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#2120 by rfmwguy on 08 May, 2016 22:12
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Been swamped today...anyhow, yes, my dc 4kv lead has a 5 kv rating...no arcs. I did plan ahead on that one.
Secondly, glad to see the slides getting a thorough discussion. I did post that as a latest fyi for all and by no means titled it THE emdrive theory. Mr shawyer has this and there are others out there to ponder. Its actually very useful for me personally to read professional critiques as my theoretical physics is well behind most...guess its an engineers glass ceiling
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#2121 by Tellmeagain on 08 May, 2016 22:49
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I spent most of today getting the frame woman handled around (help didn't show up). Gusseted flat angle iron pieces on the sides to give greater strength. Left the front open for ease of access. Just finishing off painting it and hope to have it on the bench late today or tomorrow.
Hope you all are having a great day.
Shell
Steel can be magnetized. I would use wood frame in this case. -
#2122 by SeeShells on 09 May, 2016 00:47
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frobnicat...
Not requiring a vacuum chamber : it is known that magnetic couplings have been a major factor in some of the values reported for previous experiments. Lorentz forces of explicit (known) DC components can be "mitigated" and I see this is discussed here, but this is only a best effort that has no guaranty of perfect cancellation (bends, imperfect contacts, local gradients due to ferromagnetic materials in vicinity...). And moreover it is not excluded that the RF energy itself generates significant "rectified" currents even when it shouldn't, say for instance, asymmetrical electron wind near the antennae (pure speculation, probably not) but yet if some effect persists we have to consider more surprising mechanisms, not only to explain it as a real effect (useful for space propulsion) but also to see how it could be from local coupling (not useful for space propulsion but not obvious either).
Anyway, local DC geomagnetic field, perturbed by ferromagnetic materials nearby (steel reinforced concrete, whatever...), ie. not necessarily perfectly constant in magnitude and direction in the volume of the experiment, appears as a major potential for non obvious spurious (rotational and/or linear) momentum exchange with surrounding. DC magnetic field hardly can be zeroed out. My proposition is to quantify the influence of local environmental magnetic field. For instance that you make a (crude) Helmholtz coils assembly that can encompass at least the test article, and with strong enough induced magnetic field that it can overcome in magnitude the local geomagnetic field. No need to invest into expansive gaussmeter at first, a magnetic compass would be conclusive enough that the Helmholtz coils do overcome the local field (or smart phone magnetometer app, though I'd personally prefer good old compass). Among your various experiments, take the best configuration in term of reproducibility (apparently giving cleanest signal) and record results with/without added local field, for various orientations of Helmholtz coils assembly and magnitude (current in coils), and also with only one coil at a time (higher divergence rather than "flat" volumetric field). Repeat a few time at various magnitude to extract a plot of measured force as function of forward and backward current in coils with a reasonable low noise.
Either the plots (force wrt. coils intensity for X Y Z) are strictly horizontal, ie. there is no influence of local DC magnetic field on the result, the effect (and applicability to space propulsion holds) up to magnitude characteristics of geomagnetic field. Or there is a slope, indicating the force needs (pushes on) a local field, which is bad news for space propulsion, but better to know than ignore. If this later case appears then further quantitatively precise characterisation should be done...
Maybe if Helmholtz coils prove to be too expensive in copper wiring, or too time consuming, a simple strong permanent magnet (from a dismantled speaker, whatever) strong enough to deviate a magnetic compass from a few 10s of centimeters can be used to probe possible influence on results (all other things being equal).
That would make your experiment the first (in experimented EM drive devices I think ?) to go beyond "care has been taken of local magnetic field interactions to minimize spurious couplings", to an experimentally strong characterization of this specific systematic error source, whatever the specifics, including surprising and/or improbable ones. I don't count in that league experiments where DC field has been varied but indirectly and not all other parameters being kept equal and not enough data points to assess statistical significance (shielding of the magnetic dampener at EagleWorks for instance). I would personally take that as a very important progress (before self containment and vacuum testing).
