Dave on TMRO Live 9.16.
Really great interview Dave!!
Dave on TMRO Live 9.16.
Really great interview Dave!!
This was an EXCELLENT interview, a pleasure to watch. You handled the questions very well !
I highly recommend everyone to watch it: https://www.tmro.tv/live/ 9.16
Well...that was fun 
That was really enjoyable, and it certainly piqued some interest in the chat room. Well done!
...
So I updated again to reflect your suggestions. I think I have carefully read your suggestions and the drawing is accurate. Is it? Thank you！
Yes, I agree with what you have drawn. Of course it is always a good idea to have the DC switched and fused. If I was building it I would use a higher DC voltage and a suitable inverter because with the power level involved a lot of current has to be supplied at 12 V. DC.
,,,
I am not talking about magnetic fields extending outside a power cable! You are!
I am talking about the fact that electromagnetic fields carry momentum, and that you are transmitting momentum through the power cables from a stationary device (that is being depleted) to the EM Drive that may self-accelerate as a result of the electromagnetic power flowing through your coaxial cable. I am discussing the issue of center of energy-momentum and that in electromagnetics momentum and energy are tied together in the same equation, for several posts now.
In electromagnetics, energy and momentum are tied together: (*)
in the same equation!
To quote GilbertDrive:
It is like if I was wanting to prove telekinesis powers, by making move a spoon that is attached to my finger by a cord. Even if I try to convince the spectators that the cord can not help, that I am not using it to make move the spoon, they will tell me "And why not without the cord ?"
______________
(*) where the electromagnetic energy density is uem and S is the momentum. It is improper to ignore the momentum that is being supplied from a location outside the moving platform.
The best test uses batteries self-integrated with the device, as done by Yang in her latest tests that nullify her previous tests with power cords.
If I am not mistaken the change in momentum happens while the wave propagates down the coax or waveguide. After the wave has reached the end of the coax or waveguide and is dissipated in the terminal impedance (50 Ohms) the change in momentum wrt time = 0. If the RF is switched off the change in momentum is in the opposite direction as the EM field collapses. Do I have this right?
,,,
I am not talking about magnetic fields extending outside a power cable! You are!
I am talking about the fact that electromagnetic fields carry momentum, and that you are transmitting momentum through the power cables from a stationary device (that is being depleted) to the EM Drive that may self-accelerate as a result of the electromagnetic power flowing through your coaxial cable. I am discussing the issue of center of energy-momentum and that in electromagnetics momentum and energy are tied together in the same equation, for several posts now.
In electromagnetics, energy and momentum are tied together: (*)
in the same equation!
To quote GilbertDrive:
It is like if I was wanting to prove telekinesis powers, by making move a spoon that is attached to my finger by a cord. Even if I try to convince the spectators that the cord can not help, that I am not using it to make move the spoon, they will tell me "And why not without the cord ?"
______________
(*) where the electromagnetic energy density is uem and S is the momentum. It is improper to ignore the momentum that is being supplied from a location outside the moving platform.
The best test uses batteries self-integrated with the device, as done by Yang in her latest tests that nullify her previous tests with power cords.
If I am not mistaken the change in momentum happens while the wave propagates down the coax or waveguide. After the wave has reached the end of the coax or waveguide and is dissipated in the terminal impedance (50 Ohms) the change in momentum wrt time = 0. If the RF is switched off the change in momentum is in the opposite direction as the EM field collapses. Do I have this right?
The steady-state force due to the electromagnetic momentum carried by the coaxial cable is as expressed below, a function of cosine squared vs. time. As such its time-average is 1/2 of the maximum.
The force is purely
along the longitudinal direction of the cable. It has nothing to do with any fields escaping off the cable in the radial direction (as others were discussing).
It is an electromagnetic force, it is not a thermal force (as others were discussing).
The force in the longitudinal direction is proportional to
the energy density (the energy transported by the cable) times the cross-sectional area of the coaxial cable, times the natural log of the ratio of the outer to inner diameters of the coaxial cable times the square of the cosine function.
I don't have an answer for the transient response upon switching on and off the RF. Given all the vagueries of who is using what (I don't have any idea of what SeeShells is using at this point in time, Dave Distler's report indicated that for NSF-1701 he used a magnetron that he was switching on and off during the whole test) I would think in terms of the time average.
