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#1080 by Flyby on 28 Sep, 2016 08:40
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I notice that the whole debate about CoM/CoE starts with the assumption of a constant force.
But what if that is not the case?
Why is there that assumption when we do not even know what the "mechanism" behind the apparent forces is?
There are a lot of examples in science/engineering that bring up surprising results at first, but when fully understood, make perfect sense.
fe
For nearly 100 years of aerodynamics, we believed a perfectly smooth surface was by far the best performance solution, until a decade ago, engineering research showed that a "shark skin" had superior qualities.
It's only after understanding and developing/applying vortex hydrodynamics that it could be understood why it gave a better performance.
But nobody thought about applying this knowhow on the theoretical models that were developed prior to that discovery...
In a similar way, it might be jumping the gun, when you assess the Emdrive's CoM/CoE problem with what you currently know.
A theoretical model is only as good as the elements it took into account to mimic reality.
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#1081 by Fan Boi on 28 Sep, 2016 12:52
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I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one." -
#1082 by Mezzenile on 28 Sep, 2016 14:59
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1) The discussions about conservation of energy continue to take place without taking into account whether these are open systems. Any discussion about conservation of energy of an open system that does not take into account the external fields ,( for example one based on gravitation, like the Mach/Sciama/Woodward effect) is futile. Of course there will be an overunity problem if one does not take into account the external field (in the case of the Mach/Sciama effect: gravitation)! It would be like calculating conservation of energy for a gravity assist while ignoring the effect of gravity
The above statement “Energy can be neither created nor destroyed ” is certainly false in our expanding space-time ruled by General relativity :
.
...
Completely futile to discuss conservation of energy while ignoring the external field !
...
- Photons running in inter-galactic space have increasing wavelength and consequently smaller energy proportional to the inverse of the physical dimension of our universe.
- The total energy imposed by the cosmological constant increases with the third power of the physical dimension of our universe.
- Galaxies accelerate away from each other as the universe expands and consequently their relative cinetic energy increases.
The main point to understand is that in General relativity physical objects or fields do not propagate in a pre-existing translationally invariant spacetime. Consequently there is no energy conservation law applicable at whole space-time scale as the Noether's argument of translation invariance in time either fails, or becomes approximate, or becomes vacuous, or survives exclusively in spacetimes that preserve a special structure at infinity. At any rate, the status of energy conservation is not a reliable invariant on which we can base our analysis of a device which is thought to interact with the whole content of an universe which itself is not a closed system. -
#1083 by Bob012345 on 28 Sep, 2016 17:16
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I notice that the whole debate about CoM/CoE starts with the assumption of a constant force.
But what if that is not the case?
Why is there that assumption when we do not even know what the "mechanism" behind the apparent forces is?
There are a lot of examples in science/engineering that bring up surprising results at first, but when fully understood, make perfect sense.
fe
For nearly 100 years of aerodynamics, we believed a perfectly smooth surface was by far the best performance solution, until a decade ago, engineering research showed that a "shark skin" had superior qualities.
It's only after understanding and developing/applying vortex hydrodynamics that it could be understood why it gave a better performance.
But nobody thought about applying this knowhow on the theoretical models that were developed prior to that discovery...
In a similar way, it might be jumping the gun, when you assess the Emdrive's CoM/CoE problem with what you currently know.
A theoretical model is only as good as the elements it took into account to mimic reality.
I think the debate now is about whether a constant force producing a constant acceleration is even possible in classical mechanics regardless of the EmDrive. Some are suggesting it's not possible, that nature won't allow it because it runs into 'overunity'. Some say a true constant force will produce a gradually reduced acceleration. I
find that position untenable.
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#1084 by dustinthewind on 28 Sep, 2016 17:41
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I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one."
Wow, thanks for sharing this. I'm looking forward to reading about this. It sounds a lot like what I was thinking about the vacuum and possibly indicating some of the concepts Richard Feynman and Wheeler were suggesting.
The paper also mentions the Wheeler Feynman connection with signals propagating backwards in time and the negative energy fields. This reminded me of the thought that the vacuum may be made up of matter and anti-matter superimposed with time running backwards for anti-matter, and it also having anti-mass. With anti-mass running backwards in time, it seems like it would appear to have positive mass, which then allows us to push off it with normal momentum. If the anti-matter/mass/time overlaps with its mirror twin, then maybe it seems the anti-mass may lose its positive mass properties becoming negative mass and canceling the positive mass, cloaking into the vacuum.
