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#2660 by Gilbertdrive on 11 Nov, 2016 18:30
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Maybe. But some think that CoM allows the momentum to be converted into energy.In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.
Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.
Here is something that I find really confusing... when we see a small object hit the Earth, we observe that its momentum has changed from non-zero to zero. On the other hand, we know that the total momentum of the system "earth + object" has not changed, so the Earth must have gained some momentum. Obviously this cannot be measured, but we know it must be true (otherwise CoM would be violated). Now when we look at "anomalous thrust" devices (such as EmDrive), we observe that they apparently gain momentum. It would be logical to assume that this is caused by interaction with some other object (or objects) which are gaining the opposite momentum, but we don't know the mechanism of this interaction yet (woodward effect and interaction with other objects in the universe is one hypothesis). Why do some people choose to throw away CoM and assume that it's not "pushing against" (interacting with) anything?
Because that's how they rationalize the EmDrive can't work at all. I don't know anyone who thinks it does work that argues CoM is not applicable.
And some others (Shawyer) think that CoM allows a system to gain momentum without changing the momentum of anything else in the universe.
Others (like me) consider that, in a flat spacetime, and for an inertial reference frame, CoM means a strict conservation of momentum for each isolated system.
It is not very usefull to all agree on CoM if we don't have the same notion of what it is.
EDIT Also there is often a context problem. For example, in many cases, flat spacetime, isolated systems, and inertial reference frame are not mentionned, because they seems contextually evident. -
#2661 by wicoe on 11 Nov, 2016 18:41
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Because that's how they rationalize the EmDrive can't work at all. I don't know anyone who thinks it does work that argues CoM is not applicable.
Here is how I see it:
Fact: a seemingly anomalous thrust is being observed in experiments. No obvious exhaust is detected. The device seems to be gaining momentum.
Explanation #1: this is the result of a systematic error or some spurious force that has not been taken into account yet. If true, EmDrive cannot work. This can be confirmed or ruled out by doing further experiments (in space, etc).
Explanation #2: the thrust is real, but it is caused by interaction with some object/field (hopefully not just the Earth). This interaction may require a new physical theory to be developed, but this theory would not overturn CoM. If true, this would mean that the object(s) it's interacting with acts as a propellant, and as the relative "device/propellant" velocity increases, the acceleration rate will drop (otherwise CoM/CoE would not be observed, as has been previously discussed many times in this thread). This does not mean that EmDrive cannot work, it just means that there are some limitations to the thrust it can deliver, as dictated by CoM/CoE.
Explanation #3: the thrust is real, there is no interaction with external fields/objects, CoM/CoE is not observed in the classical sense and must be corrected. If true, the device could potentially deliver constant acceleration for constant power regardless of its relative movement (since it's not interacting with any external fields/objects).
All I'm saying is that even if further experiments show that #1 does not explain the thrust, then #2 is much more likely than #3, because #3 implies free energy or perpetual motion.
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#2662 by Gilbertdrive on 11 Nov, 2016 18:47
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Because that's how they rationalize the EmDrive can't work at all. I don't know anyone who thinks it does work that argues CoM is not applicable.
Here is how I see it:
Fact: a seemingly anomalous thrust is being observed in experiments. No obvious exhaust is detected. The device seems to be gaining momentum.
Explanation #1: this is the result of a systematic error or some spurious force that has not been taken into account yet. If true, EmDrive cannot work. This can be confirmed or ruled out by doing further experiments (in space, etc).
Explanation #2: the thrust is real, but it is caused by interaction with some object/field (hopefully not just the Earth). This interaction may or may not require a new physical theory, but this theory would not overturn CoM. If true, this would mean that the object(s) it's interacting with acts as a propellant, and as the relative "device/propellant" velocity increases, the acceleration rate will drop (otherwise CoM/CoE would not be observed, as has been previously discussed many times in this thread).
