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#1420 by Rodal on 19 Mar, 2015 10:44
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......
As for the scalar-tensor theory of gravity, predictions (falsifiability) for the EmDrive have been calculated by Pr. Fernando Minotti in his peer-reviewed paper Scalar-tensor theories and asymmetric resonant cavities.
This is the citation for the peer-reviewed version of the article:
Scalar-tensor theories and asymmetric resonant cavities
F. O. Minotti
Gravitation and Cosmology
July 2013, Volume 19, Issue 3, pp 201-208
Date: 29 Aug 2013
The author recognizes that his theory is "highly speculative" (his own words) and that "The weakest part of the theory seems to be that there is no clear way of preventing large gravitational effects due to the magnetic field of the Earth" (large gravitational effects due to the Earth's magnetic field which are contrary to present evidence)
Here is a description of this journal, from its publisher (Springer):
"Gravitation and Cosmology is a peer-reviewed periodical, dealing with the full range of topics of gravitational physics and relativistic cosmology and published under the auspices of the Russian Gravitation Society and Peoples Friendship University of Russia. The journal publishes research papers, review articles and brief communications on the following fields: theoretical (classical and quantum) gravitation; relativistic astrophysics and cosmology, exact solutions and modern mathematical methods in gravitation and cosmology, including Lie groups, geometry and topology; unification theories including gravitation; fundamental physical constants and their possible variations; fundamental gravity experiments on Earth and in space; related topics. It also publishes selected old papers which have not lost their topicality but were previously published only in Russian and were not available to the worldwide research community."
EDITOR-IN-CHIEF:
Vitaly N. Melnikov
Dr. Sci., Prof., Head of the Center for Gravitation and Fundamental Metrology, VNIIMS; and Deputy Director of the Institute of Gravitation and Cosmology of Peoples’ Friendship University of Russia (PFUR), Moscow, Russia -
#1421 by Rodal on 19 Mar, 2015 11:15
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NASA's spaceflight internal "search" capabilities for information posted in these threads is, unfortunately, practically worthless. It is not uncommon to search for terms and get no answers.Re. Hypotheses looked at - where does our lengthy discussions of dark matter fit?
we had a lengthy discussion of dark matter and i didn't know about it?!
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1347946#msg1347946
http://www.sciencedaily.com/releases/2015/03/150306091617.htm
http://phys.org/news/2015-03-mini-black-holes-lhc-parallel.html
Well, I just searched the complete advanced concepts forum and found no mention of dark matter on any EM drive developments thread, so I guess either my memory is faulty or there has been some heavy clean-up of what many consider to be "Uggy-Bogy" science. That means we won't be including it in "hypotheses discussed."
It is actually better to use Google to search NASA's Spaceflight forum. For example, to search for what you are looking for, if you enter the following into Google:
EM Drive NASA Spaceflight dark matter
you will get a number of hits:
EM Drive Developments - related to space flight applications ...
forum.nasaspaceflight.com/index.php?topic...660
NASASpaceFlight.com
Feb 15, 2015 - 20 posts - 7 authors
But, check out the Axion Dark-Matter Experiment in the PNAS article. That is much much more sensitive than the EM Drive - they are looking for ...
160 20 posts Nov 13, 2014
76 20 posts Oct 5, 2014
56 20 posts Sep 29, 2014
More results from forum.nasaspaceflight.com -
#1422 by Mulletron on 19 Mar, 2015 11:30
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All:
Sorry I didn't make the time to participate in this ME-Drive forum for the last 6-to-8 months up, but I will try to catch up with everyone else in due course. That said lets try to answer the questions that popped up since my morning post.
1. I was not the lead author for the Eagleworks' 2014 AIAA/JPC paper and in fact I only supplied pictures and data for same during that period because Dr. White thought that my time was best spent in the lab gathering data instead of report writing. Thus some of the details that Dr. Rodal is looking for may have been lost or garbled in the report writing by the others on the author list.
2.0 The thrust vector for the four resonant modes examined in detail, (the cavity's fundamental TM010, TE012, TM211 & TM212 for our copper frustum is normally in the frustum's large OD to small OD direction for most, but not all the E&M resonant modes checked. However, one can also reverse this thrust vector for this copper frustum by just changing which excited resonant mode is used and/or mounting the dielectric discs at the large OD end of the cavity instead of the small OD end, see attached resonant mode map. Sorry, but a one size fits all solution to this EM-Drive thrust direction is not available in this venue because of the importance of the ExB phase relationship of the expressed Lorentz forces between the excited E&M fields and the possible dielectric and QV plasma flow phenomenon that may be at work in each resonant mode expressed. That is why this type of E&M thruster is so hard to get a handle on, for there are far too many degrees of freedom in the system to track let alone directly control.
3. The Eagleworks vacuum chamber's main body is made from 304L stainless steel while its swing out door is made from aluminum. Most of the nuts and bolts in the vacuum chamber are also made from 18-8, 304 or 316 stainless steel alloys.
