Quote from: deltaMass on 06/03/2015 08:36 pmAs has been pointed out, getting Q*photon-rocket thrust might be OK so long as it isn't allowed to do work. Well, much work, anyway. We have equations for that, using the stored energy and the power input.Well, I never promised you a rose garden with constant acceleration for constant power. This thing has been tested at NASA for periods of what ? about 40 seconds ? and people are already extracting conclusions based on constant acceleration for constant power going to the stars, and forgetting about the 2nd Law
As has been pointed out, getting Q*photon-rocket thrust might be OK so long as it isn't allowed to do work. Well, much work, anyway. We have equations for that, using the stored energy and the power input.
Quote from: Rodal on 06/03/2015 08:53 pmQuote from: sneekmatrix on 06/03/2015 08:43 pmWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.
Quote from: sneekmatrix on 06/03/2015 08:43 pmWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.
Wouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?
Quote from: Rodal on 06/03/2015 08:53 pmQuote from: sneekmatrix on 06/03/2015 08:43 pmWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.When I first visited this blog and started to review the tons of papers and wonderful ideas here just to try to get up to speed I ran across this article. It got me to ask (not only for the thermal issues) but the tunneling effect, if anyone had used or considered using extruded metal. I'm not sure but wouldn't the tunneling effect be greater (correct selection of sized holes) with the extruded metal as the deformation of the waveforms impacting the holed areas woconstructionyCrazy idea maybe and just thought I'd throw it out there. I'm still planning on using a solid copper construction
Quote from: X_RaY on 06/03/2015 09:08 pmQuote from: Rodal on 06/03/2015 08:53 pmQuote from: sneekmatrix on 06/03/2015 08:43 pmWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.Are you sure that's a net blue shift? The frustum has to gain momentum which means the photon loses energy and red shifts. Is the blue shift something that photon's do when they tunnel?
...It is interesting that the understanding of the problem has not progressed since I was last here....
Quote from: phaseshift on 06/03/2015 09:12 pmQuote from: X_RaY on 06/03/2015 09:08 pmQuote from: Rodal on 06/03/2015 08:53 pmQuote from: sneekmatrix on 06/03/2015 08:43 pmWouldn't the tunnelling effect also be constrained by conservation of momentum and therefore apply at both ends of the frustrum?You have to look at the energy density regarding radiation pressure, and don't ignore the lateral conical walls.Then perform a quantum tunneling analysis. Momentum will be favored to one side if there is a gradient of emission.correct andThe tunneling effect acts instantaneous. At the moment a photon is tunneling it impulse acts, that's like its reflected in a wall <z (lower qua the real length of the cavity). There has to be a blue shift of the signal means higher frequency like calculated r and z dependent.Are you sure that's a net blue shift? The frustum has to gain momentum which means the photon loses energy and red shifts. Is the blue shift something that photon's do when they tunnel?Yes, if there is a potential barrier (cutoff frequency, diameter )most of the photons would be reflected (may be at the sidewall may be at the energy barrier) but some photons able to tunneling that barrier in just zero time, i think than the cavity acts like shorter than it is.The small end looks like it is narrow to the small end. Its more a intuitiv thing, i have the luck to work with conical cavities for special applications. Got network analyser, Spectrum Analyzer, circulator, load, tapered cavities all available and i am able to build conical cavities like a want but in K-Band area
Apart from the F = P/v (trash Einstein) and F = constant (trash Noether) dynamic models, I did propose a third model which is probably best named "frustrated momentum". In this case, the static F persists until a certain momentum value has been established, equal to an initial impulse given to the system. This momentum having been fully established, F returns to zero Newton.Shawyer's video seems to fit the "frustrated momentum" bill. McCullough's theory also predicts it IIRC.
Quote from: rfmwguy on 06/03/2015 06:17 pmWell goup, I'm taking the plunge...right now. At the risk of being ridiculed by my wife, and maybe a couple on these threads , I have attached a Preliminary rev of my proposed emdrive experiment. I welcome any constructive comments, corrections and suggestions. I am putting it out in rough/prelim form to elicit feedback before I get underway in earnest this summer.In addition, it might motivate others out there to get busy themselves!p.s. Special thanks to Zellerium for "inspiration" on the experiment outline...Note: My approach is not to replicate. I've decided on a lower power model for reasons stated in the paper. Nothing written yet has precluded the use of these lower power levels. Perhaps my humble efforts might help with that aspect.DaveGood luck with that! As regards the effect of heated air, you'll find (either by calculation or experiment) that if the device is able to let any air escape or enter, the change in weight due to lost air far exceeds the change in weight to due to buoyancy in air caused by ballooning.You can do a lot better than 100 mg rez on your weighing device for quite moderate bucks. I bought my used Mettler H20 for $80 online and it gets 10 ug.I'd recommend a fully mechanical weighing device, so as to avoid e/m effects on its electronics.
