Author Topic: EM Drive Developments Thread 1  (Read 764364 times)

Offline Rodal

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Re: EM Drive Developments
« Reply #3460 on: 11/27/2014 12:53 PM »
Ok, time for me to demonstrate my lack of comprehension here again:

1) The Chinese paper says the thermal increase was greatest at the small end of the device.

2) Yet if I remember right, the thrust was towards the large end.

....

1) No, as I remarked (in bold) in my message http://forum.nasaspaceflight.com/index.php?topic=29276.msg1293800#msg1293800, Fig.1 of the 2014 Chinese paper (attached below) shows the force (indicated by "F" at the small end) directed towards the small end.  The same end that gets heated up the most and gets heated much faster: the small end.

2) As apparent from the discussion we had with Mulletron several pages ago, the EM Drive researchers present contradictory and sometimes (as in Shawyer) even self-contradictory information concerning thrust direction.  As remarked by Mulletron, Shawyer defines thrust in the opposite direction as to what is the conventional definition of thrust in aerospace.   The lack of clarity of different authors in showing clearly the direction of thrust and defining thrust as per standard conventions should be very disappointing (to say the least) to anyone looking seriously at these experiments.   To confuse matters further, take a look at Shawyer's chart below: where Shawyer admits that different places measured force in opposite directions, and that Shawyer himself measured force for the "Demonstrator" in opposite directions (214 in "Shawyer thrust" direction and 243 in "Shawyer reaction" direction").  Shawyer indicates the Chinese (NWPU) as measuring force in the "Shawyer reaction" direction, which Shawyer defines as directed towards the small end, and this is consistent with Fig.1 of the Chinese 2014 paper attached below.

3) If the Chinese had a dielectric on the large end interior surface, I would interpret it as insulating the large end from direct heating by eddy currects from the axial magnetic field and hence only the center of the small end being heated directly through the thickness. 

Otherwise, if the Chinese are measuring significant thrust without a dielectric (so much then for NASA's remarks concerning the importance of the dielectric to couple with the Quantum Vacuum !) one would need to analyze the actual magnetic field in this cavity: does the axial magnetic field in the transverse electric operating mode only contact the small end and does not contact the large end? (This is the interpretation that follows from the Chinese paper.).

 Later (a slower diffusion process) the large end would still be heated by conduction from the walls (as the thermal diffusivity and thermal conductivity of copper is -relatively to other materials in general- very high).  This will be shown as the large end having the same temperature rise as the walls.  This is what is observed. 

I leave it to others to come up with an interpretation using the Quantum Vacuum, Woodward effect, or other exotica (non-classical physics).

4) Kudos to the Chinese for being the first researchers inserting thermocouples throughout the cavity to measure and display temperature vs. time at different locations (instead of summarily dismissing thermal effects as done by others or to use an infrared camera to look at the outside of the cavity with very low resolution instead of measuring the inner surface temperature which is what matters, due to the skin effect).  Neither Shawyer nor NASA had inserted thermocouples on the inner surfaces to measure temperature vs. time.

5) To this date, nobody (not the Chinese, not Shawyer, not Cannae and not NASA) has reported force measurements of the EM Drives in a vacuum, and nobody has reported measurements as a free-body (as done by Goddard with his early rocket experiments or by Freeman and Taylor under Project Orion for their explosive-impulsively loaded experiments). 
« Last Edit: 11/27/2014 04:41 PM by Rodal »

Offline ThinkerX

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Re: EM Drive Developments
« Reply #3461 on: 11/27/2014 08:55 PM »
::Memo to self.  Post while awake!  It helps with reading comprehension.::

Rodal -

So if I follow you correctly this time, you advocate a purely or mostly thermal explanation for the thrust produced by the Chinese devices?

And, in one of the more recent links, I seem to remember Woodward testing his device in an improvised (?) vacuum chamber. 

Offline cuddihy

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Re: EM Drive Developments
« Reply #3462 on: 11/27/2014 11:16 PM »
Rodal, this has to be an NSF first - professional physics paper rebuttal exclusive to NSF! Impressive.

It would be possible for Eagleworks to eliminate thermal buckling as source of observed force by simply changing the attachment point of the device to the balance, no?