Very good advise! Thank you. I'ts been hmmm 35 years since I did a Helmholtz coil and I'm a little rusty but you read my mind, as I have a compass to probe(ing) the area around the frustum and stand. If if proves that it's going to be a issue them I WILL build a Helmholtz coil to go inside of the test stand and negate magnetic fields.
When that time comes I'll pick your brain (only if it's ok?). If needed I'll poke the gofundme team for a few more dollars, they have been wonderfully supportive and I couldn't do it without them not to mention the fantastic people here.
Thanks,
Shell
Shell -
#2123 by otlski on 09 May, 2016 01:11
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There has also been mention of rotating test stands. Recall that Shawyer has actually done this, and posted a video on the internet. A prominent sceptic here aeons ago posted an analysis of that data concluding that the dynamics were consistent with Shawyer's explanation.
R.
Thanks for mentioning it; I went back and downloaded the 43MB video and watched it. Unfortunately, it does not show a complete 360 degrees of rotation, rather it stops at 270 degrees. This demonstration does not rule out gravity pendulum phenomena where the constrained axis of rotation is not precisely parallel to gravity. This, combined with an offset CoG can look exactly like the demo. I have done this several hundred times (not on purpose) while testing air bearings. Furthermore, Lorentz forces could be in play, as well as several other artifacts. His use of coiled wires bridging from the experiment to its power supply on the ground will induce sizable torque errors. Lastly, the camera did not roll long enough to let us see if the apparatus would back-swing after it "stopped". These questions and many more... -
#2124 by zen-in on 09 May, 2016 01:16
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..
Take a look of the equivalent circuit. I re-post it below, and change the color of the previously-too-faint overlaid circuit. The high current DC power leads are not even in the equivalent circuit.
Your diagram is somewhat confusing and you keep changing it. What I said earlier stands: there is no need to twist the RF leads together (if in fact you have that option) So showing that in your diagram just adds to the confusion. The high voltage DC supply to the magnetron can't be twisted together to minimize the size of the current loop because that might cause arcing. I was mistaken in saying the filament wires could arc but since that is AC at a high - potential there is no reason to twist them together anyway. I don't know what the anode current of the magnetron is but I suspect it is so low as to not cause any significant Lorentz force so twisting that with the filament leads is not necessary. Conclusion: Your "equivalent circuit" can be ignored.QuoteI agree with the theoretical part of your post that I did not quote. It is just you did not apply the theory correctly to this circuit. Thank you!
Excuse me for that but your diagram was too confusing. However that should not be a problem now because it can be ignored by all. -
#2125 by Tellmeagain on 09 May, 2016 01:32
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..
Take a look of the equivalent circuit. I re-post it below, and change the color of the previously-too-faint overlaid circuit. The high current DC power leads are not even in the equivalent circuit.
Your diagram is somewhat confusing and you keep changing it. What I said earlier stands: there is no need to twist the RF leads together (if in fact you have that option) So showing that in your diagram just adds to the confusion. The high voltage DC supply to the magnetron can't be twisted together to minimize the size of the current loop because that might cause arcing. I was mistaken in saying the filament wires could arc but since that is AC at a high - potential there is no reason to twist them together anyway. I don't know what the anode current of the magnetron is but I suspect it is so low as to not cause any significant Lorentz force so twisting that with the filament leads is not necessary. Conclusion: Your "equivalent circuit" can be ignored.QuoteI agree with the theoretical part of your post that I did not quote. It is just you did not apply the theory correctly to this circuit. Thank you!
Excuse me for that but your diagram was too confusing. However that should not be a problem now because it can be ignored by all.
please note that I modified the circuit to reflect your and other's suggestions. I am sorry that I have just realized that arguing can not be constructive so I will stop. Please feel free to ignore my equivalent circuits. I brought up this topic to help See-Shell on her experiment. Fortunately she acknowledged the existence of ground loop in her experiment and would improve her experiment accordingly. Since it has serviced its purpose perfectly, it is time to stop this topic. -
#2126 by frobnicat on 09 May, 2016 01:35
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.../...
