Author Topic: EM Drive Developments - related to space flight applications - Thread 10  (Read 716084 times)

Offline SeeShells

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Shell,

You could always go to a klystron.

D
I'll take the 250Kw one right behind me at the SSC.  :o
Added: I debated at first look, but magnetrons were easier to come by.
Best,
Shell
« Last Edit: 05/28/2017 05:09 PM by SeeShells »

Online Monomorphic

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People seem to like 2.4 Ghz because of the availability of magnetrons for it, but there's a lot of RF noise in that band. Magnetrons seem to be dismissed because of their noisiness (even if there are ways to stabilize them, does it matter at experimenter's power levels?)

I like 2.45Ghz as that frequency band is unlicensed and therefore safe to leak into. I would hate to have the FCC call as those fines are quite substantial.

Magnetrons also require cooling to keep the frequency stable. If it is not actively cooled, then runaway thermal heating causes the frequency to drift lower, eventually damaging the magnetron. The frequency drift makes holding resonance very difficult and active cooling makes precise measurements very difficult.

Offline 1

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All: "Apprentice Sorcerer Gravity Appliances Reaction Devices (ASGARD) works for me!  :)  I just hope Thor doesn't mind...

Boy, be busy and you miss the fun. What about "Paul's Texas Quantum Bar and Boson BBQ"

I think that the "Boson BBQ" may be more appropriate for Shells since, apparently, she likes roasting antennas  ;D ;D

ħ & Grill

Offline SeeShells

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People seem to like 2.4 Ghz because of the availability of magnetrons for it, but there's a lot of RF noise in that band. Magnetrons seem to be dismissed because of their noisiness (even if there are ways to stabilize them, does it matter at experimenter's power levels?)

I like 2.45Ghz as that frequency band is unlicensed and therefore safe to leak into. I would hate to have the FCC call as those fines are quite substantial.

Magnetrons also require cooling to keep the frequency stable. If it is not actively cooled, then runaway thermal heating causes the frequency to drift lower, eventually damaging the magnetron. The frequency drift makes holding resonance very difficult and active cooling makes precise measurements very difficult.
That's why my was cooled.

My Best,
Shell

Offline dustinthewind

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I wanted to suggest or ask if the EM drive may be squeezing light inside.  The apparent wavelength at the large end appears to have a shorter wavelength while at the narrow end of the frustum a longer wavelength along the frustum symmetric axis.  Perpendicular to this axis it was brought to my atention some time ago that the wavelength while at the narrow end appears longer along the axis, perpendicular to the axis the wavelength appears to be shorter than at the large end. 

So to summarize if z axis is the axis of the frustum then
wavelength at large end (z-axis: shorter, x-y-axis more relaxed/longer)
wavelength at narrow end (z-axis: longer, x-y-axis more compact/shorter)

I have been thinking about squeezed light for some time and LIGO's use of it to detect gravitational waves.  My thoughts were, squeezed light may be necessary to detect such gravitational waves as to increase interaction with the vacuum.  Along that line of thought, to cause light to interact with the vacuum may require squeezed states. 

Now I'lll share one power point that glosses over squeezed states and its connection with negative energy which may have been shared by some one else but I can't remember where I got this link: http://old.earthtech.org/reports/Davis-Puthoff_STAIF_Neg.Energ.Lab.Exp.pdf

Quote
Squeezed Electromagnetic Vacuum:
...
-One can "squeeze" variance of one observable provided variance in conjugate observable is stretched

- Observable that gets squeezed will have its fluctuations reduced below the vacuum ZPF

o Since the vacuum is defined to have vanishing energy density, any region with less energy density than the vacuum actually has a negative (renormalized) expectation value for the energy density

So is it possible there could be squeezed light near the narrow region.  Is there a measurement that could detect such squeezed light?  I believe there is some factor where a squeezed state becomes more certain about one aspect while becoming more uncertain about another.  similar to this article here: http://physicsworld.com/cws/article/news/2016/sep/12/squeezed-light...

