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#1320 by Bob012345 on 14 Aug, 2019 18:04
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Roger explains EmDrive Doppler shift during acceleration.
If the net effect of the Doppler shift is to decrease thrust (which it is to a negligible extent despite the multiple issues in Shawyer's explanation), then it is nonsensical to claim that there must be pre-existing acceleration for thrust to be generated. Honestly not worth me going into specifics since you simply ignored my previous post, and Shawyer uses no real equations anyway.
http://www.emdrive.com/IAC13paper17254.v2.pdf page 2.
I just don't see your point. Decreasing thrust decreases acceleration but doesn't necessarily eliminate or reverse it. -
#1321 by meberbs on 14 Aug, 2019 18:29
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Shawyer is simultaneously saying "Doppler shift decreases the force" and "Doppler shift is required for the force to be non-zero" (i.e. increases the force from 0) This is a contradiction, and is rooted in Shawyer's repeated issues with doing basic force calculations.Roger explains EmDrive Doppler shift during acceleration.
If the net effect of the Doppler shift is to decrease thrust (which it is to a negligible extent despite the multiple issues in Shawyer's explanation), then it is nonsensical to claim that there must be pre-existing acceleration for thrust to be generated. Honestly not worth me going into specifics since you simply ignored my previous post, and Shawyer uses no real equations anyway.
http://www.emdrive.com/IAC13paper17254.v2.pdf page 2.
I just don't see your point. Decreasing thrust decreases acceleration but doesn't necessarily eliminate or reverse it. -
#1322 by Bob012345 on 14 Aug, 2019 20:20
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Shawyer is simultaneously saying "Doppler shift decreases the force" and "Doppler shift is required for the force to be non-zero" (i.e. increases the force from 0) This is a contradiction, and is rooted in Shawyer's repeated issues with doing basic force calculations.Roger explains EmDrive Doppler shift during acceleration.
If the net effect of the Doppler shift is to decrease thrust (which it is to a negligible extent despite the multiple issues in Shawyer's explanation), then it is nonsensical to claim that there must be pre-existing acceleration for thrust to be generated. Honestly not worth me going into specifics since you simply ignored my previous post, and Shawyer uses no real equations anyway.
http://www.emdrive.com/IAC13paper17254.v2.pdf page 2.
I just don't see your point. Decreasing thrust decreases acceleration but doesn't necessarily eliminate or reverse it.
Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks. -
#1323 by dustinthewind on 15 Aug, 2019 05:27
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Shawyer is simultaneously saying "Doppler shift decreases the force" and "Doppler shift is required for the force to be non-zero" (i.e. increases the force from 0) This is a contradiction, and is rooted in Shawyer's repeated issues with doing basic force calculations.Roger explains EmDrive Doppler shift during acceleration.
If the net effect of the Doppler shift is to decrease thrust (which it is to a negligible extent despite the multiple issues in Shawyer's explanation), then it is nonsensical to claim that there must be pre-existing acceleration for thrust to be generated. Honestly not worth me going into specifics since you simply ignored my previous post, and Shawyer uses no real equations anyway.
http://www.emdrive.com/IAC13paper17254.v2.pdf page 2.
I just don't see your point. Decreasing thrust decreases acceleration but doesn't necessarily eliminate or reverse it.
What Shawyer is saying, I believe, from reading the document is that the thrust decreases because, as light becomes non-resonant with the cavity, it becomes rejected by the cavity. Normally they have to have a path for the rejected radiation to be shunted into a resistor of some sort, or it will go back to the signal generator or magnetron. Am I wrong?
If the radiation is rejected by the cavity, the cavities Q decreases, or it cant store as much energy. The stored energy/pressure in a diesel engine for instance increases its torque, increasing its conversion of the stored thermal energy to motion. I don't see much problem with this, but I think he lacks any explanation as to how the photons are losing energy and gaining momentum.
In a diesel engine the gas pushes on a moving cylinder wall and they cool, or a parallel for photons is they red-shift. In a closed cavity there is no moving wall for them to push on. If you accelerate the cavity, photons bounce off one wall blue shifting, hitting the wall that accelerates to them, and red-shift off the receding wall - inducing a traveling wave that travels with the cavity. Effectively, accelerating their effective mass but they shouldn't lose energy, except by heat loss, so were still missing what is causing his claimed red-shift.
