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#2700 by Mulletron on 08 Feb, 2016 02:02
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Are you saying that's the reason for the sign change?
It is for an asymmetric electromagnetic resonant cavity (theoretically (Minotti) it can display a force in either direction depending on the electromagnetic mode shape). I don't know what experiment you are referring to when stating <<The diametric drive experiment we keep kicking around >> ? who is kicking it around? what experiment? A real physical experiment or a though-experiment?
This one. We've talked about this MANY times.
http://www.creol.ucf.edu/Research/Publications/7155.pdf -
#2701 by Bob Woods on 08 Feb, 2016 02:13
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Does anyone know what town in Australia Phil lives in? I'd like to be able to check the local news.
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#2702 by Rodal on 08 Feb, 2016 02:24
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Are you saying that's the reason for the sign change?
It is for an asymmetric electromagnetic resonant cavity (theoretically (Minotti) it can display a force in either direction depending on the electromagnetic mode shape). I don't know what experiment you are referring to when stating <<The diametric drive experiment we keep kicking around >> ? who is kicking it around? what experiment? A real physical experiment or a though-experiment?
This one. We've talked about this MANY times.
http://www.creol.ucf.edu/Research/Publications/7155.pdf
Pulses propagating in a nonlinear optical mesh lattice, with a nonlinear Kerr optical effect of the optical fibers?
I had forgotten about that paper.
Ouch
Who is up to analyze the expected force direction for that ? I certainly have not done such analysis
The paper seems to be an experimental paper.
Certainly I don't see how that can be obtained from the simple analysis of Bondi and Forward, and I don't see a direct analogy between this and the EM Drive either...
Do the authors of the paper claim that it can? -
#2703 by Rodal on 08 Feb, 2016 02:35
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Does anyone know what town in Australia Phil lives in? I'd like to be able to check the local news.
I suggest that anybody interested may try to contact him by joining his Google Group for more information, as I expect that he wants to keep such information private. -
#2704 by Mulletron on 08 Feb, 2016 02:47
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Are you saying that's the reason for the sign change?
It is for an asymmetric electromagnetic resonant cavity (theoretically (Minotti) it can display a force in either direction depending on the electromagnetic mode shape). I don't know what experiment you are referring to when stating <<The diametric drive experiment we keep kicking around >> ? who is kicking it around? what experiment? A real physical experiment or a though-experiment?
This one. We've talked about this MANY times.
http://www.creol.ucf.edu/Research/Publications/7155.pdf
Pulses propagating in a nonlinear optical mesh lattice, with a nonlinear Kerr optical effect of the optical fibers?
I had forgotten about that paper.
Ouch
Who is up to analyze the expected force direction for that ? I certainly have not done such analysis
The paper seems to be an experimental paper.
Certainly I don't see how that can be obtained from the simple analysis of Bondi and Forward, and I don't see a direct analogy between this and the EM Drive either...
Do the authors of the paper claim that it can?
I can't see a direct connection either. What surprises me is the direction is opposite of what I expected and I didn't even notice it before. Guess that was a case of confirmation bias. I wonder why it is different from Bondi/Forward? Is it because it's effective mass or what? -
#2705 by dustinthewind on 08 Feb, 2016 04:06
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Are you saying that's the reason for the sign change?
It is for an asymmetric electromagnetic resonant cavity (theoretically (Minotti) it can display a force in either direction depending on the electromagnetic mode shape). I don't know what experiment you are referring to when stating <<The diametric drive experiment we keep kicking around >> ? who is kicking it around? what experiment? A real physical experiment or a though-experiment?
This one. We've talked about this MANY times.
http://www.creol.ucf.edu/Research/Publications/7155.pdf
Pulses propagating in a nonlinear optical mesh lattice, with a nonlinear Kerr optical effect of the optical fibers?
I had forgotten about that paper.
Ouch
Who is up to analyze the expected force direction for that ? I certainly have not done such analysis
The paper seems to be an experimental paper.
Certainly I don't see how that can be obtained from the simple analysis of Bondi and Forward, and I don't see a direct analogy between this and the EM Drive either...
Do the authors of the paper claim that it can?
I can't see a direct connection either. What surprises me is the direction is opposite of what I expected and I didn't even notice it before. Guess that was a case of confirmation bias. I wonder why it is different from Bondi/Forward? Is it because it's effective mass or what?
