Author Topic: EM Drive Developments - related to space flight applications - Thread 2  (Read 2106774 times)

Offline zen-in

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It is clear that we are operating under other than usual symmetry conditions and that Maxwell's equations as we were trained to use them do not apply.

In conclusion, this whole affair appears to be the work of someone who has convinced himself his theory is right and is on a fishing expedition for evidence that supports it. The experimental design is poor (camera pictures of LabView windows? unable to find an RF amplifier to deliver more than 100W of power? inability to measure forces that would be measurable in the 1800's?), the past 100+ years of physical experiments contradict the experiments, and there is no coherent underlying theory.

This is not science, it is cargo cult science.

Calling it cargo cult science is a bit too harsh.   I reserve that description for individuals who have Bizarro World concepts of science, physics, etc.   This is not the case here.   What is missing are controlled experiments that would validate any conventional explanations for the anomalous thrust.   These researchers are over-reaching.  They are too eager to show just positive results.     I am 99% certain there is nothing here.   To explain the 1%:  There remains a possibility that Shawyer has discovered something and the Eagleworks team are just not able to replicate what he has done.   To their credit the Eagleworks team have provided a lot of experimental results in the last year.   Shawyer has not done this.   What I have seen in both the Eaglework's thrust graphs and the  few of Shawyer's that I have seen is a lack of consistency in the step response of these devices.   The calibration force (a capacitor on the Eagleworks setup) produces a driving function that can be considered to be two step functions.   Anything else that drives this torque pendulum with a step function should cause the same system response.   That is fundamental physics any mechanical or electrical engineer would agree with.   But we don't see this happening when the RF is switched on.   We also see an effect that looks like there is stored momentum.   How is this happening?  There is something else causing the "anomalous thrust".   Until the effects of that other cause are nulled out any actual warp-drive or em-drive thrust has not been observed because a priori it must have the same system response as the calibration drive.


Offline Zach Swena

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If you have a new physical theory which predicts some phenomenon, it should reduce to previously known physical theories, and be able to explain existing experiments and observations. If I believe that the EM drive is actually providing some nonclassical, unexplained thrust, I must throw out 100+ years of physics experiment and theory. I choose not to do that, which is why I do not believe further experimentation is warranted. Others may choose differently, but then they should ask themselves why they are so eager to disregard such a large body of established science.

Forget all these new theories for the moment. Concentrate on the experiment.

If all there is to these experiments is experimental error, then we can forget the whole thing.

If there is anomalous thrust from these experiments, then theorists can try to figure out how it works.

Some very intelligent and highly trained people here have been trying to show these results are experimental error. They are still talking about it because they can't explain away the results yet.

As an engineer, I am extremely skeptical of law breaking stuff like this, but the statement above is where it is at.  You don't have to throw out all of the old body of science when new as of yet unexplained phenomenon like this come up.  The proper role of science now is to figure out if these experiments are flawed in some way or if this points out one of the many flaws in our understanding of physics today. 

If you view scientific knowledge as a static group of absolutes, then your understanding of science is extremely flawed.  It is healthy to have faith in the existence of an absolute reality, but we shouldn't be so vain to think that we have a full understanding of such that can't be subject to revision when we see more of the picture.

Something like this, if true will most likely just result in a few additional coefficients or terms in our equations.  If it does pan out, that would be awesome.  I suspect it is just a side effect of not controlling for enough variables in the experiment.

Offline ragingrei

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Not a physicist, but is it really that unusual or unprofessional for a researcher to tinker with unexplained phenomena?

They haven't even made any official claims yet about why they think they're seeing what they are; they're just sharing screenshots of their observations and ideas about them on a forum the way they might with colleagues.

If they publish a paper and it turns out to be complete garbage, then sure, but right now it seems like they're still at the scratching-their-heads phase as much as anyone else is -- albeit scratching with a little more vigor and excitement than many.
« Last Edit: 04/30/2015 11:18 PM by ragingrei »

Offline Star One

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It is clear that we are operating under other than usual symmetry conditions and that Maxwell's equations as we were trained to use them do not apply.

