The idea is correct, often used to demonstrate the twin paradox in General Relativity not Special Relativity. (My pet peeve) Special is only for Inertial frames. Forces and acceleration require General Relativity, so they wind up using the limit of an approximation instead.Edit: I have to read this paper in more detail, but first glance, it looks like you might get an impulse during this rather select interval but I don't (yet) see any consideration of the recovery of initial conditions w/o reversing it.

FYIhttp://www.technologyreview.com/view/536091/spacecraft-traveling-close-to-light-speed-should-be-visible-with-current-technology-say/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+arxivblog%2FGmoU+%28The+Physics+arXiv+Blog%29

The movement of a relativistic spacecraft will have another effect. It should scatter the cosmic microwave background in a way that produces a unique signature. “As a baryonic spacecraft travels at relativistic speeds it will interact with the CMB through scattering to cause a frequency shift that could be detectable on Earth with current technology,” say Yurtsever and Wilkinson.

Quote from: Notsosureofit on 03/25/2015 08:00 PMThe idea is correct, often used to demonstrate the twin paradox in General Relativity not Special Relativity. (My pet peeve) Special is only for Inertial frames. Forces and acceleration require General Relativity, so they wind up using the limit of an approximation instead.Edit: I have to read this paper in more detail, but first glance, it looks like you might get an impulse during this rather select interval but I don't (yet) see any consideration of the recovery of initial conditions w/o reversing it.I second you on the (also at first glance) apparent problem of having any kind of stationary net average force in a direction with this approach. From the article (at least what is on arxiv) : the meat is equation (66) F=cst*I1bar*I2bar/tau˛ (number of turns assumed constant).I don't know the academic history and prestige of the journal in which this is published, but unless the published version is significantly edited, this is a case of notation abuse and almost deceit in conclusion drawing from correct equations, (I assume they are correct, would took me some weeks to understand and check in details). The bar notation usually denotes a time averaged value of a time varying stationary value, be it periodic, or quasiperiodic, or random, but it must be that ( integral(0 to T) V(t)dt )/T converges to some value when T->+infinity for Vbar to have a meaning. Unless there are other usages I'm unaware of ? Please educate me if so.Anyway (bottom page 12) : A constant force may be achieved by having a direct current in one loop I1(t) =I1bar and a current of uniform second derivative on the other I2(t)=1/2 I2bar*t˛/tau˛Green sensible use of bar notationRed deceiving use of bar notation : I2(t) defined as having a uniform second derivative (wrt time) can't be stationary. I2bar is ill defined. For instance if a given I2(t) is defined by I2bar=1 and tau=1, the exact same I2(t) could also be defined by by I2bar=100 and tau=10. There are 2 "free parameters" introduced when in fact saying "uniform second derivative" requires only one : I2(t) = 1/2 CurAcc*t˛ where CurAcc (Current Acceleration) is the only needed parameter and has units of A/s˛. This might be ugly, maybe a "representative" current value in A (I2bar) + "representative" time value in s (tau) is more "expressive" and elegant. As absolute values, it's not clear what they are representative of though, since 1A 1s is equivalent to 100A 10sBut abuse of notation and introducing more parameters than necessary is not the problem by itself, and the equation (66) is still as valid written with I2bar/tau˛ term as it would be with CurAcc term. Equations all right. But then we forget that I2bar notation was just a commodity, that there is no real stationary I2(t) behind that, and that the force given by the expression can only be a transient, since 1/2 CurAcc*t˛ will soon exceed any reasonable current carrying capacity (superconducting or not). And assuming a clever possibility, like cutting the current abruptly (in the loop) to put it back to 0 periodically, is doomed to fail as much as any attempt to transform repetitive mechanical effects inside a capsule into net acceleration (Dean drive...). What was gained during an acceleration phase will be lost by a deceleration phase, if the driving parameter (Intensity, Position...) is to be made periodic.This derives clearly from eq. (51) (from which eq. (66) itself derives) : F(t) proportional to I1(t)*I2dotdot(t) - I1dotdot(t)*I2(t)Is it conceivable to have 2 stationary I1(t) and I2(t) (in the sense defined above that I1bar and I2bar have a real meaning) that yield Fbar different from 0 ? I don't see a clever elegant mathematical proof to that but I'm rather sure it is impossible. If someone disagree please state a clear explicit counter example I1(t) I2(t) (for any t) with Fbar different from 0 and I1 and I2 stationary, that is ( integral(0 to T) I(t)dt )/T converges to some value (0 or whatever) when T->+infinity.The example I1 constant and I2 "uniformly accelerated" given by the paper don't meet the requirement : I2 not stationary. This is a one shot effect. It's not really different from shooting a bullet at constant m/s˛ in a mass driver fixed to the hull of a spacecraft. As long as the bullet is accelerating in the mass driver, the mass driver gives a constant "thrust" to the spacecraft. But then what ? Either the bullet is free to leave the spacecraft : conventional reaction propulsion, spacecraft loses propellent mass. Or else it is "recycled", which implies some deceleration of it to 0 (wrt spacecraft), which will cancel exactly the gained momentum, be it hard or soft is irrelevant (damages or sparks aside).BTW we also understand that playing with "delayed" forces in relativity it's not surprising to get non null instant forces on a system. If "a system" is an ensemble of elements separated by some distance, then there is not really such thing as an instant force on the system as a whole since there is no such thing as an instant for the system. SR is enough to show that the notion of intrinsic instant is ill defined wrt the system's parts : "instant sum of local forces seen by each part" depend on arbitrary inertial rest frame.What is going on with hard science those days ? Do brilliant people make a living of writing correct complicated equations to hint at spectacular but delusional conclusions from them ?