Not requiring a vacuum chamber : it is known that magnetic couplings have been a major factor in some of the values reported for previous experiments. Lorentz forces of explicit (known) DC components can be "mitigated" and I see this is discussed here, but this is only a best effort that has no guaranty of perfect cancellation (bends, imperfect contacts, local gradients due to ferromagnetic materials in vicinity...). And moreover it is not excluded that the RF energy itself generates significant "rectified" currents even when it shouldn't, say for instance, asymmetrical electron wind near the antennae (pure speculation, probably not) but yet if some effect persists we have to consider more surprising mechanisms, not only to explain it as a real effect (useful for space propulsion) but also to see how it could be from local coupling (not useful for space propulsion but not obvious either).
Anyway, local DC geomagnetic field, perturbed by ferromagnetic materials nearby (steel reinforced concrete, whatever...), ie. not necessarily perfectly constant in magnitude and direction in the volume of the experiment, appears as a major potential for non obvious spurious (rotational and/or linear) momentum exchange with surrounding. DC magnetic field hardly can be zeroed out. My proposition is to quantify the influence of local environmental magnetic field. For instance that you make a (crude) Helmholtz coils assembly that can encompass at least the test article, and with strong enough induced magnetic field that it can overcome in magnitude the local geomagnetic field. No need to invest into expansive gaussmeter at first, a magnetic compass would be conclusive enough that the Helmholtz coils do overcome the local field (or smart phone magnetometer app, though I'd personally prefer good old compass). Among your various experiments, take the best configuration in term of reproducibility (apparently giving cleanest signal) and record results with/without added local field, for various orientations of Helmholtz coils assembly and magnitude (current in coils), and also with only one coil at a time (higher divergence rather than "flat" volumetric field). Repeat a few time at various magnitude to extract a plot of measured force as function of forward and backward current in coils with a reasonable low noise.
Either the plots (force wrt. coils intensity for X Y Z) are strictly horizontal, ie. there is no influence of local DC magnetic field on the result, the effect (and applicability to space propulsion holds) up to magnitude characteristics of geomagnetic field. Or there is a slope, indicating the force needs (pushes on) a local field, which is bad news for space propulsion, but better to know than ignore. If this later case appears then further quantitatively precise characterisation should be done...
Maybe if Helmholtz coils prove to be too expensive in copper wiring, or too time consuming, a simple strong permanent magnet (from a dismantled speaker, whatever) strong enough to deviate a magnetic compass from a few 10s of centimeters can be used to probe possible influence on results (all other things being equal).
That would make your experiment the first (in experimented EM drive devices I think ?) to go beyond "care has been taken of local magnetic field interactions to minimize spurious couplings", to an experimentally strong characterization of this specific systematic error source, whatever the specifics, including surprising and/or improbable ones. I don't count in that league experiments where DC field has been varied but indirectly and not all other parameters being kept equal and not enough data points to assess statistical significance (shielding of the magnetic dampener at EagleWorks for instance). I would personally take that as a very important progress (before self containment and vacuum testing).
p.s.
in https://forum.nasaspaceflight.com/index.php?topic=39772.msg1529226#msg1529226 you write "I feel the strong need to do this especially if I'm seeing something above 3.33mn/KW that would violate known conservation laws.". Self-powered propellantless propulsion is in tension with conservation laws as soon as exceeding 3.33µN (micro-Newtons) not 3.33mN (milli-Newtons) per kW (kilo-Watts) of input power as sole sacrificed flow.
I believe that a test apparatus which is allowed to continuously rotate could mitigate the majority of Lorentz force anomalies. The 360 degree rotation would experience additive as well as equal and opposite subtractive Lorentz during each full rotation. This appears to be the reason The Traveler seems unconcerned regarding Lorentz forces.
To accomplish the low friction required for a continuous rotation device, one would have to use a rotary air bearing or a magnetic bearing. Each presents unique problems. The air bearing (my area) could have self induced motoring which can be characterized and maybe canceled, but also has vacuum chamber compatibility issues. The magnetic bearing such as what The Traveler intends to use, concerns me. The principal thrust which supports the payload is a strong servo magnetic field, and as I understand, many types have anti-rotational-cogging features (active current control) that act directly in the rotary domain. I don't know enough about the magnetic bearing to understand how problematic these concerns might be.
Maybe there is a light at the end of the tunnel. Interesting reading on the simple photon.
Shell
<Snip>
. Conclusions
Starting from Maxwell’s equations, the origin of an effective mass acquired by photons
propagating in a plasma or a rectangular waveguide has been analysed. We have discussed
how such constrained circumstances give the equations a form equivalent to those for
massive particles propagating in vacuum, with a mass that depends on the parameters of
the environment.
