Quote from: francesco nicoli on 10/31/2014 11:49 amSorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?thanks! Francesco, we are getting close to showing, analytically, that the EM Drives test results are likely an experimental artifact.
Sorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?thanks!
Quote from: francesco nicoli on 10/31/2014 11:49 amSorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?thanks! Hi there. I wouldn't put much stock in the ostensibly technical speculations that fill this thread. The results are certainly wrong and are in clear violations of macroscopic conservation of momentum. All explanations or "models" proposed to explain this (quantum plasma, virtual particles, etc.) are all based on incredibly bad physics. Any signal these experimenters find is almost certainly due to a terrible experimental method and questionable data analysis. As far as I can tell, along with the greater physics and engineering communities (from what I have seen), this is a fantasy device.
Sorry for asking, but -as the discussion is getting very technical- could someone of you make a quick update for the non-physicists among us (like myself)? is there any tangible progress, or has the device been demistified once for all?
Fascinated member of the peanut gallery here. Peanut crop was good this year, eh? I can take a shot at the highlights covered over the past 100 or so pages in this thread ....... Rodal ... was of the view the reported results were an experimental artifact, most likely thermal in nature. After a post ... he and the other regular posters here began looking for alternatives, especially experimental artifacts. ... the explanations for the device's performances were seen ... to be flawed from the outset.A number of reasonably rational scientific explanations were considered should all the experimental artifacts be ruled out. Of these, few showed any promise:1) The device was somehow pushing against hypothetical 'Dark Matter.' This might be valid, if one accepts a very high estimate for the local abundance of Dark Matter, which stell needs to be found. But still dubious. 2) Ion Wind devices, using the Bifield - Brown effect. This is a real effect, used by...hobbyist...to make pure electrical flying devices. ... this was ruled out because of the very low power levels involved and because it needs atmosphere of a higher density than space to create ions out of. 3) Unruh Radiation, which is a sort of 'inertia radiation', which is an element in a branch of physics attempting to make General Relativity and Quantum Mechanics play well together, and which is also sort of hypothetical. [Unruh radiation] also negates many of the more dubious elements theorists have conjured to explain observed astronomical reality - things like dark matter and dark energy. A professor McCulloch has been promoting this on his blog, which is occasionally linked to in this thread. So... http://physicsfromtheedge.blogspot.com/Many of the last few dozen pages have been dedicated to gathering enough info about the various EM devices tested to run 'back of the envelope' calculations as to whether or not Unruh Radiation is a viable solution. Results have been mixed, in no small part because even basic information about these devices - like their size and proportions - is color=blue]unnecessarily[/color] very difficult to come by thru no fault of the thread's theorists. Additionally, this explanation is very frequency dependent, and worse, the frequency shifts. The experimenters are essentially blundering about in the dark, hitting the correct frequency by occasional accident. Unruh Radiation is still considered a possibility, and I believe several members here find the theory of great interest even if they doubt the EM Drive is somehow tapping into it. Which brings us to where matters stand now:The experimenters are demonstrating an across the board failure to understand certain 'stress forces' which have a high possibility of giving at least partial false results in their experiments. The "across the board failure" is particularly troublesome, since there is no good reason for that failure. Furthermore, the explanatory equations put forth by both Doctor White and Shawyer have errors within them. Which means the results may be false positives - the EM Drive does not work.That said, the notion of tapping into Unruh Radiation and using it to propel a starship is interesting in its own right.And even if Unruh Radiation does not exist, some force, currently termed 'Dark Energy' exerts enough force on space-time to drive galaxies apart at a continuous 1 kilometer per second per kilo parsec. (I hope I didn't get too many things wrong here.)
I expanded the photo as big as it will go, and slowed my mouse as slow as it will go to take out my hand shake, and picked off a 5 pixel width of the big end edge. At that scale the 3.81 cm Frzl? beam end was 110 pixels but close to the same distance from the camera.Five pixels at that scale comes out to be 0.173 cm, or 1/16". But there is the question as to just what I measured because the ends of the cavity seem to be a board of some sort, and not all copper.What are you trying to do? I guess you want to see if the vibration comes from flexing of the thin copper. But at a GHz, that seems unlikely. Better to analyze than guess, though. But if the end is a copper covered board, as has been suggested, what would be the density of that? And what would be the likelihood of the copper covering vibrating independently of the board? Coming loose, so to speak.