...
if large enough electric fields were to cause polarization of the vacuum such that a current developed in the vacuum... -
#1085 by Fan Boi on 28 Sep, 2016 17:42
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
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#1086 by Fan Boi on 28 Sep, 2016 17:46
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I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one."
Wow, thanks for sharing this. I'm looking forward to reading about this. It sounds a lot like what I was thinking about the vacuum and possibly indicating some of the concepts Richard Feynman and Wheeler were suggesting.
I thought so too. If those virtual particles can become real particles then you can push on them in some way I would think. But even then, why no exhaust of these now real particles? Could they become real for only a brief moment and then become virtual again? -
#1087 by Bob012345 on 28 Sep, 2016 17:55
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With regards to the formula on page 8, the power is the mechanical power, not the electrical input and the formula is not an instantaneous dynamical equation. It concerns the entire trip. It assumes the acceleration was constant in the first place so it is not saying acceleration is inversely proportional to velocity at all.
Basically, he's deriving that the mechanical power is proportional to mass x acceleration x average velocity. This is always true for any system at constant acceleration. It's nothing new.
Pk is the part of the electrical power that is not lost.
There is written P0=Pe+Pk where P0 is the imput power of the emdrive system, and Pe the losses, so Pk is realy the part of the electrical power that is converted into Kinetic energy. And by definition, Pk can not be superior to P0, since the losses can not be negative (the best possible case, there are zero losses) Is it Ok with that precise point ?
I see that but my suspicion is that like Woodward, he could pulse his ship is steps with this concept. By that I mean as Q goes down when v rises he has to re-guage the system by shutting it down and staring up the cavity fresh. Once it's off he should be able to start it from any frame. Max v is always measured with respect to the starting instantaneous rest frame. After each boost it doesn't matter what the instantaneous rest frame was at. So, the max v in this paper amounts to a delta v boost for each step. But he could do any number of steps one after another. If that is the case, there would ultimately still be the argument we were debating. All he's saying in this paper is that during each boost, energy is conserved. In later papers I think he assumes Q remains fixed so acceleration is always constant because he can compensate.
I think this is Shawyer's equivalent argument to Woodward's. I think this adds to my understanding of why this works. Thanks. -
#1088 by Rodal on 28 Sep, 2016 17:58
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Yes, thank you, the statement you are objecting to was the first thing I grabbed from Google Images to drive home a visual aid of the difference between closed systems and open systems, and it deals with conservation of energy in Non-General-Relativistic terms.
The above statement “Energy can be neither created nor destroyed ” is certainly false in our expanding space-time ruled by General relativity :
- Photons running in inter-galactic space have increasing wavelength and consequently smaller energy proportional to the inverse of the physical dimension of our universe.
- The total energy imposed by the cosmological constant increases with the third power of the physical dimension of our universe.
- Galaxies accelerate away from each other as the universe expands and consequently their relative cinetic energy increases.
The main point to understand is that in General relativity physical objects or fields do not propagate in a pre-existing translationally invariant spacetime. Consequently there is no energy conservation law applicable at whole space-time scale as the Noether's argument of translation invariance in time either fails, or becomes approximate, or becomes vacuous, or survives exclusively in spacetimes that preserve a special structure at infinity. At any rate, the status of energy conservation is not a reliable invariant on which we can base our analysis of a device which is thought to interact with the whole content of an universe which itself is not a closed system.
The point I made <<The discussions about conservation of energy continue to take place without taking into account whether these are open systems. Any discussion about conservation of energy of an open system that does not take into account the external fields ,( for example one based on gravitation, like the Mach/Sciama/Woodward effect) is futile. Of course there will be an overunity problem if one does not take into account the external field>> remains valid in either case. Both for General Relativity and also within Special Relativity and classical mechanics. As there are other open systems that do not involve General Relativity.
