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#2500
by
Jim Davis
on 27 Oct, 2017 21:00
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I have attached his book here...
I note the copyright date is 1995 and it is still available for sale on Amazon and no doubt elsewhere.
I don't think we should be attaching copyrighted material so cavalierly.
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#2501
by
flux_capacitor
on 27 Oct, 2017 21:15
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"Field Propulsion." That reminds me of a short book that goes into a detailed analysis of "unconventional flying objects." The author, a professional in the field of aerospace, concludes that said objects must utilize a gravitational-like field for propulsion. I have attached his book here, in the hope that it might spur someone to think along a track only slightly different than has been long discussed in this thread, and maybe bring us closer to the resolution of the EM drive conundrum.
Enjoy.
In this book, the author considers the technical feasibility of objects of several tons able to fly silently at very high speeds, at high altitude bur also in dense air, or levitate near the ground without noticing air moving around them. The second proposition disqualifies MHD propulsion (magnetohydrodynamics, also called magnetoplasmadynamics when ionized gas is involved or magnetoaerodynamics in the case of ionized air) that the author simply calls "ion propulsion" and "magnetojet propulsion" because such propulsion system would displace much air around, like a helicopter. So the author thinks that "negative gravity" (i.e. antigravity) is the key.
The problem is, to levitate an object with antigravity in the Earth gravitational field, one would have to make a negative gravitational potential the same magnitude as the local positive gravitational potential produced by the whole Earth. This seems enormous, especially as gravity seems so weak force compared to electromagnetism.
But if negative mass is a bimetric effect of the universe as the hypothesis I presented earlier, an object would not have to create an enormous antigravitational field of the same intensity as Earth gravity to levitate. Such an hypothetical device able to invert its own mass would be attracted by the Earth when its mass is positive but repulsed when its mass is negative. Quickly alternating between positive and negative mass inversions, the object would fall down then up at a rapid pace. One could set the frequency of the mass inversion cycles, either to come down gently or climb the sky, or let the craft hover fixedly above the ground.
Obviously, even if negative bigravity was real, can the mass of a whole object be really inverted, and is the total required energy for such mass inversion relatively limited or necessarily huge… this remain to be answered of course.
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#2502
by
Rodal
on 27 Oct, 2017 21:57
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The last gravitational and luminal observations of merging neutron stars falsified bigravity (https://arxiv.org/abs/1710.06394 & https://arxiv.org/abs/1703.07785). Instead of dipole membranes there can be "bigravitational" emergent mechanisms in the Einsteinian monogravity: the info signals of gravitational changes can occur as bias of spherical symmetry in parts of sum curvature. Info signals carries energy and can affect extra or lack of gravitational hyper liquid current in vacuum implicating dark mass or dark energy phenomena.
In the regularly changing galaxial systems info signals form loop structure (spiral galaxies, galaxy clusters, bullet cluster) consisting energy i.e. mass. Between galaxial systems there can be lack of loop structures in respect of vacuum average. Modified gravity without differing gravity scalar-tensor function or acceleration function but with genuine mass, not particle-based but big-loop-based...
Is it correct that what has been falsified are theories that predict some gravitational waves travelling at a speed different than c, for example any theory (like bigravity) having massive gravitons, or any kind of massive particle involved in gravitation (that would necessarily imply a gravitational wave speed < c). But theories that involve
massless particles, for example scalar-tensor theories that have dilatons (mass zero, spin zero, closed strings) like Jordan-Brans-Dicke are not necessarily falsified because gravitational waves due to dilatons will also travel at speed c. Since the Brans-Dicke coupling constant omega > 40,000, the energy involved in such scalar-field dilaton waves would be too small for present gravitational wave detectors to be able to detect. So scalar-tensor gravitational field theories are still alive.
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#2503
by
Stormbringer
on 28 Oct, 2017 00:24
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#2504
by
aero
on 28 Oct, 2017 01:43
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I have attached his book here...
I note the copyright date is 1995 and it is still available for sale on Amazon and no doubt elsewhere.
I don't think we should be attaching copyrighted material so cavalierly.
No, I shouldn't have. How do I un-attach it?
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#2505
by
aero
on 28 Oct, 2017 02:53
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I have attached his book here...
I note the copyright date is 1995 and it is still available for sale on Amazon and no doubt elsewhere.
I don't think we should be attaching copyrighted material so cavalierly.
No, I shouldn't have. How do I un-attach it?
The original post is removed because I don't want to knowingly violate copyright. Others don't seem to have that problem.
http://redwheelweiser.com/downloads/unconventionalflyingobjects.pdfOriginal Post.