Well goup, I'm taking the plunge...right now. At the risk of being ridiculed by my wife, and maybe a couple on these threads , I have attached a Preliminary rev of my proposed emdrive experiment. I welcome any constructive comments, corrections and suggestions. I am putting it out in rough/prelim form to elicit feedback before I get underway in earnest this summer.In addition, it might motivate others out there to get busy themselves!p.s. Special thanks to Zellerium for "inspiration" on the experiment outline...Note: My approach is not to replicate. I've decided on a lower power model for reasons stated in the paper. Nothing written yet has precluded the use of these lower power levels. Perhaps my humble efforts might help with that aspect.Dave
Quote from: WarpTech on 06/03/2015 03:27 pm{Yeah, we're on the same page alright. I can't answer this right now, I'm working on the same puzzle but with the TM01 mode, because with an axial conductor down the middle, it's easier to calculate. For any mode, you need to solve the equation;force density = dD/dt X B + D X dB/dtSurface charge is one way to look at it, another is the magnetic moment. In free space, the "difference" between these 2 cross products is typically a photon rocket. Inside a cavity however, it becomes an "attenuation rocket". I'm not sure of the outcome yet, so I'm working on it....}WarptechWhen you get some free time have a look at papers by Martin Tajmar.
{Yeah, we're on the same page alright. I can't answer this right now, I'm working on the same puzzle but with the TM01 mode, because with an axial conductor down the middle, it's easier to calculate. For any mode, you need to solve the equation;force density = dD/dt X B + D X dB/dtSurface charge is one way to look at it, another is the magnetic moment. In free space, the "difference" between these 2 cross products is typically a photon rocket. Inside a cavity however, it becomes an "attenuation rocket". I'm not sure of the outcome yet, so I'm working on it....}
Quote from: WarpTech on 06/03/2015 05:20 pm...A mass in a gravitational field "falls" yet nothing is coming out of the enclosing control volume either. It falls precisely because the stress energy Tensor in that volume is skewed to one side. This is what is happening inside the frustum, but only over a narrow bandwidth of the EM spectrum.If I get it right, you are assuming that a gravitational field is induced by the electromagnetic fields within the frustrum, which I concede since EM fields are sources of the Einstein equations. However, back of the envelope calculations (looking for the gravity due to the mass of a huge EM field within a 1 m**3 volume) show that even in the best scenario the expected gravitational thrusts effects are orders of magnitude below what it has been observed (or claimed). I would like to have a look at a peer-reviewed reference where the amplification mechanism for narrow bandwith of the EM spectrum is duly explained.
...A mass in a gravitational field "falls" yet nothing is coming out of the enclosing control volume either. It falls precisely because the stress energy Tensor in that volume is skewed to one side. This is what is happening inside the frustum, but only over a narrow bandwidth of the EM spectrum.
Quote from: ppnl on 06/03/2015 09:24 pm...It is interesting that the understanding of the problem has not progressed since I was last here....We have been having fun over here. Have you had any fun since you were last here?
Quote from: deltaMass on 06/03/2015 08:36 pmAs has been pointed out, getting Q*photon-rocket thrust might be OK so long as it isn't allowed to do work. Well, much work, anyway. We have equations for that, using the stored energy and the power input.Would greatly appreciate a link to this discussion, or maybe a quick summary if it isn't too much trouble.
