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#2980 by rfmwguy on 20 Feb, 2016 03:17
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Good news and bad news...unwrapped new copper plates tonight. Good news is they'll probably never warp due to heating. Bad news is they weigh a ton. Once cut and machined, they will be lighter, but the frustum assembly will need to be moved from the end of moment arm more towards the center of the fulcrum. Will still keep the 3.5kg balance weights on far end where they were. The new thickness is to evaluate doc rodals interest in experimenting with higher mass copper and move away from the old coper clad pcb. Starting to get all supplies needed and looking forward to the build starting up soon.
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#2981 by CW on 20 Feb, 2016 08:49
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Hey emory, been a while...its puzzling as you are injecting energy into the cavity, but no one has cracked the code yet. Simplisticly, fill a water balloon. Ignoring the nozzles reactive force, the water baloon remains closed to the outside world until it reptures. Bigtime reaction then. A pinhole leak would supply a small force. But em isn't a fluid, leaking em will not create movement.
It must be open somehow. Mulletron and others contemplate em/gravity interractions. Em and gravity are no mass long distance forces. Gravity flows through matter. It passes thru a frustum like it wasn't there. Em, not so much.
So wave or particle? Mass or massless? Been trying to focus on mass-gap papers for guidance. Think I'll stick with building and testing...a lot of brilliant people haven't cracked the mass gap code yet.
I was just thinking this: If space were an n-dimensional information matrix that can be accurately described by fomulae and thus the information of any point in spacetime, then it could, perhaps, make sense to take this actually seriously and consider the possibility, that the 'field configuration' of the enclosed spatial volume of the frustum creates a time-averaged non-zero entropic gradient across the volume of space? Could a dynamically created entropic gradient cause a unidirectional stress and thus accelerating force? I would imagine such a process to 'dynamically reprogram' the information matrix of the spatial volume to be anisotropically biased, as opposed to the 'natural static isotropic ground state' of spacetime.
Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume? -
#2982 by Notsosureofit on 20 Feb, 2016 12:08
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Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume?
Well, yes, but difficult to do exactly. As far as i got it looked to increase w/ acceleration. Perhaps that could be a subject for a numerical solution ?
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#2983 by Rodal on 20 Feb, 2016 12:35
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Good news and bad news...unwrapped new copper plates tonight. Good news is they'll probably never warp due to heating. Bad news is they weigh a ton. Once cut and machined, they will be lighter, but the frustum assembly will need to be moved from the end of moment arm more towards the center of the fulcrum. Will still keep the 3.5kg balance weights on far end where they were. The new thickness is to evaluate doc rodals interest in experimenting with higher mass copper and move away from the old coper clad pcb. Starting to get all supplies needed and looking forward to the build starting up soon.
I think you may be confusing me with Minotti, unless this refers to thermal buckling, in which case jump to my final point #5 at the bottom of this post
I had to look back to old messages to find this: http://forum.nasaspaceflight.com/index.php?topic=39214.msg1489879#msg1489879
where I answer user ThinkerX, regarding Minotti's paper:Ok, trying to wrap what's left of my mind around this:
Actually Minotti's theory predicts that the force is proportional to the total thickness of the copper as long as it is significantly thicker than the skin depth (and the wall is "thin", not much thicker than 1 mm), for example at ~2 GHz, for copper, the skin depth is about 1 micrometer and the total thickness considered in his example was 1 mm.Quote4) Minotti's paper predicts, that for copper wall thickness ~1 mm, the thicker the copper (as long as significantly greater than the skin depth), the greater the force.
So, say you have two EM Drive units that are identical, except one has 'skin depth' of 1 mm and the other has 'skin depth' of say 3 mm. According to this theory, the second device should perform significantly better. Is that correct?
If so, this appears to be something within the capabilities of our DIY crowd.
But...
1 - would the increased weight of the device with the thicker skin offset the thrust measurements? (I suspect I am missing something glaringly obvious here.)
2 - Does the entire skin need to be thicker, or just the end plates?Quote from: MinottiAssuming a cavity with thin walls (but much thicker than the penetration depth ,
in order to the boundary conditions used to be correct) of mass surface density ...
There are no details in the literature as to the precise dimensions of the cavities
used in the experiments, so that an example roughly similar to the overall dimension
reported and with the proportions observed in the published photographs will be used.
Assuming a wall of thickness 1 mm, and a copper mass density of 8.9 × 103 kg/m3, we
have = 8.9 kg/m2.
According to the theory, if another EM Drive with the same geometry, same copper material and operating at the same frequency and mode shape has a total wall thickness of 2 mm (0.079 in), the force should be two times greater than in the EM Drive with 1 mm (0.039 in) thick.