Quote
The uncertainty principle puts a lower limit on the product of the variance in the amplitude (or number) of photons and the variance in the phase. Vacuum photons naturally have equal variance in both amplitude and phase. It is, however, possible to create a "squeezed state" of light, in which either one of these quantities is minimized (squeezed) and the other is allowed to increase (antisqueezed).

also it may be possible we want at least 2 frequencies involved.  Here is why and possibly the magnetron putting out both of these frequencies may be desirable?  Is it desirable for the cavity to have 2 resonant frequencies close together both excited by the magnetron? 

Quote
The Hannover team has now improved several aspects of its instrumentation. Most significantly, they have used a new, doubly resonant cavity: "You need two wavelengths to generate the squeezed light and we had a resonator that was resonant for both," explains team member Moritz Mehmet. In addition, says his teammate Henning Vahlbruch, they upgraded several other features: "We used the best available materials, a different cavity topology and custom-made photodetectors." The researchers broke their own record, squeezing vacuum photons by a factor of 32.

Normally I have heard squeezed states have commonly been accomplished with a crystal/accelerated mirror, but above they mention a cavity and I wonder if it's possible to accomplish squeezed states with just a cavity. 
« Last Edit: 05/30/2017 01:41 AM by dustinthewind »

Online aero

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@dustinthewind
I don't know how meaningful it is but here is what meep indicates regarding resonant frequencies in a particular cavity. This is Monomorphic's DUT, in copper with two detector locations. Each is located 4 mm from the inside face of the respective end, and half the small end radius from the z-axis of rotation offset equally in x and y. If you need the imaginary component of frequency, I can provide the complete output including a ton of significant digits in a spreadsheet, if you would like.

I note that the ez component contains very little energy but what is there is enough to satisfy meep and is reported. As I understand it, no energy in the ez component is a characteristic of a TE mode of resonance.

freq.   GHz   Q   Amp   Amp SI   Comp   freq. Diff.   end
2451314734.6915   2.45131   34,362   0.29088   1.10E+02   ex   0   SE
                     
2451314734.69151   2.45131   34,362   0.29088   1.10E+02   ey   0   SE
                     
2441943271.04085   2.44194   -13,481   0.00000   2.07E-15   ez      SE
2451262522.54508   2.45126   968   0.00000   5.29E-15   ez      SE
2465495123.57696   2.46550   2,452   0.00000   9.35E-15   ez      SE
                     
2451315953.25884   2.45132   35,297   1.14531   1.14531   hx   0   SE
                     
2451315953.25884   2.45132   35,297   1.14531   1.14531   hy   0   SE
                     
2451315922.70902   2.45132   35,431   0.36909   0.36909   hz   0   SE
                     
2451314755.05473   2.45131   34,545   0.00439   1.65E+00   ex   -20.36323452   BE
                     
2451314755.05472   2.45131   34,545   0.00439   1.65E+00   ey   -20.3632049561   BE
                     
2451571816.19804   2.45157   560   0.00000   5.54E-14   ez      BE
2457576614.11381   2.45758   313   0.00000   2.48E-13   ez      BE
2465596829.68202   2.46560   5,955   0.00000   1.50E-14   ez      BE
                     
2451315943.00494   2.45132   35,343   1.73483   1.73483   hx   10.2538976669   BE
                     
2451315943.00495   2.45132   35,343   1.73483   1.73483   hy   10.2538948059   BE
                     
2451316625.84456   2.45132   35,418   0.07332   0.07332   hz   -703.1355333328   BE
Retired, working interesting problems

Offline spupeng7

(...)
One more thing: I had a dear friend donate a new/old Tektronix O-Scope for the lab, there is something about a simple O-scope that I love, the new stuff on the computer via the USB port is OK but green wiggly lines on a CRT make me smile a lot.  :P
Shell,
that O-scope may have been built in Guernsey C.I. off the coast of France (where I grew up!)   :)
Optimism equals opportunity.