If the photons red-shift in one direction they lose energy to something such that their bounce becomes less. The sum of both their paths means they transfer their gained/lost momentum to the cavity. The photons momentum becomes the cavities so their momentum is shared. This means we have missing equal and opposite momentum.
This is why I suggested the equal and opposite momentum would need to be carried off by space time some how for it to work, similar to how black holes decelerate, undergo a change in effective mass, and lose their energy or momentum and potential effective mass. This or something that escapes the cavity. Any explanation of that is missing.
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#1324 by meberbs on 15 Aug, 2019 06:22
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Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks.
The answer is that basically everything Shawyer has ever said about the behavior of the emDrive is simply wrong.
If you take a emDrive shaped resonant cavity (non-accelerating for now) you will see a larger force on the large end than the small end. This is because there is also force on the sidewalls, which when accounted for causes the forces to perfectly balance. Shawyer always handwaves the sidewall force away since that would be a problem his claims.
The group velocities being different is representative of the fact that there would be lower pressure on the small end than the large end, which you can see by imagining a laser angled so that it reflects off the large wall, the sidewalls (maybe multiple times) and then the small wall. The laser reflects at a more shallow angle off the small wall, and thus imparts less force, though this is clearly balance by the sidewall portion. Since the cavity size is comparable to the wavelength, this is not an exact analogy, but it illustrates the effect, and the guide wavelength defined by Shawyer, while taken out of context may be a reasonable estimation of this difference. There is not point in really determining how accurate that is since the sidewall force balances everything when you don't ignore it.
As for directly measuring the forces, that would be a challenging experimental setup, since you would be trying to measure very small forces, and separating the end plates from the sidewalls causes various issues (such as not having a good, closed cavity.) Actual RF modelling of the forces was done a long time ago and yields the expected results. (It doesn't cover the transient parts, but those could in general give you a photon rocket if you ignore the original emission of them, the resonant part is where all of the "maybe a force gets amplified" thoughts come from, but a million times zero is still zero.)
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html -
#1325 by meberbs on 15 Aug, 2019 06:36
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What Shawyer is saying, I believe, from reading the document is that the thrust decreases because, as light becomes non-resonant with the cavity, it becomes rejected by the cavity. Normally they have to have a path for the rejected radiation to be shunted into a resistor of some sort, or it will go back to the signal generator or magnetron. Am I wrong?
It is what Shawyer is saying that is wrong. Any attempt to explain what Shawyer is saying will also be wrong for the same reasons. RF radiation that gets absorbed by the cavity walls can turn into heat. Reflection of the initial signals back to the signal source is not relevant.
Skipping over more of you making bad analogies with combustion engines, you then say:This is why I suggested the equal and opposite momentum would need to be carried off by space time some how for it to work, similar to how black holes decelerate, undergo a change in effective mass, and lose their energy or momentum and potential effective mass. This or something that escapes the cavity. Any explanation of that is missing.
"Carried off by space-time" is just a handwave statement, it means nothing. If it is similar to how black holes can change velocity by emitting gravitational waves, it means that it is no better than a photon rocket, and therefore useless, since there are easier and more effective ways to build a photon rocket. I have already explained that your use of the term "effective mass" defies any attempt at definition and is equally meaningless. Do you have any interest in trying to communicate using words that actually have meaning, or are you just here to waste people's time?
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#1326 by dustinthewind on 15 Aug, 2019 14:00
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That's right. Any attempt to suggest Shawyer's claims light is Doppler shifted in the cavity is wrong. So proclaimed. sigh.What Shawyer is saying, I believe, from reading the document is that the thrust decreases because, as light becomes non-resonant with the cavity, it becomes rejected by the cavity. Normally they have to have a path for the rejected radiation to be shunted into a resistor of some sort, or it will go back to the signal generator or magnetron. Am I wrong?
It is what Shawyer is saying that is wrong. Any attempt to explain what Shawyer is saying will also be wrong for the same reasons. RF radiation that gets absorbed by the cavity walls can turn into heat. Reflection of the initial signals back to the signal source is not relevant.
Assuming he isn't making it up...
Ignore his side wall explanation. It's nonsense.Quote
Skipping over more of you making bad analogies with combustion engines, you then say:This is why I suggested the equal and opposite momentum would need to be carried off by space time some how for it to work, similar to how black holes decelerate, undergo a change in effective mass, and lose their energy or momentum and potential effective mass. This or something that escapes the cavity. Any explanation of that is missing.