Quote from: aero on 10/31/2014 08:42 pmQuote from: Mulletron on 10/31/2014 08:26 pmQuote from: Rodal on 10/31/2014 06:08 pmTo explain the impulse part of the response,I need to have an independent estimate of the copper thickness in these devices.could anyone please provide a guesstimate or a range for what the thickness of the copper in these EM drives maybe ?I am also interested in the thickness of the NASA test article. Shawyer and the Chinese I don't care about because of my lack of confidence in their reporting. It is important to my evanescent wave coupling hypothesis; in the quest for yet another plausible artifact to explain away reports of thrust from an empty copper can under high power. I've been getting indications and warnings of 1/8" thickness, but I cannot confirm with high confidence.I expect the cavities were made of some commonly available copper sheet. I doubt that Eagleworks did anything more difficult than go to the hardware store and buy a sheet of copper. Here is a web site that sells copper sheet. Look at the choices and take your pick. Or find your own favorite copper sheet retailer. Or call your local hardware store and ask them what thicknesses they have in stock. But from looking at the photo I can't tell, the resolution isn't good enough.The cone looks like it was made from 20 gauge or thinner copper, possibly the same material roofers use. You sometimes see trucks with a big spool of it on the back. 1/8" Thick copper would require machine tools like a metal press to form. Even 1/16" thick copper (14 gauge is the closest) requires a lot of work to form into a cone and the tool marks would show. Also the weight would be an issue. I think it is most likely 20 to 26 gauge (.032" - .016"). Building an apparatus like the eagleworks em-drive would not be difficult. Just a few large pieces of FR4, some lightweight Copper sheets and a jig for forming it into the cone shape.
Quote from: Mulletron on 10/31/2014 08:26 pmQuote from: Rodal on 10/31/2014 06:08 pmTo explain the impulse part of the response,I need to have an independent estimate of the copper thickness in these devices.could anyone please provide a guesstimate or a range for what the thickness of the copper in these EM drives maybe ?I am also interested in the thickness of the NASA test article. Shawyer and the Chinese I don't care about because of my lack of confidence in their reporting. It is important to my evanescent wave coupling hypothesis; in the quest for yet another plausible artifact to explain away reports of thrust from an empty copper can under high power. I've been getting indications and warnings of 1/8" thickness, but I cannot confirm with high confidence.I expect the cavities were made of some commonly available copper sheet. I doubt that Eagleworks did anything more difficult than go to the hardware store and buy a sheet of copper. Here is a web site that sells copper sheet. Look at the choices and take your pick. Or find your own favorite copper sheet retailer. Or call your local hardware store and ask them what thicknesses they have in stock. But from looking at the photo I can't tell, the resolution isn't good enough.
Quote from: Rodal on 10/31/2014 06:08 pmTo explain the impulse part of the response,I need to have an independent estimate of the copper thickness in these devices.could anyone please provide a guesstimate or a range for what the thickness of the copper in these EM drives maybe ?I am also interested in the thickness of the NASA test article. Shawyer and the Chinese I don't care about because of my lack of confidence in their reporting. It is important to my evanescent wave coupling hypothesis; in the quest for yet another plausible artifact to explain away reports of thrust from an empty copper can under high power. I've been getting indications and warnings of 1/8" thickness, but I cannot confirm with high confidence.
To explain the impulse part of the response,I need to have an independent estimate of the copper thickness in these devices.could anyone please provide a guesstimate or a range for what the thickness of the copper in these EM drives maybe ?
