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#2600 by aero on 25 Oct, 2014 18:16
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Also the latest paper by Shawyer contains no actual data, it is just another quick and dirty powerpoint type of presentation designed to stir hearts and minds. I smell a rat in all this. This all ties into why I give much more credence to the Nasa conference paper than other sources. The Nasa papers have no conflict of interest. Shawyer is trying to sell me a cow, but where's the beef!??!] Also the latest paper by Shawyer contains no actual data, it is just another quick and dirty powerpoint type of presentation designed to stir hearts and minds. I smell a rat in all this. This all ties into why I give much more credence to the Nasa conference paper than other sources. The Nasa papers have no conflict of interest. Shawyer is trying to sell me a cow, but where's the beef!??!
It is true that Shawyer had reduced or eliminated the publication of test results for his different devices.
It would be good to have actual test data from his superconducting demonstration thruster (see photo above). It is pretty clear that with the thruster in a liquid nitrogen (or whatever) bath there won't be air leaks or other spurious aero forces. So - where is the data? Just one test run, that's all I ask. -
#2601 by Supergravity on 25 Oct, 2014 18:45
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What's shocking to me is how this thread made it even past page 2. This is so clearly in violation of known physical laws and it has to be that these experimenters botched the entire thing, failing to take precautions that an undergraduate would be mindful of.
How about we spend all of this energy on more productive and realizable technologies, not fantasy devices that are so clearly in breach of conservation laws and require silly hokum such as "quantum vacuum plasma" and a terrible experiment procedure to even be somewhat plausible? -
#2602 by Mulletron on 25 Oct, 2014 18:52
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@MikeMcCulloch
http://physicsfromtheedge.blogspot.it/2014/10/mihsc-motion-from-logic.html
I think Spock would say, "Proper context and perspective are paramount Doctor......"
After all, we're accelerating 9.8m/s2. Not huge accelerations required for special relativistic effects, and not micro accelerations which are the domain of MiHsC.
From P.F.T.E., linked to above, "Now imagine Spock fires a back pack rocket motor and accelerates forward."
There's no rocket backpacks on the test bench.
Sir your theory is indeed revolutionary, IMHO of course, but let's not paint with so wide a brush stroke.
Your theory does indeed fit into the framework of this silly copper can's anomalous thrust, but not by virtue of teaching light new tricks.
Your theory appears sound, but it must be applied in the most logically salient direction, in the proper context.
Given the core tenets of MiHsC, does this theory really predict any useful effect here on the Earth's surface, where we are dominated by relatively strong interactions, compared to tiny Casimir interactions which are only measurable at extremely tiny scales?
I saw relatively quickly how MiHsC applied to EMdrive, but the practical effect is essentially zero when applied to a copper cone here on Earth.
I ask you sir, "Where are the lowest accelerations possible, with respect to a reference frame, within the bounds of MiHsC?"
Do the walls of the cavity define such a reference frame?
Where is the demarcation point along a wire/waveguide leading from the signal generator to the emdrive RF connector? Where does one reference frame end/begin?
Is it possible that there is no line of demarcation? I see there is absolutely no such line.
Instead we must go back to Feynman, who said all mass is interaction. This interaction (from all scales) defines your reference frame, which is defined isotropically. In areas where interactions are small but not zero (uncertain), such as the low accelerations you may see at the edges of galaxies, this interaction becomes an uncertain value.
This is the heart of MiHhC.
You are in a very good position to achieve a second look, but be careful to not over extend.
Others may throw the baby out with the dirty bath water.....Trying to discredit you in favor of old paradigms. How many years will that cost?
Thank you Doctor.
Please educate me/us.
Edited, added more questions. -
#2603 by Ron Stahl on 25 Oct, 2014 18:52
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There is just to much money being spent on these devices for the test results to be bogus or caused by some bogus effect and not be detected.