Not much new views from Shawyer to further the discussion. Linear (translational) kinetic energy is a covariant value that depends on arbitrary choice of frame, not an invariant intrinsic measure. Saying that something "converts electric energy to kinetic energy" is ill defined because "kinetic energy" is ill defined, unless a frame is explicit. For direct contact propulsion like wheels on ground there is a convenient view that the work done by the force of the wheels on the ground can be related to the acquired kinetic energy of vehicle as accounted relative to ground frame. This is convenient, but it is well known that this is correct only in this specific ground frame, and that to make proper assessment of both energy and momentum conservation in a fully relativistic manner (ie. showing that same calculations can be made independent of arbitrary frame of observation) one has to take into account the recoil of the ground (yes, the whole Earth).
Shawyer's argument relies on a false sense of evidence, a common intuition (of Earth dwellers) that has been proven wrong : not only there is no such thing as "intrinsic kinetic energy" to start with but there is no "intrinsic delta kinetic energy" either. Same observed deltaV will yield wildly different deltas in kinetic energy even in Newtonian relativity (where deltaV is invariant because of simple additivity of velocities) depending on frame. Introducing a term that is ill defined in an equation can't give correct results. This would be evidenced if he did explain us what his theory predicts quantitatively for an EMdrive as thrust=function(history of spent flows and of trajectory wrt. environment). And of course a trajectory doesn't depend only on a single propulsive device, trajectory can be forced by other devices attached to same hull (rails, chemical propulsion, whatever).
All we have are obscure qualitative statements such as that the EMdrive should be free to accelerate to engage in motor mode or the such. Does an EMdrive tested in a train at constant velocity shows same results (in the train) as on the ground ? Yes or no ? How could the "must be free to accelerate" prescription change anything when averaging multiple bumps of an EMdrive driven periodically against a spring against a large mass buffer, ie. transforming an intermittent "freely accelerating" device into an averaged constant force at constant velocity device ? We need the function.
I don't see that in his public record. Is it a trade secret ? Any "theory" for any propulsion scheme must be able to give this function, even a purely phenomenological (observational) theory that explains nothing. How are the engineers supposed to design missions without such a function ? Have we ever seen applied such a function (beyond trivially over-unit constant thrust for constant power) when proponents are illustrating the concept ? Trying to discern a sense of logic behind the theoretical bread crumbs of Shawyer is a complete waste of time IMHO, frankly looking more like reduction of cognitive dissonance mantras when science and mere practical engineering needs quantitative predictive frameworks. This can't be addressed quantitatively since this quantitatively addresses nothing.
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#2127 by rfmwguy on 09 May, 2016 01:36
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Here's the hd webcast I was on:
Here's the after-show segment where more questions were asked by viewers:
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#2128 by zen-in on 09 May, 2016 02:14
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Take a look of the equivalent circuit. I re-post it below, and change the color of the previously-too-faint overlaid circuit. The high current DC power leads are not even in the equivalent circuit.
Your diagram is somewhat confusing and you keep changing it. What I said earlier stands: there is no need to twist the RF leads together (if in fact you have that option) So showing that in your diagram just adds to the confusion. The high voltage DC supply to the magnetron can't be twisted together to minimize the size of the current loop because that might cause arcing. I was mistaken in saying the filament wires could arc but since that is AC at a high - potential there is no reason to twist them together anyway. I don't know what the anode current of the magnetron is but I suspect it is so low as to not cause any significant Lorentz force so twisting that with the filament leads is not necessary. Conclusion: Your "equivalent circuit" can be ignored.QuoteI agree with the theoretical part of your post that I did not quote. It is just you did not apply the theory correctly to this circuit. Thank you!
Excuse me for that but your diagram was too confusing. However that should not be a problem now because it can be ignored by all.
please note that I modified the circuit to reflect your and other's suggestions.
...
