## EM Drive

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Aero
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### Re: EM Drive

kunkmiester wrote:
That is that evanescent wave photons can, in some circumstances have superluminal momentum.
What's the difference between momentum and velocity(?) here?

Of course you know that momentum in general is given by p = m*v, so p is velocity multiplied by a mass. Here we are looking at a mathematical result in an area of optics very unfamiliar to most. This mathematical result is couched in terms of momentum, not mass, not velocity but the product of mass and velocity. My education and experience is insufficient to allow me to assume knowledge of evanescent photon mass in order to extract information about velocity and similarly insufficient to assume knowledge about velocity to extrct information about mass.

http://en.wikipedia.org/wiki/Photon Wikipedia discusses photon momentum at some length. Momentum is given by p = hf/c where h is Planck's constant, f is frequency and c, the speed of light. But evanescent waves are expotentially decaying waves with (to my knowledge) no real frequency so I can't use this classic result to extract information about evanescent wave photon mass. Maybe someone else knows where this line of reasoning leads, not me.

And maybe there is an answer within the details of the mathematical derivation. One could look there.
Aero

GIThruster
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### Re: EM Drive

Well, this is an interesting explanation for the thrust down at Eagleworks. I think you might consider sharing it with Paul March as well as Dr. Rodal over at NSF. While I'm unconvinced there is any thrust measured at all since they haven't yet provided any significant scientific controls--all released results thus far have been with no vacuum--it is certainly possible they are getting thrust, and it is not possible it is coming from QVF. So yeah, shoot Paul a note as well as Rodal as he is a very sharp guy who has given a lot of time to this.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

GIThruster
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### Re: EM Drive

Just glancing over the piece in wiki about evanescent waves, and I don't think this can generate thrust. For one thing is is non-radiative and only occurs when a wave is reflected inside a material. The wave is therefore limited to the interior of that materials, like a waveguide; and does not appear outside the waveguide, in empty space, etc.

So how could this possibly generate thrust, especially in space? Not seeing it.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

kunkmiester
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### Re: EM Drive

So where is the extra energy to give a "superluminal" momentum without an FTL speed? I got your math, most articles on this stuff unfortunately use the higher formulas that can't really be understood without advanced calculus and they assume you know what a lot of variables and stuff mean.
Evil is evil, no matter how small

Aero
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### Re: EM Drive

GIThruster wrote:Just glancing over the piece in wiki about evanescent waves, and I don't think this can generate thrust. For one thing is is non-radiative and only occurs when a wave is reflected inside a material. The wave is therefore limited to the interior of that materials, like a waveguide; and does not appear outside the waveguide, in empty space, etc.

So how could this possibly generate thrust, especially in space? Not seeing it.

Did you happen to notice this paragraph in the wiki?
In electrical engineering, evanescent waves are found in the near-field region within one third of a wavelength of any radio antenna. During normal operation, an antenna emits electromagnetic fields into the surrounding nearfield region, and a portion of the field energy is reabsorbed, while the remainder is radiated as EM waves.

One third of a wavelength will take the evanescent waves well outside the waveguide. For some radio frequencies, quite a long way. For the EM thruster, maybe 5 cm.
Aero

GIThruster
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### Re: EM Drive

It's not radiated energy. It stays within the waveguide. It is from reflection, and that reflection cannot occur where there is space, since in order to travel in space, you have to have a radiated form. At least that is my quick reading of this at wiki.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Aero
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### Re: EM Drive

kunkmiester wrote:So where is the extra energy to give a "superluminal" momentum without an FTL speed? I got your math, most articles on this stuff unfortunately use the higher formulas that can't really be understood without advanced calculus and they assume you know what a lot of variables and stuff mean.

Were does the "extra" energy come from? With our current state of knowledge of evanescent waves, I'm not sure the assumption of "extra" energy is safe to make.

I don't think it works this way because of the test data we have. In those tests, thrust, or p increased by a factor of thousands over an ideal photon rocket, but there was no corresponding increase in Energy consumption.
Aero

kunkmiester
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### Re: EM Drive

Okay, lets see if I can get this written out properly. Don't know half the proper terms I probably should to say this, so bear with me.