Now to try to answer Dr. Rodal's specific questions:
"1) In the NASA experiments the truncated cone's center of mass moved towards the [ ? ] diameter end (where ? stands for big or small)"
For the TE012 and TM212 excited resonant modes, our copper frustum's center of mass moved toward the small OD end of the frustum when RF power was applied to the copper frustum.
"2) In the NASA experiments, we at NASA Eagleworks define the thrust force direction to be in the [? ] direction as the movement of the truncated cone's center of mass (where ? stands for same or opposite)"
For just the TE012 & TM212 excited resonant modes, the thrust force direction AKA thrust vector was observed to be in the same direction as the movement of the frustum's center of mass when RF power was applied to the frustum's magnetic loop antenna.
If I missed a question along the way keep asking, but I'll be in and out of the house for the rest of the day, so I may not get to answer them until late this evening or tomorrow afternoon USA based CST.
Best, Paul M.
I understand that we need to wait for Paul March to explicitly "re-verify" the manner in which thrust reversal was achieved, but it does appear to me that he has already addressed this in the above quote from Feb 14. Quoting Mr. March: "one can also reverse this thrust vector for this copper frustum by just changing which excited resonant mode is used and/or mounting the dielectric discs at the large OD end of the cavity instead of the small OD end". To my admittedly untrained eye, this appears to be in agreement with Dr. Rodal's earlier statements, and in conflict with Mr. Frobnicat's contention that reversal was achieved by simply rotating the entire mechanism 180 degrees.
And let's not forget about the "interesting failure" which produced thrust in the "wrong direction."
http://forum.nasaspaceflight.com/index.php?topic=36313.msg1335190#msg1335190
It would be nice to have the actual data concerning the thrust reversals without flipping the device. For me, word from the experimenter is good enough at least for now. Let's just hope this thing continues to be tested after the end of March.
I think that (until proven otherwise) the broken bolt also broke the Casimir-type geometry mentioned here:
http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.96.130402
One of the things I intend to test if I ever get this copper kettle I have to move in the first place. -
#1423 by Mulletron on 19 Mar, 2015 14:46
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These 1" thick by 6.25" (actually 6 5/16" because I left them a little wide for milling) wide HDPE circles need a ride in a lathe. Trouble is, I don't have a lathe.
Cutting these with a jigsaw was not fun. Because the HDPE was so thick, the waste material would just bunch up around the cut in long ribbons and it was very tough to see the cut. Normally such thick material would be cut at low speed, but running the saw at full speed helped to clear out the pesky waste material so I could see better.
Rest of pics:
https://drive.google.com/folderview?id=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM&usp=sharing
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#1424 by Rodal on 19 Mar, 2015 17:06
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These 1" thick by 6.25" (actually 6 5/16" because I left them a little wide for milling) wide HDPE circles need a ride in a lathe. Trouble is, I don't have a lathe.
Great idea to put the pictures in the google drive to be able to share them !
Cutting these with a jigsaw was not fun. Because the HDPE was so thick, the waste material would just bunch up around the cut in long ribbons and it was very tough to see the cut. Normally such thick material would be cut at low speed, but running the saw at full speed helped to clear out the pesky waste material so I could see better.
Rest of pics:
https://drive.google.com/folderview?id=0B4PCfHCM1KYoTXhSUTd5ZDN2WnM&usp=sharing
Thanks and Godspeed
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#1425 by Rodal on 19 Mar, 2015 19:14
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Paul's statement that "For the TE012 and TM212 excited resonant modes, our copper frustum's center of mass moved toward the small OD end of the frustum when RF power was applied to the copper frustum." Would seem to explicitly contradict the calculated chart as to the direction for those modes.
Please notice
1) The chart shows TM211 instead of TM212
2) The direction of the highest intensity Poynting vector fields is opposite in modes TM211 and TM212 (which I think should be labeled TM221 and TM222)
TM211 (without a dielectric) has a clear Poynting vector field (at 45, 135, 225 and 315 degrees in the azimuthal direction) pointing towards the small base of the truncated cone. It looks like TM211 would work even without a dielectric section.
TM212 (without a dielectric) has the maximum intensity Poynting vector field group (at 45, 135, 225 and 315 degrees in the azimuthal direction) pointing towards the big base of the truncated cone. The Poynting vector groups for TM212 seem to cancel out (by eyesight, I would have to integrate to be sure) or be slightly towards the small base. I would not be surprised if TM212 needs a dielectric to enhance the Poynting vector (will need to confirm this conjecture by computation).
The direction of the electromagnetic vectors should be irrelevant to @Frobnicat's conjecture (*) but it is of critical important to the ExB electromagnetic Poynting vector.
I am attaching my calculations for these two modes showing that the Poynting vector fields are in opposite directions for these two modes.