Propellantless propulsion by definition is something accelerating without pushing on anything else. This by definition violates Newton's third law and conservation of momentum, and it is simple to go from there and show it also violates conservation of energy.
I can't answer your question of what to call a working emDrive without knowing how it works. It is much more likely that a working emDrive pushes on something unknown than violates conservation of momentum. It is much more likely than either of those that there is no such thing as a working emDrive, and it is just an experimental artifact.
This is why Rodal explained many times in these threads the difference between a closed system i.e. a true reactionless drive (which could not exist without violating laws of conservation of momentum) VS an open system as represented by a propellantless drive (in the sense the drive would not carry any propellant, i.e. nothing would be thrown off the back of the spacecraft from something stored in a tank aboard; but still this drive would exchange momentum with external mass-energy through a field). That kind of propellantless drive, which would not be reactionless, representing an open system, used to be referred to as field propulsion.
"Field Propulsion." That reminds me of a short book that goes into a detailed analysis of "unconventional flying objects." The author, a professional in the field of aerospace, concludes that said objects must utilize a gravitational-like field for propulsion. I have linked the book above, in the hope that it might spur someone to think along a track only slightly different than has been long discussed in this thread, and maybe bring us closer to the resolution of the EM drive conundrum.
Enjoy.
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#2506
by
RERT
on 28 Oct, 2017 10:32
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Warptech - I wouldn't be so hard on GR. Recall the field equation is G=0 in free space. So the vacuum is as you might wish (Ricci) flat, or as flat as it can be given the boundary condition to mesh it with spacetime elsewhere which is locally distorted by the local stress-energy tensor. It is not a stretch to imagine objects responding to the residual distortions of free space which are detectable locally, eg the 'time dilation gradient'.
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#2507
by
WarpTech
on 28 Oct, 2017 16:32
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Warptech - I wouldn't be so hard on GR. Recall the field equation is G=0 in free space. So the vacuum is as you might wish (Ricci) flat, or as flat as it can be given the boundary condition to mesh it with spacetime elsewhere which is locally distorted by the local stress-energy tensor. It is not a stretch to imagine objects responding to the residual distortions of free space which are detectable locally, eg the 'time dilation gradient'.
I think GR is a totally fine "descriptive" theory. It makes falsifiable predictions, and has led to enormous advances in math, physics and geometry.
However, my contention is that it should ONLY be considered as descriptive, not "causative". It is the notion that "empty" space can be curved even where the stress-energy tensor says there should not be "anything" at all! That's what I disagree with and why it's been so difficult for others to quantize the theory. As I said previously, it is that which GR intentionally excludes under the theory of space-time curvature, where the quantum mechanical exchange of energy & momentum takes place. Hence, it is imperative that in order to understand QG, one must reject the notion of space-time curvature as being causative, and realize it is nothing more than ONE interpretation that "describes" the motion of celestial bodies based on the data at hand, but there is nothing conclusively causative about it. I find the hardest part of conveying my model of QG, is that people stubbornly adhere to the idea that space-time has to be curved as a cause, rather than an alternative interpretation.
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#2508
by
Bob012345
on 28 Oct, 2017 17:02
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There are precisely 0 drives demonstrated with propellantless propulsion that have been conclusively demonstrated. I am also fairly certain that Rodal has never claimed that the MEGA drive works via true propellantless propulsion.
I'd say some have been shown fairly convincingly if not yet conclusively. But what exactly constitutes a 'true' PP drive? Are you basically saying a 'true' PP drive violates physics or that if it can be explained by an interaction with the universe or some such thing, it's not really a PP drive. Is that part of your basic operating definition? What would you call a working EMdrive, a pseudo, a virtual or an effective PP?
Propellantless propulsion by definition is something accelerating without pushing on anything else. This by definition violates Newton's third law and conservation of momentum, and it is simple to go from there and show it also violates conservation of energy.
I can't answer your question of what to call a working emDrive without knowing how it works. It is much more likely that a working emDrive pushes on something unknown than violates conservation of momentum. It is much more likely than either of those that there is no such thing as a working emDrive, and it is just an experimental artifact.
Using an initial velocity of another rest frame, will generate a different KE change and work done in every rest frame. As there is no fuel mass and no potential energy change of the fuel mass, nor exhaust mass nor mass exhaust velocity to adjust the KE change, how to make each frame see the same change in KE?
You are finally starting to see the problem. There is no way to make a true propellantless propulsion obey conservation of energy, since the same work will generate a different kinetic energy in every frame, and there is no propellant to balance this. Your repeated attempts to do so simply result in you using equations that simply give wrong and inconsistent answers.