Your diagrams do not represent anything that I have stated. The reason I believe is because I have been unable to make you understand that these fictious ground loops have nothing to do with any possible Lorentz force (actually it would be a torque). To minimize any interaction with the geomagnetic field one has to consider current loops. These are only important in the high current DC parts of the circuit. There are 3 parameters to consider in a current loop:
1) How much DC current is circulating
2) What is the area of the loop
3) What is the angle of the loop wrt to the geomagnetic field.
Of these 3 parameters the only one that can be practically minimized is (2) - the area of the loop. By twisting high current DC wires together the area is minimized.
A ground loop is something entirely different. If a circuit has a ground loop there will be a common mode voltage superimposed on part of the circuit, resulting in measurement errors or some other degraded behavior of the circuit. Since voltages do not interact with magnetic fields no lorentz force would be produced. -
#2129 by Rodal on 09 May, 2016 02:19
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Excellent point about kinetic energy not being an invariant..../...
Not much new views from Shawyer to further the discussion. Linear (translational) kinetic energy is a covariant value that depends on arbitrary choice of frame, not an invariant intrinsic measure. ...
The following quantities:
* the Electric Field E
* the Magnetic Field B
* the Poynting vector Field S
are not Lorentz-invariant quantities either. They are not even invariant under rotations. One of the things I did not like about NSF's Meep runs is that he was showing the Electric and Magnetic fields (in Cartesian coordinates), when these fields are not even rotationally invariant. Thus the MEEP output pictures shown at NSF EM Drive thread were being misleadingly interpreted very often. (By contrast when postprocessing with Wolfram Mathematica I displayed the norms of the fields, which are rotationally invariant).
By contrast, one of the many things I like about FEKO (run by Monomorphic, and also COMSOL run by NASA) both display the norm: the square root of the dot product of the fields with themselves (√E·E or √B·B) which are, rotationally invariant.
But even when using rotationally invariant measures, the use of quantities that are not Lorentz-invariant leads to confusion in many treatments, as for example the common misconception that the radiation pressure can always be obtained from the time average of the Poynting vector (which is false).
A magnetic field in one moving frame may be seen as an electric field in a different moving frame, and vice-versa (since E and B are not Lorentz invariant quantities). One observer’s E field is another’s B field (or a mixture of the two), as viewed from different inertial reference frames.
In here, I am developing an analysis in term of invariant quantities: http://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577
One of the things I prove is that there is indeed pressure on the side walls of a truncated cone with spherical ends. Shawyer is completely wrong. In this latest write-up he writes that there are travelling waves as well as standing waves in an EM Drive and that there is no side pressure on the side walls for the travelling waves. It is very incorrect for him to state this, as it is known that standing waves can be interpreted as composed of travelling waves travelling in opposite directions, that satisfy the boundary conditions.
It looks like Shawyer never saw this image ?
One wonders whether Shawyer himself ever analyzed the EM Drive problem, because what he proposes completely ignores the boundary conditions of the problem, and fails to understand that all standing waves are composed of travelling waves.
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#2130 by Tellmeagain on 09 May, 2016 02:21
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Take a look of the equivalent circuit. I re-post it below, and change the color of the previously-too-faint overlaid circuit. The high current DC power leads are not even in the equivalent circuit.
Your diagram is somewhat confusing and you keep changing it. What I said earlier stands: there is no need to twist the RF leads together (if in fact you have that option) So showing that in your diagram just adds to the confusion. The high voltage DC supply to the magnetron can't be twisted together to minimize the size of the current loop because that might cause arcing. I was mistaken in saying the filament wires could arc but since that is AC at a high - potential there is no reason to twist them together anyway. I don't know what the anode current of the magnetron is but I suspect it is so low as to not cause any significant Lorentz force so twisting that with the filament leads is not necessary. Conclusion: Your "equivalent circuit" can be ignored.QuoteI agree with the theoretical part of your post that I did not quote. It is just you did not apply the theory correctly to this circuit. Thank you!
Excuse me for that but your diagram was too confusing. However that should not be a problem now because it can be ignored by all.
please note that I modified the circuit to reflect your and other's suggestions.
...