EDIT: corrected some minor issues with the vector field plots on 03/23/2015
Therefore the importance of these electromagnetic modes: if the EM Drive experiences forces in opposite directions for these two modes, this imparts a death knell to any mechanistic conjecture to explain the anomalous force (including the mechanistic conjectures of Mr. Frobnicat), as they would show that the force is electromagnetic and not mechanical in nature.
(*) @Frobnicat asked whether the direction of the electromagnetic vector should matter for heat production due to electromagnetic power dissipation. The answer is NO !, because of the 2nd Law of Thermodynamics: a reversal of the direction of the electromagnetic field cannot possibly lead to a cooling or a thermal contraction.
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#1426 by frobnicat on 20 Mar, 2015 01:10
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(*) @Frobnicat asked whether the direction of the electromagnetic vector should matter for heat production due to electromagnetic power dissipation. The answer is NO !, because of the 2nd Law of Thermodynamics: a reversal of the direction of the electromagnetic field cannot possibly lead to a cooling or a thermal contraction.
Never thought about cooling for even one second. That's not about direction (toward or away, this is AC anyway so symmetrically going back and forth), I was caring about the vector field going back and forth tangent to surface or normal to surface, as far as heating magnitude is concerned. And your reply was very clear and helpful, thank you.
What do you think of the formula used in the plot titled "S21 and surface integral of cavity with 1W input power" ? There appear to be no cross-product but a sum of e and b(h actually) fields' energy densities taken separately. Is it equivalent ? It looks to me like a piston model with electromagnetic energy considered pushing like pressure against displacement along the axis of the frustum (Z in the expression). There is electromagnetic pressure of course, but isn't it supposed to integrate to 0, at least in known frameworks ? Do you see what motivates this particular formula ?
Anyway, factually, using Eagleworks mode nomenclature for convenience, the reported experiments of "anomalous thrust..." show both TE012 and TM211 modes in the same direction (the small end). And the blue plot says it should really reverse between TE012 and TM211. I won't go into battle as saying that it definitely - how you say that ? ah yes - imparts a death knell to this blue plot, but those initial results do weaken the theoretical statement, to put that in diplomatic terms.
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#1427 by Rodal on 20 Mar, 2015 15:09
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Concerning the equation used in http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image, the discussion should preferably be carried on the following basis:
What do you think of the formula used in the plot titled "S21 and surface integral of cavity with 1W input power" ?
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Do you see what motivates this particular formula ?
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1) Preferably the author of the equation should explain what is the background, context and significance of the equation and the assumptions under which it holds.
2) The peers should review the equation (and the assumptions under which it holds). Review means "the equation appears in the following references" or "the equation cannot be found in the existing literature". Review means "the equation conflicts with experimental knowledge and/or accepted scientific principles and/or scientific logic etc."
While waiting for Paul March (@Star-Drive) to explain the background, context and significance of the equation, the following is apparent:
The terms in the http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image equation coincide with the Kronecker's delta (the unit dyadic) negative terms of Maxwell's stress tensor ("times the normal component in the z direction"). The remaining dyadic terms of Maxwell's stress tensor component are missing from this expression.
See:
Minkowski, H. (1908). "Die Grundgleichungen für die elektromagnetischen Vorgänge in bewegten Körpern". Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse: 53–111.
http://en.wikisource.org/wiki/Translation:The_Fundamental_Equations_for_Electromagnetic_Processes_in_Moving_Bodies
Abraham, M. (1909). "Zur Elektrodynamik bewegter Körper". Rendiconti del Circolo Matematico di Palermo 28: 1–28. doi:10.1007/bf03018208.
http://en.wikisource.org/wiki/Translation:On_the_Electrodynamics_of_Moving_Bodies_%28Abraham%29There is electromagnetic pressure of course, but isn't it supposed to integrate to 0, at least in known frameworks ?
What should integrate to zero (for no external forces, assuming a closed system of conservative forces) is the divergence of Maxwell's stress tensor minus the time derivative of Poynting's vector. The equation in question does not include all the terms in Maxwell's stress tensor (it lacks the dyadic product of E (or D) with E( or D) and the dyadic product of B (or H) with B (or H)), these missing terms have a different sign than the included terms, so no, there is no reason why the posted equation should integrate to zero (and what should integrate to zero anyway is the divergence of Maxwell's stress tensor minus the time derivative of Poynting's vector).There appear to be no cross-product but a sum of e and b(h actually) fields' energy densities taken separately. Is it equivalent ?
You maybe referring to equivalence of scalar components, for example, but there is no such apparent equivalence here either (for the equation in question and the scalar terms of Poynting's vector).
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Poynting's vector is the cross-product of E (or D) and B (or H): it is indeed a vector (a first order tensor). Maxwell's stress tensor is a 2nd order tensor involving dyadic product of base vectors.
A vector has a scalar component (its magnitude) and a direction (given by the base vectors).
A second order tensor has scalar terms, vector terms (perpendicular to the faces of the unit dyadic), and a dyadic basis (the dyadic product of the base vectors).