In answer to both, there is another way. The total change in KE if you include the 'exhaust', however that is interpreted, is invariant but the change in ship KE depends on observer if you include both parts I showed. The 'exhaust' comes from realizing that any force truly operating from within a reference frame is acting like that reference frame has infinite inertia. You can model the situation by assuming the EMDrive conserves momentum with a really really big mass, the reference frame it's in, and let that mass go to infinity in the limit which balances everything out for all observers.
I am not sure what you are trying to say here. Specifically, I can't parse the phrase "any force truly operating from within a reference frame " in any meaningful way.
Your description of the emDrive at the endbasically is saying that there is something the emDrive is pushing against to balance out energy and momentum. You are referring to what it is pushing against as a "reference frame" but this doesn't make sense because a reference frame is a mathematical construct, not a physical object.
Thanks for your definition of PP which is not what I mean by the term. I assume a reaction with something. As to my phrase, if I push an object giving it a constant acceleration I must increase my power to maintain that acceleration or it will not continue. If every step I take to push it is from a massive platform co-moving with the object then every step takes the same power and increases the speed by the same amount. If I'm expending the energy I'd rather do it always in the reference frame co-moving with the object. Of course the concept of a reference frame is a construct but a very useful one. There may be no real perfect physical embodiments of reference frames as moving massive platforms one can react against but the jet stream, ocean or river currents carrying ships are practical examples. Launching rockets from a planet already moving with respect to another is also a example meaning you launch from earth and the Moon in certain directions to take advantage of their relative motion. Certainly the concept of the entire universe, if you can react against that, comes the closest.
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#2509
by
Rodal
on 28 Oct, 2017 17:24
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Definition:
Propellant: "a substance, usually a mixture of fuel and oxidizer, for propelling a rocket."
" a chemical substance used in the production of energy or pressurized gas that is subsequently used to create movement of a fluid or to generate propulsion of a vehicle, projectile, or other object."
Thus, a propellantless rocket can be understood to be one
that does not eject internally stored propellant.
In this definition commonly used by aerospace engineers,
solar sails, magnetic tethers, externally directed energy probes (by laser), etc. are propellantless because they do not rely on ejecting (internally stored) propellant, and
instead they rely on external fields.Under this definition,
propellantless space drives already exist (examples given above) and respect classical physics. These propellantless space drives obey conservation of momentum and conservation of energy.The examples given rely on external fields. What makes them propellantless is simply that the acceleration is achieved without ejecting internally stored propellant.
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#2510
by
RERT
on 28 Oct, 2017 18:15
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Warptech - just one part of what you said catches my ear. It seems wrong to expect that space will be minkowski flat, just because stress energy there is zero. Matter is creating real physical effects in its locality, which by continuity at least are present nearby. If the physical effects local to matter are interpreted as spacetime curvature, then the nearby physical effects will/may also seem like curvature.
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#2511
by
mboeller
on 28 Oct, 2017 19:22
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I have not followed the EM-drive threads closely so I have a question:
was the "photonic" EM-Drive proposal from Travis Taylor already discussed?
I have read about his proposal in the latest issue of the JBIS ( Vol. 70 No. 7) last week.
The article is: Propulsive Forces using High-Q Asymmetric High Energy Laser Resonators.
I was a little bit flabbergasted about the high Thrust from this proposal (up to 100N/KW of Laser Energy, or 30-50N/KW of electrical energy depending how good the efficiency of Lasers will be in the future). The Proposal is based on the theory from McCulloch.
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#2512
by
tchernik
on 28 Oct, 2017 23:45
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First time I hear about that paper. And volume 70 no. 7 isn't available on JBIS website yet.
Recalls me some comments I saw in Mike McCulloch's site, referring that some people have been talking to him about his theory's predictions, and thinking about doing experiments with visible light lasers in an optical fiber loop, instead of microwaves in a cavity. A concept called LEmdrive, if I recall correctly, that he proposed on his site some time ago.
I think this is the overall idea description:
http://physicsfromtheedge.blogspot.mx/2016/07/lemdrive.html
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#2513
by
Augmentor
on 29 Oct, 2017 01:08
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tchernik,
If a light version of the emdrive (actually, just e will do, m is induced), and one used a big laser array such as a Lubin array (UCSB)as the source, and a very large optical circulatory system. one might be able to sail to the stars limited only by the melting point of the mirrors.
DavidM
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#2514
by
TheTraveller
on 29 Oct, 2017 01:24
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An update on Jakub and his EmDrive builder team in Poland.