What can we look forward to this year in regards to your journal’s content or development?EPJ Plus is a newly born journal of the EPJ series, a continuation of Il Nuovo Cimento B formely published by the Italian Physical Society. It has been launched in 2011 as an electronic-only journal, with a new interdisciplinary approach in terms of topics and a wider portfolio of possible article formats. EPJ Plus is also meant as a "cascade" journal for the other EPJs. In the last two years, the number of articles published in EPJ Plus has significantly grown and its impact factor expectations are definitely promising. According to the recent editorial policy of the journal, invited contents, grouped in topical "Focus Points", will be boosted and contributions from new fields, such as accelerator physics or physics applied to cultural heritage or to energy, will be strongly encouraged.

(Dustinthewind - here is a quote from the other thread, "A scientific paper that clarifies how newtons 3rd law does not apply to the time delay of information and how it can be used for electromagnetic propulsion. It provides a mathematical background for the time delayed magnetic fields but first illustrating how the static equations miss the effect. https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48" it is titled, "Newton's Third Law in the Framework of Special Relativity" )

Quote from: dustinthewind on 03/24/2015 08:11 PM(Dustinthewind - here is a quote from the other thread, "A scientific paper that clarifies how newtons 3rd law does not apply to the time delay of information and how it can be used for electromagnetic propulsion. It provides a mathematical background for the time delayed magnetic fields but first illustrating how the static equations miss the effect. https://scholar.google.com/scholar?cluster=7136673109349846373&hl=en&as_sdt=0,48" it is titled, "Newton's Third Law in the Framework of Special Relativity" )I'll have to apologize if I wasted anyone's time. I realized the paper is not what I thought it was about after frobnicat's review. I expected two current loops changing in time out of phase but per the review I went back and sure enough it is about a current loop constantly on while one changes.

Very interesting paper! Especially considering what Roger Shawyer says about conservation of momentum in "open systems"… To summarize his point of view, standard Newtonian mechanics and thus the law of conservation of momentum indicate that, no matter what shape the cavity is, the forces exerted upon it from within must balance to zero. Shawyer claims this statement ignores special relativity, in which separate frames of reference have to be applied when velocities approach the speed of light. He declares that in the EmDrive, the system of electromagnetic waves and the waveguide can be regarded as an open system, both having separate frames of reference. He also says this effect is similar to the principle of the laser gyroscope, which is also an apparently closed system device, but where the beams act as if having an external frame of reference (which they have, since the speed of light is constant).However, Shawyer was severely criticized by the scientific community for this "not even wrong" idea. And frankly, I wonder if Tuval & Yahalom's initial assumption regarding the "transmission of any information limited by the speed of light" is really correct, since it is established the Abraham–Lorentz force and inertial reaction forces are instantaneous. Another counterexample involving instantaneousness is quantum entanglement.[EDIT]I didn't saw at first that Roger Shawyer's idea is opposite (the "open system") than the "closed system" treatment in special relativity by Miron Tuval & Asher Yahalom. It's weird because both seem to claim the same idea: decoupling the EM effects between two interacting electric circuits.