I would argue the opposite. With this kind of money spent, why has the science not been settled and why is there no reliable technology that everyone can agree on? I think this is all wishful thinking. Certainly Shawyer's explanation for how the thing should produce thrust is completely wrong, and he's had 11 years to make it right. How is it he is still championing this mishandling of the "group velocity" concept? Clearly demonstrates he's off in pathological science land--I would not trust anything one hears from someone so committed to reasoning he knows must be flawed. -
#2604 by Mulletron on 25 Oct, 2014 18:59
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There is just to much money being spent on these devices for the test results to be bogus or caused by some bogus effect and not be detected.
I would argue the opposite. With this kind of money spent, why has the science not been settled and why is there no reliable technology that everyone can agree on? I think this is all wishful thinking. Certainly Shawyer's explanation for how the thing should produce thrust is completely wrong, and he's had 11 years to make it right. How is it he is still championing this mishandling of the "group velocity" concept? Clearly demonstrates he's off in pathological science land--I would not trust anything one hears from someone so committed to reasoning he knows must be flawed.
Yes you are absolutey right on all counts and welcome back. Shawyer in my view is a good engineer and a great public relations engineer, but he left his skeptic and scientific method hats at home. -
#2605 by Mulletron on 25 Oct, 2014 19:02
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Seriously guys, this evanescent field junk I'm going on about isn't pseudoscience bs. It is a real method by which internal RF dynamics directly influence the outside of a waveguide/cavity. A perfectly designed resonator can give rise to leaky modes. It is pure science. Not even a tiny leap.
This can put the bs to bed and bring order back to EMdrive. Just takes work. Not magic. And many heads. -
#2606 by Mulletron on 25 Oct, 2014 19:23
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What's shocking to me is how this thread made it even past page 2. This is so clearly in violation of known physical laws and it has to be that these experimenters botched the entire thing, failing to take precautions that an undergraduate would be mindful of.
How about we spend all of this energy on more productive and realizable technologies, not fantasy devices that are so clearly in breach of conservation laws and require silly hokum such as "quantum vacuum plasma" and a terrible experiment procedure to even be somewhat plausible?
I think it is clear the experimentalists (at Nasa at least) are professionals. I'm not going to sell these men and women short. Eagleworks has been at it for several years and they have lessons learned under their belt before the EMdrive test campaigns. (not conjecture, look for yourself) At the very least they have personal and organizational reputations to protect.....and they work for a NASA. I have no reason not to respect NASA. Even with the screw ups over the years at NASA, the AARs have been completely pitch perfect on par scientific and analytical......eg. No bs.
I can tell you that it is not acceptable to release a conference paper without following up (they have to know this) with an actual study asap. They concluded the conference paper with a way forward to more studies. -
#2607 by JohnFornaro on 25 Oct, 2014 19:24
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As I understand it, to heat the air inside the cavity by microwave heating the air needs to have water molecules (it needs to be humid) because the gases in air are non-polar (nitrogen, oxygen, etc.) and hence do not get heated by the microwaves.
I don't recall that ambient humidity was mentioned in any of the experimental protocols.
This OSHA document recommends a relative humidity of 30% to 60% on p7:Quote from: OSHACheck whether the temperature and humidity are maintained in a recommended comfort range (temperature: 68 to 78 degrees and relative humidity: 30% to 60%)
If the lab followed these recommendations, then there should be a certain amount of moisture in the ambient air of the cavity.
As to whether the "warm jets" are coming out of the seam or boltholes, good luck modeling where all those random directions and random holes are!
Whatever that M/W effect is on the water vapor in the cavity, it can't amount to much, but I guess it points again to the desireability of testing in vacuum.
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#2608 by JohnFornaro on 25 Oct, 2014 19:26
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I really feel like a Faraday without Maxwell.
I hate it when that happens. -
#2609 by JohnFornaro on 25 Oct, 2014 19:30
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It is true that Shawyer had reduced or eliminated the publication of test results for his different devices.
And how does that tie in with credibility? -
#2610 by Rodal on 25 Oct, 2014 19:31
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As I understand it, to heat the air inside the cavity by microwave heating the air needs to have water molecules (it needs to be humid) because the gases in air are non-polar (nitrogen, oxygen, etc.) and hence do not get heated by the microwaves.
I don't recall that ambient humidity was mentioned in any of the experimental protocols.