In conclusion, this whole affair appears to be the work of someone who has convinced himself his theory is right and is on a fishing expedition for evidence that supports it. The experimental design is poor (camera pictures of LabView windows? unable to find an RF amplifier to deliver more than 100W of power? inability to measure forces that would be measurable in the 1800's?), the past 100+ years of physical experiments contradict the experiments, and there is no coherent underlying theory.

This is not science, it is cargo cult science.

Calling it cargo cult science is a bit too harsh.   I reserve that description for individuals who have Bizarro World concepts of science, physics, etc.   This is not the case here.   What is missing are controlled experiments that would validate any conventional explanations for the anomalous thrust.   These researchers are over-reaching.  They are too eager to show just positive results.     I am 99% certain there is nothing here.   To explain the 1%:  There remains a possibility that Shawyer has discovered something and the Eagleworks team are just not able to replicate what he has done.   To their credit the Eagleworks team have provided a lot of experimental results in the last year.   Shawyer has not done this.   What I have seen in both the Eaglework's thrust graphs and the  few of Shawyer's that I have seen is a lack of consistency in the step response of these devices.   The calibration force (a capacitor on the Eagleworks setup) produces a driving function that can be considered to be two step functions.   Anything else that drives this torque pendulum with a step function should cause the same system response.   That is fundamental physics any mechanical or electrical engineer would agree with.   But we don't see this happening when the RF is switched on.   We also see an effect that looks like there is stored momentum.   How is this happening?  There is something else causing the "anomalous thrust".   Until the effects of that other cause are nulled out any actual warp-drive or em-drive thrust has not been observed because a priori it must have the same system response as the calibration drive.

Well then let's hear your suggestions for how these concerns can be dealt with then? After all that's what this thread is all about.:)
« Last Edit: 04/30/2015 11:18 PM by Star One »

Offline FutureStormtrooper

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While I do not share Squid's absolute certainty that all the experimental data is a fluke, and that the theories are bunk, there is one question of his that I would be very interested in an explanation being made for. Namely, how is that this phenomenon hasn't been discovered and documented in centuries past?

What is so unique about the experimental setups of Eagleworks, Yang, and Shawyer compared to the presumably millions of other microwave cavities which have been experimented on in the past? Is it actual physical differences in these setups, is it that the forces produced are so small that nobody noticed beforehand, is it something else?

I think that this is a very good question, and I'd be interested in the enlightened answers of the denizens of this thread   :)
« Last Edit: 04/30/2015 11:33 PM by FutureStormtrooper »

Offline zen-in

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It is clear that we are operating under other than usual symmetry conditions and that Maxwell's equations as we were trained to use them do not apply.

In conclusion, this whole affair appears to be the work of someone who has convinced himself his theory is right and is on a fishing expedition for evidence that supports it. The experimental design is poor (camera pictures of LabView windows? unable to find an RF amplifier to deliver more than 100W of power? inability to measure forces that would be measurable in the 1800's?), the past 100+ years of physical experiments contradict the experiments, and there is no coherent underlying theory.

This is not science, it is cargo cult science.

Calling it cargo cult science is a bit too harsh.   I reserve that description for individuals who have Bizarro World concepts of science, physics, etc.   This is not the case here.   What is missing are controlled experiments that would validate any conventional explanations for the anomalous thrust.   These researchers are over-reaching.  They are too eager to show just positive results.     I am 99% certain there is nothing here.   To explain the 1%:  There remains a possibility that Shawyer has discovered something and the Eagleworks team are just not able to replicate what he has done.   To their credit the Eagleworks team have provided a lot of experimental results in the last year.   Shawyer has not done this.   What I have seen in both the Eaglework's thrust graphs and the  few of Shawyer's that I have seen is a lack of consistency in the step response of these devices.   The calibration force (a capacitor on the Eagleworks setup) produces a driving function that can be considered to be two step functions.   Anything else that drives this torque pendulum with a step function should cause the same system response.   That is fundamental physics any mechanical or electrical engineer would agree with.   But we don't see this happening when the RF is switched on.   We also see an effect that looks like there is stored momentum.   How is this happening?  There is something else causing the "anomalous thrust".   Until the effects of that other cause are nulled out any actual warp-drive or em-drive thrust has not been observed because a priori it must have the same system response as the calibration drive.