Quote from: Mulletron on 06/02/2015 09:26 amQuote from: Rodal on 06/02/2015 03:04 amQuote from: Notsosureofit on 06/02/2015 02:51 amYesThen, if the fellows in Aachen, Germany, have scaled all their cavity dimensions for Baby EM Drive such thatbigdiameterAACHEN = bigdiameterNASA / (frequencyAACHEN/frequencyNASA)smalldiameterAACHEN =smalldiameterNASA / (frequencyAACHEN/frequencyNASA)lengthAACHEN = lengthdiameterNASA / (frequencyAACHEN/frequencyNASA)they don't have to worry about operating at frequencyAACHEN = 24 GHz, since the number of cycles needed for the photons in the cavity to accelerate to c (if they were free to do so), the coupling, would be what your curve shows at around frequencyNASA = 2 GHz, the NASA frequency ?Photons don't accelerate. No reference required. It is basic. Any theory requiring such condition needs to go.Eh- it might just be my peanut gallery prowess speaking here but... what happens when photons or other particles are in one medium and cross the boundary to another medium? Fer instance... particles in the water bath of a nuclear pile (they produce blue glowey stuff known as Cherenkov radiation) because they exceed the speed of light for that medium and shed energy. Bear with me...So now they leave the water for open air or a vacuum. what happens then? The speed limit is now faster than they are traveling...could they ( here I mean photons not massive particles) accelerate to the new limit?EDIT: And what of experiments with "slow light?" That's where photons are slowed down below their natural speed in recent high tech experiments. Does a slow or trapped photon mean a photon that can be accelerated?
Quote from: Rodal on 06/02/2015 03:04 amQuote from: Notsosureofit on 06/02/2015 02:51 amYesThen, if the fellows in Aachen, Germany, have scaled all their cavity dimensions for Baby EM Drive such thatbigdiameterAACHEN = bigdiameterNASA / (frequencyAACHEN/frequencyNASA)smalldiameterAACHEN =smalldiameterNASA / (frequencyAACHEN/frequencyNASA)lengthAACHEN = lengthdiameterNASA / (frequencyAACHEN/frequencyNASA)they don't have to worry about operating at frequencyAACHEN = 24 GHz, since the number of cycles needed for the photons in the cavity to accelerate to c (if they were free to do so), the coupling, would be what your curve shows at around frequencyNASA = 2 GHz, the NASA frequency ?Photons don't accelerate. No reference required. It is basic. Any theory requiring such condition needs to go.
Quote from: Notsosureofit on 06/02/2015 02:51 amYesThen, if the fellows in Aachen, Germany, have scaled all their cavity dimensions for Baby EM Drive such thatbigdiameterAACHEN = bigdiameterNASA / (frequencyAACHEN/frequencyNASA)smalldiameterAACHEN =smalldiameterNASA / (frequencyAACHEN/frequencyNASA)lengthAACHEN = lengthdiameterNASA / (frequencyAACHEN/frequencyNASA)they don't have to worry about operating at frequencyAACHEN = 24 GHz, since the number of cycles needed for the photons in the cavity to accelerate to c (if they were free to do so), the coupling, would be what your curve shows at around frequencyNASA = 2 GHz, the NASA frequency ?
Yes
The BEC is usually opaque, but the researchers made the material transparent by exposing it to a specific arrangement of laser beams. The lasers allowed incoming photons to combine with atoms to form a hybrid particle known as a polariton. Because polaritons get mass from the atoms, they move slower than c. In a BEC, many atoms condense to form one large, super atom. The super atoms are very heavy, and so are the polaritons formed with the incoming photons, and as a result they move much slower than c.
Quote from: Mulletron on 06/02/2015 09:26 amQuote from: Rodal on 06/02/2015 03:04 amQuote from: Notsosureofit on 06/02/2015 02:51 amYesThen, if the fellows in Aachen, Germany, have scaled all their cavity dimensions for Baby EM Drive such thatbigdiameterAACHEN = bigdiameterNASA / (frequencyAACHEN/frequencyNASA)smalldiameterAACHEN =smalldiameterNASA / (frequencyAACHEN/frequencyNASA)lengthAACHEN = lengthdiameterNASA / (frequencyAACHEN/frequencyNASA)they don't have to worry about operating at frequencyAACHEN = 24 GHz, since the number of cycles needed for the photons in the cavity to accelerate to c (if they were free to do so), the coupling, would be what your curve shows at around frequencyNASA = 2 GHz, the NASA frequency ?Photons don't accelerate. No reference required. It is basic. Any theory requiring such condition needs to go.I can't say I am exactly following them but there is this article here, http://www.nature.com/nphys/journal/v9/n12/full/nphys2777.html . They seem to suggest acceleration of the beam. I always thought of photons more of as waves though considering the path followed by them from a double slit experiment has them emanating not from the holes but from between the holes and then they follow curved paths near the holes then straight paths later on. On the other hand there is quantum physics. I also thought light slowed down when entering a gravitational well but one being in that gravitational well still measures speed c from inside due space time distortion but still I think light should slow down in the well with respect to the rest of space. I am not sure I would call the change in speed acceleration, though maybe it is. I noticed their equation f*c/g is unit-less. Again, I can't say I understand it but I thought maybe it was in context of the article above?