"Carried off by space-time" is just a handwave statement, it means nothing. If it is similar to how black holes can change velocity by emitting gravitational waves, it means that it is no better than a photon rocket, and therefore useless, since there are easier and more effective ways to build a photon rocket. I have already explained that your use of the term "effective mass" defies any attempt at definition and is equally meaningless. Do you have any interest in trying to communicate using words that actually have meaning, or are you just here to waste people's time?
It means momentum is carried off by something that escapes the cavity. Why is that so hard for you to understand? That is the only way light is Doppler shifted is if its giving up energy.
Fundamentally his explanation is missing the conservation of momentum. End of conversation. -
#1327 by meberbs on 15 Aug, 2019 14:36
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That's right. Any attempt to suggest Shawyer's claims light is Doppler shifted in the cavity is wrong. So proclaimed. sigh.
There is Doppler shifting that happens in an accelerating cavity, and I already explained how this works. Shawyers explanation of it is wrong, like basically everything else he has ever said including sidewalls, and what direction something moves when you push on it.It means momentum is carried off by something that escapes the cavity. Why is that so hard for you to understand?
Saying that "something" carries off momentum to conserve momentum is the clear minimum requirement to get something else to move while conserving momentum. However if you are trying to explain how that works, you have to actually explain what that something is and how the interaction with that something works. Saying that maybe the emDrive works by transferring momentum to florbs, does not provide useful information.That is the only way light is Doppler shifted is if its giving up energy.
No, Doppler shifts can actually increase the energy in the light too, transferring a bit of kinetic energy from the cavity to the photons. In a frame where the cavity has velocity in the same direction that it is accelerating this happens, and is part of the mechanism by which the mass-energy of the photons gets accounted for in the total mass-energy of the cavity when someone pushes on the cavity to accelerate it.Fundamentally his explanation is missing the conservation of momentum.
We can agree on that. -
#1328 by Bob012345 on 15 Aug, 2019 18:10
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Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks.
The answer is that basically everything Shawyer has ever said about the behavior of the emDrive is simply wrong.
If you take a emDrive shaped resonant cavity (non-accelerating for now) you will see a larger force on the large end than the small end. This is because there is also force on the sidewalls, which when accounted for causes the forces to perfectly balance. Shawyer always handwaves the sidewall force away since that would be a problem his claims.
The group velocities being different is representative of the fact that there would be lower pressure on the small end than the large end, which you can see by imagining a laser angled so that it reflects off the large wall, the sidewalls (maybe multiple times) and then the small wall. The laser reflects at a more shallow angle off the small wall, and thus imparts less force, though this is clearly balance by the sidewall portion. Since the cavity size is comparable to the wavelength, this is not an exact analogy, but it illustrates the effect, and the guide wavelength defined by Shawyer, while taken out of context may be a reasonable estimation of this difference. There is not point in really determining how accurate that is since the sidewall force balances everything when you don't ignore it.
As for directly measuring the forces, that would be a challenging experimental setup, since you would be trying to measure very small forces, and separating the end plates from the sidewalls causes various issues (such as not having a good, closed cavity.) Actual RF modelling of the forces was done a long time ago and yields the expected results. (It doesn't cover the transient parts, but those could in general give you a photon rocket if you ignore the original emission of them, the resonant part is where all of the "maybe a force gets amplified" thoughts come from, but a million times zero is still zero.)
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Thanks. You seem to be saying radiation pressure forces in a cavity amounts to virtually nothing. YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces. I believe Fetta (Cannae) believes Lorentz forces are the primary cause of pressure in his cavities which are much larger. Photon presure is 2X3.3nN/W for reflection but for a Q of one million at a power of 1000 watts that's 6.6N, not nothing.**
I'm looking at the link you supplied but I can to tell if it's peer reviewed or just self-published. I'm also wondering if the analysis looked at all possible modes.
** Update: it looks like the forces are measurable according to the link you supplied. ~9N/J so for say 1J of total EM energy in the cavity at a given instant, the forces on an endplate would be ~9N. -
#1329 by Bob012345 on 15 Aug, 2019 18:21
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Fundamentally his explanation is missing the conservation of momentum.
We can agree on that.
If the forces reported turn out to be real it woudn't matter what his explanation is or isn't. Someone else would figure that out eventually. -
#1330 by X_RaY on 15 Aug, 2019 18:45
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As long as you do not present other (new) physical correlations we stick to Maxwell. Why? Because it works! As a result, the inner forces cancel each other out, as meberbs already explained.Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks.