In this statement, both EM Drives should have uniform thickness: same thickness for walls as for end plates.
Yes, this should be carefully tested in experiments.
So, please notice:
1) I am explaining Minotti's paper claiming that thicker copper used for the EM Drive should translate into greater forces. ThinkerX gets this right: it is Minotti's paper that claims that the thicker copper will result in greater force. It is not me. Do I think it is interesting to test Minotti's theory? Yes, but Minotti's theory implies uniform thickness for the whole EM Drive, and not just for the end plates. To test Minotti's theory one has to test two EM Drive's, one EM Drive having thicker copper thickness throughout than the first one.
2) I wrote 2 mm (0.079 in) thick, and not 3 mm ( 0.118 in). But the thickness of 3 mm or 2 mm is not important by itself, what is important to test Minotti's theory is to test two separate EM Drive's having different thickness from each other (the thicker one doesn't need to be 2 mm or 3 mm as long as it is thicker than the first one).
3) Minotti's paper deals with the thickness of the copper used for the whole, entire EM Drive, uniformly, and not just for the end plates.
4) OK, now you have these heavy end plates. Yes, it is still interesting to test them. Do I know what Minotti would predict to happen when using thicker end plates than the thickness of the walls? No idea, as I said, Minotti deals with the whole EM Drive having the same uniform thickness for the end plates as for the conical walls. Can't tell what Minotti would predict with just the end plates thicker.
__________________________________________
5) Another possibility as to where the "thick end plate" interest may be coming from is my thermal buckling paper. Yes, if you are concerned about thermal buckling of the end plates, the thicker the end plate, the better to prevent thermal buckling.
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#2984 by rfmwguy on 20 Feb, 2016 13:00
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No problem doc. I had already decided to go w/thicker plates anyway to avoid thermal buckling and provide better support for the magnetron assembly. The paper you mention was just a bonus from my perspective. Shell did this with a ceramic glued on to thinner copper. Its worth a try...hey, its an experiment, right?
edit - thermal stresses to thermal buckling per Doc's more descriptive post. -
#2985 by CW on 20 Feb, 2016 16:25
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Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume?
Well, yes, but difficult to do exactly. As far as i got it looked to increase w/ acceleration. Perhaps that could be a subject for a numerical solution ?
That would certainly be interesting. It would be great, if anyone with the necessary skills and especially tools (math+software) were up to this task. I'm especially interested in a possible induced, time-averaged non-zero entropy gradient across the inner EM-drive volume occurring, and its maybe existent connection to the predicted net force direction of EM-drive theoretical models, that we have so far. -
#2986 by Notsosureofit on 20 Feb, 2016 16:32
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Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume?
Well, yes, but difficult to do exactly. As far as i got it looked to increase w/ acceleration. Perhaps that could be a subject for a numerical solution ?
That would certainly be interesting. It would be great, if anyone with the necessary skills and especially tools (math+software) were up to this task. I'm especially interested in a possible induced, time-averaged non-zero entropy gradient across the inner EM-drive volume occurring, and its maybe existent connection to the predicted net force direction of EM-drive theoretical models, that we have so far.
All you really need to calculate is an increase in entropy w/ a decrease in dispersion. -
#2987 by cosmo on 20 Feb, 2016 16:42
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Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume?
Well, yes, but difficult to do exactly. As far as i got it looked to increase w/ acceleration. Perhaps that could be a subject for a numerical solution ?
That would certainly be interesting. It would be great, if anyone with the necessary skills and especially tools (math+software) were up to this task. I'm especially interested in a possible induced, time-averaged non-zero entropy gradient across the inner EM-drive volume occurring, and its maybe existent connection to the predicted net force direction of EM-drive theoretical models, that we have so far.
Possibly related?
http://arxiv.org/abs/1601.07558 -
#2988 by Rodal on 20 Feb, 2016 17:40
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Question to our local physics gods here:
Is it possible to calculate the entropy distribution over time of an exemplary EM-drive volume?
Well, yes, but difficult to do exactly. As far as i got it looked to increase w/ acceleration. Perhaps that could be a subject for a numerical solution ?
That would certainly be interesting. It would be great, if anyone with the necessary skills and especially tools (math+software) were up to this task. I'm especially interested in a possible induced, time-averaged non-zero entropy gradient across the inner EM-drive volume occurring, and its maybe existent connection to the predicted net force direction of EM-drive theoretical models, that we have so far.