Your diagrams do not represent anything that I have stated. The reason I believe is because I have been unable to make you understand that these fictious ground loops have nothing to do with any possible Lorentz force (actually it would be a torque). To minimize any interaction with the geomagnetic field one has to consider current loops. These are only important in the high current DC parts of the circuit. There are 3 parameters to consider in a current loop:
1) How much DC current is circulating
2) What is the area of the loop
3) What is the angle of the loop wrt to the geomagnetic field.
Of these 3 parameters the only one that can be practically minimized is (2) - the area of the loop. By twisting high current DC wires together the area is minimized.
A ground loop is something entirely different. If a circuit has a ground loop there will be a common mode voltage superimposed on part of the circuit, resulting in measurement errors or some other degraded behavior of the circuit. Since voltages do not interact with magnetic fields no lorentz force would be produced.
I have said that the theory you stated was correct. There is no doubt about it. -
#2131 by zen-in on 09 May, 2016 02:32
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Very good advise! Thank you. I'ts been hmmm 35 years since I did a Helmholtz coil and I'm a little rusty but you read my mind, as I have a compass to probe(ing) the area around the frustum and stand. If if proves that it's going to be a issue them I WILL build a Helmholtz coil to go inside of the test stand and negate magnetic fields.
When that time comes I'll pick your brain (only if it's ok?). If needed I'll poke the gofundme team for a few more dollars, they have been wonderfully supportive and I couldn't do it without them not to mention the fantastic people here.
Thanks,
Shell
Shell
You will need to scale up the size of your Helmholtz coils. I have a pair with an ID of about 300 mm. I can create a uniform field or null the geomagnetic field in a volume of about 10 mm on a each side, according to my Bell Gaussmeter. I have seen other Helmholtz coils and believe my observations are standard fare. I know some NASA labs have highbay sized Helmholtz coils for this very reason. There really isn't anything you can do to shield something from the geomagnetic field. having a permanent magnet near the cone will just increase the torque that is generated, as the EW lab found out. A very large mumetal shield with multiple shells could be built to divert the geomagnetic field around the experiment. I'm sure this has been done before where cost is no object. -
#2132 by SeeShells on 09 May, 2016 03:41
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Interesting. Like I said if if becomes a issue that I can't map and profile then I'll see what it will take to enclose the drive area. And Mu metal becomes costly http://www.ebay.com/itm/Mumetal-Nikel-Permalloy-Magnetic-shielding-Sheet-Mu-metal-0-35T-30-100cm-/172016021862?hash=item280cf43166:g:qIgAAOSwmrlUuaRV
Very good advise! Thank you. I'ts been hmmm 35 years since I did a Helmholtz coil and I'm a little rusty but you read my mind, as I have a compass to probe(ing) the area around the frustum and stand. If if proves that it's going to be a issue them I WILL build a Helmholtz coil to go inside of the test stand and negate magnetic fields.
When that time comes I'll pick your brain (only if it's ok?). If needed I'll poke the gofundme team for a few more dollars, they have been wonderfully supportive and I couldn't do it without them not to mention the fantastic people here.
Thanks,
Shell
Shell
You will need to scale up the size of your Helmholtz coils. I have a pair with an ID of about 300 mm. I can create a uniform field or null the geomagnetic field in a volume of about 10 mm on a each side, according to my Bell Gaussmeter. I have seen other Helmholtz coils and believe my observations are standard fare. I know some NASA labs have highbay sized Helmholtz coils for this very reason. There really isn't anything you can do to shield something from the geomagnetic field. having a permanent magnet near the cone will just increase the torque that is generated, as the EW lab found out. A very large mumetal shield with multiple shells could be built to divert the geomagnetic field around the experiment. I'm sure this has been done before where cost is no object.
Helmholtz coils (hoops) on three perpendicular axes used to cancel the Earth's magnetic field inside the vacuum tank in a 1957 electron beam experiment.
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#2133 by Tetrakis on 09 May, 2016 04:28
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Well, to be fair the geomagnetic field can be rigorously excluded from a small volume. Its done all the time in zero field magnetic resonance spectroscopy.