-ed: what I mean is if they attached the device at a different point, for instance, by a strut attached to both the small and large end, it should eliminate buckling force, correct?
« Last Edit: 11/28/2014 05:24 PM by cuddihy »

Offline Rodal

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Re: EM Drive Developments
« Reply #3463 on: 11/28/2014 02:27 PM »
::Memo to self.  Post while awake!  It helps with reading comprehension.::

Rodal -

So if I follow you correctly this time, you advocate a purely or mostly thermal explanation for the thrust produced by the Chinese devices?

I have found a number of classical physics mechanisms for the results: thermal buckling (published in this forum) under TE modes, thermoelastic dynamic coupling (have obtained solution, too complicated and lengthy to publish in this forum) under TE modes, and electric charge buckling (similar to what happens in MEMS) under TM modes.  All three of this require very thin (significantly less than 1/16 of an inch) copper thickness.

Concerning an exotic physics explanation, it is interesting that this latest paper by Prof. Juan Yang (2014) in its section 5.2.2 "Cavity surface temperature variation" explains the experimental fact that the inner surface center of the small base of the truncated cone experiences a much higher temperature and much higher temperature rise than the other surfaces using similar group velocity argumentation (based on the earlier numerical calculations by Prof. Yang).  The Chinese paper never discusses whether they used a dielectric that could have insulated the big end.  Their lack of discussion of any dielectric and the fact that they argue that the measured force towards the small end and the temperature increase of the small end are due to the group velocity leads one to understand that the Chinese did not use a dielectric.   

They write that the wavelength (lambda) at the small end needs to be close to the cut-off wavelength (lambdaC) lambda=lambdaC, such that the group velocity is close to zero vg = c Sqrt[1- (lambda/lambdaC)^2] = 0 at the small end. They write that at the large end the required wavelength of electromagnetic waves is the free-space wavelength (lambda0) such that the the group velocity at the large end is vg = c Sqrt[1- (lambda0/lambdaC)^2]. They write that this indicates that the electromagnetic wave energy transfer to the small end must all be converted into heat within the skin depth of the small end face and that this agrees with their previous numerical calculations for an unequal force pointing towards the center of the small end.

So, the Chinese use similar "group velocity, free-space wavelength and cut-off wavelength" rationale as Shawyer.  However, the Chinese have conducted a more thorough experimental program than Shawyer: the Chinese have conducted numerical finite element analysis of the TE modes (I have not seen similarly reported analysis by Shawyer) and the Chinese have measured and reported the effect of temperature on the frequency and Quality "Q" factor.

Even if one dismisses Shawyer's and the Chinese explanation, the fact remains that they claim to have measured a signficant force pointing towards the small end and that their temperature measurements show that the small end heated much more and with a much higher temperature rise than the large end. 

These experimental results are completely contrary to Greg Egan's http://gregegan.customer.netspace.net.au/SCIENCE/Cavity/Cavity.html  temperature (that shows significantly higher temperature at the walls than at the ends:)

and force results. I think that Greg Egan's temperature calculations are incorrect:  Egan does not take into account eddy-current heating from the axial magnetic field in the TE modes, and Egan relies on a straight heat conversion from the energy density (which to me is an incorrect way to calculate temperature, as heat transfer is not due to energy density but it is due to specific heat transfer mechanisms: mainly eddy current heating in the TE mode as the electric field in the TE mode must be zero at the inner surface).
« Last Edit: 11/28/2014 03:45 PM by Rodal »

Offline Rodal

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Re: EM Drive Developments
« Reply #3464 on: 11/28/2014 02:47 PM »
1) No, as I remarked...

2) As apparent from the discussion we had with Mulletron...

3) If the Chinese had a dielectric...

4) Kudos to the Chinese...

5) To this date, nobody...

Rodal: After giving thanks for making it thru a year of "massive" life changes, I sit again before the screen and keyboard and offer you thanks for your patient repetition, over and over again, regarding these results.  And the work which you prosecute with remarkable thoroughness.

At least I grasp at real straws with detectable mass.

(You too, Mulletron, Frobnicat, and others.)

Thank you  :)

Offline Rodal

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Re: EM Drive Developments
« Reply #3465 on: 11/28/2014 02:53 PM »
Rodal, this has to be an NSF first - professional physics paper rebuttal exclusive to NSF! Impressive.

It would be possible for Eagleworks to eliminate thermal buckling as source of observed force by simply changing the attachment point of the device to the balance, no?