Offline ThatOtherGuy

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"Seeking the fifth force"

While it may be unrelated (and possibly off-topic) to EMdrive, I think that this research initiative may be of interest for the people on this forum

"Physicists Are Probing The Centre of Our Galaxy to Find The Missing Fifth Force of Nature"

also because it's an attempt to (better) understand gravity :)

detailed informations can be found here


Offline ThatOtherGuy

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freq.                GHz       Q       Amp       Amp SI   Comp   freq. Diff.   end
2451314734.6915    2.45131   34,362   0.29088   1.10E+02   ex             0     SE
2451314734.69151   2.45131   34,362   0.29088   1.10E+02   ey             0     SE
2441943271.04085   2.44194  -13,481   0.00000   2.07E-15   ez                   SE
2451262522.54508   2.45126  968       0.00000   5.29E-15   ez                   SE
2465495123.57696   2.46550    2,452   0.00000   9.35E-15   ez                   SE
2451315953.25884   2.45132   35,297   1.14531   1.14531    hx             0     SE
2451315953.25884   2.45132   35,297   1.14531   1.14531    hy             0     SE
2451315922.70902   2.45132   35,431   0.36909   0.36909    hz             0     SE
2451314755.05473   2.45131   34,545   0.00439   1.65E+00   ex  -20.36323452     BE
2451314755.05472   2.45131   34,545   0.00439   1.65E+00   ey  -20.3632049561   BE
2451571816.19804   2.45157  560       0.00000   5.54E-14   ez                   BE
2457576614.11381   2.45758  313       0.00000   2.48E-13   ez                   BE
2465596829.68202   2.46560    5,955   0.00000   1.50E-14   ez                   BE
2451315943.00494   2.45132   35,343   1.73483   1.73483    hx   10.2538976669   BE
2451315943.00495   2.45132   35,343   1.73483   1.73483    hy   10.2538948059   BE
2451316625.84456   2.45132   35,418   0.07332   0.07332    hz -703.1355333328   BE


just trying to improve readability :)


Offline SeeShells

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(...)
One more thing: I had a dear friend donate a new/old Tektronix O-Scope for the lab, there is something about a simple O-scope that I love, the new stuff on the computer via the USB port is OK but green wiggly lines on a CRT make me smile a lot.  :P
Shell,
that O-scope may have been built in Guernsey C.I. off the coast of France (where I grew up!)   :)
Considering I cut my teeth on an old 555 dual trace. :) It's good to know they do good work in Guernsey C. I.


Still getting the shop straightened up and still need to move some of the cabinets out to make space for the lab benches and tidy up the other half of the space.

My Very Best,
Shell

Offline JonCard

Hi,

I'm not a regular here, but I am running an organization to try to put an EMDrive into orbit on a CubeSat and demonstrate whether it works in-situ. I have 3 minutes at the Smallsat Conference in Logan, UT, this summer to present a brief overview of the "state of the art" of EMDrive, and I have an opportunity to submit a paper along with my talk. I was thinking of including the attached document as an appendix, and I was hoping one of you could look at it and tell me what you think of it, or if it would be worth it. I don't know if it is useful, or even something everyone already knows. I'm sure it's not something helpful to someone with access to COMSOL, but I am not among that number.

It is a an attempt to derive an equation for the cut-off diameter in a frustum in TM mode, given that (I believe) the equations for the cut-off for a cylinder are not valid for that case.

A little about my project: www.buildanemdrive.org is a non-profit to raise money to put a test article of the EMDrive into orbit on a CubeSat. I am working on a test article myself, and I am currently working with the State Department to try to get approval to make it open source. I am interested in partnering with other groups that want the chance to go to orbit and I will share any funds raised towards a launch with whoever is ready to fly and will likely provide a definite answer of whether an EMDrive will work free of testing equipment and in control. If enough people are interested, I think we can put together a judging event with celebrity judges at one of the annual space conferences, or something like that. Fundraising is going a bit slowly just now, mostly because I have to choose between making progress on my drive and doing fundraising. Please let me know if you are interested in working together. If you are unwilling to share technical data, that's OK; I don't really need to know that right now.

Sorry to be a bit terse. If anyone has any questions, I'll try to answer them.