Could it be that the fiber is the propellant? So the light is accelerated toward the negative energy region where as the fibers would then be accelerated in the positive work direction?
Sort of opposite of a phased array, where the radiation seems to emit from the arrays that do positive work, and the array assembly is pushed in the direction where the arrays do negative work?
Mmm, maybe like the energy for the reaction is coming from the light and into the fiber.
Where as for the array assembly the energy is coming from the arrays and going into the light. -
#2706 by SteveD on 08 Feb, 2016 04:34
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Just an interesting observation.
Photons are moving between point C and D in the frustum (for the purposes of this, assume point D is perfectly absorptive so that their is no reflection). Doesn't the kinetic energy they generated by the release of the photons have to travel from point C by moving from C to A and B and then finally to D, a longer path than light takes to go from C to D. That would mean that the impact of photons at point D creates its own energy with the energy generated from the original emission of a photon from C and the absorption of the photon at D meeting and cancelling each other out at some point other than D.
All of which seems trivial but let's say instead of an absorption there is a reflection. The forward motion generated by the emission of a photon at point C causes it to be redshifted to a theoretical observer standing directly behind the device if a endplate was not in the way (the device is moving away from the observe at the appropriate speed for a photon rocket). This movement must happen unless the photon has some way of knowing what the conditions will be like at point D so that I can't, for example, use a perfectly timed set of explosions to break the physical link between points C and D while the light is still in transit.
When the photons hit point D, they arrive with or behind the light cone placing the device in motion away from point C. This motion causes point D to exactly accelerate, blueshifting the incoming light equals to the initial redshift. But doesn't that mean that point D lacks energy corresponding to its velocity when the reflection occurs?
Going to get some sleep now. I'm obviously misunderstanding something. -
#2707 by RERT on 08 Feb, 2016 10:11
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1) TT - all the best, get well soon.
2) Dr.Rodal: no, I wasn't thinking of a mini-blackhole. Just: there is stuff in the frustrum <then a miracle happens> there is less stuff in the frustrum, and something carrying momentum which is invisible and to which the copper walls are transparent, exits asymmetrically. As you remark, we can discuss negative mass when there is <then a miracle happens> when we discuss creating it, so why not for this concept?
3) A couple of references to spacetime flow. No-one would expect a uniformly moving spacetime to have any impact at all - that's (more or less) special relativity. But the frustrum can't move the whole of spacetime, so its effects will be local. In particular there will be local flow-velocity gradients. A rotating frame has local velocity gradients, and consequent (pseudo) forces. If spacetime flows were real, not just co-ordinate based, one might expect non-zero local curvature and real forces as a result of spatial inhomogeneity of flows.
R.
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#2708 by TheTraveller on 08 Feb, 2016 11:17
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1) TT - all the best, get well soon.
Not sick as such. My bowel doesn't like all the close quarters surgery and 40 days of rad it had to endure. Was going toward a bag job but I said NO. Engineers always know there is another solution. Have agreed to new diet and a few drugs to try to get it settled down. If this works and it settles down, should be home in a week or so.
Guys get your prostate checked. I had no symptoms. Had they not found it, via another exam (my PSA was mid 3s, which for my age was ok), would have been dead in 1-2 years.
BTW I did fix the PSU (using 2 x lead acid car batts & existing bench PSU as charger to get 27vdc). Forward power climbed into the 90W region and reaction force got close to 5mN. Cavity Q is still very low. Believe need to eliminate the sidewall butt joint seam via a cast and machined frustum and machine the end flanges to a high tolerance to ensure very parallel end plates as otherwise will get a walk off of the Rf energy to the side wall.
Also plan to try end planes with a very slight concave surface so as to try to combat walk off from slightly non parallel flat end plates. Believe this walk off issue is behind many frustum builds with low Q. -
#2709 by Rodal on 08 Feb, 2016 13:58
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...
Because I stated several times that my discussion was for a closed system that does not eject any mass-energy out of the system (which is what is proposed by Shawyer). Conservation of momentum-energy is trivial to show for a system that ejects mass-energy, in essence, a conventional rocket. The controversy about Shawyer's proposal is that he claims that the EM Drive is a closed-system that self-accelerates without the ejection of any mass-energy.