Thank you  :).

The best way to eliminate the possibility of thermal buckling (or electric charge buckling as experienced in MEMS) or thermoelastic dynamic coupling is simply to make the copper wall thick enough.  I am confident that for the power inputs and diameter dimensions that have been used a 1/4 inch thickness of copper would be significantly more than enough to rule out the possibility of buckling.  1/8 of an inch is much more than enough for the NASA experiments.

Concerning support if the whole truncated cone has equal stiffness it would not make much difference where it is supported along the axis of the cone, as the reaction force still would be transmitted.  In a real situation there may be compliance at the connections that will diminish the measured dynamic magnification factor of the pendulum response, but the reaction will still be measurable (although the dynamic magnification factor may be smaller due to greater compliance: lower stiffness at the connections).  So I think that the best way to rule out buckling is simply to employ thicker copper, as buckling is a nonlinear function of thickness.
« Last Edit: 11/28/2014 03:05 PM by Rodal »

Offline Ron Stahl

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Re: EM Drive Developments
« Reply #3466 on: 11/28/2014 04:02 PM »
. . .To this date, nobody (not the Chinese, not Shawyer, not Cannae and not NASA) has reported force measurements of the EM Drives in a vacuum, and nobody has reported measurements as a free-body (as done by Goddard with his early rocket experiments or by Freeman and Taylor under Project Orion for their explosive-impulsively loaded experiments).

This is why I have taken the stand that I don't think there's anything here.  Given all the proposed theories of operation violate one important part of accepted science or another and that they don't get thrust in vacuum, it seems very odd to me that anyone gives this their attention.  The fact this had lots of funding for years, and finally the Brits cut it loose, seems explanation enough.

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #3467 on: 11/28/2014 04:52 PM »
Finally got a few (snowed in) minutes to look at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator.

g= (X[subm,n])^2*c^2*lambda*((1/a^2)-(1/b^2)) where a anb b are the end plate radii and the X are the Bessel function zeros.  Lambda < cutoff wavelength.

Notice that the axial index does not appear here but should appear when forces are derived.  So-so for now.

Edit: Should have mentioned: to 1st order using massless, perfectly conducting cavity.
« Last Edit: 11/28/2014 05:05 PM by Notsosureofit »

Offline Rodal

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Re: EM Drive Developments
« Reply #3468 on: 11/28/2014 06:12 PM »
Finally got a few (snowed in) minutes to look at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator.

g= (X[subm,n])^2*c^2*lambda*((1/a^2)-(1/b^2)) where a anb b are the end plate radii and the X are the Bessel function zeros.
...

The zeros of the Bessel functions of the first kind (J) ?

BesselJZero[0, 1] = 2.40483
BesselJZero[0, 2] = 5.52008
BesselJZero[0, 3] = 8.65373
and so on?
« Last Edit: 11/28/2014 06:13 PM by Rodal »

Offline Notsosureofit

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Re: EM Drive Developments
« Reply #3469 on: 11/28/2014 06:45 PM »
Finally got a few (snowed in) minutes to look at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator.

g= (X[subm,n])^2*c^2*lambda*((1/a^2)-(1/b^2)) where a anb b are the end plate radii and the X are the Bessel function zeros.
...

The zeros of the Bessel functions of the first kind (J) ?



BesselJZero[0, 1] = 2.40483
BesselJZero[0, 2] = 5.52008
BesselJZero[0, 3] = 8.65373
and so on?

X[subm,n] = m-th root of dJ[subn](x)/dx = 0

[1,0]= 3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc

Quickie calculation to rotate waveguide into doppler frame for g.  Needs more work but should be able to get to forces if I get time to keep head clear.
« Last Edit: 11/28/2014 06:47 PM by Notsosureofit »

Offline Rodal

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Re: EM Drive Developments
« Reply #3470 on: 11/28/2014 08:36 PM »
Finally got a few (snowed in) minutes to look at the proposition that dispersion caused by an accelerating frame of reference implied an accelerating frame of reference caused by a dispersive cavity resonator.

g= (X[subm,n])^2*c^2*lambda*((1/a^2)-(1/b^2)) where a anb b are the end plate radii and the X are the Bessel function zeros.
...

The zeros of the Bessel functions of the first kind (J) ?