Photons don't accelerate. No reference required. It is basic. Any theory requiring such condition needs to go.
Similarly, in photonic guiding structures, the effective photon mass can be positive or negative depending on the sign of the associated group velocity dispersion3,4
light speeds up as it ascends from floor to ceiling, and it slows down as it descends from ceiling to floor; it's not like a ball that slows on the way up and goes faster on the way down. Light travels faster near the ceiling than near the floor. But where you are, you always measure it to travel at c; no matter where you place yourself, the mechanism that runs the clock you're using to measure the light's speed will speed up or slow down precisely in step with what the light is doing. If you're fixed to the ceiling, you measure light that is right next to you to travel at c. And if you're fixed to the floor, you measure light that is right next to you to travel at c. But if you are on the floor, you maintain that light travels faster than c near the ceiling. And if you're on the ceiling, you maintain that light travels slower than c near the floor.
You are correct. Anyone who thinks photons do not accelerate needs to study General Relativity. A gravitational field "Is" an accelerated reference frame and photons in a g field "do" accelerate relative to a distant observer who is not in the g field. It is called the "coordinate speed of light". To someone observing from inside the g field, c appears to be constant on their relative tangent plane, but that is only because gravitational length contraction and time dilation conspire to make it so in that coordinate system. From the respective coordinate system of a distant observer, c/K in a gravitational field slower than c in free space! This is a fact, if you don't believe it please study GR and the PV Model of GR. The speed of light is ONLY constant in an inertial reference frame. As soon as you introduce acceleration or gravity, it is not constant.Thank you.Todd
Quote from: Rodal on 06/02/2015 06:30 pmQuote from: phaseshift on 06/02/2015 06:11 pmQuote from: Rodal on 06/02/2015 05:59 pmQuote from: phaseshift on 06/02/2015 05:51 pmAs many have said before the EW drive just can't work without violating CoM. ...Who has said that "the EM Drive drive just can't work without violating CoM"? I don't know of any author that has advocated that the EM Drive works by violating Conservation of Momentum. Every single theory I know of, Shawyer, McCulloch, Yang, White, you name it, postulates that the EM Drive does not violate conservation of momentum (they all have different explanations as to why momentum is conserved).I think you can find the forum is full of extremely knowledgeable people who have said as such. Yes, the authors you listed have made claims but in each case have opened their system such that CoM appears to not be violated and that's how they make the 'claim' they are not violating basic physics.Focusing on the question I asked might be more productive. How did Yang open her system such that CoM does not appear to be violated? Or do you really believe that the EM Drive, a closed cavity, is not violating CoM without a mechanism for opening it up and therefore in your opinion this line of questioning can lead no where?Perhaps we are using different languages to express this.I use the following definition of an open system:"A open system is a system that has external interactions. Such interactions can take the form of information, energy, or material transfers into or out of the system boundary, depending on the discipline which defines the concept. An open system is contrasted with the concept of an isolated system which exchanges neither energy, matter, nor information with its environment. An open system is also known as a constant volume system or a flow system."According to that definition Dr. White's theory is opening the system by involving the Quantum Vacuum, if we take that the Quantum Vacuum was not part of the system being considered. I think that neither Shawyer, McCulloch or Yang are "opening the system". I don't think that discussing a gradient of group velocity, or Unruh radiation, or considering current density J is opening the system. But I guess that it all depends on what one means by an open system.As to what Prof. Yang is doing, I don't completely understand it, but my take (with a grain of salt) is that she maybe considering the case of a cavity coupled externally with a waveguide or a coaxial. Thus, the excitations of a mode in a cavity can be modeled by an equivalent electric ( J ) or magnetic ( Jm ) density current representing the sources of the modes. The equivalent magnetic sources are, for example, the magnetic field on a coupling slot between the waveguide and the cavity and the magnetic field generated by a loop coupled with a cavity, while the equivalent electric sources are the currents on a small antenna coupled with the cavity.We are using the same definition of open system I do think Shawyer attempted to "open" the cavity by invoking Special Relativity (incorrectly). White uses the QV (almost in an extra dimensional way) to open the system. Yang appears to make no attempt at doing so and thus the reason for my question. Going extra dimensional, 4+1, also opens up the cavity. However, in looking over Randall/Sundrum I realized that their +1 is not on our D-Brane and is rather the bulk itself. According to string theory this means RF energy can not enter the +1 dimension,yet in the same breath Randall wonders if Standard Model particles are in the bulk. Of course there is the possibility of other dimensions outside of their theory.I am hoping that given Yang's substantially higher thrust that the manner in which the cavity is opened up could be discerned helping theory move forward.