2) Dr.Rodal: no, I wasn't thinking of a mini-blackhole. Just: there is stuff in the frustrum <then a miracle happens> there is less stuff in the frustrum, and something carrying momentum which is invisible and to which the copper walls are transparent, exits asymmetrically. As you remark, we can discuss negative mass when there is <then a miracle happens> when we discuss creating it, so why not for this concept?
...
Yet now you are suggesting that I should consider that mass-energy << exits asymmetrically>> out of the EM Drive, which is similar to a conventional rocket, and violates the "closed-system" condition that I was discussing. Furthermore having mass-energy exiting asymmetrically is not <<continuous destruction of positive mass-energy>>, which was what you previously stated:The discussion around continuous creation of negative mass-energy triggers a thought: what about the continuous destruction of positive mass-energy?...
I'm sorry but I get the impression that your posts answering mine are becoming an endless loop, since I stated several times that I was considering how can momentum be conserved for a closed system where mass-energy was not being ejected, to which you answered that I should consider mass-energy destruction, and when asked how are you proposing to destroy mass-energy: whether you are proposing a black hole, you answer that no, that I should consider ejection of mass-energy, which is similar to a conventional rocket, and goes completely against what I was considering in the first place
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#2710 by rfmwguy on 08 Feb, 2016 15:50
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Think you have to realize the R forum advertises this prominently on each page:Perhaps my memory is failing me or I wasn't participating in the discussion at the time, but were the reference provided in the link below to the other forum discussed here? I searched and couldn't find. I know we've covered this sort of thing in detail.
(snip)
https://www.reddit.com/r/EmDrive/comments/448i2k/is_the_emdrive_a_negative_energyevanescent_wave/czr1626
https://iafastro.directory/iac/archive/tree/IAC-13/C4/P/IAC-13,C4,P,1.p1,x16863.brief.pdf
http://arxiv.org/abs/1001.0839
Edit:
Surely one of the evanescent wave theory fans or diametric drive theory fans have already covered this right?
Some people in the "R forum" don't seem to understand that it is routine in physics to consider "what if" questions (like whether one can stabilize a wormhole with negative mass) without getting into practical engineering of whether the concept could ever be possible from an engineering feasibility viewpoint. Discussing whether one could stabilize a wormhole does not imply that one claims to have a way to make wormholes or create negative mass
"Snoo (our time traveling alien mascot)"
Pretty much explains the level of seriousness there. -
#2711 by RotoSequence on 08 Feb, 2016 17:55
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Interesting breakthrough on the subject of chirality, parallel magnetic fields, and quantum currents from Brookhaven National Labs:
https://www.bnl.gov/newsroom/news.php?a=11811QuoteUPTON, NY—Scientists at the U.S Department of Energy's (DOE) Brookhaven National Laboratory and Stony Brook University have discovered a new way to generate very low-resistance electric current in a new class of materials. The discovery, which relies on the separation of right- and left-"handed" particles, points to a range of potential applications in energy, quantum computing, and medical imaging, and possibly even a new mechanism for inducing superconductivity—the ability of some materials to carry current with no energy loss.
The material the scientists worked with, zirconium pentatelluride, has a surprising trait: When placed in parallel electric and magnetic fields, it responds with an imbalance in the number of right- and left-handed particles—a chiral imbalance. That imbalance pushes oppositely charged particles in opposite directions to create a powerful electric current.
This "chiral magnetic effect" had long been predicted theoretically, but never observed definitively in a materials science laboratory at the time this work was done. -
#2712 by RERT on 08 Feb, 2016 18:41
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TT - great to hear from you! Look after yourself.
Dr.Rodal - maybe it would be easier if I said that we should question whether the EMDrive us a closed system, because in the context of 'exotic physics' there is absolutely no evidence that it is? The idea is that might facilitate an explanation.
R. -
#2713 by rfmwguy on 08 Feb, 2016 20:49
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Tangent Alert - JPL's past present and future (on propulsion)
Recently, JPL has branched out by hiring climatologists as they continue to expand on their original purpose for NASA. However, a 2014 video does lay out some future plans regarding space propulsion. As you probably already know, they are 100% behind classic rocket propulsion, but the speaker does mention "something else" towards the end...