Strictly speaking, a vector cannot be equivalent to a 2nd order tensor anymore than a scalar can be equivalent to a vector. The divergence of Maxwell's stress tensor is a vector that is not equivalent to Poynting's vector. Actually, the divergence of Maxwell's stress tensor minus the time derivative of Poynting's vector gives the electromagnetic force. Strictly speaking, none of the above are equivalent (different quantities: different scalars, different vectors and a second order tensor: Maxwell's stress tensor).
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#1428 by Rodal on 20 Mar, 2015 16:14
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....
But this thread should really be focused on:
Anyway, factually, using Eagleworks mode nomenclature for convenience, the reported experiments of "anomalous thrust..." show both TE012 and TM211 modes in the same direction (the small end). And the blue plot says it should really reverse between TE012 and TM211. I won't go into battle as saying that it definitely - how you say that ? ah yes - imparts a death knell to this blue plot, but those initial results do weaken the theoretical statement, to put that in diplomatic terms.
EM Drive Developments - related to space flight applications
A discussion about EM Drive experiments to try to ascertain their validity and significance for space flight applications.
1) Experiments (like reversing at will the direction of the thrust from the small base to the big base directions) that would nullify yet another mechanism (like the one you proposed) pretending to show the EM Drive experiment as an artifact, are very important in that they advance our state of knowledge about "EM Drive Developments - related to space flight applications."
On the other hand, discrepancies in sign between a blue plot and other plots, do not rise to the same level of significance.
One explanation, for example, could be simply that one (or both) of the plots have the wrong sign. Such errors in presentation do not rise to the same level of significance.
Do you know how many plots and equations contain errata in Feynman's original QED and path integral publications?
Ultimately what matters is whether the EM Drive experiments show phenomena that can be used for spaceflight applications, and ultimately what will matter least is whether plots were mislabeled.
When finding a contradiction between plots, one should not rush to judgement to toll the bell that the experiment is an artifact: it may simply be an innocent error in labeling a plot.
2) That there may be labeling questions is shown by:
2a) What NASA Eagleworks labels as mode TM212 I have shown should be labeled TM222
2b) The mode labeled as TM211 in the "Anomalous ..." report was reported to occur at 1.9326 GHz and 1.9367
GHz, with COMSOL FEA frequency calculated at 1.947 GHz. Yet now they report mode labeled TM212 to be tested and to occur at about the same frequency range.
I calculate that the mode labeled "TM212" (which I think should be labeled TM222) -which does not appear in http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image should occur at a significantly higher frequency than TM211, never at the same frequency ( "TM212" at 2.49 GHz without dielectric and "TM211" at 2.01 GHz without dielectric). These modes were analyzed and labeled (I understand) by different engineers. It is possible that they may be one and the same mode that has been mislabeled.
3)All the emphasis you place on the signs on the blue NASA Eagleworks plot and the other plots (which could be just an error in labeling the plots), yet you ignore the fact that Roger Shawyer published experimental information showing his EM Drive Demonstrator Engine showed practically the same magnitude thrust was experimentally observed to be reversed: Shawyer reports forces in opposite directions (towards the big end and towards the small end of practically the same magnitude: 214 mN/kW and 243 mN/kW) for his Demonstrator engine.
The data being ignored (showing forces in opposite directions, towards the big end and towards the small end of practically the same magnitude), what should I say , oh yes, defenestrates, mechanical explanations for the EM Drive measurements being a mechanical artifact. -
#1429 by frobnicat on 20 Mar, 2015 23:14
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Thank for later part of previous answer. It does answer clearly to some aspects of my innocent questions, for the other aspects I'll have to learn German. Thank for editing the beginning. Unfortunately the tone is becoming a bit harsh so it becomes difficult to talk casually about just, you know, "what you think of ... patati patata", without resorting to lawyers. So I will stop asking casual questions.
...
1) Experiments (like reversing at will the direction of the thrust from the small base to the big base directions) that would nullify yet another mechanism (like the one you proposed) pretending to show the EM Drive experiment as an artifact, are very important in that they advance our state of knowledge about "EM Drive Developments - related to space flight applications."
Yes. The problem is that we have no experimental data (from Eagleworks) concerning such EM mode induced reversal.QuoteOn the other hand, discrepancies in sign between a blue plot and other plots, do not rise to the same level of significance.
If the discrepancies prevent to ascertain or leave ambiguity about the the experimental existence of reversal, then it becomes significant.QuoteOne explanation, for example, could be simply that one (or both) of the plots have the wrong sign. Such errors in presentation do not rise anywhere to the same level of significance.
The same blue plot is up for TE modes and down for TM modes. The sign changes in function of mode in the theoretical prediction (never mind up and down, a change of orientation is what is expected) and don't change in function of mode in the experiments.