Quote from: phaseshift on 06/02/2015 06:11 pmQuote from: Rodal on 06/02/2015 05:59 pmQuote from: phaseshift on 06/02/2015 05:51 pmAs many have said before the EW drive just can't work without violating CoM. ...Who has said that "the EM Drive drive just can't work without violating CoM"? I don't know of any author that has advocated that the EM Drive works by violating Conservation of Momentum. Every single theory I know of, Shawyer, McCulloch, Yang, White, you name it, postulates that the EM Drive does not violate conservation of momentum (they all have different explanations as to why momentum is conserved).I think you can find the forum is full of extremely knowledgeable people who have said as such. Yes, the authors you listed have made claims but in each case have opened their system such that CoM appears to not be violated and that's how they make the 'claim' they are not violating basic physics.Focusing on the question I asked might be more productive. How did Yang open her system such that CoM does not appear to be violated? Or do you really believe that the EM Drive, a closed cavity, is not violating CoM without a mechanism for opening it up and therefore in your opinion this line of questioning can lead no where?Perhaps we are using different languages to express this.I use the following definition of an open system:"A open system is a system that has external interactions. Such interactions can take the form of information, energy, or material transfers into or out of the system boundary, depending on the discipline which defines the concept. An open system is contrasted with the concept of an isolated system which exchanges neither energy, matter, nor information with its environment. An open system is also known as a constant volume system or a flow system."According to that definition Dr. White's theory is opening the system by involving the Quantum Vacuum, if we take that the Quantum Vacuum was not part of the system being considered. I think that neither Shawyer, McCulloch or Yang are "opening the system". I don't think that discussing a gradient of group velocity, or Unruh radiation, or considering current density J is opening the system. But I guess that it all depends on what one means by an open system.As to what Prof. Yang is doing, I don't completely understand it, but my take (with a grain of salt) is that she maybe considering the case of a cavity coupled externally with a waveguide or a coaxial. Thus, the excitations of a mode in a cavity can be modeled by an equivalent electric ( J ) or magnetic ( Jm ) density current representing the sources of the modes. The equivalent magnetic sources are, for example, the magnetic field on a coupling slot between the waveguide and the cavity and the magnetic field generated by a loop coupled with a cavity, while the equivalent electric sources are the currents on a small antenna coupled with the cavity.
Quote from: Rodal on 06/02/2015 05:59 pmQuote from: phaseshift on 06/02/2015 05:51 pmAs many have said before the EW drive just can't work without violating CoM. ...Who has said that "the EM Drive drive just can't work without violating CoM"? I don't know of any author that has advocated that the EM Drive works by violating Conservation of Momentum. Every single theory I know of, Shawyer, McCulloch, Yang, White, you name it, postulates that the EM Drive does not violate conservation of momentum (they all have different explanations as to why momentum is conserved).I think you can find the forum is full of extremely knowledgeable people who have said as such. Yes, the authors you listed have made claims but in each case have opened their system such that CoM appears to not be violated and that's how they make the 'claim' they are not violating basic physics.Focusing on the question I asked might be more productive. How did Yang open her system such that CoM does not appear to be violated? Or do you really believe that the EM Drive, a closed cavity, is not violating CoM without a mechanism for opening it up and therefore in your opinion this line of questioning can lead no where?
Quote from: phaseshift on 06/02/2015 05:51 pmAs many have said before the EW drive just can't work without violating CoM. ...Who has said that "the EM Drive drive just can't work without violating CoM"? I don't know of any author that has advocated that the EM Drive works by violating Conservation of Momentum. Every single theory I know of, Shawyer, McCulloch, Yang, White, you name it, postulates that the EM Drive does not violate conservation of momentum (they all have different explanations as to why momentum is conserved).
As many have said before the EW drive just can't work without violating CoM. ...