If the velocity is more than C than you have to completely rewrite physics. So the "superluminal" wave is still traveling at C right?

But, if you simply add energy to a wave, you increase the amplitude or frequency, to increase the momentum. This isn't "superluminal" since everything still works out and the speed of propagation is still C.

So when you have an evanescent wave, that has "superluminal momentum" it has some extra energy somewhere, that's more energy than the wave should have, but isn't in the frequency or anything, or it wouldn't be "superluminal," but also doesn't add to the speed, or you'd violate the light-speed barrier and break physics.

So where is the extra energy to give it that momentum, or is it actually going faster than the speed of light? Or is this one of those things about the speed of light in the materials that make up the boundary that the wave propagates along, versus C, speed of light in a vacuum?

Am I making sense?
Evil is evil, no matter how small

Aero
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### Re: EM Drive

kunkmiester wrote:Okay, lets see if I can get this written out properly. Don't know half the proper terms I probably should to say this, so bear with me.

If the velocity is more than C than you have to completely rewrite physics. So the "superluminal" wave is still traveling at C right?

But, if you simply add energy to a wave, you increase the amplitude or frequency, to increase the momentum. This isn't "superluminal" since everything still works out and the speed of propagation is still C.

So when you have an evanescent wave, that has "superluminal momentum" it has some extra energy somewhere, that's more energy than the wave should have, but isn't in the frequency or anything, or it wouldn't be "superluminal," but also doesn't add to the speed, or you'd violate the light-speed barrier and break physics.

So where is the extra energy to give it that momentum, or is it actually going faster than the speed of light? Or is this one of those things about the speed of light in the materials that make up the boundary that the wave propagates along, versus C, speed of light in a vacuum?

Am I making sense?

I wish I knew the answer. I don't. I do know that energy can not be added to an evanescent wave by increasing the evanescent wave frequency, because evanescent waves don't have a frequency. They are not propagating waves in the sense we think of, rather they are expotentially decaying waves.
But I reiterate, the Eagleworks experiment didn't say anything about excess energy being consumed at the level needed to explain the thrust in classical terms. Evanescent waves are not classical in this sense.

I'll think about it some more.
Aero

CellJeffe
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### Re: EM Drive

Aero wrote:I wish I knew the answer. I don't. I do know that energy can not be added to an evanescent wave by increasing the evanescent wave frequency, because evanescent waves don't have a frequency. They are not propagating waves in the sense we think of, rather they are expotentially decaying waves.
But I reiterate, the Eagleworks experiment didn't say anything about excess energy being consumed at the level needed to explain the thrust in classical terms. Evanescent waves are not classical in this sense.
I'll think about it some more.

Woohoo! Something I can actually comment on, based on years of doing evanescent wave microscopy.
Yes, evanescent waves are propagating waves. They propagate in the direction of the interface, so their momentum is parallel to the boundary. It is just their amplitude that decays exponentially away from the interface layer. For example, at a glass/air interface with light entering from the glass at or above the critical angle of 41º to the normal, the "reflected" light travels within the glass along the glass/air interface (41º incident) or is reflected back into the glass at the incident angle (>41º incident). There is also a thin layer of evanescent photons in the air traveling just above the glass air interface. They travel in the same direction as the reflected ray but always parallel to the interface. The amplitude of that evanescent layer decreases exponentially further away from the interface. The evanescent layer is typically only ~100 nm thick. However, the sum of the energy in the evanescent wave in the air and the reflected light traveling within the glass sum to the energy in the input wave. In other words, the reflected ray has a slightly smaller Poynting energy than the incident wave. That energy goes to the evanescent wave. Evanescent waves arise because the electric fields must be continuous across the boundary. The electric field amplitude cannot jump from high in the glass to zero in the air.

You can see this evanescent wave propagation direction. For microscopy, I typically use a glass/water interface and a thin layer of fluorescent liquid to calibrate and insure total internal reflection. One can see the evanescent wave diffracting around defects in the glass, like a wake from a boat. That wake also indicates the evanescent wave propagation direction.