BesselJZero[0, 1] = 2.40483
BesselJZero[0, 2] = 5.52008
BesselJZero[0, 3] = 8.65373
and so on?

X[subm,n] = m-th root of dJ[subn](x)/dx = 0

[1,0]= 3.83, [1,1]=1.84, [1,2]=3.05, [2,0]=7.02, [2,1]=5.33, [2,2]=8.54, [3,0]=10.17, etc

Quickie calculation to rotate waveguide into doppler frame for g.  Needs more work but should be able to get to forces if I get time to keep head clear.

Thanks.  For anybody interested, these values can be found on page 411 of this classic:

Handbook of Mathematical Functions, Abramowitz and Stegun, National Bureau of Standards, 3rd printing, 1965

http://www.amazon.com/Handbook-Mathematical-Functions-Formulas-Mathematics/dp/0486612724/ref=sr_1_1?ie=UTF8&qid=1417210659&sr=8-1&keywords=Handbook+of+Mathematical+Functions%2C+Abramowitz+and+Stegun

Also, for those with Mathematica, here is a code to compute them:   http://www.me.rochester.edu/courses/ME201/webexamp/derbesszer.pdf

« Last Edit: 11/28/2014 09:27 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3471 on: 11/28/2014 10:01 PM »

So...do we have a straight thermal artifact/effect?  Or a thermal/artifact effect plus something else?


IMHO, we have heat artifacts (mostly evident to me in the TE012 plot, figure 22 page 18, and through Rodal's exhaustive work) and something else. That something else is IMHO related to Casimir effects, as I've posted.

It certainly is interesting how it seems that TE mode seems to be the best Q thruster solution in terms of input power to thrust. I've been torn between the diamagnetic QED vacuum idea and the asymmetric QV/RF interaction with atoms, not summing to zero in the asymmetric cavity, giving rise to a force. Given the TE mode outlier, I think the answer is both.  I remember Dr. White mentioning in the video I recently posted here, that a great RF solution doesn't necessarily mean a great Q thruster solution. I've taken that to heart.

Over the last few days, I've been trying fit all the Casimir momentum/dielectric stuff I've posted over the last few months, into the framework of Cavity QED. I think this is the final concept to understand in order to create a fully functional QV framework in order to describe the Anomalous thrust from these two devices. I can't find a single paper on Casimir cavity QED, but I've found talk about this stuff dating way back to 2004. These guys were chasing the same idea long long ago it turns out.

http://cosmoquest.org/forum/showthread.php?14897-Casimir-Effect-and-Vacuum-Fluctuation-Propulsion

In a nutshell, what I'm getting at here (and I'll put it into math if I can ever find the confidence to express ZPE IIRC 1/2 hbar omega for the given frequencies inside a sloping cavity), in a sloping resonant Casimir cavity, you end up with a situation inside the cavity where the modes allowed isn't just a simple to derive value, as you would get in parallel plates for example (see the Milonni video). You end up with a continuously changing value over the length of the cavity. This Casimir force acts on the atoms in the cavity. That is one side of the interaction....... The other side of the interaction is the RF behaving in a similar manner, both interacting with the atoms in the air and dielectric in the cavity. The resulting non zero summation of these competing forces is IMHO the cause of the thrust.

So essentially I've reached the pinnacle of this avenue with a horrendous math problem that is Dr. Milonni caliber. Will I ever figure it out? Probably not. It is fun trying to find One-Eyed Willy's gold though. Somebody will eventually figure it out.




« Last Edit: 11/28/2014 10:49 PM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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Re: EM Drive Developments
« Reply #3472 on: 11/29/2014 02:56 AM »

So...do we have a straight thermal artifact/effect?  Or a thermal/artifact effect plus something else?


IMHO, we have heat artifacts (mostly evident to me in the TE012 plot, figure 22 page 18, and through Rodal's exhaustive work) and something else. That something else is IMHO related to Casimir effects, as I've posted.

It certainly is interesting how it seems that TE mode seems to be the best Q thruster solution in terms of input power to thrust. I've been torn between the diamagnetic QED vacuum idea and the asymmetric QV/RF interaction with atoms, not summing to zero in the asymmetric cavity, giving rise to a force. Given the TE mode outlier, I think the answer is both.  I remember Dr. White mentioning in the video I recently posted here, that a great RF solution doesn't necessarily mean a great Q thruster solution. I've taken that to heart.