Absence of proof is not proof of absence : that's why I say it is not a death blow to the theoretical formula used to get this plot. The magnitude also, of 10µN/W up or 20µN/W down is much higher than those recorded. That is also not by itself a nullification of the formula. It could be that the theory behind the formula is ok but that the exciting frequency is not right on peak, or too spread, or not enough spread. Very well. But excuse me, at some point, one is to say the case for the formula is weakened. Not more, not less. If saying that, after spending quite a lot of time of reading and checking the publicly available data, is immaterial, then all what we say on this forum is immaterial, and we should then all shut up and wait the next peer reviewed publication of those research.
I'm a very reasonable person. I do approach the thrust anomaly with a sceptical eye, but I wouldn't be here in the first place if I hadn't a little excitation at the prospect that it might be worth a discovery (of new physics or new possibility inside known physics). Most sceptical people hearing about the anomaly will dismiss the case on short notice, and having forged an opinion that it must be an artefact just plain don't care.
Sceptics that do care like me don't even require the EM thrust to exhibit reverse modes. It could be (in the hypothesis that there is indeed a thrust) that the still unknown principle of operation involved prevents any possibility of thrust toward the big end of the asymmetrical cavity (when it is a frustum). If the effect is checked on other scales, at other labs, is phenomenologically consistent and reproducible, all people that do care (sceptics and enthusiasts along) will be very pleased, even if there is no reverse mode. If it does show mode reversal, all the better, mechanistic artefact hypothesis (as unique source of signal) defenestrate right now. Other artefacts might hold. If it don't reverse, well then it don't reverse, and then neither EM thrust nor purely mechanistic explanations are ruled out, yet. Isn't it reasonable ?QuoteDo you know how many plots and equations contain errata in Feynman's original QED and path integral publications?
No I don't. But I'm sure that it attracted a lot more competent and sceptical peers and third parties to get involved than the experiments at Eagleworks so far.QuoteUltimately what matters is whether the EM Drive experiments show phenomena that can be used for spaceflight applications, and ultimately what will matter least is whether plots were mislabeled.
Showing a phenomena requires a minimum of care in the communication of the results. I find the communication from Eagleworks is reasonably clear and consistent most of the time, but unfortunately a bit scarce on some data, we would really like to see the "negligible thrusts" charts of tests without dielectric, as this could by itself be enough to "slaughter" the mechanistic thermal hypothesis. Also it would have been nice that the report gave the "detail" that the horizontal pendulum wasn't quite horizontal after all and that the tilt in axis played a role in stabilizing the equilibrium rest position. I doubt that without my attempts at clarifying the mechanical aspects of the experiment and my attention to "insignificant" problems of labels and scale we would have this little piece of extra info, with due thanks to Paul March for answering with clarity to my request on that (and taking time to check and take pictures, unfortunately hardly workable due to parallax). Before savagely assassinating the competing artefactual hypothesis shouldn't we be eager to learn all the gory details below the signal ?
Ultimately, if 10 years from now, the EM thrust is still in a state of indetermination, with people believing in real EM thrust in spite of inconsistencies of EM thrust signals in one camp, and people believing in artefactual explanations in spite of inconsistencies wrt some experimental results in the other camp, science (and spaceflight) is not the winner. The EM drive effect could float a long time in such a state of indetermination before it floats in space.QuoteWhen finding a contradiction between plots, one should not rush to judgement to toll the bell that the experiment is an artifact: it may simply be an innocent error in labeling a plot.
So when finding a contradiction between a WIP classical explanation and some interpretation of ambiguous statements (or the reverse) about the results, one should jump to the throat of the classical explanation...
If I really wanted to pinpoint and quibble miserably on insignificant label contradiction, long time I would have raised the fact that the file name (in the picture, the Browse box of the display) in one of the charts states 3 10^-3 Torr when the picture is commented 5 10^-6 Torr, and that in another one (hot topic recently) we have "In-Air" vs 5 10^-4 Torr. As anyone who saw that apparent disparity, I just classified that in the "innocent error", probably that was the previous file recorded (before the new conditions). That is insignificant and mean. Can do that. Significance of other discrepancies I raised and put emphasis on, you are not the only judge.Quote
2) That there may be labeling questions is shown by:
2a) What NASA Eagleworks labels as mode TM212 I have shown should be labeled TM222
2b) The mode labeled as TM211 in the "Anomalous ..." report was reported to occur at 1.9326 GHz and 1.9367
GHz, with COMSOL FEA frequency calculated at 1.947 GHz. Yet now they report mode labeled TM212 to be tested and to occur at about the same frequency range.
I calculate that the mode labeled "TM212" (which I think should be labeled TM222) -which does not appear in http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image should occur at a significantly higher frequency than TM211, never at the same frequency ( "TM212" at 2.49 GHz without dielectric and "TM211" at 2.01 GHz without dielectric). These modes were analyzed and labeled (I understand) by different engineers. It is possible that they may be one and the same mode that has been mislabeled.