Well then let's hear your suggestions for how these concerns can be dealt with then? After all that's what this thread is all about.:)

My first suggestion was to replace the RF feed with a suitably sized power resistor.  What happens when the same amount of power is delivered to the interior of the cavity, but with no RF?   Use the same test protocol (is there a protocol?).  Move the power resistor around.  Clamp it to different parts of the cavity (magnets on the outside will do this) and plot the response to a thermal drive with the same power level.   I made this suggestion over 6 months ago.

Of course this type of test is difficult to perform because anytime something is added or removed from the em-drive the balance has to be adjusted again.   And there has been a lot of discussion about how this torque pendulum works and whether it is contributing to alleged erroneous results.    So another way to do this test is to use focused  heat lamps or direct the RF energy at the outside of the cone using feedhorns.
« Last Edit: 05/01/2015 12:40 AM by zen-in »

Offline MADscientist

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Just (mostly) a lurker here, and by far NOT anything other than an "armchair scientist" (lol), but it would seem to me that if you are having trouble telling whether there really is "thrust" from this thing or not, presumably because that thrust is either so small it is hard to detect reliably, or because it is drowned out by "background noise" or whatever, then perhaps you need to "get closer" to it to "see" it better. In my line of work I have to "see" very small differences in "things". I do this using magnification. Now, magnification merely allows me to get my eyeball "closer" to that which I am looking at. Another way I  COULD accomplish the same thing would to be to make the "thing" larger (which is what magnification sort of does). Obviously, you can't get closer to this phenomena you are trying to examine and verify, but you COULD make it larger. Why not increase the effect's size? Pump MORE initial energy into it? Stop pussyfooting around with it and take this baby past Warp11!

Personally, I am MORE interested in the reporting about the experiment(s) having suggestively produced a (manipulable?) space-warp bubble. I think that holds more promise.

Offline Nemo

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If new non-classical physics models are required to explain the EM Drive thrust as mentioned above by Squid we would have to apply any new physics models to astrophysical observations. Quoting Squids question
Quote
Why don't we see any interaction in these vastly larger fields, or any "spacetime bending"?
. Assuming that the EM Drive thrust is eventually confirmed could it be that this same effect is responsible for Dark Energy and the expanding universe?

Offline virtualighter

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Well then let's hear your suggestions for how these concerns can be dealt with then? After all that's what this thread is all about.:)

See my post 4/30 10:43 PM by virtualighter

All squid's concerns are based on the assumption that the effect is via quantum mechanics.  This paper explains that it's not QM, it's relativity.  Refute this paper, then there will be something to discuss. 

http://www.emdrive.com/theorypaper9-4.pdf


« Last Edit: 05/01/2015 12:16 AM by virtualighter »

Online JasonAW3

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Well then let's hear your suggestions for how these concerns can be dealt with then? After all that's what this thread is all about.:)

Well, for one thing, it might be an idea to take a less cynical approach to this situation, and go back and reread the the data in the threads concerning the EM drive.  The results have been reproduced numerous times in the UK and China. Variations of the output compared to input seems related to experiment set up, but all have had similar results, all of them producing some measure of detectable thrust.  By varying the input voltage and frequency of the RF feed, they have varied the amount of thrust.

Something IS happening, something that is reproducible with the same setups.  There had been no attempts to withhold data, if anything, we've been overwhelmed with data and math.

Yes,  there are those who have their own theories as to what is happening, and for all we know, all of those theories could be wrong.  We don't know yet.  Thrust IS being produced, and has done so both in atmosphere and in vacume, so air, as a factor, has been effectively eliminated.

Science requires both an open mind and a degree of skepticism.  Science is experimentation, hypothisizing, theorizing and observation.  Not in that order, but let's be honest. Science is messy and we don't know all there is to know.

More than once, experiments have produced results completely outside of accepted theories.  Sometimes it's because the experiment was set up wrong, sometimes its because of observer bias, and sometimes we discover something new that we never expected.  The core here is repeatability of the results by other experimenters using the same sort of set ups.