Over the last few days, I've been trying fit all the Casimir momentum/dielectric stuff I've posted over the last few months, into the framework of Cavity QED. I think this is the final concept to understand in order to create a fully functional QV framework in order to describe the Anomalous thrust from these two devices. I can't find a single paper on Casimir cavity QED, but I've found talk about this stuff dating way back to 2004. These guys were chasing the same idea long long ago it turns out.

http://cosmoquest.org/forum/showthread.php?14897-Casimir-Effect-and-Vacuum-Fluctuation-Propulsion

In a nutshell, what I'm getting at here (and I'll put it into math if I can ever find the confidence to express ZPE IIRC 1/2 hbar omega for the given frequencies inside a sloping cavity), in a sloping resonant Casimir cavity, you end up with a situation inside the cavity where the modes allowed isn't just a simple to derive value, as you would get in parallel plates for example (see the Milonni video). You end up with a continuously changing value over the length of the cavity. This Casimir force acts on the atoms in the cavity. That is one side of the interaction....... The other side of the interaction is the RF behaving in a similar manner, both interacting with the atoms in the air and dielectric in the cavity. The resulting non zero summation of these competing forces is IMHO the cause of the thrust.

So essentially I've reached the pinnacle of this avenue with a horrendous math problem that is Dr. Milonni caliber. Will I ever figure it out? Probably not. It is fun trying to find One-Eyed Willy's gold though. Somebody will eventually figure it out.

Cavity QED with Single Atoms and Photons

T. E. Northup, K. M. Birnbaum, A. Boca, A. D. Boozer, J. McKeever, R. Miller, and H. J. Kimble
Norman Bridge Laboratory of Physics 12-33, California Institute of Technology, Pasadena, CA 91125

http://authors.library.caltech.edu/2781/1/NORaipcp05.pdf
« Last Edit: 11/29/2014 01:20 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3473 on: 11/29/2014 09:19 PM »
Challenge your preconceptions, or they will challenge you. - Velik

Offline Rodal

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Re: EM Drive Developments
« Reply #3474 on: 11/29/2014 09:43 PM »
Slide 66  :)

http://aphyr.com/media/pwl-2014-casimir.pdf

He wrote this in 2009/06/07:

"I just finished my last undergrad assignment—Hector's E&M test. Got an A in the course, actually, which really surprised me. I'm now done with Carleton, and graduate in a week. I'll be living in Madison for a few weeks, and then moving out to San Francisco for my new job. Should be exciting!"  http://aphyr.com/tags/carleton

And here is his presentation as of that time:  http://aphyr.com/media/comps.pdf

Anyway here is his October 22, 2014 video presentation at the Meetup group in San Francisco http://www.meetup.com/papers-we-love-too/events/187600122/ .  Quite a good presenter, he involves the audience and makes it simple and practical.


At approximately 47:30 he addresses the EM Drive, he says it appears to violate conservation of momentum, which is "not good", he says it is a "mystery".   He doesn't buy Dr. White's virtual particles plasma explanation as the quantum vacuum "is not a plasma":

« Last Edit: 11/29/2014 10:23 PM by Rodal »

Offline ThinkerX

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Re: EM Drive Developments
« Reply #3475 on: 11/29/2014 11:55 PM »
Professor McCulloch has updated his blog:

http://physicsfromtheedge.blogspot.com/

This time he included a list of anomalies his theory predicts or accounts for in full or in part, including some terrestrial ones:

Quote
Cosmic acceleration: MiHsC predicts this as an effect of the cosmic horizon.
 The low-l cosmic microwave background anomaly: MiHsC predicts it as above.
 Cosmic mass: just enough to keep the cosmos closed: MiHsC predicts it.
 The anomalous motion of galaxy clusters: MiHsC predicts it without dark matter.
 Bullet cluster: MiHsC might fit, but there's not enough data to test it yet.
 The galaxy rotation anomaly: MiHsC predicts it without dark matter.
 Globular cluster rotation anomaly: MiHsC might fit, needs a computer model.
 Observed minimum galactic masses: MiHsC agrees.
 Is Alpha Centauri-C bound?: MiHsC predicts it's bound, agrees with independent data.
 Flyby anomalies: MiHsC agrees partly, but the analysis is incomplete.
 Pioneer anomaly: MiHsC agrees, but there's another 'complex' thermal explanation.
 Tajmar effect: MiHsC predicts it.
 EmDrive: MiHsC predicts it.
 Poher experiments: MiHsC is consistent, not enough data to test numerically.
 Podkletnov effect: MiHsC predicts the non-spinning part of it. needs more work..
 Sonoluminescence: MiHsC predicts the observed core temperature.
 Planck mass: MiHsC predicts it within 26%.