Explanation #3: the thrust is real, there is no interaction with external fields/objects, CoM is not observed in the classical sense and must be corrected. If true, the device could potentially deliver constant acceleration for constant power regardless of its relative movement (since it's not interacting with any external fields/objects).
All I'm saying is that even if further experiments show that #1 does not explain the thrust, then #2 is much more likely than #3.
It is the same if I see a $500 bill on the ground, there are also several possibilities.
1 : It is a monopoly bill.
2 : It is a real bill. I am lucky.
3 : A crazy man deposes a bill at the same place each day. I just have to go each day to get another $500
Of course, 3 is not impossible, but 2 is more likely. -
#2663 by Bob012345 on 11 Nov, 2016 18:55
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Because that's how they rationalize the EmDrive can't work at all. I don't know anyone who thinks it does work that argues CoM is not applicable.
Here is how I see it:
Fact: a seemingly anomalous thrust is being observed in experiments. No obvious exhaust is detected. The device seems to be gaining momentum.
Explanation #1: this is the result of a systematic error or some spurious force that has not been taken into account yet. If true, EmDrive cannot work. This can be confirmed or ruled out by doing further experiments (in space, etc).
Explanation #2: the thrust is real, but it is caused by interaction with some object/field (hopefully not just the Earth). This interaction may require a new physical theory to be developed, but this theory would not overturn CoM. If true, this would mean that the object(s) it's interacting with acts as a propellant, and as the relative "device/propellant" velocity increases, the acceleration rate will drop (otherwise CoM/CoE would not be observed, as has been previously discussed many times in this thread). This does not mean that EmDrive cannot work, it just means that there are some limitations to the thrust it can deliver, as dictated by CoM/CoE.
Explanation #3: the thrust is real, there is no interaction with external fields/objects, CoM/CoE is not observed in the classical sense and must be corrected. If true, the device could potentially deliver constant acceleration for constant power regardless of its relative movement (since it's not interacting with any external fields/objects).
All I'm saying is that even if further experiments show that #1 does not explain the thrust, then #2 is much more likely than #3, because #3 implies free energy or perpetual motion.
Oh joy, here we go again!
I don't see why #2 means it has to reduce its acceleration as it gains speed to conserve CoE. If the "propellant" of unknown mechanism is real, there is no need to impose limits on how it works without further data. It could be just like a physical propellant released from the ship which would always conserve momentum and energy no matter how fast it goes. Like a physical propellant, the faster you observe it, the more 'base' energy it has to give.
I suspect it keeps accelerating and just goes and goes and goes. It doesn't violate CoM or CoE by doing so.
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#2664 by SeeShells on 11 Nov, 2016 19:06
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cute program for designing a helical quadfire antenna or as called a eggbeater.
http://jcoppens.com/ant/qfh/calc.en.php
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#2665 by wicoe on 11 Nov, 2016 19:08
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Oh joy, here we go again!
My thoughts exactly! And yet if you take the system "device + objects it's pushing against" and write the CoE/CoM equations, it becomes obvious that as the relative velocity increases, the same acceleration (dV over dT) would require more energy. I'm not sure why this may not be obvious to some people, but writing down the simple newtonian equations usually helps. If there is another hypothetical way to write these equations without requiring dE (required energy to accelerate by dV) to grow with V, please provide an example. -
#2666 by Star One on 11 Nov, 2016 19:23
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Oh dear the leak has now reached larger space sites.
http://www.universetoday.com/131895/physics-really-violated-em-drive-leaked-nasa-paper/ -
#2667 by Bob012345 on 11 Nov, 2016 19:32
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Oh joy, here we go again!
My thoughts exactly! And yet if you take the system "device + objects it's pushing against" and write the CoE/CoM equations, it becomes obvious that as the relative velocity increases, the same acceleration (dV over dT) would require more energy. I'm not sure why this may not be obvious to some people, but writing down the simple newtonian equations usually helps. If there is another hypothetical way to write these equations without requiring dE (required energy to accelerate by dV) to grow with V, please provide an example.