This has been accomplished.  Thrust has been produced by all of these set ups.  How its being produced? That seems to be the major sticking point.  Nobody's really sure.  That's why we do science to these experiments to figure out why something does what it does.  Even when starts out with a theory that turns out to be wrong, sometimes you get legitmate results for completely different reasons.  This may be what is happening.

Me,  I'm excited about the results so far, as it once again proves a smart man knows a lot of things, but a wise man knows how much he really doesn't know.
« Last Edit: 05/01/2015 12:29 AM by JasonAW3 »
My God!  It's full of universes!

A lot of the skepticism of the results thus far has been centered around the support setups for the drive.  Seems like a lot of time and energy could be saved if someone could convince Mr. Musk to tote one up into orbit and turn it on.
« Last Edit: 05/01/2015 12:34 AM by lasoi »

Online JasonAW3

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A lot of the skepticism of the results thus far has been centered around the support setups of the drive.  Seems like a lot of time and energy could be saved if someone could convince Mr. Musk to tote one up into orbit and turn it on.

I suspect that that all be one of the next experiments.  I also suspect that performance may be far better than expected the further it is from Earth.
My God!  It's full of universes!

Offline ragingrei

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A lot of the skepticism of the results thus far has been centered around the support setups of the drive.  Seems like a lot of time and energy could be saved if someone could convince Mr. Musk to tote one up into orbit and turn it on.

I suspect that that all be one of the next experiments.  I also suspect that performance may be far better than expected the further it is from Earth.

Could you explain for a layman why they couldn't simply test it on the ground with the power cranked up or with multiple drives in concert, in order to drown out any other effects? It would probably be less expensive than launching a satellite, wouldn't it?

Offline LasJayhawk

The "Edison Effect" predates the discovery of the electron by 15 years. Manipulating something that you didn't know existed or wasn't fully understood would appear to be doable.

Does Eagleworks have a motto? If not may I suggest something Robert Heinlein once wrote:
"Always listen to experts. They'll tell you what can't be done, and why. Then do it."

Online JasonAW3

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There's a lot more experimentation that needs to be done before sending something like this into space.  However: it's been suggested that this could be put together in a cubs at format, although I am a bit skeptical about that, as it would still require a significant amount mof test equipment to observewhat happens in orbit.
My God!  It's full of universes!

Online JasonAW3

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The "Edison Effect" predates the discovery of the electron by 15 years. Manipulating something that you didn't know existed or wasn't fully understood would appear to be doable.

Does Eagleworks have a motto? If not may I suggest something Robert Heinlein once wrote:
"Always listen to experts. They'll tell you what can't be done, and why. Then do it."

Always a good quote.  This whole situation kind of reminds me of "Waldo and Magic, Inc."

There was another author who'd written a story about a student who'd built a cold fusion bomb.  He did this as the result of a question in his college physics class.  "Explain why cold fusion is impossible."  Sometimes the answer is all in how you ask the quesdtion.
« Last Edit: 05/01/2015 01:36 AM by JasonAW3 »
My God!  It's full of universes!

Offline laika

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I haven't read this entire thread, maybe it has already been covered. I was disappointed by the complexity and even crudity of the Chinese test setup, and also the poor spectral output of their microwave generator, all of this tending to add noise to their results.
I would be interested in the return loss of the cavity, and what load it presents to the microwave generator during acceleration. Presumably the microwave power is turned into kinetic energy in the device, so what effect does loaded Q have on thrust generation in the device?

Offline squid

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It doesn't have anything to do with quantum mechanics, it has to do with relativity.  So refutations based on quantum mechanics are irrelevant.

Read the paper.  The paper shows that there will be a force.  Yes, the content of the paper is hard to keep in your head, but it's in there. 

http://www.emdrive.com/theorypaper9-4.pdf

As I understand it, the speed of light, being constant no matter what, essentially creates a separate reference frame from what is going on inside the cavity.  The propulsive force is generated because of differences between the two reference frames.  Going out on a metaphoric limb, it's like the EM waves in the cavity get squeezed against the speed of light, and it doesn't budge, so the cavity has to.