Jamie, Roger and myself are now working with Jakub to ensure his test data is as rock solid as it can be as we know the reception it will receive.
He has done vertical testing and horizontal testing. Vertical testing exhibits strong thrust that gives a result in agreement with the SPR thrust equation. Horizontal testing shows very little thrust.
Further testing is being arranged.
For those wishing to run the resonance numbers, here are the, as manufactured, internal cavity dimensions plus a few images of the test setup and schematic, which is based on the system Jamie has developed and is using the same 30W Rf amp.
Additionally Jakub uses a wireless data link, as can be seen in the horizontal test setup image.
Can add the test rig seems to be very stable and capable of sub 10uN force resolution. It uses 2 ceramic bearings on the centre bar of the balance beam.
Comments most welcome.
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#2515
by
RotoSequence
on 29 Oct, 2017 03:06
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https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.177201Control of Chiral Magnetism Through Electric Fields in Multiferroic Compounds above the Long-Range Multiferroic Transition
Polarized neutron scattering experiments reveal that type-II multiferroics allow for controlling the spin chirality by external electric fields even in the absence of long-range multiferroic order. In the two prototype compounds TbMnO3 and MnWO4, chiral magnetism associated with soft overdamped electromagnons can be observed above the long-range multiferroic transition temperature TMF, and it is possible to control it through an electric field. While MnWO4 exhibits chiral correlations only in a tiny temperature interval above TMF, in TbMnO3 chiral magnetism can be observed over several kelvin up to the lock-in transition, which is well separated from TMF.
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#2516
by
flux_capacitor
on 29 Oct, 2017 11:34
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An update on Jakub and his EmDrive builder team in Poland.
Jamie, Roger and myself are now working with Jakub to ensure his test data is as rock solid as it can be as we know the reception it will receive.
Thank you for this. You don't deliver your own pictures, but sure you help with the data of others.
For those wishing to run the resonance numbers, here are the, as manufactured, internal cavity dimensions
The internal cavity dimensions lack the internal length of the constant diameter section "cup" at small end. What length this cup is?
In a previous post you deduced from a (quite blurry) freeze-frame of the YouTube video:
Looks to be based on Roger's Demonstrator EmDrive.
Even has the short constant diameter section at the big end, which in the Demonstrator is 1/4 guide wave long.
[…]
This technique was also used by Prof Yang.
Do you confirm or disconfirm that Jakub Jędrzejewski's drive use a short constant diameter section at big end? In the dimension diagram "engine.png" you provided, such constant diameter section after big end is absent.
Knowing all lengths precisely and the operating resonant frequency, does the small end operate "below Shawyer's cutoff" (as you implied in
a previous post last week) or not? It seems the estimated dimensions you used to conclude "the small end is below cutoff diameter" were different to the ones you have just provided, so that question is still open.
Then, what is the calculated Df and your predicted thrust force?
He has done vertical testing and horizontal testing. Vertical testing exhibits strong thrust that gives a result in agreement with the SPR thrust equation. Horizontal testing shows very little thrust.
In which direction does his thruster move: Small or Big end leading?
Assuming it is small end leading for now. Is that vertical thrust "strong" only when small end is pointing upwards (this would be normal, as the buoyancy of the "hot air balloon" effect would make the drive lighter, and heated air convection currents circulating from bottom to top outside the device would slightly help to push it upwards) or also when small end is pointing downwards?
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#2517
by
SteveD
on 30 Oct, 2017 03:46
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An update on Jakub and his EmDrive builder team in Poland.
Jamie, Roger and myself are now working with Jakub to ensure his test data is as rock solid as it can be as we know the reception it will receive.
He has done vertical testing and horizontal testing. Vertical testing exhibits strong thrust that gives a result in agreement with the SPR thrust equation. Horizontal testing shows very little thrust.
Comments most welcome.
Have they measured an actual (not net) downward force?
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#2518
by
Ricvil
on 30 Oct, 2017 15:32
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#2519
by
Bob012345
on 30 Oct, 2017 16:52
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In the typical EMDrive cavity, what typical values of radiation pressure exist on the endplates? I'm guessing it's something on the order of Q* (power/c )/area where area is average area of the endplates. Is that anywhere close to being reasonable? I'm asking about pressure, not thrust. Thanks.
I found my answer here:
http://casa.jlab.org/publications/viewgraphs/USPAS2016/L_10_Fundam_RF_Cav.pdfFor the conditions of the cavity in this tutorial, it's about 3000N/m^2.
Perhaps this tutorial may be if some use to those readers like myself who are not experts in RF.