If you are wondering if they would be/are supportive of EMDrive research or testing, its probably best if you view the video...a total about 90 minutes. The first hour is simply a JPL history lesson. Future propellant considerations include green fuel and "something else".
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#2714 by dustinthewind on 08 Feb, 2016 22:34
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I just had an idea that kind of merges EM Cavities, Dielectrics, and may possibly be related to the Woodward idea but not in an obvious way. At the moment it seems like a closed system, so far.
We start with a cavity that lets light in one way (cinnamon roll shape) and was suggested by some one in the early threads. I can not remember where, but am grateful for their suggestion of the cavity shape. I think I remember rfmwguy commenting on their cavity shape. The light should travel around one way in a circle.
The next idea is to fill half this cavity with a dielectric such that when the light enters the dielectric it slows down. I assumed momentum is conserved so to slow down the light I changed the effective mass of the light by adding "dm".
I then considered the circular path the light takes and assumed a force F = m*a = m*v^2/r which isn't relativistic but the photon doesn't approach infinite mass at light speed anyways. Maybe I am making the wrong assumption here. The force around the circular path appears to be different for the photon in the dielectric than for free space.
I found another paper called, "An Effective Photon Momentum in a Dielectric Medium:
A Relativistic Approach" which appears relatively new 2015. Department of Physics, Weber State University, Ogden, UT. I can't seem to find it on googlescholar but the link is here: http://physics.weber.edu/galli/EffectivePhotonV2-1.PDF
Their paper suggest the effective momentum P_eff = P/n where n is index of refraction so that unless I am mistaken they don't take momentum to be conserved. Maybe upon entry and exit of the dielectric some momentum is transferred. I am not certain about equation 10 where they say it reduces to Snell's law when u->0. With u->0 I think it reduces to sin(theta2)/cos(theta2)=sin(theta1)/[n*sqrt(1-sin(theta2)^2/n^2)] where (1-sin(theta)^2)=cos(theta)^2, which is close but I don't think it is the same, unless I am mistaken. Regardless I think their effect may only enhance the Force difference in the idea I was contemplating (or come out the same possibly if momentum is transfered to the dielectric upon entry and back to the photon upon exit. - momentum is conserved.). Image attached below.
It is interesting it requires a cavity and it appears the Q of the cavity may enhance the effect. At the moment it looks like a closed system and possibly related to the Woodward idea based on the light changing in mass. Am I terribly off here?
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#2715 by rfmwguy on 08 Feb, 2016 23:38
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@dustinthewind (I'm also a Kansas fan)
Thanks for your ideas on this. Early on, EM vortices interested me...High Q would limit the losses in the cavity, allowing for more circular EM "rotation". Only a guess, but losses would mount exponentially when compared to linear reflections or "bounces". The "bounces" would follow the entire reflector (cavity wall) and losses increase. I eventually moved away from EM vortices. after several brain cramps.
Regarding dielectric material, Doc has stated on EWs behalf that no force was measured without it. I think this is true, but some of us including Iulian, have not used a dielectric in testing. A dielectric naturally lowers Q but inversely saves space since its dielectric constant is much higher than air. That's been my only exposure to the material in the past. Think of a common N connector, the transmission line, or diameter, is made much smaller by the use of Teflon (or similar) dielectric material between the outer shell and the center conductor. On EIA air lines, teflon discs are only used to support the center conductor. The rest of it is air...so the nickname air lines.
However, something else peaked my interest recently about a dielectric. It was discussed in an actuator paper you might have noted I posted a couple of pages ago...it changes the velocity or propagation of Ions and Free Electrons. I find this interesting as I've been focusing on particles rather than wave theories lately. Sort of an anti-meep approach, but hey, I'm a confirmed non-conformist.
I think we still have CoE/CoM to deal with. A true closed system is not supposed to interact with the outside world. Yet, many are not yet convinced its a truly closed system. Whatever is outside of the system would need to be inside the system as well and conversely, something inside the system must interact with the outside.
So, there we are, up against the old laws of physics
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#2716 by rfmwguy on 09 Feb, 2016 03:23
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General space news - NASA state of the Union address tomorrow, 2/9 @ 1:30 est. Expect mars and asteroid mentions, earth science and aerospace leadership plus commercial viability of ISS is my prediction...not difficult BTW.