Offline JonCard

@dustinthewind

Yes, you are right. Feynman discusses this in his great book, the Feynman Lectures on Physics, Vol 2, and he's very good at explaining it in a way that makes sense.  It's called the guide wavelength. In a waveguide, like a fiberoptic cable or an resonance cavity, the interaction with the walls causes an interference pattern that behaves as if the light has a longer wavelength and the same frequency, causing a strange effect as the "phase velocity" and the "group velocity" of the light to go out of sync.

Offline dustinthewind

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@dustinthewind

Yes, you are right. Feynman discusses this in his great book, the Feynman Lectures on Physics, Vol 2, and he's very good at explaining it in a way that makes sense.  It's called the guide wavelength. In a waveguide, like a fiberoptic cable or an resonance cavity, the interaction with the walls causes an interference pattern that behaves as if the light has a longer wavelength and the same frequency, causing a strange effect as the "phase velocity" and the "group velocity" of the light to go out of sync.

c=f*lambda->f=c/lambda  with f constant and lambda growing larger then c must become larger which maybe suggests a decrease in the effective mass of light near the cutoff.  (considering momentum conservation if mass decreases then phase velocity should increase - phase being the individual photon, group being the collective behavior) . 
https://www.microwaves101.com/encyclopedias/waveguide-mathematics
Its not obvious with the equation E=h*f because f is constant and effective mass E/c^2 but E/c^2=m_eff=h*c/(lambda*c^2)=h*f/c^2  If both c and lambda increase then it suggests the effective mass decreases.  https://physics.stackexchange.com/questions/60441/does-a-photon-have-mass

This means in a collision the photon transfers less kinetic energy to the narrow end of the cavity as it does the large side.   ... Maybe.  Proof is in the pudding. 

I haven't done much on it recently but I think it still needs more work.  https://www.researchgate.net/project/Is-the-frustum-EM-Drive4-decelerating-light-for-propellantless-propulsion

light carries lots of energy but little momentum can be harnessed from it due the ridiculous small effective mass.  Part of the heat death of the universe.  It would be nice if there was a way to re-collect that energy in an effective manner. 

The question comes up if we can drain energy from the light in one direction how does this conserve momentum.  Not sure but there is known the be a Lens Thirring effect https://en.wikipedia.org/wiki/Lense%E2%80%93Thirring_precession where the vacuum can appear to be in motion around a rotating object. 

Also a Doppler shift from a photon impacting and object and transferring energy tends to red-shift the photon as a 2nd order effect that I derive in the paper on researchgate.  The light appears to undergo a change in frame.  If the light was pushed on before the reflection it would appear to be pushed against but what is light.  Maybe it is a disturbance of the quantum vacuum so could pushing against light be pushing against the QV? 

Why is it a disturbance of the Quantum Vacuum?  If you let and electron-positron pair annihilate light is generated from them coming together.  Now reverse time and let the light come together and you get the particles back.  Imagine an e-p pair in the vacuum together and you get (zero rest mass) just like light. 
« Last Edit: 05/31/2017 05:48 AM by dustinthewind »

Offline JonCard

I have not had a chance to read your papers yet, but in regards to the change in speed, yes, sort of. The velocity that increases is the "phase velocity"; another speed called the "group velocity" is actually lower. There's a good graphic about the difference on Wikipedia (https://en.m.wikipedia.org/wiki/Phase_velocity). Because it is not the velocity of the photons themselves, it's not clear whether Planck's constant can be used with it, since it isn't quantised energy packets like a photon. Obviously, the whole is a bit up in the air because of this device, but I think observed thrust is in the direction of the small end.

Online Rodal

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Hi,

I'm not a regular here, but I am running an organization to try to put an EMDrive into orbit on a CubeSat and demonstrate whether it works in-situ. I have 3 minutes at the Smallsat Conference in Logan, UT, this summer to present a brief overview of the "state of the art" of EMDrive, and I have an opportunity to submit a paper along with my talk. I was thinking of including the attached document as an appendix, and I was hoping one of you could look at it and tell me what you think of it, or if it would be worth it. I don't know if it is useful, or even something everyone already knows. I'm sure it's not something helpful to someone with access to COMSOL, but I am not among that number.