This OSHA document recommends a relative humidity of 30% to 60% on p7:Quote from: OSHACheck whether the temperature and humidity are maintained in a recommended comfort range (temperature: 68 to 78 degrees and relative humidity: 30% to 60%)
If the lab followed these recommendations, then there should be a certain amount of moisture in the ambient air of the cavity.
As to whether the "warm jets" are coming out of the seam or boltholes, good luck modeling where all those random directions and random holes are!
Whatever that M/W effect is on the water vapor in the cavity, it can't amount to much, but I guess it points again to the desireability of testing in vacuum.
Testing rapidly in an ambient vacuum without waiting until the cavity itself is free of air would not be enough.
The air that needs to be humid is the one inside the cavity. Hence before the test is conducted the researchers must make sure that the medium inside the cavity itself is at a vacuum. -
#2611 by JohnFornaro on 25 Oct, 2014 19:36
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What's shocking to me is how this thread made it even past page 2. This is so clearly in violation of known physical laws and it has to be that these experimenters botched the entire thing, failing to take precautions that an undergraduate would be mindful of.
How about we spend all of this energy on more productive and realizable technologies, not fantasy devices that are so clearly in breach of conservation laws and require silly hokum such as "quantum vacuum plasma" and a terrible experiment procedure to even be somewhat plausible?
WEll, I gotta say, I'm learning a lot about people, am getting practice in scientific rhetoric, and learning somewhat less math than French, but hey.
Best I can tell, is that the mhe math whiz bangs here think that something could be happening, and are snapping their synapses over just what could be happening that is consistent with the reported results.
Although I'm with you on the sloppy experimental protocols, even by amateur standards. -
#2612 by Rodal on 25 Oct, 2014 19:44
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Assessment of Shawyer's and McCulloch's formulas for EM Drive experimental thrust
From the comparison with experimental results in http://forum.nasaspaceflight.com/index.php?topic=29276.msg1276053#msg1276053
the formulas from Shawyer and McCulloch are close to each other for the range of geometries, power input, Q and frequencies explored during the measurements. The following big difference can be pointed out:
A) McCulloch's formula blows up for the ratio of smallDiameter/cavityLength -> 0 (approaching zero).
B) Shawyer's formula blows up much sooner, due to his introduction of the "Correction Factor" due to group velocity (see Eq.8 p.4 of http://www.emdrive.com/IAC-08-C4-4-7.pdf ). It is obvious that this correction factor goes to infinity as the free-space wavelength becomes equal to the Geometric Average of the diameters of the big and small bases of the truncated cone. Shawyer's formula goes to infinity for
(free-space wavelength) --> GeometricAverage[bigDiameter,smallDiameter] or
(free-space wavelength) --> Sqrt[bigDiameter*smallDiameter]
or, equivalently:
smallDiameter/bigDiameter --> (RFwavelength/bigDiameter)^2 / (1+(RFwavelength/(2*cavityLength))^2)
or, equivalently for:
smallDiameter/bigDiameter --> (c/(bigDiameter*RFfrequency))^2 / (1+(c/(2*cavityLength* RFfrequency))^2)
As a numerical example, for Shawyer's experimental drive with
(* Shawyer Experimental *)
rfFrequency=2.45*10^9;
cavityLength=0.156;
bigDiameter=0.16;
smallDiameter=0.11;
designFactor= 1.23205
power = 850
Q = 5900
measured force = 16
ShawyerForce = 41 (2.56)
McCullochForce = 7 (0.438)
Shawyer's formula blows up (it goes to infinity), for these values, when the small diameter is about 1/2 the big diameter
smallDiameter/bigDiameter = 0.506912
Or, in this case for smallDiameter = 0.081 m
This is the reason why Shawyer's formula gives such a large predicted value (6 times greater than McCulloch's formula) for this case, as of all the experiments we have reviewed (UK and USA) Shawyer's demo drive is the one that has the smallest smallDiameter (just 35% bigger than the dimension for which Shawyer's formula gives an infinite force).
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#2613 by JohnFornaro on 25 Oct, 2014 19:44
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Testing rapidly in an ambient vacuum without waiting until the cavity itself is free of air would not be enough.