Yes, all right, sounds possible. So ? There is no clear experimental data showing thrust toward big end, thermal is not dead, EM thrust is not dead, blue plot is not dead but weakened (not all mode tested but no reversal so far TE vs TM as seen in the plot)Quote
3)All the emphasis you place on the signs on the blue NASA Eagleworks plot and the other plots (which could be just an error in labeling the plots), yet you ignore the fact that Roger Shawyer published experimental information showing his EM Drive Demonstrator Engine showed practically the same magnitude thrust was experimentally observed to be reversed: Shawyer reports forces in opposite directions (towards the big end and towards the small end of practically the same magnitude: 214 mN/kW and 243 mN/kW) for his Demonstrator engine.
The data being ignored (showing forces in opposite directions, towards the big end and towards the small end of practically the same magnitude), what should I say , oh yes, defenestrates, mechanical explanations for the EM Drive measurements being a mechanical artifact.
Excuse me but when I see how Shawyer treats the sign conventions with his "special Newtons" that do accelerate (but the other way) and don't know how to push on a spring, I wouldn't care defenestrating any attempt at explaining that classically. Why do we spend so much time here on Eagleworks results that are 2 orders of magnitude below the µN/W yields of Shawyer ? That was your own interrogation (long ago, thread 1). Maybe because the work at Eagleworks is much more transparent, is in vacuum, is rather clearly communicated, gives a better impression of reliability overall ?
I won't trash a mechanical explanation specific to Eagleworks' balance in vacuum just to be consistent with Shawyer's partially known apparatus and inconsistent sign conventions in results reporting. Hell, at 200µN/W how Shawyer hasn't succeeded in convincing the 3 or 4 hard headed sceptics needed to get a chain reaction of replications all over the world ? Wake up, it's reality we are talking about. Those things have been around for years and years, and always failed to get ... momentum.
Also if I can't put emphasis on what IMO I find weak in the publicly available data, then end of discussion. I don't deter you from putting emphasis on whatever you see fit. If some of my emphasis points seem insignificant to you, don't answer them.
Best
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#1430 by Rodal on 20 Mar, 2015 23:52
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So we have to wait for either Paul March or another report from NASA Eagleworks to clear up this issue of where is the experimental data (position vs. time) for the truncated cone exhibiting a force (and acceleration) directed towards the big end. Are some of the plots in this thread experiments exhibiting a force (and acceleration) directed towards the big end ? At what frequencies and mode shapes ? Which plots (if any) exhibited a force (and acceleration) directed towards the big end due to the placement of the dielectric in the opposite end?Quote
2) That there may be labeling questions is shown by:
2a) What NASA Eagleworks labels as mode TM212 I have shown should be labeled TM222
2b) The mode labeled as TM211 in the "Anomalous ..." report was reported to occur at 1.9326 GHz and 1.9367
GHz, with COMSOL FEA frequency calculated at 1.947 GHz. Yet now they report mode labeled TM212 to be tested and to occur at about the same frequency range.
I calculate that the mode labeled "TM212" (which I think should be labeled TM222) -which does not appear in http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image should occur at a significantly higher frequency than TM211, never at the same frequency ( "TM212" at 2.49 GHz without dielectric and "TM211" at 2.01 GHz without dielectric). These modes were analyzed and labeled (I understand) by different engineers. It is possible that they may be one and the same mode that has been mislabeled.
Yes, all right, sounds possible. So ?...
If none of the plots examined in this thread exhibited a force (and acceleration) directed towards the big end...do such plots exist? Can they make them available?
Or perhaps we just have to wait for @Mulletron and @Notsosureofit's experiments to clear up this matter
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#1431 by Rodal on 21 Mar, 2015 00:03
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Thank for later part of previous answer. It does answer clearly to some aspects of my innocent questions, for the other aspects I'll have to learn German....
No need to learn German. I included the English translation links (by the way, these are excellent translations), which I copy again here:
See:
Abraham, M. (1909).
http://en.wikisource.org/wiki/Translation:On_the_Electrodynamics_of_Moving_Bodies_%28Abraham%29
Minkowski, H. (1908).
http://en.wikisource.org/wiki/Translation:The_Fundamental_Equations_for_Electromagnetic_Processes_in_Moving_Bodies
These are excellent papers. The paper by Abraham is very comprehensive (it includes a review of efforts by Minkowski, Lorentz, Einstein, Hertz, etc.).
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#1432 by Rodal on 21 Mar, 2015 00:53
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Thank for later part of previous answer. It does answer clearly to some aspects of my innocent questions, for the other aspects I'll have to learn German. Thank for editing the beginning. Unfortunately the tone is becoming a bit harsh so it becomes difficult to talk casually about just, you know, "what you think of ... patati patata", without resorting to lawyers....
Thanks for the (yes, strong, but very) illuminating exchange. I learned many aspects of the Eagleworks experiments that I had not realized before you brought them up to our attention, and I better understand your viewpoint. Thanks for your patience and for taking your time to explain this
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#1433 by Flyby on 21 Mar, 2015 11:29
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Such a pity there is - currently- no way to dramatically increase the power input on the eagleworks setup.