And things on his 'to look at' list:

Quote
Quasars are aligned with each other and cosmic filaments.
 The Andromeda satellite galaxies orbit in a disk.
 Galactic relativistic jets.
 The wide binary rotation anomaly.
 Anomalous, non-tidal, increase of lunar distance.
 Increase in the Astronomical Unit.
 Modanese effect: jump of masses near a cooler superconductor.
 Anomalies in the gravitational constant, big G.

To me, it seems as though his theory has more supporting evidence going for it than does Dark Matter, Dark Energy, or String theory.

Offline Mulletron

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Re: EM Drive Developments
« Reply #3476 on: 11/30/2014 12:35 AM »
Slide 66  :)

http://aphyr.com/media/pwl-2014-casimir.pdf

At approximately 47:30 he addresses the EM Drive, he says it appears to violate conservation of momentum, which is "not good", he says it is a "mystery".   He doesn't buy Dr. White's virtual particles plasma explanation as the quantum vacuum "is not a plasma":


Good find on the video. Indeed the mystery here is the still not well accepted or understood behavior of the QV. From what I've learned so far about the QV and quantum fluctuations, which I may be wrong because I'm learning about them, is that these fluctuations don't have a defined or net momentum. They don't have any particular direction of travel. Also they are known to violate conservation of energy for short periods of time, and apparently that is okay over very short periods of time. Over the long haul, energy is conserved, which is nice.

But using the QV approach, would make the thruster appear to violate conservation of momentum at first.

So here's some observations I have based on the above.....The Dr. White approach of pushing on the QV, does violate conservation of energy and momentum. Here's why I think so. He is essentially trying to push on something (particle pairs) which later goes on carry away that momentum into oblivion when they annihilate, thus destroying the energy used to impart momentum to those virtual particles. Also, the act of trying to push on something that isn't there, at least to me, has no meaning. See below, for Ralph's explanation.

The other issue is calling the QV a plasma. We all know that is bad. He seems to have switched to Q-thruster, which is nice. That'll keep those celebrity physicists off his back, but the damage is done. Couldn't  Sean Carroll and John Baez have picked a more academic thing to argue about instead of nitpicking words? Deplorable. But I digress...

What I'm exploring with all this QV stuff is how to convert this random walk, see video below, into a less random walk, with a bias in direction I want to fly. I'm trying to figure out how the shape of the cavity and the dielectrics (should work with just air too, just not as well) used can allow the QV to push a particle in the direction of intended travel, when RF is switched on, resulting in thrust. I'm not trying to push against the QV, instead I'm letting the QV do all the pushing. I'm trying to show, that the anisotropic rf environment inside the emdrive can influence the isotropic vacuum environment, which in turn becomes an anisotropic vacuum environment locally inside the cavity. I don't think this is woo woo science, just not easy to understand science.

Edit:
Adding on to the above, and the stuff posted way back about about how the QV interacts with dielectrics....Inside the resonant cavity, given the nature of the Casimir effect, there is no doubt a very small, but non zero force, similar to what was measured by Casimir et al using parallel plates and cantilevers. Being that the walls of the cavity are far away from each other and not parallel, this force must be indeed extremely small. Don't even ask me to calculate it. :)

We know that copper conical frustums don't try and move on their own. Only when RF is applied is a force measured. So the cavity must be serving to amplify and direct the effect of these vacuum fluctuations in a fashion similar to here: http://www.sciencedaily.com/releases/2014/07/140722091425.htm. Sorry to post a news article, but that's all I have at the moment. This is all pretty new stuff, published papers on amplifying vacuum fluctuations and Casimir cavities are pretty thin. I did post a bunch of papers way back (page 88) that led me to believe that the force inside Casimir cones was repulsive.