In the case of propagation through a tenuous neutral plasma, owing to the interaction with
the mobile electrons, light behaves as massive particles moving in vacuum with a velocity
lower than c. The acquired mass is proportional to the plasma frequency and for typical values of this parameter it may be as low as a fraction 10−10 of the rest mass of the electron.
https://www.researchgate.net/publication/258272518_Can_there_be_massive_photons_A_pedagogical_glance_at_the_origin_of_mass
AND
The momentum of light in media remains one of the most controversial topics in physics [1–6]. The debate has continued for more than a century since Minkowski and Abraham formulated 4 × 4 energy-momentum tensors in the early 1900s [7–9].
https://www.researchgate.net/publication/292342272_Kinetic-energy-momentum_tensor_in_electrodynamics
Shell, I don't believe that photons can travel faster than c, because they define c. Truth is I am mystified as to why complex time is not considered a complete resolution of the photon. The photon may be nothing more than a quirk of human perception. It is always going to be difficult to observe photon energy with respect to a distant place where time has a different rate. Complex time allows the photon to exist as an interaction without any independent energy.
If we can step aside from our habitual belief that distance is something more than fractions of the real time component of complex time, then we may comprehend the impossibility of photons having any intrinsic energy. Quantum Mechanics can still agree with Special Relativity but General Relativity takes its proper place as a clever means of interpreting things otherwise unintelligible from the human perspective.
The mechanism of action of the emdrive may yet be resolved as a consequence of the behaviour of charges within a Machian universe. Energy could be conserved and time a-symmetry survive, because no retarded waves are required to account for the immediacy of inertial interaction with a distant universe, within complex time. Gravity and inertia would then be defined by the dynamic location of the zero of electromagnetic force for individual charges in motion. Photons being single interactions, gravity and inertia being the dynamic result of all attractions and repulsions.
These ideas require development, of course. I wish I could state them in more acceptable terms but am out of my depth. I do know that, c is the speed of a photon but only from a point perspective which does not allow a complete description due to uncertainty. Complex time will always be required to define that uncertainty, perhaps because complex time is reality. JMN..
I believe that a test apparatus which is allowed to continuously rotate could mitigate the majority of Lorentz force anomalies. The 360 degree rotation would experience additive as well as equal and opposite subtractive Lorentz during each full rotation. This appears to be the reason The Traveler seems unconcerned regarding Lorentz forces.
....
Only if the apparatus rotates a whole round. But that is yet to happen. The Traveler speculated 120 rpm but that is not realized yet. He is too confident. I start to worry about him.
...
So I updated again to reflect your suggestions. I think I have carefully read your suggestions and the drawing is accurate. Is it? Thank you！
Yes, I agree with what you have drawn. Of course it is always a good idea to have the DC switched and fused. If I was building it I would use a higher DC voltage and a suitable inverter because with the power level involved a lot of current has to be supplied at 12 V. DC.
I drew an equivalent circuit, overlaying on your design. Now the ground loops are apparent. The conductors all have resistance, no matter how small it is. The DC in the loops when interacted with ambient magnetic field, will generate Lorents force. Note that when you turn your frustum 180 degree, the shape of loop 1 changes, so does the Lorentz force. This will give you false thrust. I make this brain experiment to help make it clear that Lorentz force exist in many Emdrive experiments, NASA and Tajmar included. I hope rfmwguy and Shell can avoid the same problem.
And this is the correct scheme to avoid Lorentz force. I think rfmwguy has adopted this design.
I propose two ways to measure the movement. They will avoid problem caused by mass center shift.
1) Method 1 is superior to method 2
2) By all means avoid increasing the degrees of freedom, and avoid extra rotational moments of inertia
I propose two ways to measure the movement. They will avoid problem caused by mass center shift.
Consider mounting the mirror on the two ^ sections of wire.
I propose two ways to measure the movement. They will avoid problem caused by mass center shift.
Consider mounting the mirror on the two ^ sections of wire.
We just cut a piece from a hard drive disk to use as a mirror. We used dremel to cut to make sure it would not bend.
Sorry to interject, but I just had a thought regarding frustum materials and construction methods...