One example where it doesn't is this. Imagine a uniform expansive gravitational field that our ship was falling through. Assume that field was of infinite extent. Our ship would maintain its acceleration indefinitely. The means it imparts energy is based on distance covered (work) not speed or time. Perhaps the EmDrive create such a local field that it falls through. CoM and CoE are always conserved for all situations and observers. -
#2668 by WarpTech on 11 Nov, 2016 19:41
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In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.
Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.
Here is something that I find really confusing... when we see a small object hit the Earth, we observe that its momentum has changed from non-zero to zero. On the other hand, we know that the total momentum of the system "earth + object" has not changed, so the Earth must have gained some momentum. Obviously this cannot be measured, but we know it must be true (otherwise CoM would be violated). Now when we look at "anomalous thrust" devices (such as EmDrive), we observe that they apparently gain momentum. It would be logical to assume that this is caused by interaction with some other object (or objects) which are gaining the opposite momentum, but we don't know the mechanism of this interaction yet (woodward effect and interaction with other objects in the universe is one hypothesis). Why do some people choose to throw away CoM and assume that it's not "pushing against" (interacting with) anything?
Look at it this way. The frustum is pushing against the field inside it, and the field is pushing back against the frustum. The direction it goes should be opposite the side which has the highest power dissipation, assuming the power dissipation is not symmetrical. This is ALL that is required. The equations that say it shouldn't move assume no dissipation, or symmetrical dissipation ONLY.
Quantum mechanics tells us that when the copper atoms and bulk metal absorb momentum from the field, It feels a recoil in the direction of the momentum vector to satisfy CoM. When it re-emitts the momentum, it does not necessarily have to have the "equal and opposite" value! The recoil of the atom is opposite the momentum of the emitted photon. It's direction and momentum is a probability distribution, partly determined by the motion of the atoms (heat). The emitted photons could be doppler shifted, for example. Like a laser, where pumping the laser to create a population inversion, requires a frequency "higher" than the one the laser will later emit.
In other words, absorption of the photon (momentum) and it's recoil is one process of CoM. Re-emission of the photon (momentum) and it's recoil is another process of CoM, that is influenced by heat and motion of the atom emitting it. GR does not consider QM processes, it is purely classical. So GR will need to be modified. So what? It's a classical approximation of a Quantum theory anyway and we know this. We need to stop acting like physics MUST be interpreted through a geometrical perspective to be correct. That's a preference, not a requirement.
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#2669 by kaublezw on 11 Nov, 2016 19:45
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Oh joy, here we go again!
My thoughts exactly! And yet if you take the system "device + objects it's pushing against" and write the CoE/CoM equations, it becomes obvious that as the relative velocity increases, the same acceleration (dV over dT) would require more energy. I'm not sure why this may not be obvious to some people, but writing down the simple newtonian equations usually helps. If there is another hypothetical way to write these equations without requiring dE (required energy to accelerate by dV) to grow with V, please provide an example.
One example where it doesn't is this. Imagine a uniform expansive gravitational field that our ship was falling through. Assume that field was of infinite extent. Our ship would maintain its acceleration indefinitely. The means it imparts energy is based on distance covered (work) not speed or time. Perhaps the EmDrive create such a local field that it falls through. CoM and CoE are always conserved for all situations and observers.
This is kind of what I've been thinking. Some of the energy is being absorbed by the atoms, but not as heat...as some other type of non-random internal deformation. This deformation is most pronounced in the large plate and it induces a kind of anti-gravity field. This field causes the device to "fall" forward. But it will only keep "falling" so long as the field is there, which is generated by the energy going into the system. So I don't see how this violates CoE. But I'm sure I'm wrong....just my idle musings.