It is a an attempt to derive an equation for the cut-off diameter in a frustum in TM mode, given that (I believe) the equations for the cut-off for a cylinder are not valid for that case.

A little about my project: www.buildanemdrive.org is a non-profit to raise money to put a test article of the EMDrive into orbit on a CubeSat. I am working on a test article myself, and I am currently working with the State Department to try to get approval to make it open source. I am interested in partnering with other groups that want the chance to go to orbit and I will share any funds raised towards a launch with whoever is ready to fly and will likely provide a definite answer of whether an EMDrive will work free of testing equipment and in control. If enough people are interested, I think we can put together a judging event with celebrity judges at one of the annual space conferences, or something like that. Fundraising is going a bit slowly just now, mostly because I have to choose between making progress on my drive and doing fundraising. Please let me know if you are interested in working together. If you are unwilling to share technical data, that's OK; I don't really need to know that right now.

Sorry to be a bit terse. If anyone has any questions, I'll try to answer them.

On Thread 3, two years ago, 06/21/2015 08:07 PM, I posted:

https://forum.nasaspaceflight.com/index.php?topic=37642.msg1392223#msg1392223


with this attachment report, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities:

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1030954;sess=45576

Offline SeeShells

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Hi,

I'm not a regular here, but I am running an organization to try to put an EMDrive into orbit on a CubeSat and demonstrate whether it works in-situ. I have 3 minutes at the Smallsat Conference in Logan, UT, this summer to present a brief overview of the "state of the art" of EMDrive, and I have an opportunity to submit a paper along with my talk. I was thinking of including the attached document as an appendix, and I was hoping one of you could look at it and tell me what you think of it, or if it would be worth it. I don't know if it is useful, or even something everyone already knows. I'm sure it's not something helpful to someone with access to COMSOL, but I am not among that number.

It is a an attempt to derive an equation for the cut-off diameter in a frustum in TM mode, given that (I believe) the equations for the cut-off for a cylinder are not valid for that case.

A little about my project: www.buildanemdrive.org is a non-profit to raise money to put a test article of the EMDrive into orbit on a CubeSat. I am working on a test article myself, and I am currently working with the State Department to try to get approval to make it open source. I am interested in partnering with other groups that want the chance to go to orbit and I will share any funds raised towards a launch with whoever is ready to fly and will likely provide a definite answer of whether an EMDrive will work free of testing equipment and in control. If enough people are interested, I think we can put together a judging event with celebrity judges at one of the annual space conferences, or something like that. Fundraising is going a bit slowly just now, mostly because I have to choose between making progress on my drive and doing fundraising. Please let me know if you are interested in working together. If you are unwilling to share technical data, that's OK; I don't really need to know that right now.

Sorry to be a bit terse. If anyone has any questions, I'll try to answer them.

On Thread 3, two years ago, 06/21/2015 08:07 PM, I posted:

https://forum.nasaspaceflight.com/index.php?topic=37642.msg1392223#msg1392223


with this attachment report, titled:

Cut-off of Resonant Modes in Truncated Conical Cavities:

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=37642.0;attach=1030954;sess=45576
Because of your write up we did sims in meep with an extended frustum cavity past cutoff to see if it did indeed act the way you wrote. It does.
« Last Edit: 05/31/2017 09:08 PM by SeeShells »

Offline dustinthewind

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I have not had a chance to read your papers yet, but in regards to the change in speed, yes, sort of. The velocity that increases is the "phase velocity"; another speed called the "group velocity" is actually lower. There's a good graphic about the difference on Wikipedia (https://en.m.wikipedia.org/wiki/Phase_velocity). Because it is not the velocity of the photons themselves, it's not clear whether Planck's constant can be used with it, since it isn't quantised energy packets like a photon. Obviously, the whole is a bit up in the air because of this device, but I think observed thrust is in the direction of the small end.

Problem is the group velocity of purely reflected light in the cavity would be standing still because of it being a standing wave.  I don't think we can think of the photons as standing.  Also if their wavelength stretches out with out their frequency changing then their velocity must increase. 