So that pretty much closes the rough idea loop on how this thing might work, in my mind anyway.

http://youtu.be/lWlkDXtUDgQ?list=UUrumw1oc1Tt8hL3jGFtXDMg





« Last Edit: 11/30/2014 04:54 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

Online aero

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Re: EM Drive Developments
« Reply #3477 on: 11/30/2014 02:07 AM »
I've been off fooling with Maxwell's equations in the time domain for a little while. Still not done but I did make up a little table of information that might interest some folks. I found it interesting at least.

      resonate cavity
Dielectric   resonate   length, d
constant   frequency   d=3*Lamda/2
1.1   2.12532E+009   0.2115868083
1.7599   1.88050E+009   0.2391327204
2.3   1.76365E+009   0.2549755493
2.6   1.71550E+009   0.2621326819
2.8   1.68780E+009   0.2664351324
4.2   1.54831E+009   0.2904389858

The first column is the dielectric constant of the P.E. dielectric resonator. Turns out that the Brady cavity dielectric was neither soft nor dense. The dielectric constant for 100% density P.E. is 2.3, and it is 1 for 0% density of course. It looks like the Brady cavity dielectric was about 1.76, or about 50% P.E. density.

You'll note that as the dielectric constant increases, the resonate frequency goes down so the wavelength goes up, hence the resonate length, 2 d = n Lamda, n= 1, 2, 3, 4, ... For the Brady cavity, n = 3 so d= 3 Lamda / 2. The resonate length of the cavity goes up, but of course the physical length of the cavity doesn't change.

I've been trying to formulate a thought experiment to examine the momentum as the RF radiation enters and leaves the dielectric, but no luck so far. Does light slow down in the dielectric? The above numbers would say that it speeds up, that is if light speed = c in the empty part of the cavity. What does momentum say? E = h f and p = h f /c where h is Plancks constant and f is frequency. Light slows down as it enters water, then speeds again as it exits. The RF waves must behave similarly on entering and leaving the dielectric.

So I wonder what really happens inside the cavity?  ;)
Retired, working interesting problems

Offline cuddihy

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Re: EM Drive Developments
« Reply #3478 on: 11/30/2014 02:14 AM »
Rodal, this has to be an NSF first - professional physics paper rebuttal exclusive to NSF! Impressive.

It would be possible for Eagleworks to eliminate thermal buckling as source of observed force by simply changing the attachment point of the device to the balance, no?

Thank you  :).

The best way to eliminate the possibility of thermal buckling (or electric charge buckling as experienced in MEMS) or thermoelastic dynamic coupling is simply to make the copper wall thick enough.  I am confident that for the power inputs and diameter dimensions that have been used a 1/4 inch thickness of copper would be significantly more than enough to rule out the possibility of buckling.  1/8 of an inch is much more than enough for the NASA experiments.

Concerning support if the whole truncated cone has equal stiffness it would not make much difference where it is supported along the axis of the cone, as the reaction force still would be transmitted.  In a real situation there may be compliance at the connections that will diminish the measured dynamic magnification factor of the pendulum response, but the reaction will still be measurable (although the dynamic magnification factor may be smaller due to greater compliance: lower stiffness at the connections).  So I think that the best way to rule out buckling is simply to employ thicker copper, as buckling is a nonlinear function of thickness.

Unfortunately there are plenty of excuses possible for not changing the end caps if you're ambivalent about falsification. From the perspective of White et al, "we just got it working!..."

So I doubt they'll jump on any test that requires physically modifying a "working" device. I'm suggesting, however, if you instead support the device at both ends with a fork-shaped strut, Eagleworks could falsify or confirm the thermal buckling theory without changing the actual cone.
« Last Edit: 11/30/2014 02:15 AM by cuddihy »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3479 on: 11/30/2014 02:25 AM »
I've been trying to formulate a thought experiment to examine the momentum as the RF radiation enters and leaves the dielectric, but no luck so far. Does light slow down in the dielectric?

IIRC it is the phase velocity that changes when light/RF enters a medium and is refracted IAW Snell's law. So frequency stays the same, c (in a vacuum) stays the same, phase velocity changes. The speed of light does slow in a medium though by absorption and re-emission. Hope I answered what you were asking for.

Here:
http://en.wikipedia.org/wiki/Refractive_index#Dielectric_constant
« Last Edit: 11/30/2014 03:15 AM by Mulletron »
Challenge your preconceptions, or they will challenge you. - Velik

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