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#2670 by Peter Lauwer on 11 Nov, 2016 19:47
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Start with some basics.
https://en.wikipedia.org/wiki/Loop_antenna
https://en.wikipedia.org/wiki/Loop_antenna#Small_loops_as_transmitting_antennas
ID and OD of a small loop will cause phase differences in radiating fields and in a high Q cavity lead to a higher VWSR.
Thanks!
The next best way is a helical antenna which makes a plane wave although it doesn't fit well in a cavity being very long, it still has low VWSR and couples well to the magnetic field locking a TE mode.
Fit could be just one reason why Shawyer went to a modified quadrifiler helical.
It fits well into the cavity, low VWSR, couples to the fields and can lock in a TEmode.
You could also build one like monomorphic modeled in FEKO for Shawyer's design which works quite well. Or just spend 5 bucks or so and get it from Ebay making sure your frequencies match.
Shell
That looks like an interesting alternative. I have to look into it, get better understanding of its radiation pattern.
regards, Peter
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#2671 by FattyLumpkin on 11 Nov, 2016 20:52
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Am considering purchase of Niobium sheet (1 mm) where I could sell of amounts not used to those who would be interested in purchasing various pieces at my cost only. (no charge for shipping etc.) If any NSF members are interested, please let me know as it would affect what I might purchase. FL
BTW 1 mm is just being thrown out there ....thinner or thicker might be preferred by most of y'all.
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#2672 by SeeShells on 11 Nov, 2016 21:06
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Good reference.Start with some basics.
https://en.wikipedia.org/wiki/Loop_antenna
https://en.wikipedia.org/wiki/Loop_antenna#Small_loops_as_transmitting_antennas
ID and OD of a small loop will cause phase differences in radiating fields and in a high Q cavity lead to a higher VWSR.
Thanks!
The next best way is a helical antenna which makes a plane wave although it doesn't fit well in a cavity being very long, it still has low VWSR and couples well to the magnetic field locking a TE mode.
Fit could be just one reason why Shawyer went to a modified quadrifiler helical.
It fits well into the cavity, low VWSR, couples to the fields and can lock in a TEmode.
You could also build one like monomorphic modeled in FEKO for Shawyer's design which works quite well. Or just spend 5 bucks or so and get it from Ebay making sure your frequencies match.
Shell
That looks like an interesting alternative. I have to look into it, get better understanding of its radiation pattern.
regards, Peter
http://www.intechopen.com/books/advances-in-satellite-communications/helical-antennas-in-satellite-radio-channel#F15 -
#2673 by M.LeBel on 11 Nov, 2016 21:07
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Oh joy, here we go again!
My thoughts exactly! And yet if you take the system "device + objects it's pushing against" and write the CoE/CoM equations, it becomes obvious that as the relative velocity increases, the same acceleration (dV over dT) would require more energy. I'm not sure why this may not be obvious to some people, but writing down the simple newtonian equations usually helps. If there is another hypothetical way to write these equations without requiring dE (required energy to accelerate by dV) to grow with V, please provide an example.
I think that the problem here is about mixing physical description and understanding. CoM is descriptive physics; it gives results and doesn`t promise any explanation. On the other hand, GR presents us with both description and some explanation. There is no push or pull or forces i.e source to source interaction. Both the Earth and the Moon, for example, move into and according to the influence field of each other where they are in in that field. Since we are trying to understand/speculate on what the emDrive does, it might be better, for now, to leave the strict descriptive physics behind. In other words, we (you) do the physics for the inside of the cavity, but you have not worked out the influence escaping the cavity...
... this makes it hard to optimize a cavity input/output when using, in the end, a CoM based pendulum test. .... Action at a distance??? Where and what is the field?
EDIT: I understand that the cavity is sometimes mounted on the actual pendulum arm... -
#2674 by meberbs on 11 Nov, 2016 22:32
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P = F * v. As the velocity increases, the power (rate of energy added to the object) also increases, so it is constant force, but not constant power. As you say, energy comes from distance covered, and since it covers more distance per time as it is moving faster it also gets more kinetic energy per time (converted from potential energy) as its velocity increases.Oh joy, here we go again!