There is some traveling group waves due to energy loss, but I still have my reservations as qualifying the group waves as the photons.  There may be some Merritt to it.  I'll give it some thought. 

If we consider a photon recycling thruster we can get what appears to be a standing wave but once the mirror starts accelerating there should be 2nd order Doppler shifting via transferred energy so that also sets up a difference in frequency traveling wave. 

With out the mirror moving, perfectly collimated light, and hypothetically negligible heat loss there should still be large pressure via the photons while sustaining what appears to be a standing group wave so I have a hard time distinguishing which wave really defines the photon (group or phase).  I wan't to say phase but not exactly sure.  Also the phase waves in superpositions make up the group wave behavior which is similar to light which in superpositions makes up the sum. 
« Last Edit: 06/01/2017 05:12 AM by dustinthewind »

Offline JonCard

@dustinthewind - Well, in a standing wave the phase velocity is 0, too. :)

@SeeShells - Thanks! That's amazing. I appreciate it very much and let me know if you want to be a part of the the launch project.

@Rodal - That's great! I gave it one read through, and I know it'll need some time to digest it. One thing that I know I will be paying attention to is conclusion #8; to my reading, Shawyer's equation does not predict that thrust is maximized by a greatest difference between the plate sizes (while McCulloch obviously does). He predicts that thrust is maximized for a given large plate by the small plate being as close to the cut-off as possible. That is the point where the guide wavelength goes to infinity and that term, lambda0/lambdag2, goes to 0. It is one of the things my paper for the Smallsat Conference is going to list as one of the testable predictions I would like to gather data around, with future fundraising: Shawyer suggests that thrust is maximized as we approach cut-off, and McCulloch predicts thrust is maximized when the small plate is infinitely small and cut-off is an unavoidable prohibition preventing greater efficiency.

I think this is why the Eagleworks found greater thrust in the TM mode than in the TE mode; with a larger cut-off diameter in the TM mode, the small plate in the cavity was closer to the TM mode cut-off when resonating in the TM mode than the small plate was to the TE mode cut-off when resonating in the TE mode. I wish they had released those numbers; that's almost as important as their thrust measurements, to my mind. I'm not sure what the conditions were for those tests. I wonder if a cavity with a small plate close to the TE mode cut-off resonating in TE mode would have as great a thrust as a cavity with a small plate equally close to the TM mode cut-off resonating in the TM mode. I'm fascinated that the Shawyer equation predicts the TM/TE mode difference (once I knew there was one; I didn't predict it in advance).

If I am repeating what everyone already knows, I apologize.

Offline dustinthewind

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@dustinthewind - Well, in a standing wave the phase velocity is 0, too. :)

...

Think of a stationary wave as the sum of two travelling waves. If the two waves move in opposite directions and have the same frequency, the result is a stationary wave. The travelling waves have a well defined speed (or phase velocity). You're allowed to do this because of the principle of superposition.
« Last Edit: 06/01/2017 05:28 AM by dustinthewind »

Offline qraal

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Hi Guys

Normally I lurk and enjoy the show, but I spotted this pertinent preprint on the arXiv today:

Theoretical calculation of the fine-structure constant and the permittivity of the vacuum

Quote
Light traveling through the vacuum interacts with virtual particles similarly to the way that light traveling through a dielectric interacts with ordinary matter. And just as the permittivity of a dielectric can be calculated, the permittivity ϵ0 of the vacuum can be calculated, yielding an equation for the fine-structure constant α. The most important contributions to the value of α arise from interactions in the vacuum of photons with virtual, bound states of charged lepton-antilepton pairs. Considering only these contributions, the fully screened α≅1/139
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An intriguing suggestion at the end is that considering the vacuum in this manner allows for a variable speed of light in the very early universe. But the fact that the Fine Structure Constant can be computed from assuming the vacuum is filled with virtual positronium (some ~10^39 per cubic metre) does lend some credence to Harold White's suggestions about how EM-Drives and kin *might* work.

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