I was thinking about weights and costs and people wanting to build emdrive cubesats and it occurred to me that it might be possible to construct a light weight, collapsable frustum out of mylar. I did a quick something search and it looks like NASA already did a little bit of testing for us.
https://directory.eoportal.org/web/eoportal/satellite-missions/i/iaeObviously the tolerances and the Q wouldn't be as high, but one might actually be able to fit a collapsable mylar frustum, microwave source and batteries into a 1U cubesat.
Sheeshell, following the Pr Yang nullification, I support Dr Rodal's advice. Compared to the time and money that you used to make your build, making it battery powered will not take you so long time. And, if it is a positive result, the comparison with the data with external power will be very interesting.
This is why I have advanced to this test stand. I'll be keeping most of the hardware and be able to change very basic items like power source, rotational versus teeter totter (rotate the stand 900), rotational acceleration and even just a thrust component.
I welcome any ideas to enhance this test bed (other than a vacuum chamber).
Shell
Not requiring a vacuum chamber : it is known that magnetic couplings have been a major factor in some of the values reported for previous experiments. Lorentz forces of explicit (known) DC components can be "mitigated" and I see this is discussed here, but this is only a best effort that has no guaranty of perfect cancellation (bends, imperfect contacts, local gradients due to ferromagnetic materials in vicinity...). And moreover it is not excluded that the RF energy itself generates significant "rectified" currents even when it shouldn't, say for instance, asymmetrical electron wind near the antennae (pure speculation, probably not) but yet if some effect persists we have to consider more surprising mechanisms, not only to explain it as a real effect (useful for space propulsion) but also to see how it could be from local coupling (not useful for space propulsion but not obvious either).
Anyway, local DC geomagnetic field, perturbed by ferromagnetic materials nearby (steel reinforced concrete, whatever...), ie. not necessarily perfectly constant in magnitude and direction in the volume of the experiment, appears as a major potential for non obvious spurious (rotational and/or linear) momentum exchange with surrounding. DC magnetic field hardly can be zeroed out. My proposition is to quantify the influence of local environmental magnetic field. For instance that you make a (crude) Helmholtz coils assembly that can encompass at least the test article, and with strong enough induced magnetic field that it can overcome in magnitude the local geomagnetic field. No need to invest into expansive gaussmeter at first, a magnetic compass would be conclusive enough that the Helmholtz coils do overcome the local field (or smart phone magnetometer app, though I'd personally prefer good old compass). Among your various experiments, take the best configuration in term of reproducibility (apparently giving cleanest signal) and record results with/without added local field, for various orientations of Helmholtz coils assembly and magnitude (current in coils), and also with only one coil at a time (higher divergence rather than "flat" volumetric field). Repeat a few time at various magnitude to extract a plot of measured force as function of forward and backward current in coils with a reasonable low noise.
Either the plots (force wrt. coils intensity for X Y Z) are strictly horizontal, ie. there is no influence of local DC magnetic field on the result, the effect (and applicability to space propulsion holds) up to magnitude characteristics of geomagnetic field. Or there is a slope, indicating the force needs (pushes on) a local field, which is bad news for space propulsion, but better to know than ignore. If this later case appears then further quantitatively precise characterisation should be done...
Maybe if Helmholtz coils prove to be too expensive in copper wiring, or too time consuming, a simple strong permanent magnet (from a dismantled speaker, whatever) strong enough to deviate a magnetic compass from a few 10s of centimeters can be used to probe possible influence on results (all other things being equal).
That would make your experiment the first (in experimented EM drive devices I think ?) to go beyond "care has been taken of local magnetic field interactions to minimize spurious couplings", to an experimentally strong characterization of this specific systematic error source, whatever the specifics, including surprising and/or improbable ones. I don't count in that league experiments where DC field has been varied but indirectly and not all other parameters being kept equal and not enough data points to assess statistical significance (shielding of the magnetic dampener at EagleWorks for instance). I would personally take that as a very important progress (before self containment and vacuum testing).
p.s.
in https://forum.nasaspaceflight.com/index.php?topic=39772.msg1529226#msg1529226 you write "I feel the strong need to do this especially if I'm seeing something above 3.33mn/KW that would violate known conservation laws.". Self-powered propellantless propulsion is in tension with conservation laws as soon as exceeding 3.33µN (micro-Newtons) not 3.33mN (milli-Newtons) per kW (kilo-Watts) of input power as sole sacrificed flow.
Another simpler way to assess the Lorentz force is to position the test apparatus at several orientations relevant to the earth magnetic field. If the thrust is reversed with opposite orientations you know something is wrong. If the thrust is constant with different orientations, we can start to take serious look of the experiment.