Polarized evanescent photons can do some fun twisting as they propagate, depending on the input polarization angle with respect to the interface normal.

Aero
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### Re: EM Drive

CellJeffe wrote:
Aero wrote:I wish I knew the answer. I don't. I do know that energy can not be added to an evanescent wave by increasing the evanescent wave frequency, because evanescent waves don't have a frequency. They are not propagating waves in the sense we think of, rather they are expotentially decaying waves.
But I reiterate, the Eagleworks experiment didn't say anything about excess energy being consumed at the level needed to explain the thrust in classical terms. Evanescent waves are not classical in this sense.
I'll think about it some more.

Woohoo! Something I can actually comment on, based on years of doing evanescent wave microscopy.
Yes, evanescent waves are propagating waves. They propagate in the direction of the interface, so their momentum is parallel to the boundary. It is just their amplitude that decays exponentially away from the interface layer. For example, at a glass/air interface with light entering from the glass at or above the critical angle of 41º to the normal, the "reflected" light travels within the glass along the glass/air interface (41º incident) or is reflected back into the glass at the incident angle (>41º incident). There is also a thin layer of evanescent photons in the air traveling just above the glass air interface. They travel in the same direction as the reflected ray but always parallel to the interface. The amplitude of that evanescent layer decreases exponentially further away from the interface. The evanescent layer is typically only ~100 nm thick. However, the sum of the energy in the evanescent wave in the air and the reflected light traveling within the glass sum to the energy in the input wave. In other words, the reflected ray has a slightly smaller Poynting energy than the incident wave. That energy goes to the evanescent wave. Evanescent waves arise because the electric fields must be continuous across the boundary. The electric field amplitude cannot jump from high in the glass to zero in the air.

You can see this evanescent wave propagation direction. For microscopy, I typically use a glass/water interface and a thin layer of fluorescent liquid to calibrate and insure total internal reflection. One can see the evanescent wave diffracting around defects in the glass, like a wake from a boat. That wake also indicates the evanescent wave propagation direction.

Polarized evanescent photons can do some fun twisting as they propagate, depending on the input polarization angle with respect to the interface normal.

Thank you for speaking up. Now help me out here.
I have the Brady cone modeled (FDTD s/w model) with source resonanting in the X direction. The cone is leaky to RF, I can place the leaks on either end or on the sides. How should I orient my detecters to measure the Pointing Energy? I currently have modeled leaks in the X end of the cavity with my detecter some distance further from the source in the X direction. That is, source, leak and detecter plane normal are in general alignment though the leak is off to the side of the cavity end. I measure about 6 times more force with the leak off to the side than with it in perfect alignment.

Thanks for your input.
Aero

Carl White
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### Re: EM Drive

GIThruster wrote:Well, this is an interesting explanation for the thrust down at Eagleworks. I think you might consider sharing it with Paul March as well as Dr. Rodal over at NSF. While I'm unconvinced there is any thrust measured at all since they haven't yet provided any significant scientific controls--all released results thus far have been with no vacuum--it is certainly possible they are getting thrust, and it is not possible it is coming from QVF. So yeah, shoot Paul a note as well as Rodal as he is a very sharp guy who has given a lot of time to this.

I've been under the impression they did do tests in vacuum:

http://www.libertariannews.org/wp-conte ... dyEtAl.pdf

To simulate the space pressure environment, the test rig is rolled into the test chamber. After sealing the
chamber, the test facility vacuum pumps are used to reduce the environmental pressure down as far as 5x10E-6 Torr.
Two roughing pumps provide the vacuum required to lower the environment to approximately 10 Torr in less than
30 minutes. Then, two high-speed turbo pumps are used to complete the evacuation to 5x10E-6 Torr, which
requires a few additional days. During this final evacuation, a large strip heater (mounted around most of the
circumference of the cylindrical chamber) is used to heat the chamber interior sufficiently to emancipate volatile
substances that typically coat the chamber interior walls whenever the chamber is at ambient pressure with the
chamber door open. During test run data takes at vacuum, the turbo pumps continue to run to maintain the hard
vacuum environment. The high-frequency vibrations from the turbo pump have no noticeable effect on the testing
seismic environment.

birchoff
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### Re: EM Drive

Carl White wrote:
GIThruster wrote:Well, this is an interesting explanation for the thrust down at Eagleworks. I think you might consider sharing it with Paul March as well as Dr. Rodal over at NSF. While I'm unconvinced there is any thrust measured at all since they haven't yet provided any significant scientific controls--all released results thus far have been with no vacuum--it is certainly possible they are getting thrust, and it is not possible it is coming from QVF. So yeah, shoot Paul a note as well as Rodal as he is a very sharp guy who has given a lot of time to this.