The authors have a patent application in the US:https://www.google.com/patents/US20140152227?dq=US20140152227&hl=en&sa=X&ei=D2ITVcTUJ8uigwSb34PoAQ&ved=0CB8Q6AEwAA

Quote from: Notsosureofit on 03/25/2015 01:00 PMFYIhttp://www.technologyreview.com/view/536091/spacecraft-traveling-close-to-light-speed-should-be-visible-with-current-technology-say/?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+arxivblog%2FGmoU+%28The+Physics+arXiv+Blog%29QuoteThe movement of a relativistic spacecraft will have another effect. It should scatter the cosmic microwave background in a way that produces a unique signature. “As a baryonic spacecraft travels at relativistic speeds it will interact with the CMB through scattering to cause a frequency shift that could be detectable on Earth with current technology,” say Yurtsever and Wilkinson.Please excuse the somewhat off topic question, but would this also apply to the interaction of an Alcubierre drive or similar manipulation of space-time with the CMB?

Quote from: Rodal on 03/23/2015 04:54 PMQuote from: Star-Drive on 03/22/2015 07:16 PM....The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...... I think that this mode shape correct designation is TM011 instead of TM010 because:1) There can be no TMmn0 modes for a truncated cone. TMmn0 modes need to have a constant electromagnetic field in the longitudinal direction of the cavity. This is possible for a cylindrical cavity (containing no other dielectrics inside besides the cavity medium) because it has constant geometrical and material properties in the longitudinal direction. But a conical cavity has variable cross-section in the longitudinal direction, therefore the TMnn0 mode is not possible. The first possible mode (if it is not cut-off) is TMmn1. The exact solution for the truncated cone shows this. See for example: http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html :The quantum mode number "p" for a truncated cone is related to k. k cannot be zero for a truncated cone, since k = ω/c for a truncated cone , therefore k = 0 implies zero frequency for a truncated cone. 2) As the attached plot shows, COMSOL's FEA plot shows an electromagnetic field that is not constant in the longitudinal direction, therefore this is not TM010, it looks instead as TM011 upon closer inspection.(Therefore the analyst's designation for TM011 should be changed to TM012 and so forth for TM01p modes)I have been examining higher modes for the truncated cone cavity and mode shapes for truncated cones with larger cone angle and for smaller base diameters at the same cone angle.For these cases (mode shapes with higher "m" azimuthal quantum number, and those with smaller base diameters compared to the big base diameter) the difference between the truncated mode shapes and the cylindrical mode shape becomes more significant.Ultimately this was unavoidable, because the only quantum number that the truncated cone and the cylindrical cavity have in common is "m" the azimuthal quantum mode number. The variation along the circumference is described by a harmonic function in both the truncated cone and the cylindrical cavity.On the other hand, the variation along "n" is described by Associated Legendre P functions in terms of the cone's angle for the truncated cone while it is described in terms of zero Bessel functions of the radial polar coordinate for the cylindrical cavity. Different functions in terms of different variables.And the variation along "p" is described by Spherical Bessel functions in terms of the spherical radial coordinate for the truncated cone, while it is described in terms of harmonic functions of the longitudinal polar coordinate for the cylindrical cavity. Different functions in terms of different variables.I have not found in the literature a commonly accepted nomenclature to designate mode shapes for the truncated cone.Furthermore, for this thread's audience, the cylindrical mode shapes are something that the audience can more immediately relate to, since the cylindrical mode shape nomenclature is found in the literature, and @Notsosureofit's formula is based on an analogy to the cylindrical cavity mode shapes (using the Bessel zero functions to characterize the mode shapes).Therefore, to better communicate these mode shapes, and to avoid confusion I have decided to identify the truncated mode shapes in future communications as follows:1. Always specifying the frequency at which they take place.2. Whenever possible to provide plots to illustrate the actual mode shape.3. Whenever possible to provide the designation for the closest cylindrical mode shape. I will identify these as "Cyl. TM_{mnp}" Of course, for high mode numbers and/or large cone angles we will find mode shapes that cannot be described in terms of a cylindrical cavity analogy. In those cases those modes are best described by their frequency and a plot showing the actual mode shape.Therefore, I will describe what NASA Eagleworks describes as mode TM212 as "Cyl. TM212" from now on.There is still a discrepancy regarding what NASA Eagleworks describes as mode TM010, which I think should be described "Cyl. TM011" because this mode shape for the truncated cone is not constant along the longitudinal axis of the truncated cone (as NASA Eagleworks's own plot shows).