Possibly related?
http://arxiv.org/abs/1601.07558
https://en.wikipedia.org/wiki/Entropic_gravity#Criticism_and_experimental_testsQuoteentropic gravity in its current form has been severely challenged on formal grounds. Matt Visser, professor of mathematics at Victoria University of Wellington, NZ in "Conservative Entropic Forces" [19] has shown that the attempt to model conservative forces in the general Newtonian case (i.e. for arbitrary potentials and an unlimited number of discrete masses) leads to unphysical requirements for the required entropy and involves an unnatural number of temperature baths of differing temperatures. Visser concludes:
There is no reasonable doubt concerning the physical reality of entropic forces, and no reasonable doubt that classical (and semi-classical) general relativity is closely related to thermodynamics [52–55]. Based on the work of Jacobson [1–6], Thanu Padmanabhan [7– 12], and others, there are also good reasons to suspect a thermodynamic interpretation of the fully relativistic Einstein equations might be possible. Whether the specific proposals of Verlinde [26] are anywhere near as fundamental is yet to be seen — the rather baroque construction needed to accurately reproduce n-body Newtonian gravity in a Verlinde-like setting certainly gives one pause.
For the derivation of Einstein's equations from an entropic gravity perspective, Tower Wang shows in [20] that the inclusion of energy-momentum conservation and cosmological homogeneity and isotropy requirements severely restrict a wide class of potential modifications of entropic gravity, some of which have been used to generalize entropic gravity beyond the singular case of an entropic model of Einstein's equations. Wang asserts that
As indicated by our results, the modified entropic gravity models of form (2), if not killed, should live in a very narrow room to assure the energy-momentum conservation and to accommodate a homogeneous isotropic universe.
Entropic gravity and quantum coherence (experiments)
Another way of criticism of the entropic gravity is a reason that entropic processes should break quantum coherence. Recent experiments with ultra-cold neutrons in the gravitational field of Earth show that neutrons lie on discrete levels exactly as predicted by Schrödinger equation considering the gravitation to be a conservative potential field without any decoherent factors. Archil Kobakhidze argues that this result disproves entropic gravity.[21][22] Luboš Motl gives popular explanations of this problem in his blog. -
#2989 by X_RaY on 20 Feb, 2016 19:55
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Random thoughts on quantum entanglement.
Inside the cavity there are different quantum states at both end of the cavity due to the different volume, surface area, squeezed states and so on, but all of these conditions along the central axis are entangled to each other, also the resonance inside of the magnetron cavity is entangled to the resonance inside of the truncated conical cavity. (Change something in one of the cavities there will be a reaction in the other also... like small frequency shifts for example)
The question is now: Why the different states of the quantum field inside the conical cavity seems to generates thrust but the different states of the EM quantum field(s) between the magnetron resonator and a simple cylindrical cavity does not? All this parts of the system are in resonance to each other and for sure the field conditions are quite different between these two resonance rooms(magnetron cavity <-> any connected resonator) such like in the conical case.
Ideas on that?
BTW this video is fascinating.
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#2990 by JohnFornaro on 20 Feb, 2016 23:24
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You need to un-clamp the chemical rocket from the stand, for the chemical rocket engine to self accelerate and move.
THAT's what I've been doing wrong... -
#2991 by JohnFornaro on 20 Feb, 2016 23:28
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Completely parenthetically, that's my engine from the AirLaunch program in 2007! So far, that's my only contribution to this fascinating thread...
Play fair, all. Somebody give the kid back his engine. Sheesh. -
#2992 by zen-in on 21 Feb, 2016 03:42
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Random thoughts on quantum entanglement.
Inside the cavity there are different quantum states at both end of the cavity due to the different volume, surface area, squeezed states and so on, but all of these conditions along the central axis are entangled to each other, also the resonance inside of the magnetron cavity is entangled to the resonance inside of the truncated conical cavity. (Change something in one of the cavities there will be a reaction in the other also... like small frequency shifts for example)
The question is now: Why the different states of the quantum field inside the conical cavity seems to generates thrust but the different states of the EM quantum field(s) between the magnetron resonator and a simple cylindrical cavity does not? All this parts of the system are in resonance to each other and for sure the field conditions are quite different between these two resonance rooms(magnetron cavity <-> any connected resonator) such like in the conical case.
Ideas on that?
BTW this video is fascinating.
This needs to be done in a vacuum chamber, maybe with solenoids to start each metronome. Without air currents do the metronomes synchronize? Is there a mystic force that causes the metronomes to synchronize? We must have answers. -
#2993 by RotoSequence on 21 Feb, 2016 03:58
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This needs to be done in a vacuum chamber, maybe with solenoids to start each metronome. Without air currents do the metronomes synchronize? Is there a mystic force that causes the metronomes to synchronize? We must have answers.
