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#3180 by SeeShells on 15 Jun, 2016 22:02
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Never confused, but sometimes befuddled....
While I also realized the limitations of this article I also realized that the authors seemed to have had access to COMSOL data which you say they didn't properly credit NASA. This seems to be a incorrect statement.
...
What is incorrect about what I stated?
Again, I stated that the authors directly credit an accumulation site that posted information taken from NSF (and links to NSF), but the authors failed to reference NSF directly (or the original material from Paul March/NASA posted at NSF) in their article.
They should have credited NSF instead of crediting the accumulation site !
They should have but it's not a huge mistake and it is obvious they used COMSOL to generate their images.
And what does rfmwguy's actions have on the impact of the article. It was reported as I got the information. Sorry, it seems to have upset you somehow, it shouldn't.
Shell
1) You are the one that made an incorrect statement. Your own post shows that I said that they failed to credit NSF, not NASA.
2) So what that they used COMSOL to generate their own comparison??? They generated that comparison based on data that was originally posted at NSF where the dimensions of the EM Drive was originally posted and other details that are necessary to run the COMSOL analysis.
You seem confused about the facts, judging by your statements.
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#3181 by FattyLumpkin on 15 Jun, 2016 22:09
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Shell, Dr. Rodal would you please share your thoughts with me re this question:
Therefore a high Q cylindrical resonant cavity with a small collimated opening in it would generate no more "force" than the emitter supplying the cavity, were all the energy from the emitter collimated. yes? Still attempting to learn, K
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#3182 by Rodal on 15 Jun, 2016 22:41
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Shell, Dr. Rodal would you please share your thought s with me re this question:
That new question is a non-trivial question to answer in a few words (force instead of time-averaged force/PowerInput)
Therefore a high Q cylindrical resonant cavity with a small collimated opening in it would generate no more "force" than the emitter supplying the cavity, were all the energy from the emitter collimated. yes? Still attempting to learn, K
----
Please refer to previous statements regarding the time-averaged Force/PowerInput. -
#3183 by SeeShells on 15 Jun, 2016 22:45
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Shell, Dr. Rodal would you please share your thought s with me re this question:
Wouldn't that depend on what you were causing to exit the collimated opening? Light will be on the order of a photon rocket, but ions will be more massive (light has zero rest mass), imparting greater reactionary force.
Therefore a high Q cylindrical resonant cavity with a small collimated opening in it would generate no more "force" than the emitter supplying the cavity, were all the energy from the emitter collimated. yes? Still attempting to learn, K
What perplexes (befuddles as well) me is reported force anomalies greater than an ion reactionary thrust in an enclosed cavity.
That should be a energy signature that should be measured, but like notsosureofit's and Dr. White's and this current article we are discussing it would seem we'll find it hard to prove. If it is a warping of space like EagleWorks seemed to measure (just out of the error margin) with the michelson laser informeter test then it will be easier.
White's virtual particles and then this current photon pairs can't, well at least I can't in my home lab. notsosureofit's theory? Well, I'm not so sure how yet.
BTW we all are learning here and count me as well.
Shell -
#3184 by frobnicat on 15 Jun, 2016 23:15
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Shell, Dr. Rodal would you please share your thought s with me re this question:
Therefore a high Q cylindrical resonant cavity with a small collimated opening in it would generate no more "force" than the emitter supplying the cavity, were all the energy from the emitter collimated. yes? Still attempting to learn, K
If I may answer that : yes. The wavelength or the process of emission is irrelevant to the momentum radiated (and hence gained as reaction momentum) for a fixed amount of energy radiated in a collimated direction. As Rodal explained, when counted as flow of momentum per unit of time (thrust, Newtons in SI units) for a given flow of energy per same unit of time (power, Watts in SI units) this is always about 3.33µN/kW.
This is also the same "figure of merit" that would stand for any collimated emission of any massless particles (travelling at c) like err, let me check the standard model, say for a gluon rocket (actually I don't think it's possible to emit gluons due to color confinement...) or a graviton rocket (should the graviton exist and be massless). For very light particles emitted at relativistic velocities, say neutrinos, the figure of merit would be very close, so a neutrino rocket would definitely be very close to 3.33µN/kW (assuming one could tame the neutrino emission process to be collimated or nearly so). This is accounting for the energy emitted in the flow of said particles, not counting the inefficiency of production (per kW of electric power would give less thrust)
For massive particles that travel below c, the figure of merit is lower than that. Notice that it is counting the energy content of what is emitted, if mass m is expelled the mc˛ is accounted in the expanded energy on top of the energy needed to accelerate the expelled mass (wrt the thrusting device). Obviously a chemical rocket or ion thruster does much more than 3.33µN/kW if power accounts only for the later, which is the usual way to talk of spent power for rockets or ion thrusters, but much lower if it accounts for both, which is the only sensible way to compare with "propellantless" thruster that by definition lose no other mass that the mass equivalent of spent energy, that is E/c˛
For hypothetical particles of imaginary rest mass known as tachyons, that travel above c (spacelike trajectory), then energy momentum in special relativity allows figure of merit above 3.33µN/kW. My take on it : hypothesis 3/ of this post.