The coupling coefficient is non-trivial. But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivitythermalDiffusivity = 1.11*10^(-4) m/sso for thickness of copper = 1/8 in = 0.00318 mhence time = 0.0908 sso for thickness of copper = 1/16 in = 0.00159 mhence time = 0.0227 sso for thickness of copper = 0.022 in = 0.000559 mhence time = 0.0028 sSo, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)
Quote from: Rodal on 11/01/2014 01:57 pmThe coupling coefficient is non-trivial. But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivitythermalDiffusivity = 1.11*10^(-4) m/sso for thickness of copper = 1/8 in = 0.00318 mhence time = 0.0908 sso for thickness of copper = 1/16 in = 0.00159 mhence time = 0.0227 sso for thickness of copper = 0.022 in = 0.000559 mhence time = 0.0028 sSo, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s)Great! Look at the drumhead expansion of the big end .002" copper FRP w/ resistve heating from the Cu loss!http://en.wikipedia.org/wiki/FR-4
The coupling coefficient (basically due to the strain rate being larger than the temperature rate) is non-trivial. But calculating the Fourier non-dimensional time is trivial, so let's calculate the time for which the Fourier non-dimensional = 1, which is simply ((thickness)^2)/thermalDiffusivitythermalDiffusivity = 1.11*10^(-4) m/sso for thickness of copper = 1/8 in = 0.00318 mhence time = 0.0908 sso for thickness of copper = 1/16 in = 0.00159 mhence time = 0.0227 sso for thickness of copper = 0.022 in = 0.000559 mhence time = 0.0028 sSo, the initial thermal effect on the copper thickness is clearly impulsive, from the point of view of the much slower response of the inverted torsional pendulum (with period ~ 4.5 s as provided by Paul March himself, or 4.8 s as measured by frobnicat, and both of them corroborated by my analytical model of the inverted torsional pendulum)
It is not the intent here to detail the theory or engineering of quantum vacuum plasma thrusters (Q-Thrusters). Rather, an overview of the foundational physics and laboratory findings are given.Q-Thrusters attempt to use the properties of the “quantum vacuum” to propel a spacecraft. Quantum Electrodynamics (QED) predicts that the quantum vacuum (the lowest state of the electromagnetic field) is not empty, but rather a sea of virtual particles and photons that pop into and out of existence stemming from the Heisenberg uncertainty principle.A number of approaches to utilize this quantum vacuum to transfer momentum from a spacecraft to the vacuum have been synopsized in [1].A Q-Thruster uses the same principles as conventional plasma thrusters, namely magnetohydrodynamics, where plasma is exposed to crossed electric and magnetic fields which induce a drift of the entire plasma in a direction orthogonal to the applied fields. The difference arises in that a Q-Thruster uses quantum vacuum fluctuations as the “propellant” source, eliminating the need for conventional on-board propellant. A discussion of spacecraft “conservation of energy” is given in Appendix A. Recent laboratory test results [2] indicate the expected thrust-to-power ratio for flight applications could be in the 0.4 – 4.0 N/kWe range, which is one to two orders of magnitude greater than current operational electric thrusters. This combination of characteristics – relatively high specific thrust combined with essentially zero on-board propellant requirement - suggest space mission performance levels significantly exceeding current capabilities.
Did the NASA researchers place that polymer composite on the Big Diameter end on purpose to insulate that end and use the copper/PCBoard to create a bimaterial end to maximize thermal waves ?Funny they would not comment about its effect on the experiment.Maybe they didn't think about it 'cause they were spending too much time thinking of the quantum vacuum, General Relativity, and Mach Effects in comparison with classical effects... Too much time thinking about the speed of light and not enough thinking about the speed of sound
Quote from: Rodal on 11/01/2014 09:22 pmDid the NASA researchers place that polymer composite on the Big Diameter end on purpose to insulate that end and use the copper/PCBoard to create a bimaterial end to maximize thermal waves ?Funny they would not comment about its effect on the experiment.Maybe they didn't think about it 'cause they were spending too much time thinking of the quantum vacuum, General Relativity, and Mach Effects in comparison with classical effects... Too much time thinking about the speed of light and not enough thinking about the speed of soundDidn't they do the same thing on the small diameter end? It would have the same effect, but at a different frequency. How would the two ends interact? This could get complicated.
This is a little better picture showing the mounting. Looks like the cavity is freely resting on the beam. If it is not securely attached at that point, it might transmit vibration even better than through the cantilever.