The point you are making is true for General Relativity. However, even if a poster would not agree that General Relativity may be at play, there are other possible theories that may explain EM Drive acceleration as an open system. Hence posters continuing to pontificate that the EM drive violates conservation of energy based on simplistic arguments considering it as a closed system, who disregard external fields and also disregard entropy are proving nothing new. It is obvious that a closed electromagnetic cavity as a closed system that would self-accelerate would violate conservation of energy and conservation of momentum. At the very least they should qualify their statements by clearly stating that their analysis is only valid for a closed system, and that they are ignoring external fields.
It is interesting that people have continued to post about conservation of energy of the EM Drive without qualifying their statements that they are ignoring external fields and they are assuming a closed system. It would be helpful if they would clarify their point.
Thanks -
#1089 by Bob012345 on 28 Sep, 2016 18:17
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
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#1090 by Fan Boi on 28 Sep, 2016 18:26
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
The more I read that the more awkward it appears. What I was trying to say is:
The EM drive seems to convert electrical energy into kinetic energy without a reaction mass, but is their a configuration where it does the opposite? (I am not even sure what 'opposite' means in this context, but thought I would put it out there). -
#1091 by flux_capacitor on 28 Sep, 2016 20:32
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
The more I read that the more awkward it appears. What I was trying to say is:
The EM drive seems to convert electrical energy into kinetic energy without a reaction mass, but is their a configuration where it does the opposite? (I am not even sure what 'opposite' means in this context, but thought I would put it out there).
In the following I don't consider the EmDrive breaking CoE, because I consider it as a relativistic open system.
It appears you're supposing that the EmDrive acts like any electromagnetic device. All electromagnetic devices can indeed be built either to generate mechanical energy (while electric energy is injected into the device) or conversely generate electric energy (while mechanical energy is applied to the device). Most common devices doing this are electric motors and electric generators (like dynamos and alternators). It is well known that electric vehicles now retrieve energy while braking for example.
However in your example in space there is no friction. When you switch off the thruster, your spaceship still moves at the same speed. It doesn't slow down.
The EmDrive may be a new kind of device converting electric energy into kinetic energy, not through Maxwell but through an inertial interaction with gravity (not necessarily the local gravitational field, see Mach effects).
So is there some similar mechanism that would slow down the EmDrive through some Machian momentum exchange with the universe mass, generating electric power? I don't have the answer.
Shawyer talks about a generator mode when the EmDrive slows down:Quote from: Roger ShawyerWith a negative acceleration, the overall Doppler shift will be positive. This will lead to an increase in stored energy, which is balanced by the loss of kinetic energy from the cavity. This is EmDrive in “generator” mode.
Reading between the lines it appears Shawyer says an EmDrive slowing down can indeed gain energy (the "stored" energy" in the cavity). But I don't know what to do with this claim since Shawyer's theory involves a closed system and obviously breaks CoE if the EmDrive has constant acceleration under constant power. How and why would Shawyer's EmDrive slow down anyway?
If this claim is true, like an E.V. braking on the road, it seems the increased stored energy in the cavity while slowing down could "preserve battery life" but that it could not act like a true power plant. -
#1092 by Fan Boi on 28 Sep, 2016 20:56
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That was very helpful, and you pretty much nailed my thought process. The quote above is really what I was trying to say. I also hadn't heard the term "generator mode" used for this until now.
So is there some similar mechanism that would slow down the EmDrive through some Machian momentum exchange with the universe mass, generating electric power? I don't have the answer. -
#1093 by foob on 28 Sep, 2016 20:59
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
The more I read that the more awkward it appears. What I was trying to say is:
The EM drive seems to convert electrical energy into kinetic energy without a reaction mass, but is their a configuration where it does the opposite? (I am not even sure what 'opposite' means in this context, but thought I would put it out there).
Not awkward at all. I thought rather insightful. A flywheel gains energy when spun by a motor and can deliver some of that energy when the motor is reconfigured.
Can an emdrive do this? If it is an open system as proclaimed by some there is reason to expect it to emit microwaves when it is pushed. -
#1094 by rq3 on 29 Sep, 2016 00:32
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
The more I read that the more awkward it appears. What I was trying to say is:
The EM drive seems to convert electrical energy into kinetic energy without a reaction mass, but is their a configuration where it does the opposite? (I am not even sure what 'opposite' means in this context, but thought I would put it out there).