I think it is correct to say that there is consensus in the thread now on a few points.
1) Shawyer's "data" is unreliable/nonexistent and his ideas are nonsense. Shawyer's wrong claims got this whole thing started.
2) None of Yang's positive results were real. She retracted her earlier claims and is no longer working in this area.
3) Tajmar saw no significant evidence in his data of thrust and stated so himself.
4) NASA's data does not exist in the sense that there is insufficient error analysis and none of it has really been subject to peer review. There is no significant public data, only social media hearsay and preprint powerpoint.
5) Robust tests are pretty straightforward to design and execute. High vacuum chamber, torsional balance, batteries, validation of resonance.
6) There are no really good hypotheses to test. Shawyer's model is just plain wrong. Baez dealt a pretty damning blow to McCulloch, so thats out. There is even disagreement about whether or not a "clean" RF source is needed, which indicates that a virtually limitless variable space needs to be tested for a signal.
My personal takeaway: Institutional findings (Yang, Tajmar, NASA) are either null or very weak/unverified. Hypothesis testing is significantly weakened by the fact that there is no clear question being asked; the proposed "effect" is thought to be caused by many different stimuli, so really experiments have a huge variable space to optimize (Cavity shape, "cleanliness" of the RF source, dielectrics, wavelength, quality of resonance, mode shape, applied power, geomagnetic field strength, the list goes on). This implies a huge required investment of resources in precision machining, which will be very expensive, for a very slim chance of success compared to the ROI-type value of other work (mainstream science). I'm amazed that so many people have poured so much effort into the EMDrive considering that the real evidence for it is so amazingly weak compared to the "screaming in your face" quality of other historical new physics data such as spectral lines, accelerating expansion of the universe, crystal structures of molecules, etc. Not to mention the really "screaming in your face" qualities of existing new physics data being encountered today: see dark matter. I really wonder why the EMDrive threads have so many millions of views when threads about dark matter/dark energy, which are really important and widely acknowledged new physics problems, don't have millions of views.
I understand that DIY efforts are valiantly moving forward, but most of them are less robust than the NASA effort. I also recognize that I won't convince DIY folks to drop their wrenches, and rightly so. Still, I wonder if the herculean efforts to mine a tiny patch of data here would be better spent elsewhere. -
#2134 by spupeng7 on 09 May, 2016 05:54
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Been swamped today...anyhow, yes, my dc 4kv lead has a 5 kv rating...no arcs. I did plan ahead on that one.
Secondly, glad to see the slides getting a thorough discussion. I did post that as a latest fyi for all and by no means titled it THE emdrive theory. Mr shawyer has this and there are others out there to ponder. Its actually very useful for me personally to read professional critiques as my theoretical physics is well behind most...guess its an engineers glass ceiling
Dave,
one of the joys of being an engineer is thinking outside the box to find a solution. Theory can catch up later if it works JMN..
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#2135 by frobnicat on 09 May, 2016 10:07
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.../...
I really wonder why the EMDrive threads have so many millions of views when threads about dark matter/dark energy, which are really important and widely acknowledged new physics problems, don't have millions of views.
.../...
This sounds like a naive question, or maybe your heart is so scientifically inclined (as in "pure science") that you don't share the more general public passion for spectacular applications ?
The EMdrive wasn't (and still isn't unanimously) recognized as new physics, this was a heated debate on this thread, before the whole New Physics for Space Technology section was created on NSF. So my personal feeling on that it that it is not the "new physics" aspect that attracted the most of attention at first, proponent of the effect haven't put "new physics" on page cover, and rather minimized or dismissed some of the bigger picture consequences to concentrate only on applicability to practical propulsion. This goes basically as "this is just a new way to thrust a vehicle", and when pressed "we are not claiming violation of CoM nor violation of CoE nor violation of relativity nor violation of known frameworks...". But claiming new physics or not, the simple apparent conditions of application of this new way of thrusting clearly required new physics. Hard nosed scientifically inclined people (as in "caring about consistency") get attracted by the level of public attention raised by primary claims (application) and objected strongly against the implicit claims (wider consequences).