I've been under the impression they did do tests in vacuum:

http://www.libertariannews.org/wp-conte ... dyEtAl.pdf

To simulate the space pressure environment, the test rig is rolled into the test chamber. After sealing the
chamber, the test facility vacuum pumps are used to reduce the environmental pressure down as far as 5x10E-6 Torr.
Two roughing pumps provide the vacuum required to lower the environment to approximately 10 Torr in less than
30 minutes. Then, two high-speed turbo pumps are used to complete the evacuation to 5x10E-6 Torr, which
requires a few additional days. During this final evacuation, a large strip heater (mounted around most of the
circumference of the cylindrical chamber) is used to heat the chamber interior sufficiently to emancipate volatile
substances that typically coat the chamber interior walls whenever the chamber is at ambient pressure with the
chamber door open. During test run data takes at vacuum, the turbo pumps continue to run to maintain the hard
vacuum environment. The high-frequency vibrations from the turbo pump have no noticeable effect on the testing
seismic environment.

I had that same understanding when I read the paper initially. However, that section describing the protocol is what they WANTED to do. If you go to the conclusion you will see that they were not able to run in vacuum because, IIRC, they did not have a vacuum rated amplifier (or some such important piece of kit) which is used by both the tapered frustum and the cannae experiments. I believe the only thing they were able to do was lock the thing in an UN-evacuated vacuum chamber. They planned to get the vacuum rated device that they needed for their next test run which should have already be in progress according to some rumors I have heard.

GIThruster
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### Re: EM Drive

birchoff wrote:. . .that section describing the protocol is what they WANTED to do. If you go to the conclusion you will see that they were not able to run in vacuum because, IIRC, they did not have a vacuum rated amplifier (or some such important piece of kit) which is used by both the tapered frustum and the cannae experiments.

Actually it was their electrolytic capacitors they inserted that weren't vacuum rated.

And just one more example of the sneaky shit Dr. Harold White is routinely guilty of. This is no mistake. He wants people to believe they have done tests in vacuum despite they have not, just as he wants people to believe he ran the MLT tests there in Eagleworks rather than note they were run a decade before he and his model came on the scene.

Think about how tortured that text is, how he was able to make it appear he said something that really, he never said. He's done this repeatedly with the issue of "prediction". He regularly implies his model predicted things that he knows it could not because the data preceded the model by years. So he continues to use the word "prediction" without claiming to have made any, and the end result is through implication people believe he correctly predicted telling results when in fact, those results were like these--no scientific controls and no reason to pay them any heed.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

Tom Ligon
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### Re: EM Drive

The paper definitely is contorted. Deliberate or sloppy? Dunno. But they admit that the effect is small and they can't explain it. Short answer, they're just messing around and would have no idea how to optimize this particular accident.

I see room for improvement in the apparatus, but the basic instrumentation is OK, if somewhat sub-optimal, and really needing to run at higher thrust and in a vacuum. But the torsion pendulum used is not too bad.

I'm in communication with Aero off-line, and what he has said here so far is just a glimpse. I'll leave it to him to describe his latest results when he is ready to. And I'll believe it when I get to build the working model and have it shoot off the lab bench.

As to operating in the atmosphere, another friend of mine is building an electric drive in his basement which is specifically intended for high thrust in the atmosphere. Does is use air to make thrust? Absolutely. What's wrong with that? Half the spaceflight problem is getting to LEO. But technologies that can only muster nanonewtons need not apply.

This field needs sound theory and sound testing. It would be a hoot if Talk Polywell provides both.

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