My thoughts exactly! And yet if you take the system "device + objects it's pushing against" and write the CoE/CoM equations, it becomes obvious that as the relative velocity increases, the same acceleration (dV over dT) would require more energy. I'm not sure why this may not be obvious to some people, but writing down the simple newtonian equations usually helps. If there is another hypothetical way to write these equations without requiring dE (required energy to accelerate by dV) to grow with V, please provide an example.
One example where it doesn't is this. Imagine a uniform expansive gravitational field that our ship was falling through. Assume that field was of infinite extent. Our ship would maintain its acceleration indefinitely. The means it imparts energy is based on distance covered (work) not speed or time. Perhaps the EmDrive create such a local field that it falls through. CoM and CoE are always conserved for all situations and observers.
Yet again, your "example" of constant force/power is not one. Please work these through yourself a little more carefully before posting. -
#2675 by knowles2 on 12 Nov, 2016 01:41
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Oh dear the leak has now reached larger space sites.
Funny how they write this off as just a report leak from NASA and not a paper that has or is going through peered review process and in December will be formally publish in a journal.
http://www.universetoday.com/131895/physics-really-violated-em-drive-leaked-nasa-paper/ -
#2676 by dustinthewind on 12 Nov, 2016 01:41
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If it were a full wavelength then current flowing around the current loop would have half the current going around the loop in one direction while current around the other half of the antenna loop would be going the opposite direction.
Added some sketch to the image.The TM modes seem to have the highest Q for this cavity. Does that make sense? The loop is having its field in the axial direction of the cavity.
Thanks,
Peter
That is because you're using side wall injection. You are going to have a very difficult time (just like NASA did) trying to excite the TE01x modes. For example, I was able to locate TE012 at ~4.407Ghz, but it is VERY weak with the antenna mounted to the side and is very close to a TM mode.
If you move the loop to the center things clear up greatly. Also, FEKO says your antenna wire diameter of 2mm is too much. The ratio of wire radius and length are not ideal. You may need to switch to a thinner wire.
Thanks a lot for the advice and the sim, Monomorphic. I will make a new cavity with 1 mm wire. But, uhh..., how about the supply wires if you move the loop to the center? In a sim it is easy to do, but you will have strong influence of the wires from the side or endplate (either coax or two copper wires).
How about placing the loop on one of the endplates, halfway the center and edge, and opening (B-field) facing the center? The loop is not placed at a maximum then, that's true. I will try it out.
Peter
I thought the circumference of a loop antenna should ideally be equal to wavelength.
For the TE01 mode the electric field is only flowing in one direction so you want the current in the antenna loop to also only be flowing in one direction.
I think, Ideally, there is a parallel to the shape of the electric field of the desired mode, and the shape of the input antenna's current.
It might be possible to use a full wavelength long antenna by folding it back on itself and making a 2nd loop that is in reverse of the 1st loop. Maybe it could be like a high frequency solenoid.
I've never had the opportunity to actually test such devices. I am primarily using my minds eye to try and imagine such behavior, so its possible I am not correct, but I am fairly confident it should be correct.
The negative current should flow in the direction of the electric field to parallel with adding emitted light in the cavity, and also and it seems ideal that the electric field maximums appear about 1/4lambda from the end plates (TE012 mode in particular). By the time the current reverses in the antenna (1/2 lambda or cycle) the reflected wave from the plate 1/4lambda should have traveled (1/2 lambda or cycle) and add constructively with the antenna.
When the electric field grows large enough in the cavity it should almost stop all current in the antenna except what is lost to heat (voltage on antenna opposes voltage from light). There should develop a standing wave in the wire to the antenna and when the wave dies down periodically, there will be a very small traveling wave representing the energy carried into the cavity to maintain the energy lost. (reflected waves having less amplitude than the waves moving toward the cavity in the wire). I might be digressing a bit. -
#2677 by OnlyMe on 12 Nov, 2016 03:02
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In GR, which again is a geometric model describing the tidal effects of gravitation, momentum as a component of the math, is not an observable. It is a descriptive component of the geometric model.