Heated debate ensues. Public loves drama. There is activity, the experimental claims seem reachable by DIYers, theoretical propositions look so mad and vague that peoples at various levels of knowledge feel free to contribute, everyone can have an opinion. Look me for instance, with only some mechanical engineering background and a bit of SR I'm now one of the top specialists for CoE issues around EMdrive effect ! How gratifying... I do follow some threads about starker issues of dark energy and dark matter, can ask for a clarification in layman's terms now and then, but chances that I bring something significant to the table is vanishingly small. On serious (not fringe) "new physics" subjects most are relegated to peanut gallery but specialists. And chances that dark energy or dark matter can be investigated by some ingenuous DIYer is null, and prospects that they get us to some interesting technological more or less short term spectacular application seem extremely remote.
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#2136 by graybeardsyseng on 09 May, 2016 11:07
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frobincat: Outstanding comment!! Yes - I think there are some here ( and on other forums) who are so don't share the public appreciation for spectacular applications - although perhaps not so many as we might suspect..../...
I really wonder why the EMDrive threads have so many millions of views when threads about dark matter/dark energy, which are really important and widely acknowledged new physics problems, don't have millions of views.
.../...
This sounds like a naive question, or maybe your heart is so scientifically inclined (as in "pure science") that you don't share the more general public passion for spectacular applications ?
The EMdrive wasn't (and still isn't unanimously) recognized as new physics, this was a heated debate on this thread, before the whole New Physics for Space Technology section was created on NSF. So my personal feeling on that it that it is not the "new physics" aspect that attracted the most of attention at first, proponent of the effect haven't put "new physics" on page cover, and rather minimized or dismissed some of the bigger picture consequences to concentrate only on applicability to practical propulsion. This goes basically as "this is just a new way to thrust a vehicle", and when pressed "we are not claiming violation of CoM nor violation of CoE nor violation of relativity nor violation of known frameworks...". But claiming new physics or not, the simple apparent conditions of application of this new way of thrusting clearly required new physics. Hard nosed scientifically inclined people (as in "caring about consistency") get attracted by the level of public attention raised by primary claims (application) and objected strongly against the implicit claims (wider consequences).
Heated debate ensues. Public loves drama. There is activity, the experimental claims seem reachable by DIYers, theoretical propositions look so mad and vague that peoples at various levels of knowledge feel free to contribute, everyone can have an opinion. Look me for instance, with only some mechanical engineering background and a bit of SR I'm now one of the top specialists for CoE issues around EMdrive effect ! How gratifying... I do follow some threads about starker issues of dark energy and dark matter, can ask for a clarification in layman's terms now and then, but chances that I bring something significant to the table is vanishingly small. On serious (not fringe) "new physics" subjects most are relegated to peanut gallery but specialists. And chances that dark energy or dark matter can be investigated by some ingenuous DIYer is null, and prospects that they get us to some interesting technological more or less short term spectacular application seem extremely remote.
I am reminded of the period of the first few decades of heavier than air powered flight (i.e. 1903 plus say 20 years). There were many serious questions on the theoretical aspects of flight (still are some!) but that did not stop everyone with a bit of engineering skill and a modicum of resources from attempting to push the art of flight forward. What sparked the wild public interest and appreciation (and if you doubt that look at the history of air shows, barnstorming, military applications etc - the historical record is replete with examples of near hysterical enthusiasm) was the concept of the ability to FLY!!!. Many areas of knowledge were advanced - not just aerodynamics and aeronautics - consider just the materials technology advances from the Wright Brothers first engine compared to say a 1933 500 HP Radial to a 1940ish early jet engine.
If the EMDRIVE is shown to be real and to be "useful" (and useful will be a MUCH wider solution space than most of us currently see - the millions of folks who are watching here and other places have LOTS of ideas and will see to that! ) the explosion of interest and applications will likely be astounding, even before the theoretical basis is consensualized and settled And of course if "new physics" is required the application space may be literally beyond our current imagination.