...
So I updated again to reflect your suggestions. I think I have carefully read your suggestions and the drawing is accurate. Is it? Thank you！
Yes, I agree with what you have drawn. Of course it is always a good idea to have the DC switched and fused. If I was building it I would use a higher DC voltage and a suitable inverter because with the power level involved a lot of current has to be supplied at 12 V. DC.
I drew an equivalent circuit, overlaying on your design. Now the ground loops are apparent. The conductors all have resistance, no matter how small it is. The DC in the loops when interacted with ambient magnetic field, will generate Lorents force. Note that when you turn your frustum 180 degree, the shape of loop 1 changes, so does the Lorentz force. This will give you false thrust. I make this brain experiment to help make it clear that Lorentz force exist in many Emdrive experiments, NASA and Tajmar included. I hope rfmwguy and Shell can avoid the same problem.
Your equivalent circuit does not take into account the fact that the high current DC power leads are twisted together. Also the high voltage AC will not produce any Lorentz force. It isn't necessary to twist the high voltage AC wires together. Doing so may result in arcing. The goal is to minimize any stray magnetic fields from the high current DC wiring. As long as the + and - leads are twisted together or coaxially fed any external magnetic field will be minimal and there will be a very low Lorentz force. This is because the currents through the 2 wires are in opposite directions so the interaction with the geomagnetic field cancels when they are in close proximity. if you have a third DC wire, as I think you suggested in your figures, it will not make any difference as long as all wires are twisted together or the 2 ground (return current) wires are inside the coaxial tube. if the wires were separated you would have a current loop. That would produce a torque against the geomagnetic field in most orientations. That might be recorded as an error force in the apparatus. However if the DC wires are tightly twisted together the area of the loop is practically zero so the Lorentz force is very small. It is easier to twist smaller gauge wire together than heavy gauge so if the battery voltage was higher and the current supplied to the inverter was lower, any Lorentz force would be easier to minimize.
The goal is to minimize any Lorentz force against a current loop by minimizing the area of the loop and/or the current. The term ground loop does not actually apply in this situation.
...
So I updated again to reflect your suggestions. I think I have carefully read your suggestions and the drawing is accurate. Is it? Thank you！
Yes, I agree with what you have drawn. Of course it is always a good idea to have the DC switched and fused. If I was building it I would use a higher DC voltage and a suitable inverter because with the power level involved a lot of current has to be supplied at 12 V. DC.
I drew an equivalent circuit, overlaying on your design. Now the ground loops are apparent. The conductors all have resistance, no matter how small it is. The DC in the loops when interacted with ambient magnetic field, will generate Lorents force. Note that when you turn your frustum 180 degree, the shape of loop 1 changes, so does the Lorentz force. This will give you false thrust. I make this brain experiment to help make it clear that Lorentz force exist in many Emdrive experiments, NASA and Tajmar included. I hope rfmwguy and Shell can avoid the same problem.
I am not quite sure what wires you are referring to. I labeled the wires with numbers. Please refer to the numbers.
Your equivalent circuit does not take into account the fact that the high current DC power leads are twisted together.
These high current DC power leads are with number _ and _ ?
Also the high voltage AC will not produce any Lorentz force. It isn't necessary to twist the high voltage AC wires together. Doing so may result in arcing.
The high voltage AC wires are with number _ and _ ?
The goal is to minimize any stray magnetic fields from the high current DC wiring. As long as the + and - leads are twisted together or coaxially fed any external magnetic field will be minimal and there will be a very low Lorentz force. This is because the currents through the 2 wires are in opposite directions so the interaction with the geomagnetic field cancels when they are in close proximity. if you have a third DC wire, as I think you suggested in your figures, it will not make any difference as long as all wires are twisted together or the 2 ground (return current) wires are inside the coaxial tube.
The third DC wire is with number _ ?
if the wires were separated you would have a current loop. That would produce a torque against the geomagnetic field in most orientations. That might be recorded as an error force in the apparatus. However if the DC wires are tightly twisted together the area of the loop is practically zero so the Lorentz force is very small. It is easier to twist smaller gauge wire together than heavy gauge so if the battery voltage was higher and the current supplied to the inverter was lower, any Lorentz force would be easier to minimize.
The goal is to minimize any Lorentz force against a current loop by minimizing the area of the loop and/or the current.
These are all correct and we all agree with.
The term ground loop does not actually apply in this situation.
The loop1 I drew was a ground loop.