Not awkward at all. I thought rather insightful. A flywheel gains energy when spun by a motor and can deliver some of that energy when the motor is reconfigured.
Can an emdrive do this? If it is an open system as proclaimed by some there is reason to expect it to emit microwaves when it is pushed.
As a sealed microwave cavity, no, it cannot "emit microwaves" (act as a microwave source just because it is under acceleration). But, if the cavity is pushed (external energy applied), the EXISTING cavity microwaves (from an already applied microwave source) will undergo a doppler shift, leading to a Q mismatch, and increased reflection back to the microwave source (in most experimental cases, the magnetron).
Indeed, if you take your conjecture to the limit, the Emdrive would be an "over-unity" device. -
#1095 by dustinthewind on 29 Sep, 2016 00:44
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I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one."
The article leads to this paper: http://scitation.aip.org/content/aip/journal/pop/23/9/10.1063/1.4962567 with a quote from it,QuoteWhen the number of the electron-positron pairs becomes large, they produce more photons than the ones arrived from the electron layer. As a result, the self-sustained QED cascade characterized by exponential growth of the pair number in time can develop. It is demonstrated17 that the cascade growth rate is maximal in the magnetic nodes of the circularly polarized standing wave. However, it is discussed above that the pair positions are unstable in the magnetic nodes and is stable in the electric ones. The pair density profile is determined by the trade off between the pair production effect and the pair drift. Therefore, the density of the electron-positron plasma may peak at the electric and magnetic nodes as the pair production is the most efficient at the magnetic nodes, while the pairs after creation are attracted to the electric nodes.
Is it required for the E/M fields to be circularly polarized? Something to do with non-linear mechanics in the creation process? My thoughts on this were, what if we are creating position-electron pairs near the narrow end of the frustum where the magnetic field is large and then they are pushed toward the large electric field. This would give us our source of momentum possibly. It is interesting that if it is happening then gamma rays may be being generated in the process. If for some reason the pairs merge again but maintain their momentum I could imagine a Doppler shift but not sure how that factors in with the generated gamma rays. I would guess both could escape from the cavity.
Could this process be partly responsible for the laser measurements that detected time/space distortions in the pill shaped cavity? Also the creation of matter from the vacuum seems to me to almost suggest modifying the index of the vacuum at that point which could have an effect of modifying the mass of light. -
#1096 by WarpTech on 29 Sep, 2016 03:36
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snip...
The above statement “Energy can be neither created nor destroyed ” is certainly false in our expanding space-time ruled by General relativity :
- Photons running in inter-galactic space have increasing wavelength and consequently smaller energy proportional to the inverse of the physical dimension of our universe.
- The total energy imposed by the cosmological constant increases with the third power of the physical dimension of our universe.
- Galaxies accelerate away from each other as the universe expands and consequently their relative cinetic energy increases.
The main point to understand is that in General relativity physical objects or fields do not propagate in a pre-existing translationally invariant spacetime. Consequently there is no energy conservation law applicable at whole space-time scale as the Noether's argument of translation invariance in time either fails, or becomes approximate, or becomes vacuous, or survives exclusively in spacetimes that preserve a special structure at infinity. At any rate, the status of energy conservation is not a reliable invariant on which we can base our analysis of a device which is thought to interact with the whole content of an universe which itself is not a closed system.
All of these things can be explained by turning the Freidmann equation around, inverting the coordinate system so to speak. Consider the length scale "a", to be the scale of our ruler and not the scale of the universe. From this perspective. The universe could have a constant size, and constant energy and what we observe is perfectly natural in the case where our meter-stick is contracting at a rate of 6.9 nm/century as it loses energy, thereby showing us the Hubble constant. Photons do not need change energy, wavelengths appear to expand as our ruler contracts. The galaxies do not need to be accelerating away, the universe does not need to be expanding "except" when we assume our ruler is a fixed constant. It's all a setup, caused by our contracting meter-stick.
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#1097 by WarpTech on 29 Sep, 2016 03:40
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I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one."
Wow, thanks for sharing this. I'm looking forward to reading about this. It sounds a lot like what I was thinking about the vacuum and possibly indicating some of the concepts Richard Feynman and Wheeler were suggesting.