At the time I wrote that I was aware of the problematic implication on causality (antitelephones and the such) of tachyons but later learned a little more about tachyonic field and tachyon condensation, which I invite the interested reader to dig further to those wikipedia's introductory articles. For what I understand, imaginary rest mass is not by itself as crazy as it sounds and is actually implied in the Higgs mechanism, but intrinsic instabilities in such field make propagating on-shell excitations (aka particles, no relation to other contributor here) err, massive in the usual sense, positive mass, velocity always below c, and since propulsion by emission of flow means energy_momentum leaving the rocket for good, with no lingering coupling (opposite momentum gained must be accounted as propellant far enough from the thruster so that it is no longer interfering with it), it means in the end that what counts is on-shell particle and even in the case of tachyonic field such particles have strict positive (real) mass and can't get us more than 3.33µN/kW. A Higgs bosons rocket remains below a photon rocket in this sense (only slightly so if Higgs boson have more kinetic energy in the referential of the rocket when emitted than mc˛ where m is rest mass of one Higgs boson).
As for microwaves escaping from a small aperture, being much smaller than the wavelength would make it impossible to have a collimated emission (below diffraction limit): thrust would be significantly lower that collimated photon rocket, and this is assuming that the "high Q" is fixed by the loss of energy through the aperture with negligible induced currents dissipation in the box (relatively) otherwise there is another reducing factor in final figure of merit. Best use of a kW of microwaves : heat a small ball of dissipative material at the focus of a parabolic reflector (in IR if warm only, in visible light if white hot) and with a hemispherical mirror that bounces back the thermal radiation that would miss the parabolic reflector (same geometry as a halogen light projector, replace filament with microwave heated material).
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#3185 by SeeShells on 15 Jun, 2016 23:34
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Shell, Dr. Rodal would you please share your thought s with me re this question:
Wouldn't that depend on what you were causing to exit the collimated opening? Light will be on the order of a photon rocket, but ions will be more massive (light has zero rest mass), imparting greater reactionary force.
Therefore a high Q cylindrical resonant cavity with a small collimated opening in it would generate no more "force" than the emitter supplying the cavity, were all the energy from the emitter collimated. yes? Still attempting to learn, K
What perplexes (befuddles as well) me is reported force anomalies greater than an ion reactionary thrust in an enclosed cavity.
...
That should be a energy signature that should be measured, but like notsosureofit's and Dr. White's and this current article we are discussing it would seem we'll find it hard to prove. If it is a warping of space like EagleWorks seemed to measure (just out of the error margin) with the michelson laser informeter test then it will be easier.
White's virtual particles and then this current photon pairs can't, well at least I can't in my home lab. notsosureofit's theory? Well, I'm not so sure how yet.
BTW we all are learning here and count me as well.
Shell
This is the first I hear about this author's concept of a Quantum Vacuum composed of paired photons, so I can't comment. The first question that comes to mind is what other implications it has for the Cosmos and how do the implications of the author's theory compare with Cosmological measurements.
Just wanted to get in some online time on NSF (waiting to get new and better parts). I've been wrapped up with this test stand build I haven't kept up here other than a quick flash over reading. But it looks like I'll be back at it tomorrow as I JUST got in my 12KV diodes and 2.1kv filter caps (series 3 of them for 6.6 Kv) and my bleeder 10Megohm resistors for the 4Kv filtered and upgraded power supply.
This will give me a stable and clean DC for the magnetron along with a regulated 6.3V for the heater. (it gets cut off after 4 seconds) and the tube starts conducting. The water cooling on the magnetron works very well at keeping thermal and frequency runaway in reason.
I have been working on getting a good measurement for the torsion pendulum and I think I have it figured out, I'll post results and what i did maybe tomorrow.
Shell
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#3186 by tleach on 16 Jun, 2016 05:55
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The acoustic waves in your example give an external force to the particles.
Acoustic waves inside the particles would not be able to self-accelerate the particles. An external force is required, or the inertial mass needs to change.
The problem with the EM Drive is that the electromagnetic waves are inside the EM Drive. Furthermore, what is claimed by experimenters is that the EM Drive self-accelerates with a force that is orders of magnitude larger than the force that would be produced if the EM Drive would be open and you would let the electromagnetic waves escape asymmetrically.
That's why some people have looked at ways to open the system: Harold White and a mutable, degradable Quantum Vacuum, James Woodward and a Mach Effect on the polymer insert, McCulloch and Unruh waves, other people have tried General Relativity, etc.