The air that needs to be humid is the one inside the cavity. Hence before the test is conducted the researchers must make sure that the medium inside the cavity itself is at a vacuum.
Oh I get that.
But they are not testing in ambient vacuum. They are testing in ambient indoor air of comfortable quality, between 30% and 60% humidity, air which is inside the cavity.
So if Frobnicat wants to model warm jet leakage, I think there should be enough water vapor in the cavity to warm up to some extent. Enough to leak? IDK, ask Frob. -
#2614 by JohnFornaro on 25 Oct, 2014 19:48
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Also, can somebody tell me how you get momentum out of group velocity?
'Cuz I thought there was no relationship whatsoever between the two. -
#2615 by Rodal on 25 Oct, 2014 19:57
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Shawyer's introduction of group velocity leads to his predicted force going to infinity as ( http://forum.nasaspaceflight.com/index.php?topic=29276.msg1276505#msg1276505 )
free-space wavelength = GeometricAverage[bigDiameter,smallDiameter]
For Shawyer's demo drive experiment this effectively means that the output force becomes infinite when the small diameter becomes about 50% of the big diameter (given the other parameters in his demo drive).
If he wants to maximize the force and believes that "group velocity correction" to be correct, why didn't he then make the small diameter that size to maximize the force?
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#2616 by JohnFornaro on 25 Oct, 2014 20:02
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I dunno. 'Coz he doesn't want to make it too easy?
Stuff like this is bothersome and worse than annoying. -
#2617 by Rodal on 25 Oct, 2014 20:05
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I dunno. 'Coz he doesn't want to make it too easy?
Stuff like this is bothersome and worse than annoying.
Well Shawyer gave us his equations to predict force and he may have other constraints.
I have not found the actual equation that Dr. White at NASA uses to predict forces.
I have seen Dr. White's derivation for the electron mass, Bohr radius, gravitational coupling constant, his MHD plasma analogy, and Microsoft Excel spreadsheet predictions (see attached). But I don't know what actual equations he used in that Microsoft Excel spreadsheet to make the prediction.
Can anyone please provide Dr. White's equation to predict the thrust force from his electron-positron virtual particle quantum vacuum theory?
Seriously, we have numerical comparisons of Shawyer's and McCulloch's predictions with experiments (see : http://forum.nasaspaceflight.com/index.php?topic=29276.msg1276053#msg1276053 ).
Some people have even spent time writing a Wikipedia article on "Quantum Vacuum Plasma Thruster" http://en.wikipedia.org/wiki/Quantum_vacuum_plasma_thruster but have failed to provide an equation to calculate the thrust force from such a "Quantum Vacuum Plasma Thruster."
This is an appeal to also include Dr. White's quantum-vacuum-plasma thrust-force-prediction equations.
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#2618 by Rodal on 25 Oct, 2014 20:35
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Also, can somebody tell me how you get momentum out of group velocity?
'Cuz I thought there was no relationship whatsoever between the two.
Yes certainly, that is easy to show. For example, for a free, non-relativistic quantum mechanical particle of mass m and wavenumber k, for which we have E = (hk)^2/(2m) and angular frequency omega = h k^2/(2m) (hence we have quadratic dispersion in this case). We can calculate the group velocity (as the partial derivative of the angular frequency with respect to k) for this dispersion as vg=hk/m and this is perfectly consistent with the movement of a semiclassical particle for which the momentum is p = hk and the group velocity thus p/m = vg, or:
momentum = groupveloctiy * mass
Notice that for this case the phase velocity (omega/k) is hk/(2m) which is 1/2 of the group velocity, and hence it is the phase velocity the one that is not directly related (by mass) to the momentum.
Also, it is obvious that for the case in which a linear dispersion would apply the group velocity and the phase velocity would be identical. For example, for light in vacuum, phase and group velocity (for plane waves) are identical due to the linear dispersion omega = k * c, obviously.
Before anyone jumps the gun: look at the careful words and equations I chose, and please don't use Wikipedia as a reference to argue the above points. -
#2619 by Notsosureofit on 25 Oct, 2014 21:19
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Next you can mention that photons don't have a linear dispersion in a waveguide w/ one exception.