that has energy but no rest mass) and you get:0=(P/c^{2})c + mama=P/cSo we are back to the thrust of a perfectly collimated photon rocket.I wrote an analysis to Professor Woodward's monograph linked in your post. I posted it in the EmDrive thread,http://forum.nasaspaceflight.com/index.php?topic=40959.msg1589319#msg1589319(link to pdf available in that post)There I included a section talking about when the equation dp/dt=Mdv/dt vdM/dt holds and when it does not hold. I think it is relevant to your discussion.I had considered this discussion to be concluded. with the result being that WallOfWolfStreet having a problem that Woodward has not shown why fluctuating the mass allows him to zero out the vdM/dt term of the general equation. However, in light of new comments made about this issue. I realized that this discussion was predetermined to ending the way it did. The reason for this is neither I or any of the people who understand Woodward's theory enough believe you can draw the box to do your CoE/CoM calculation around only the MET. If you do you will end up with a violation. Woodward's Theory plainly calls for an energy exchange with the rest of the mass in the universe. I didn't have a good way of describing this before but Dr. Rodal's description of this being a type of Gravity assist I think is very apt. The only difference is you wouldn't need to sling your way around a gravitating body to gain that momentum and instead of leveraging one Gravitating mass you are leveraging all of it, chiefly the stuff very far away.Now the impasse WallOfWolfstreet and I reached about the zeroing out of the vdM/dt term probably still exists. But I think until we have a better understanding of what happens to the mass of the FMC (Fluctuating Mass Component) part of the MET during the oscillations. I don't think a firm answer of the kind that Wall would like can be put forward. For now, the only thing that can be offered is experimental results that so far agree with the theoretical predictions of not only Woodward's original Thrust equation. But also with additional refinements of that equation. Where the refinements continue to reduce the delta between what is predicted and what is observed.The first set of Refinements came, as I understand it, from Headi Fearn rederiving Mach Effects from Hoyle and Narlikar Theory of Gravitation while answering the critique that Stephen Hawking had raised about HN Theory. As of this month I learned from Dr. RodalQuote from: Rodal on 09/26/2016 03:40 PM...2. Dr. Lance Williams has shown that the Mach effect transient terms can be derived from a linearized GR. That is comforting, certainly. Whether these solutions are present in Nature has to be resolved by experiments. The Hoyle-Narlikar derivation from Heidi Fearn is robust from the point of view that she derives it from the fully nonlinear, covariant formulation. My contribution is to rigorously derive a force from those transient terms. Action at a distance (advanced waves) is needed to justify this mathematical solution as a physical solution: under either derivation.I believe Dr. Rodal has also left comments in either this thread of the EmDrive thread recently referring to successful replications being done by other experimenters outside Woodward's lab. Now, while the inner space geek in me is pretty convinced this works. My more rational side is aware of the fact that there is still work to be done. I don't think anyone is going to really accept any Mach Effect theory be it derived from HN Theory or Linearized GR until there is a high level of agreement between Experiment and predictions; they do have some of that now but the confidence bars need to further be increased.

There has been a lot of erroneous information in media articles regarding Cannae’s upcoming launch of a cubesat mission into LEO. To clarify our previous post and press release: Cannae is not using an EmDrive thruster in our upcoming launch. Cannae is using it’s own proprietary thruster technology which requires no on-board propellant to generate thrust. In addition, this project is being done as a private venture. Cannae is only working with our private commercial partners on the upcoming mission.

I am periodically updating drafts of my article on Mach Effect Propulsion, a chapter in the proceedings of the 2016 Advanced Propulsion Workshop at Estes Park Colorado, to be published in the near future.If you like, you can download my report from here:https://www.researchgate.net/project/Mach-effect-propulsionBest regards

Quote from: Rodal on 12/03/2016 06:46 PMI am periodically updating drafts of my article on Mach Effect Propulsion, a chapter in the proceedings of the 2016 Advanced Propulsion Workshop at Estes Park Colorado, to be published in the near future.If you like, you can download my report from here:https://www.researchgate.net/project/Mach-effect-propulsionBest regardsThank you, Dr. Rodal.I read through it - skipping past the maths which are way beyond me. From your expert point of view, would you say that there is something going on here? Obviously you state all the further areas that require investigation. But given the knowledge that exists now, is there a way to build a scaled up version of Woodward's lab device, which could prove or disprove whether there is an effect once and for all, by generating thrusts of useful magnitudes?