I totally get that the speaker array was exerting an external force. What I failed to articulate clearly is not that I thought there was something particularly special in the fact that the particle was levitating, but rather that the particle was levitating without exerting pressure on the speaker array causing the levitation. The speaker array is not producing thrust that holds up the particle the way a fan (or rocket) would. The speaker array is creating waves in a controlled pattern that produce constructive and destructive interference patterns that impart enough energy (or momentum?) to the particle to make it levitate.
I was about to say that I think it's a similar principal as optical tweezers, but then I looked up optical tweezers. I guess it's more like the inverse of laser cooling, except with sound waves, and macroscopic...
Anyway, what I'm trying to ask is, is the speaker array acting on the particle (through the use of momentum carrying acoustic waves) without experiencing an equal and opposite reaction?
If the speaker array is acting on the particle without experiencing an equal and opposite reaction, why couldn't an EM transmitter emit EM waves that transfer momentum to an object without experiencing an equal and opposite reaction? If an EM transmitter (or speaker array) is able to emit waves that transfer momentum without experiencing an equal and opposite reaction, then why does it matter where the speaker array (or EM transmitter) is located (internally or externally)? I'm not talking about throwing tennis balls. I'm talking about a carefully controlled wave source transferring momentum to a target without experiencing an equal amount of thrust in the opposite direction.
Perhaps I'm completely misunderstanding wave mechanics and the particle is exerting pressure on the speaker array or perhaps this is where the analogy between sound waves and EM waves breaks down... I have no idea. That's why I'm asking :-)
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#3187 by tleach on 16 Jun, 2016 06:18
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From a notice by rfmwguy... Interesting.
Shell
http://scitation.aip.org/content/aip/journal/adva/6/6/10.1063/1.4953807
On the exhaust of electromagnetic drive
Patrick Grahn1,a), Arto Annila2,3,b) and Erkki Kolehmainen4,c)
Recent reports about propulsion without reaction mass have been met on one hand with enthusiasm and on the other hand with some doubts. Namely, closed metal cavities, when fueled with microwaves, have delivered thrust that could eventually maintain satellites on orbits using solar power. However, the measured thrust appears to be without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster’s cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite phases. At the destructive interference electromagnetic fields cancel. However, the photons themselves do not vanish for nothing but continue in propagation. These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator. By this action momentum is lost from the cavity which, according to the conservation of momentum, gives rise to an equal and opposite reaction. We examine theoretical corollaries and practical concerns that follow from the paired-photon conclusion.
Destructive interference of electromagnetic fields you say? Hmmmm...QuoteAccording to elementary electromagnetism the photons will bounce back and forth between the cavity’s metal walls as well as interfere with each other. And we add, no cavity is devoid of the vacuum, and hence even a single photon will interfere with photons embodying the vacuum.18 Only those photons, whose wavelengths are multiples of a wall-to-wall distance, will interfere constructively, and hence only they will reside in the cavity. Momenta of trapped photons, as has been pointed out,14,16,17 sum up to zero, that is, standing waves do not produce thrust irrespective of the cavity’s shape.
Conversely, all other photons, whose multiple wavelengths do not match any of cavity dimension, will eventually interfere destructively. We reason that when pairing perfectly for destructive interference, the photons will escape from the resonator. In this way momentum will be lost along the exit directions.
When the cavity’s geometry guides more photons to pair along a direction than along others, the momentum loss will be biased, which will manifest itself as thrust. Dissimilar electromagnetic modes at the wide and narrow end of a tapered cavity imply to us anisotropic efflux of paired photons (Fig. 3). In fact, we expect any cavity of an asymmetric composition to deliver some thrust. Conversely, we reason, for example, that a cylindrical resonator will not generate a net force.
Well, I can't really speak to the Quantum Vacuum composed of paired photons, but I think I like where the authors are going. Interesting that a quick google search of "Quantum Vacuum composed of paired photons" turns up a wiki page on virtual particles https://en.wikipedia.org/wiki/Virtual_particle#Pair_production that happens to mention both the Unruh effect and Vacuum Polarization.QuoteIn an accelerating frame of reference, the virtual particles may appear to be actual to the accelerating observer; this is known as the Unruh effect. In short, the vacuum of a stationary frame appears, to the accelerated observer, to be a warm gas of actual particles in thermodynamic equilibrium.
QuoteA virtual particle does not precisely obey the energy–momentum relation m2c4 = E2 − p2c2. Its kinetic energy may not have the usual relationship to velocity–indeed, it can be negative.[4]:110 This is expressed by the phrase off mass shell.[3]:119 The probability amplitude for a virtual particle to exist tends to be canceled out by destructive interference over longer distances and times. As a consequence, a real photon is massless and thus has only two polarization states, whereas a virtual one, being effectively massive, has three polarization states.