The public does love drama and heated debate. There were fights and public confrontations over whether powered flight was real or a hoax - some as late as the 1910s - and that public interest made for many funding opportunities and the social energy to lead to advancements. However - a cautionary note - strike while the iron is hot, many still disbelieve the lunar landings of half a century ago. As time passes much less funding (as % GNP) is available (and we need to get off this dirt ball ASAP; come on commercial space access!!). We need every DIYer, every dreamer, every hard minded scientist and every bit of public interest.
Herman -
#2137 by Bob Woods on 09 May, 2016 11:23
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Here's the hd webcast I was on:
Good job Dave. It's good to see those folks that have a keen interest in science, helping others understand. -
#2138 by Bob Woods on 09 May, 2016 11:32
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frobincat: Outstanding comment!! Yes - I think there are some here ( and on other forums) who are so don't share the public appreciation for spectacular applications - although perhaps not so many as we might suspect..../...
I really wonder why the EMDrive threads have so many millions of views when threads about dark matter/dark energy, which are really important and widely acknowledged new physics problems, don't have millions of views.
.../...
Heated debate ensues. Public loves drama.
The public does love drama and heated debate..... We need every DIYer, every dreamer, every hard minded scientist and every bit of public interest.
Herman
Humans would still be hunter gatherers if it wasn't for that urge to look into a dark place not seen before, and to see a new light. That's what you all do.
The public follows later... -
#2139 by Tellmeagain on 09 May, 2016 12:50
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Well, to be fair the geomagnetic field can be rigorously excluded from a small volume. Its done all the time in zero field magnetic resonance spectroscopy.
I think it is correct to say that there is consensus in the thread now on a few points.
1) Shawyer's "data" is unreliable/nonexistent and his ideas are nonsense. Shawyer's wrong claims got this whole thing started.
2) None of Yang's positive results were real. She retracted her earlier claims and is no longer working in this area.
3) Tajmar saw no significant evidence in his data of thrust and stated so himself.
4) NASA's data does not exist in the sense that there is insufficient error analysis and none of it has really been subject to peer review. There is no significant public data, only social media hearsay and preprint powerpoint.
5) Robust tests are pretty straightforward to design and execute. High vacuum chamber, torsional balance, batteries, validation of resonance.
6) There are no really good hypotheses to test. Shawyer's model is just plain wrong. Baez dealt a pretty damning blow to McCulloch, so thats out. There is even disagreement about whether or not a "clean" RF source is needed, which indicates that a virtually limitless variable space needs to be tested for a signal.
My personal takeaway: Institutional findings (Yang, Tajmar, NASA) are either null or very weak/unverified. Hypothesis testing is significantly weakened by the fact that there is no clear question being asked; the proposed "effect" is thought to be caused by many different stimuli, so really experiments have a huge variable space to optimize (Cavity shape, "cleanliness" of the RF source, dielectrics, wavelength, quality of resonance, mode shape, applied power, geomagnetic field strength, the list goes on). This implies a huge required investment of resources in precision machining, which will be very expensive, for a very slim chance of success compared to the ROI-type value of other work (mainstream science). I'm amazed that so many people have poured so much effort into the EMDrive considering that the real evidence for it is so amazingly weak compared to the "screaming in your face" quality of other historical new physics data such as spectral lines, accelerating expansion of the universe, crystal structures of molecules, etc. Not to mention the really "screaming in your face" qualities of existing new physics data being encountered today: see dark matter. I really wonder why the EMDrive threads have so many millions of views when threads about dark matter/dark energy, which are really important and widely acknowledged new physics problems, don't have millions of views.
I understand that DIY efforts are valiantly moving forward, but most of them are less robust than the NASA effort. I also recognize that I won't convince DIY folks to drop their wrenches, and rightly so. Still, I wonder if the herculean efforts to mine a tiny patch of data here would be better spent elsewhere.
You wrote out my thoughts. Thank you! I think I have contributed all I can to this thread and will spend time on my other field. If anybody is calling me please send me message. I may come back when there is news. Thank you!