But it doesn't matter how it is put into words.  The reality is not in the narrative metaphors.  The reality is in the physics equations, the math.  The paper uses well-established equations from physics, and provides sources. 


First off, maybe I was a little harsh in calling in cargo cult science. So sorry about that. I will suspend value judgements and concentrate on the scientific aspect.

 I don't dispute that something is moving, what I dispute is that there are any unknown physics occurring. Experimentation without some kind of underlying theory doesn't tell us much... we need theoretical guidance to explain measurements, otherwise they do not fit in a conceptual framework. Classical physics provides us with such a conceptual framework.

I have read the paper you cite, and I find it lacking. Here is an easy refutation. Equation (7) only considers the reaction on the two end plates of the resonator, and calculates the force based on the difference between the two. But of course, there will be a reaction on the cylindrical wall of the cavity, which will exactly cancel out this extra force.

Here is a general proof that, with the equations of classical electrodynamics there can be no thrust on a cavity of ANY SHAPE. Let me remind you that Maxwell's equations are perfectly Lorentz invariant, and so obey the lays of Special Relativity:

Let us assume a source-free cavity with perfectly conducting walls. The fields in the cavity will be harmonic as a function of time, as required by solutions to the Helmholtz equation (see Rodal's excellent mathematical analysis of the conical cavity upthread for an example).

The rate of change in time of momentum (density) of the system (mechanical components and EM fields) is given by:

dp/dt = div T, where T is the Maxwell stress-energy tensor.

div T = epsilon0 ( E x curl E + c2 B x curl B - (div E)E - c2(div E)E )

Per Maxwell's equations and the absence of free charges, div E = 0, div B = 0, and using the equations for the curl of the magnetic and electric fields,

div T = - epsilon0 d( E x B)/dt = -(1/c^2)dS/dt, where S in the poyting vector.

Integrating this from t to t+2pi/omega (ie one frequency cycle), we get -(1/c^2) S(t+2pi/omega) - S(t). Since the fields are harmonic, this equals 0. There is no change in momentum on the cavity, and no net force.

Again, Rodal has calculated all this explicitly for the case of a conical cavity.

To be clear, using the equations of classical physics (including Special Relativity through Maxwell's equations), there can be no force on a closed cavity of ANY shape

Offline squid

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Furthermore, I think there has been some confusion from where I am coming from. I am merely trying to point out that new experiments must be consistent with past experiments when they overlap. No one has addressed my main concern:

Why have we not seen this effect before?

Please try to understand:

IF the EM drive is working
THEN the EM drive must be coupling electromagnetic energy to something

Then why has this coupling never been observed before? This is not a small effect. There are many many test cavities that operate in particle accelerators, as antenna feedhorns, as resonators in oscillators... if this effect were real, it would affect all of these. Why has this not been the case?

We are not working in a realm of physics that is out there... not subatomic particles, not astronomical observations of dark matter/dark energy, not trying to build a fusion device or a quantum computer. This is the kind of physics we need to know 100% to be able to design microwave antennas for cell phone towers.

Offline RotoSequence

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Furthermore, I think there has been some confusion from where I am coming from. I am merely trying to point out that new experiments must be consistent with past experiments when they overlap. No one has addressed my main concern:

Why have we not seen this effect before?

Please try to understand:

IF the EM drive is working
THEN the EM drive must be coupling electromagnetic energy to something

Then why has this coupling never been observed before? This is not a small effect. There are many many test cavities that operate in particle accelerators, as antenna feedhorns, as resonators in oscillators... if this effect were real, it would affect all of these. Why has this not been the case?

We are not working in a realm of physics that is out there... not subatomic particles, not astronomical observations of dark matter/dark energy, not trying to build a fusion device or a quantum computer. This is the kind of physics we need to know 100% to be able to design microwave antennas for cell phone towers.

I'm going to preface this by admitting straight off the bat that I don't actually know why it wouldn't have been noticed before. However, the functionality of these EM drives is dependent on resonance, which requires the broadcast energy to be absorbed, or at the very least contained, by the cavity. For the purposes of transmission, resonating cavities are a characteristic of inefficiency and loss to design against, no?
« Last Edit: 05/01/2015 02:40 AM by RotoSequence »

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