It would be so much easier to have clear significant output results, be them positive or negative.
The lack of clear results makes us spend tremendous time on debating and arguing about measurement procedures, measurement errors and anomalies, etc.
Simple because it is so hard to separate the current results from potential background noise and secondary effects...
If only some one, besides the Chinese and Shawyer would have the ability to either prove or disprove the observed thrust effect, by simply putting 2-3kW instead of 50-100w.
It would at least generate enough interest AND funds to continue fundamental research.
once you develop 720mN of thrust all discussions about thermal or other secondary effects fall away, that much is clear to me.
What I fear is that due to lacking a clear result, research on this will get marginalized and slide into the "yet another crackpot theory". Not that I particularly biased for this to be successful, but I do find previous results intriguing enough to see it continued.
Judging on what Shawyer is currently trying to develop, i think that is exactly what he's trying to do : to produce such results that it can no longer be dismissed as being an error in measurement, or a secondary effect. But we need it to be repeatable...
And even if it fails to produce anything substantial, then we'll all be able to put it finally aside as a wrongly tracked scientific experiment. No real harm done there, except from a few bruised ego's... -
#1434 by Rodal on 21 Mar, 2015 12:07
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Wikipedia has a pretty good article on Maxwell's stress tensor, see: http://en.wikipedia.org/wiki/Maxwell_stress_tensor...
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What do you think of the formula used in the plot titled "S21 and surface integral of cavity with 1W input power" ?
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Do you see what motivates this particular formula ?
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While waiting for Paul March (@Star-Drive) to explain the background, context and significance of the equation, the following is apparent:
The terms in the http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image equation coincide with the Kronecker's delta (the unit dyadic) negative terms of Maxwell's stress tensor ("times the normal component in the z direction"). The remaining dyadic terms of Maxwell's stress tensor component are missing from this expression.
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See the expression for the electromagnetic force per unit volume f at the very end of point 4 of the Motivation section http://en.wikipedia.org/wiki/Maxwell_stress_tensor#Motivation, just before the start of point 5 (which I reproduce with symbols as an attachment below -too bad that NASA Spaceflight does not allow one to use mathematical symbols in these posts
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\mathbf{f} = \epsilon_0\left[ (\boldsymbol{\nabla}\cdot \mathbf{E} )\mathbf{E} + (\mathbf{E}\cdot\boldsymbol{\nabla}) \mathbf{E} \right] + \frac{1}{\mu_0} \left[(\boldsymbol{\nabla}\cdot \mathbf{B} )\mathbf{B} + (\mathbf{B}\cdot\boldsymbol{\nabla}) \mathbf{B} \right] - \frac{1}{2} \boldsymbol{\nabla}\left(\epsilon_0 E^2 + \frac{1}{\mu_0} B^2 \right)
- \epsilon_0\frac{\partial}{\partial t}\left( \mathbf{E}\times \mathbf{B}\right).
Observe that:
1) All the terms containing the divergence (nabla) of vector field B vanish (because there are no magnetic monopoles in Maxwell's equations).
2) All the terms containing the divergence (nabla) of vector field E vanish (assuming that there are no point charges inside the microwave cavity).
3) The term epsilono*d(ExB)dt is the time derivative of Poynting's vector. Since Poynting's vector time dependence is (Cos[omega*t])^2, the time dependence of its time derivative is proportional to Sin[omega*t], whose average over a complete cycle is zero, so this term (the time derivative of Poynting's vector) also vanishes over a complete cycle.
So, all one is left for the electromagnetic force vector per unit volume f in the microwave cavity is the term:
f = - (1/2) Nabla (epsilono E^2 + (1/muo) B^2 )
So, this term is the negative divergence of the expression in the http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image plot of NASA Eagleworks:
(epsilono E^2 + (1/muo) B^2 )
(where the scalar expression E^2 =( realPart[Ex] )^2 + (imaginaryPart[Ex]) ^2 + realPart[Ey] )^2 + (imaginaryPart[Ey]) ^2 + realPart[Ex] )^2 + (imaginaryPart[Ez]) ^2 ) is the AbsoluteValue of the complex expression for E; and ditto for the scalar expression B)
Since, due to conservation of momentum, the electromagnetic force in the microwave cavity should be zero, then
f = 0 = - (1/2) Nabla (epsilono E^2 + (1/muo) B^2 )
which means that the divergence ("Nabla") of the expression in NASA Eagleworks http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image plot should be zero.
This still allows the expression in NASA Eagleworks http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image itself to be non-zero, as long as the sum of its spatial derivatives (due to the divergence operator) are zero.
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#1435 by Rodal on 21 Mar, 2015 12:49
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For yet another related interpretation, see the article "Electromagnetic stress–energy tensor" http://en.wikipedia.org/wiki/Electromagnetic_stress%E2%80%93energy_tensor.
"In relativistic physics, the electromagnetic stress–energy tensor is the contribution to the stress–energy tensor due to the electromagnetic field."