Momentum as discussed in terms of the anomalous thrust and EmDrives is an observable... Even if it has not yet been conclusively observed in published data.
Here is something that I find really confusing... when we see a small object hit the Earth, we observe that its momentum has changed from non-zero to zero. On the other hand, we know that the total momentum of the system "earth + object" has not changed, so the Earth must have gained some momentum. Obviously this cannot be measured, but we know it must be true (otherwise CoM would be violated).
Repeating myself.... What we know about momentum and the conservation of momentum is based on classical Newtonian mechanics, the way motion and momentum is transferred between billiard balls... and other collisions within our ability to accurately measure the masses and velocities involved before and after a collision... In many many discussions we then logically predict how what we know as a matter of direct observation applies to situations and conditions well outside our ability to accurately observe and measure. We do that very well. We are very clever and have an incredible innate ability to accurately imagine how what we do know might affect conditions we have not yet directly observed. As I said we are very good at this.., but we are not always right. That is why it is important to always remember the line that separates what we have actually observed and measured, from how we imagine and project those conclusions to unmeasurable conditions.
For this reason while your statements above are accurate, that last qualification, "(otherwise CoM would be violated), becomes a dangerous assumption. We cannot know that what we do understand about momentum and the CoM has no limitations. There is more to the universe and physics that we do not know than we do know.Quote from: wicoeNow when we look at "anomalous thrust" devices (such as EmDrive), we observe that they apparently gain momentum. It would be logical to assume that this is caused by interaction with some other object (or objects) which are gaining the opposite momentum, but we don't know the mechanism of this interaction yet (woodward effect and interaction with other objects in the universe is one hypothesis). Why do some people choose to throw away CoM and assume that it's not "pushing against" (interacting with) anything?
To answer the question in that last sentence.., because within the context of classical Newtonian mechanics where our understanding of CoM is rooted, for every action there is an opposite and equal reaction. To move something you have to push it or it has to push against something else. That is what we have observed, measured and experienced... And it does not seem immediately clear that anything like that is occurring in the case of an EmDrive. So in an effort to hold our world view together we reach out for explanations... or we just reject the claims of an anomalous force as artifacts of experimental or systemic error. We all do the very best we can to protect and defend our world view (of physics) and what we have come to believe.
Still many of those who might be labeled skeptics in these discussions, are just defending science itself by demanding that obvious sources of experimental and systemic error are addressed, and any apparent conflicts with established physics explained.
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#2678 by OnlyMe on 12 Nov, 2016 03:13
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.....
I've never had the opportunity to actually test such devices. I am primarily using my minds eye to try and imagine such behavior, so its possible I am not correct, but I am fairly confident it should be correct.
....
Our imagination and mind's eye may be our greatest asset and gift. Look where it has brought us, from stone tools and cold nights, to EmDrives and the very edges of what might be. . . -
#2679 by rfmwguy on 12 Nov, 2016 03:51
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"Real (unvirtual) photons carry electric, kinetic energy. Virtual photons carry potential charge energy (Electric field). Net energy is conserved."
https://www.quora.com/Real-unvirtual-photons-carry-electric-kinetic-energy-Virtual-photons-carry-potential-charge-energy-Electric-field-Net-energy-is-conserved-How-is-this-conservation-explained-using-the-quantum-field-theory
Beginning to study Photons and the conversion to/from E fields and K which conserve energy, including losses to heat. Superconductivity environment will attenuate heat loss and more efficient E/K transformation.
While early in my stage of this research, this is the rabbit hole I'm exploring. Quite a few papers on the topic. Controlling the E field transformation and vectoring K seems to be a worthwhile pastime for the moment.
E field mapping will be a high priority once testing resumes with 1701B