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#2717 by birchoff on 09 Feb, 2016 04:11
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I just had an idea that kind of merges EM Cavities, Dielectrics, and may possibly be related to the Woodward idea but not in an obvious way. At the moment it seems like a closed system, so far.
We start with a cavity that lets light in one way (cinnamon roll shape) and was suggested by some one in the early threads. I can not remember where, but am grateful for their suggestion of the cavity shape. I think I remember rfmwguy commenting on their cavity shape. The light should travel around one way in a circle.
The next idea is to fill half this cavity with a dielectric such that when the light enters the dielectric it slows down. I assumed momentum is conserved so to slow down the light I changed the effective mass of the light by adding "dm".
I then considered the circular path the light takes and assumed a force F = m*a = m*v^2/r which isn't relativistic but the photon doesn't approach infinite mass at light speed anyways. Maybe I am making the wrong assumption here. The force around the circular path appears to be different for the photon in the dielectric than for free space.
I found another paper called, "An Effective Photon Momentum in a Dielectric Medium:
A Relativistic Approach" which appears relatively new 2015. Department of Physics, Weber State University, Ogden, UT. I can't seem to find it on googlescholar but the link is here: http://physics.weber.edu/galli/EffectivePhotonV2-1.PDF
Their paper suggest the effective momentum P_eff = P/n where n is index of refraction so that unless I am mistaken they don't take momentum to be conserved. Maybe upon entry and exit of the dielectric some momentum is transferred. I am not certain about equation 10 where they say it reduces to Snell's law when u->0. With u->0 I think it reduces to sin(theta2)/cos(theta2)=sin(theta1)/[n*sqrt(1-sin(theta2)^2/n^2)] where (1-sin(theta)^2)=cos(theta)^2, which is close but I don't think it is the same, unless I am mistaken. Regardless I think their effect may only enhance the Force difference in the idea I was contemplating (or come out the same possibly if momentum is transfered to the dielectric upon entry and back to the photon upon exit. - momentum is conserved.). Image attached below.
It is interesting it requires a cavity and it appears the Q of the cavity may enhance the effect. At the moment it looks like a closed system and possibly related to the Woodward idea based on the light changing in mass. Am I terribly off here?
Assuming your idea is correct. You still missing a key part of the proposal woodward is making in his Mach Effect Thruster proposal.Sure One part is the ability to change the mass of part of the thruster in a controllable manner. But the other part is to generate a force on the fluctuating mass. From Woodwards perspective it is a 4 step process.
Lets assume that the part of the thruster that can have its mass changed controllably is called FM
1. Increase the mass of FM (FM is now FMlarger)
2. Generate a force that pushes against FMlarger
3. Reduce the mass of FM (FM is now FMlighter)
4. Generate a force that pulls on FMlighter -
#2718 by birchoff on 09 Feb, 2016 04:15
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Tangent Alert - JPL's past present and future (on propulsion)
Recently, JPL has branched out by hiring climatologists as they continue to expand on their original purpose for NASA. However, a 2014 video does lay out some future plans regarding space propulsion. As you probably already know, they are 100% behind classic rocket propulsion, but the speaker does mention "something else" towards the end...
If you are wondering if they would be/are supportive of EMDrive research or testing, its probably best if you view the video...a total about 90 minutes. The first hour is simply a JPL history lesson. Future propellant considerations include green fuel and "something else".
Really like the mention on Nuclear Thermal. I only hope this isnt just lip service. We could colonize our solar system with a mixture of VASIMIR, Fusion Rockets, and Nuclear Thermal
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#2719 by dustinthewind on 09 Feb, 2016 04:17
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...High Q would limit the losses in the cavity, allowing for more circular EM "rotation". Only a guess, but losses would mount exponentially when compared to linear reflections or "bounces". The "bounces" would follow the entire reflector (cavity wall) and losses increase. I eventually moved away from EM vortices....
That is true that with each bounce there should be a reduction in energy for the reflected light. Not to mention it is strange that as r->0 the acceleration goes up drastically but the time that force is exerted should be reduced. I'm still not sure that curving the path of a photon could actually have a Centrifugal force but each reflection should exert a force.
I wonder if such an experiment could be tested with a small looped fiber-optic where half the loop has a different index of refraction. Not sure the light would go all that far in fiber before being attenuated compared to a cavity.