The answer is that basically everything Shawyer has ever said about the behavior of the emDrive is simply wrong.
If you take a emDrive shaped resonant cavity (non-accelerating for now) you will see a larger force on the large end than the small end. This is because there is also force on the sidewalls, which when accounted for causes the forces to perfectly balance. Shawyer always handwaves the sidewall force away since that would be a problem his claims.
The group velocities being different is representative of the fact that there would be lower pressure on the small end than the large end, which you can see by imagining a laser angled so that it reflects off the large wall, the sidewalls (maybe multiple times) and then the small wall. The laser reflects at a more shallow angle off the small wall, and thus imparts less force, though this is clearly balance by the sidewall portion. Since the cavity size is comparable to the wavelength, this is not an exact analogy, but it illustrates the effect, and the guide wavelength defined by Shawyer, while taken out of context may be a reasonable estimation of this difference. There is not point in really determining how accurate that is since the sidewall force balances everything when you don't ignore it.
As for directly measuring the forces, that would be a challenging experimental setup, since you would be trying to measure very small forces, and separating the end plates from the sidewalls causes various issues (such as not having a good, closed cavity.) Actual RF modelling of the forces was done a long time ago and yields the expected results. (It doesn't cover the transient parts, but those could in general give you a photon rocket if you ignore the original emission of them, the resonant part is where all of the "maybe a force gets amplified" thoughts come from, but a million times zero is still zero.)
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Thanks. You seem to be saying radiation pressure forces in a cavity amounts to virtually nothing. YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces. I believe Fetta (Cannae) believes Lorentz forces are the primary cause of pressure in his cavities which are much larger. Photon presure is 2X3.3nN/W for reflection but for a Q of one million at a power of 1000 watts that's 6.6N, not nothing.
The quality of a resonant circuit Q is a dimensionless quantity which results from a pre-defined determination, simply multiplying it by the transmitted energy of a photon during reflection is physically nonsensical.
while Δf is the frequency difference at -3dB or even more precise: Only in the case κ=1 (κ=Coupling factor) the full 3dB half width is measured to determine the circular quality - this corresponds to ρ=1/√2 because of the power definition of the dB values (dB = 20-log(U/U0)), in all other cases the full half width must be determined:
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#1331 by Bob012345 on 15 Aug, 2019 19:05
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As long as you do not present other (new) physical correlations we stick to Maxwell. Why? Because it works! As a result, the inner forces cancel each other out, as meberbs already explained.Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks.
The answer is that basically everything Shawyer has ever said about the behavior of the emDrive is simply wrong.
If you take a emDrive shaped resonant cavity (non-accelerating for now) you will see a larger force on the large end than the small end. This is because there is also force on the sidewalls, which when accounted for causes the forces to perfectly balance. Shawyer always handwaves the sidewall force away since that would be a problem his claims.
The group velocities being different is representative of the fact that there would be lower pressure on the small end than the large end, which you can see by imagining a laser angled so that it reflects off the large wall, the sidewalls (maybe multiple times) and then the small wall. The laser reflects at a more shallow angle off the small wall, and thus imparts less force, though this is clearly balance by the sidewall portion. Since the cavity size is comparable to the wavelength, this is not an exact analogy, but it illustrates the effect, and the guide wavelength defined by Shawyer, while taken out of context may be a reasonable estimation of this difference. There is not point in really determining how accurate that is since the sidewall force balances everything when you don't ignore it.
As for directly measuring the forces, that would be a challenging experimental setup, since you would be trying to measure very small forces, and separating the end plates from the sidewalls causes various issues (such as not having a good, closed cavity.) Actual RF modelling of the forces was done a long time ago and yields the expected results. (It doesn't cover the transient parts, but those could in general give you a photon rocket if you ignore the original emission of them, the resonant part is where all of the "maybe a force gets amplified" thoughts come from, but a million times zero is still zero.)
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Thanks. You seem to be saying radiation pressure forces in a cavity amounts to virtually nothing. YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces. I believe Fetta (Cannae) believes Lorentz forces are the primary cause of pressure in his cavities which are much larger. Photon presure is 2X3.3nN/W for reflection but for a Q of one million at a power of 1000 watts that's 6.6N, not nothing.
The quality of a resonant circuit Q is a dimensionless quantity which results from a pre-defined determination, simply multiplying it by the transmitted energy of a photon during reflection is physically nonsensical.