The expression in NASA Eagleworks http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image is (the energy density): the first diagonal entry T11, purely due to the time coordinate , of the 3+1 spacetime relativistic-physics electromagnetic stress–energy tensor (in free space and flat space–time), (the other entries comprise Maxwell's stress tensor sigma in the lower sub-quadrant (these Maxwell's stress tensor sigma components are only related to the space coordinates) and Poynting's vector S divided by the speed of light c, as the remaining off-diagonal entries due to time and space coupling).
relativistic-time component ==> energy density in NASA Eagleworks http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image
relativistic-space components==> Maxwell's stress tensor sigma
coupling of relativistic-space with relativistic-time components ==> Poynting's vector components S/c
Still, the conservation laws, comprise the divergence of this relativistic electromagnetic stress–energy tensor, see
http://en.wikipedia.org/wiki/Electromagnetic_stress%E2%80%93energy_tensor#Conservation_laws
As to @frobnicat's question regarding "motivation" what I see here is either
1) A highly conceptualized, MagnetoHydroDynamics model of the Quantum Vacuum interaction for flat-space time as per Harold White's model (which he considers defensible as an engineering computational tool only for modeling purposes).
2) Allowing a non-flat spacetime, another motivation maybe a coupling of electromagnetism to gravity, see for example:
http://physics.stackexchange.com/questions/55660/einstein-field-equations-and-electromagnetic-stress-energy-tensor
and
http://en.wikipedia.org/wiki/Einstein_field_equations#Einstein.E2.80.93Maxwell_equations -
#1436 by Rodal on 21 Mar, 2015 14:58
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Still, another thing for Paul March/NASA Eagleworks to explain is, in the expression in NASA Eagleworks http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image, which also is (the energy density): the first diagonal entry T11 in
and taking the square of the AbsoluteValue E^2 and B^2 are necessarily positive scalar expressions:
epsilono* E^2+(1/muo)*B^2 >= 0
where does the change in sign come from for different modes?
Did they calculate the square of the Absolute Value for each electromagnetic field component:
(RealPart[Ex])^2+(ImaginaryPart[Ex])^2 (which is necessarily always positive)
or did they calculate instead
RealPart[Ex^2]+ImaginaryPart[Ex^2] (which can be negative)
and if so, why did they calculate RealPart[(Ex]^2]+ImaginaryPart[(Ex]^2] instead of the AbsoluteValue?
This is an issue of the order in which mathematical expressions should be interpreted:
I don't know what code did they use for the expression http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image,
but is there a code where the expression can be interpreted as
RealPart[Ex^2]+ImaginaryPart[Ex^2] +.... (which can be negative)
instead of
(RealPart[Ex])^2+(ImaginaryPart[Ex])^2 +... (which is necessarily always positive) ? -
#1437 by Notsosureofit on 21 Mar, 2015 16:05
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The +/- would seem to come from the multiplication of the surface energy by the z component of the (surface) normal vector. Why ? Beyond me ?
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#1438 by Rodal on 21 Mar, 2015 17:31
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The image http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=36313.0;attach=778912;image is dated 05/23/2014 but the image does not appear in the July 28-30, 2014 (not enough time to go to press), "Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum" paper.
The text of the image reads: "Surface integral (numeric) of this expression:.....This is the integral of the sum of the magnetic and electric field energies multiplied by the z component of the normal vector at that point"
The surface integral? the integral over what surface? The total surface of the truncated cone?
What normal vector at what point? The vector normal to the truncated cone surface? No, because the geometry is the same for different modes, so that cannot change for different modes.
The normal vector of the Electric field for a TM mode? the normal vector of the Magnetic field for a TE mode? Or vice-versa ? Why ? Over what surface(s) and why?
What is the meaning of this integral anyway? It is not a force.
EDIT: As @frobnicat correctly points out, this surface integration has the units of a force, but what I mean by "it is not a force" is that the electromagnetic force should be the divergence of the expression used by NASA Eagleworks in this image, and they did not take the divergence, which at first glance does not appear correct: since if one does not take the divergence of the expression, one is not satisfying conservation of energy/momentum
The electromagnetic force is related to the divergence of these expressions. The divergence operation is not taken...
For that component, T11, the divergence derivative is with respect to the relativistic time coordinate, (technically speaking, it is the spacetime contravariant rate of the energy density) so the electromagnetic force for that component is related to the derivative with respect to time of the energy density expression. But no time derivative is shown to us. But if the electromagnetic components are a harmonic function of time, over a complete cycle, that time derivative would give zero, anyway.
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#1439 by Notsosureofit on 21 Mar, 2015 17:45
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Sounds to me kind of like:
"Surface integral (numeric) of this expression:.....This is the integral of the sum of the magnetic and electric field surface energy densities multiplied by the z component of the vector normal to the truncated cone surface at that point"
The vector normal to the truncated cone surface does not change for different modes.
That's what it sounds like anyway.................
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