Quote from: Star-Drive on 03/22/2015 07:16 PM....The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...... I think that this mode shape correct designation is TM011 instead of TM010 because:1) There can be no TMmn0 modes for a truncated cone. TMmn0 modes need to have a constant electromagnetic field in the longitudinal direction of the cavity. This is possible for a cylindrical cavity (containing no other dielectrics inside besides the cavity medium) because it has constant geometrical and material properties in the longitudinal direction. But a conical cavity has variable cross-section in the longitudinal direction, therefore the TMnn0 mode is not possible. The first possible mode (if it is not cut-off) is TMmn1. The exact solution for the truncated cone shows this. See for example: http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html :The quantum mode number "p" for a truncated cone is related to k. k cannot be zero for a truncated cone, since k = ω/c for a truncated cone , therefore k = 0 implies zero frequency for a truncated cone. 2) As the attached plot shows, COMSOL's FEA plot shows an electromagnetic field that is not constant in the longitudinal direction, therefore this is not TM010, it looks instead as TM011 upon closer inspection.(Therefore the analyst's designation for TM011 should be changed to TM012 and so forth for TM01p modes)

....The copper frustum thrust reversal due to only its dielectric placement came when I was experimenting with the TM010 mode,...

Mr March; I assume you are far far far more familiar with Dr Woodward's nailing down spurious signals than I but I just got through that portion of his book. He basically nuked every potential source of spurious signal in his apparatus and because he is using a nearly identical set up until you get to the frustrum itself his analysis is germain to this project. He appears to have authoritatively disproved every thing we have considered here WRT spurious signals; leaving the problem of what the thrust signal really results from.That does not give us the answer to what is going on but it does tell us what it is not. I guess in replication everyone has to redo that work but I cannot help but feel that it is sort of a waste of time to do that all over again. likewise; since I am pretty sure Dr White and yourself know all about Dr Woodward's spurious signal source crushing that the Eagleworks team has also done the same. I would therefore assume you guys are very confident you have something real and that it is not explained by mundane errors.

...Dr. Rodal:I asked our first COMSOL analyst his opinion on this resonant mode naming issue and attached is Frank's comments on same.Best, Paul M.

........What happens is very neat:a) strictly speaking, the transverse magnetic field in a conical cavity cannot be constant, hence there cannot be a TM010 mode in a cone. However, for cones that have a cone angle sufficiently small (that is: truncated cones that are close enough to a cylindrical cavity) there are two TM011 modes, the lowest TM011 mode is closest to a constant field, closest to TM010, and the higher TM011 mode is closest to a true TM011 mode. Exactly the same designation chosen by Frank: TM010 for TM011a and TM011 for TM011b.b) For a cone angle approaching zero degrees (a cone approaching a cylindrical cavity) the magnetic field becomes constant in the longitudinal direction, and TM011a becomes TM010. The same designation chosen by Frank.c) For higher cone angles (for example for the example considered by Greg Egan http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html) and certainly for a cone angle > 30 degrees, the lower TM011 mode ("TM011a") disappears completely, as it is cut-off.

I still think we can violate newtons 3rd law in a way but in another way it is not violated because the propulsion device projects radiation out one end. This looks like radiation propulsion but by sticking a dielectric between the two current loops we can change the speed of light making the two current loops closer or lowering the frequency needed while also getting near field effects? What this does for the radiation projected I'm not exactly sure but I would assume it should intensify. This is assuming none of the current loops have constant current but are both changing in time and out of phase pi/2 (see figure EM Propulsion 2.png). I guess the idea was if there was something similar going on inside the radiation cavity though I can't quite say that there is. There is also the issue of the idea that radiation projected is conserving momentum but this is inside a cavity. (see figure EM Propulsion 3.png)Edit: sorry, changed pi/4 to pi/2

Quote from: Mulletron on 03/24/2015 04:06 PMStruck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.QUESTION 1: Before mounting the discs, could you please run a couple of tests without the HDPE discs?If, so I can send you a post showing the mode shapes at the two frequencies near 2.45 GHz and why .There is a mode shape at 2.49 GHz (or at 2.46 GHz according to NASA's COMSOL calculations) that should produce no force without the dielectric disc (because the Poynting vector practically cancels out)There is a mode shape at 2.46 GHz (or at 2.41 GHz according to NASA's COMSOL calculations) that may produce an electromagnetic force without the dielectric disc (because the Poynting vector does not cancel out)...

Struck out on finding a lathe to use. My belt sander did a fantastic job too. So now I have 2, 1" thick x 6.25" wide HDPE discs. Now I have to figure out how to mount them....Where there's a will, there's a way.