Are you doubting the work of Y.K. Bae? It's a scientific, proven fact that multiple reflections increase the momentum transfer and thus the force from a given beam. It's entirely Maxwellian. And if you note, I didn't claim this as a net force, just enhanced pressure. -
#1332 by X_RaY on 15 Aug, 2019 19:14
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OK, higher field strength, more reflections, more stored energy leads to higher internal radiation pressure. Agreed.
As long as you do not present other (new) physical correlations we stick to Maxwell. Why? Because it works! As a result, the inner forces cancel each other out, as meberbs already explained.Thanks. It doesn't seem necessarily contradictory to me. It may be necessary but not sufficient. However, I have my own questions such as why isn't there a component of force from the angled portions that add to the smaller end plate and why are the group velocities not equal to each other or to c? I suppose those have been answered years ago and I missed them. It seems the first question might be addressed by direct measurement of the radiation pressure on the various walls of the cavity through piezo-electric sensors. Has that been done? Both may have been addressed through modeling. Does any one know the results? Thanks.
The answer is that basically everything Shawyer has ever said about the behavior of the emDrive is simply wrong.
If you take a emDrive shaped resonant cavity (non-accelerating for now) you will see a larger force on the large end than the small end. This is because there is also force on the sidewalls, which when accounted for causes the forces to perfectly balance. Shawyer always handwaves the sidewall force away since that would be a problem his claims.
The group velocities being different is representative of the fact that there would be lower pressure on the small end than the large end, which you can see by imagining a laser angled so that it reflects off the large wall, the sidewalls (maybe multiple times) and then the small wall. The laser reflects at a more shallow angle off the small wall, and thus imparts less force, though this is clearly balance by the sidewall portion. Since the cavity size is comparable to the wavelength, this is not an exact analogy, but it illustrates the effect, and the guide wavelength defined by Shawyer, while taken out of context may be a reasonable estimation of this difference. There is not point in really determining how accurate that is since the sidewall force balances everything when you don't ignore it.
As for directly measuring the forces, that would be a challenging experimental setup, since you would be trying to measure very small forces, and separating the end plates from the sidewalls causes various issues (such as not having a good, closed cavity.) Actual RF modelling of the forces was done a long time ago and yields the expected results. (It doesn't cover the transient parts, but those could in general give you a photon rocket if you ignore the original emission of them, the resonant part is where all of the "maybe a force gets amplified" thoughts come from, but a million times zero is still zero.)
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html
Thanks. You seem to be saying radiation pressure forces in a cavity amounts to virtually nothing. YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces. I believe Fetta (Cannae) believes Lorentz forces are the primary cause of pressure in his cavities which are much larger. Photon presure is 2X3.3nN/W for reflection but for a Q of one million at a power of 1000 watts that's 6.6N, not nothing.
The quality of a resonant circuit Q is a dimensionless quantity which results from a pre-defined determination, simply multiplying it by the transmitted energy of a photon during reflection is physically nonsensical.
Are you doubting the work of Y.K. Bae? It's a scientific, proven fact that multiple reflections increase the momentum transfer and thus the force from a given beam. It's entirely Maxwellian. And if you note, I didn't claim this as a net force, just enhanced pressure.... but a million times zero is still zero...
http://www.gregegan.net/SCIENCE/Cavity/Cavity.html
As you note by yourself, no net force follows from this fact alone, but this is what we are looking for in the end. Resulting net force is the claim that must be explained or rejected.
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#1333 by Bob012345 on 15 Aug, 2019 19:23
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OK, higher field strength, more reflections, more stored energy leads to higher internal radiation pressure. Agreed. As you note by yourself, no net force follows from this fact alone, but this is what we are looking for in the end. This is the claim that must be explained or rejected.
As long as you do not present other (new) physical correlations we stick to Maxwell. Why? Because it works! As a result, the inner forces cancel each other out, as meberbs already explained.
Thanks. You seem to be saying radiation pressure forces in a cavity amounts to virtually nothing. YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces. I believe Fetta (Cannae) believes Lorentz forces are the primary cause of pressure in his cavities which are much larger. Photon presure is 2X3.3nN/W for reflection but for a Q of one million at a power of 1000 watts that's 6.6N, not nothing.
The quality of a resonant circuit Q is a dimensionless quantity which results from a pre-defined determination, simply multiplying it by the transmitted energy of a photon during reflection is physically nonsensical.