Its the sway table that communicates and synchronizes their motion. -
#2994 by Mulletron on 21 Feb, 2016 04:01
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At 1:36, what are the "recent advances which take this from science fiction to science reality"? Whatever it is, it's scalable.
http://www.outerplaces.com/science/item/11264-nasa-on-interstellar-travel-there-is-no-known-reason-why-we-cannot-do-this
https://www.nasa.gov/directorates/spacetech/niac/index.html
http://www.centauri-dreams.org/?p=33409
Edit:
Not an EmDrive.. -
#2995 by TheTraveller on 21 Feb, 2016 04:58
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Roadmap can be found here:
http://www.deepspace.ucsb.edu/projects/directed-energy-interstellar-precursors
EmDrive is more efficient at momentum to kinetic conversion.
Interesting that in the paper & attachment:
http://www.deepspace.ucsb.edu/wp-content/uploads/2015/11/Brashears-etal-SPIE-2015-Interstellar-WaferSats-v07b-comments-removed.pdf
It is shown that with constant N (force) and Power on the spacecraft's reflector, the spacecraft experiences constant acceleration and a linear increase in velocity to 26%c. Oh well so much for KE = 1/2M V^2. Seems A = F/M wins.
Please direct your objections to the paper's authors.
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#2996 by ThinkerX on 21 Feb, 2016 06:52
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.26C in ten minutes....eek...and a fine red paste where the crew used to be? Even for a robot, that kind of acceleration would be about like a bullet hitting a brick wall...at least.
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#2997 by TheTraveller on 21 Feb, 2016 07:23
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.26C in ten minutes....eek...and a fine red paste where the crew used to be? Even for a robot, that kind of acceleration would be about like a bullet hitting a brick wall...at least.
Please read the paper.
A = F/M scales as spacecraft mass varies, assuming constant reflector diameter and reflected N of force.
Point being KE = 1/2M V^2 is not involved as the propollentless spacecraft accelerates under constant g, from constant Force, constant Power & constantly increasing Velocity, obeying A = F/M.
Who will be the 1st to write the authors, pointing out their error and stating KE = 1/2M V^2 must be obeyed as otherwise the spacecraft's calculated KE will be increasing faster than the input energy?
Or just maybe there is something new at play here? -
#2998 by X_RaY on 21 Feb, 2016 07:48
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This kind of synchronization will also work in vacuum its purely mechanical coupling.Random thoughts on quantum entanglement.
Inside the cavity there are different quantum states at both end of the cavity due to the different volume, surface area, squeezed states and so on, but all of these conditions along the central axis are entangled to each other, also the resonance inside of the magnetron cavity is entangled to the resonance inside of the truncated conical cavity. (Change something in one of the cavities there will be a reaction in the other also... like small frequency shifts for example)
The question is now: Why the different states of the quantum field inside the conical cavity seems to generates thrust but the different states of the EM quantum field(s) between the magnetron resonator and a simple cylindrical cavity does not? All this parts of the system are in resonance to each other and for sure the field conditions are quite different between these two resonance rooms(magnetron cavity <-> any connected resonator) such like in the conical case.
Ideas on that?
BTW this video is fascinating.
This needs to be done in a vacuum chamber, maybe with solenoids to start each metronome. Without air currents do the metronomes synchronize? Is there a mystic force that causes the metronomes to synchronize? We must have answers.
Well known since Christiaan Huyghens experiments in 1665.
http://fisica.unav.es/~jbragard/research4.html
https://micro.magnet.fsu.edu/optics/timeline/people/huygens.html
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#2999 by dustinthewind on 21 Feb, 2016 07:56
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When you use conservation of momentum and you find the change in velocity of the ship with respect to the change in velocity of the photon upon emmission and then you take the integral with respect velocity then you get the initial energy which is zero plus some added constant = the energy divided between the two masses and some heat. When you divide everything by that energy constant that was added to the system and find the percentage of energy to the photon it is almost 100% and about 0% to the engine. So I think I get why photon propulsion is inefficient.
However, now lets us consider the light reflected between two free floating and separate mirrors and suddenly photon propulsion becomes much more efficient after many reflections. In effect the light is red-shifted till it becomes efficient for propulsion. At least here the energy is divided equally between the two mirrors.
I wonder if it is possible to have a single device (closed system) that has two mirrors but one mirror is more effective at harnessing energy from the photon than the other mirror. Maybe by giving the photon some added mass when striking one mirror? (one mirror being a super-conductor possibly?). http://physics.stackexchange.com/questions/47791/what-do-massive-photons-have-to-do-with-superconductivity . (The efficiency of photon propulsion having to do partly with the "effective" mass of the photon?) It might be like firing off a higher frequency photon that you red-shifted into non-existence? You still have a photon that leaves (possibly at a long enough wavelength) but most of its energy is transferred to one side of the engine? This vaguely reminds me of Dr. Rodal reminding us of some ones suggestion to have one end plate as fero-magnetic.
Still thinking on this but wondering if it's a possibility.