I thought so too. If those virtual particles can become real particles then you can push on them in some way I would think. But even then, why no exhaust of these now real particles? Could they become real for only a brief moment and then become virtual again?
The problem is, it takes an electric field of a billion-billion volts per meter to do it!
https://en.wikipedia.org/wiki/Schwinger_limit
It only happens on the scale of electrons and charged sub-atomic particles.
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#1098 by SeeShells on 29 Sep, 2016 04:05
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We need a bigger boat... err frustum.I found this article interesting and possibly relevant to this discussion: http://phys.org/news/2016-09-antimatter-lasers.html
Note this statement: "A key concept behind the team's work is based on the quantum electrodynamics (QED) prediction that "a strong electric field can, generally speaking, 'boil the vacuum,' which is full of 'virtual particles,' such as electron-positron pairs," explained Igor Kostyukov of IAP RAS. "The field can convert these types of particles from a virtual state, in which the particles aren't directly observable, to a real one."
Wow, thanks for sharing this. I'm looking forward to reading about this. It sounds a lot like what I was thinking about the vacuum and possibly indicating some of the concepts Richard Feynman and Wheeler were suggesting.
I thought so too. If those virtual particles can become real particles then you can push on them in some way I would think. But even then, why no exhaust of these now real particles? Could they become real for only a brief moment and then become virtual again?
The problem is, it takes an electric field of a billion-billion volts per meter to do it!
https://en.wikipedia.org/wiki/Schwinger_limit
It only happens on the scale of electrons and charged sub-atomic particles.
Shell -
#1099 by zen-in on 29 Sep, 2016 04:09
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I started thinking about this topic the other way around and was wondering if there any comments. Suppose you locate a comet making it's way through the solar system at 100,000 MPH. Using convention rockets to match speeds we send up a very small EM device and attach it to the comet facing it's direction of travel and turn it on (battery powered for this thought experiment). Will it eventually scrub off speed from the comet while at the same time making copious amounts of electricity? Could the EM drive works "both ways"? It would seem to me that if the EM drives works it will scrub speed off the comet (simple retro-rocket), but what consequence for what is happening inside the EM device?
I doubt that. I think it would take power to slow something down just as it takes power to accelerate something.
Consider going to a distant planet to explore. You want to speed up then slow down and stop. Both take power.
The more I read that the more awkward it appears. What I was trying to say is:
The EM drive seems to convert electrical energy into kinetic energy without a reaction mass, but is their a configuration where it does the opposite? (I am not even sure what 'opposite' means in this context, but thought I would put it out there).
That is a very good way of looking at the problem. A few years ago I had the same idea with another device I was experimenting with. Any electromagnetic machine should operate as a generator or a motor. The other constraint I had to consider was the CoE conundrum. However this is easily seen in electromagnets: It is easy to move a strong magnet slowly across a thick Copper plate. When you attempt to move it quickly the resistance due to increased eddy currents makes it very hard. A lot of physical phenomena are reversible when the conditions are right. Most chemical equations are shown with the ⇔ operator. An electrodynamic tether is one example of propellantless propulsion that is reversible. When the induced current along the tether is used to charge batteries or just dissipated as heat the spacecraft drops to a lower orbit and has less kinetic energy. This has been proposed as a method for de-commisioning satellites. However before this "generator" mode of an EM-Drive is considered there are many prerequsites. No one to my knowledge has built an EM-Drive with a fustrum that was self-oscillating. By that I mean a cavity oscillator configuration. If you had a self-oscillating cavity would it generate RF energy if momentum was added to it? The doppler shift theory is not credible. If it were satellites would change their orbits whenever RF was transmitted to the ground,
No-one caught the error in my earlier post with the CoE equations. If you graphed ΔKe = (F2Δt)/(2M) and P = WΔt = (FΔt)/Kc they would both be straight lines; no parabola. However they do have different slopes. If the power applied to the EM-Drive was doubled, resulting in twice the force, the rate of change of its kinetic energy would increase by 4.
The only reason why this CoE conundrum exists is because it is claimed an EM-Drive produces a constant force for some constant input power. If this condition is relaxed and we say the force produced by any reactionless drive must decrease over time so as to satisfy CoE when a constant input power is applied it might be possible to make better theoretical progress.
.