Are you doubting the work of Y.K. Bae? It's a scientific, proven fact that multiple reflections increase the momentum transfer and thus the force from a given beam. It's entirely Maxwellian. And if you note, I didn't claim this as a net force, just enhanced pressure.
My God, I was finally right about something! Thanks.
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#1334 by TheTraveller on 15 Aug, 2019 21:33
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As you note by yourself, no net force follows from this fact alone, but this is what we are looking for in the end. Resulting net force is the claim that must be explained or rejected.
Static EmDrive = NO NET FORCE, as Roger has stated.
Accelerating EmDrive = self accelerating force is generated. Initially triggered by external force causing small end forward acceleration, causing asymmetric Doppler shift, Red shift at small end & Blue shift at big end, causing more radiation pressure on the big end than on the small end, amplified by the number of times the travelling waves transit the cavity. This big end directed force Roger calls Thrust and the N3 reaction force, small end directed, he calls Acceleration.
See attached.
That others here have claimed the Thrust force is a result of the additional energy equivalent mass of the trapped photons is not correct.
The now agreed acceleration generated asymmetric Doppler shift at each end plate causes a real word asymmetric radiation pressure to be generated, which is as real as any other radiation pressure. Denying its existence is to deny the basis of radiation pressure.
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#1335 by meberbs on 16 Aug, 2019 01:24
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Physics 101. The photons are applying a force to the cavity pointed to the left as labelled thrust in your picture. The reaction force is therefore a force applied by the cavity to the photons. F=m*a, so the direction the cavity accelerates is in the direction of the force applied to the cavity. That is to the left in your picture.As you note by yourself, no net force follows from this fact alone, but this is what we are looking for in the end. Resulting net force is the claim that must be explained or rejected.
Static EmDrive = NO NET FORCE, as Roger has stated.
Accelerating EmDrive = self accelerating force is generated. Initially triggered by external force causing small end forward acceleration, causing asymmetric Doppler shift, Red shift at small end & Blue shift at big end, causing more radiation pressure on the big end than on the small end, amplified by the number of times the travelling waves transit the cavity. This big end directed force Roger calls Thrust and the N3 reaction force, small end directed, he calls Acceleration.That others here have claimed the Thrust force is a result of the additional energy equivalent mass of the trapped photons is not correct.
No matter how many times you claim otherwise, 1+1=2. The net force applied to a cavity by the internal photons in an accelerating cavity is directed opposite to the externally applied force, goes away when the external force goes away, and is proportional to the total energy of the photons in the cavity.The now agreed acceleration generated asymmetric Doppler shift at each end plate causes a real word asymmetric radiation pressure to be generated, which is as real as any other radiation pressure. Denying its existence is to deny the basis of radiation pressure.
Claiming that applying a force applied to an object causes the object to accelerate in the opposite direction of the force is to deny the most fundamental definitions in physics. -
#1336 by Monomorphic on 16 Aug, 2019 01:25
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YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces.
It is worth mentioning that YK Bae's 2015 recycling photon thruster, operating under the best laboratory conditions, at 0.5kW, generated 3.5mN of thrust.
If the emdrive is more efficient than that, then there would need to be something else going on besides recycling photons. -
#1337 by JohnFornaro on 16 Aug, 2019 12:27
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Claiming that applying a force applied to an object causes the object to accelerate in the opposite direction of the force is to deny the most fundamental definitions in physics.
I forget. Who was it who claimed exactly that? -
#1338 by meberbs on 16 Aug, 2019 13:53
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Shawyer and by extension TT. It happened again in the last post from TT with the claim that increased pressure on the inside of the large end magically causes the cavity to accelerate small end forward.Claiming that applying a force applied to an object causes the object to accelerate in the opposite direction of the force is to deny the most fundamental definitions in physics.
I forget. Who was it who claimed exactly that? -
#1339 by Bob012345 on 16 Aug, 2019 16:54
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YK Bae has demonstrated his Photonic Laser Thruster accelerates macroscopic objects so I think an EmDrive cavity of higher power and much higher Q would have large internal forces.
It is worth mentioning that YK Bae's 2015 recycling photon thruster, operating under the best laboratory conditions, at 0.5kW, generated 3.5mN of thrust.
If the emdrive is more efficient than that, then there would need to be something else going on besides recycling photons.
That's a 1000X improvement over a once reflected beam. Its a start but likely not an end to the technology. But yes, what's going on in a working EmDrive is likely more.