As to the fact that these theories apparently allow for the extraction of energy from the quantum vacuum? Well, I'd just like to point out that about 13.82 billion years ago somebody (not saying who or why) extracted an entire universe worth of matter and energy (and dark matter and dark energy) from the quantum vacuum.
Just sayin'. -
#3188 by frobnicat on 16 Jun, 2016 08:34
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.../...
Anyway, what I'm trying to ask is, is the speaker array acting on the particle (through the use of momentum carrying acoustic waves) without experiencing an equal and opposite reaction?
.../...
No. The matter is muddled a little bit because the system is open to atmosphere and atmosphere rests on the ground so a clearer situation is to enclose the experiment in a box (enclosed atmosphere). Inside the box the battery operated speaker array, enclosed air, and the bead. Say the bead weighs 1mg. When levitated by the sound wave pressure there is no way that the box and its content as a whole (speaker array + levitating bead + enclosed air) is alleviated from 1mg. No way. This is not fundamentally different from blowing on the bead with a fan. Why would it be ?QuotePerhaps I'm completely misunderstanding wave mechanics and the particle is exerting pressure on the speaker array or perhaps this is where the analogy between sound waves and EM waves breaks down... I have no idea. That's why I'm asking :-)
Well, there is nothing magical about waves as compared to flow of particles, it's all the same actually, an upward airflow can be understood down to waves in the various (quantified) fields of the standard model (electron field, quarks field, electromagnetic field...) even though it's not the most straightforward way to model it from an engineering point of view. Anyway, if waves impart upward momentum on a levitating bead then this momentum must have a downward counter component somewhere. What can make you think that it could be otherwise ? What would make sound waves special in this regard (conservation of momentum) as compared to air flows ? Air flow is some kind of movement of air molecules, sound waves is other kind of movement of air molecules. Any movement of air molecules can be (at least in principle) very accurately traced down to microscopical individual interactions, each interaction strictly conserves momentum, summation of strictly momentum conserving microscopic events yields strictly momentum conserving macroscopic effects. I think many here fail to get that and invoke "special" macroscopic configurations while failing to point to hypothetical microscopic momentum "cheating" mechanism required for such macroscopic magic to occur in the first place.
Care must be taken as this can be tricky (and it's easy to fool oneself), for instance consider rotating vanes blower that do an outward airflow radially in a plane (and suck air axially in a symmetric fashion). Put the axis horizontally, that is plane of blowing vertical. Incoming air sucked symmetrically along the axes, outgoing air blown symmetrically in the radial plane, all flows are symmetric around center of blower and hence there is no net thrust on the blower, it is neither pushed downward nor upward when switched on. And yet a ping pong ball put above the blower, in the plane of outward flow, can be levitated (not stable but this is beyond the point). This is not changing the fact that the blower device still incurs no net thrust. So where is the reaction to the net action on the ping pong ball ? Hint : consider that experiment enclosed in a small box, and now extrapolate to bigger box up to the whole atmosphere of Earth.
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#3189 by chavv on 16 Jun, 2016 09:28
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This past June 2, 2016, Rfmwguy removed his previously claimed results for the EM Drive wiki:
Can someone explain (or give a link) what happened with Rfmwguy and his experiments?!
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#3190 by xexorian on 16 Jun, 2016 09:39
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..And yet a ping pong ball put above the blower, in the plane of outward flow, can be levitated (not stable but this is beyond the point). This is not changing the fact that the blower device still incurs no net thrust. So where is the reaction to the net action on the ping pong ball ?
The ping pong ball's rest mass is considered, the entire blower device would simply hover lower, right? (by some minute fraction, the surface of the ping pong ball, and it's weight, would press against the blower, even though it is hovering (I think) against gravity, in your scenario. So, the blower device would just simply lower as to equalize the pressure difference (difference in weight, as in a correlation to wind pressure reactions on the surface) right?
Also, if we used nuclear reactors in space, can anyone tell me the energy density difference between that and a massive array of ion thrusters, vs actual rocket fuel, is there a weight/volume comparison to be made?
And, another question, wouldn't a higher energy electromagnetic wave impart more force since it takes more energy to generate? So, a gamma-ray thruster would probably be more efficient in terms of speeding up, but at the expense of massive amounts of energy? Right? What I'm getting at is, light or photons, are a higher level of energy than 2.4 Gigahertz, so something that's trillions of hertz takes more energy to vibrate the photons, how does that vibrational energy density or whatever, translate when talking about expelling light (radio, visible, ultraviolet, etc.) for thrust? Consider, for example, gamma-ray sails, instead of solar sails? Can anyone outline the math behind this for a layman? Thanks if so, if not, cool. Just asking! ^_^ -
#3191 by Gilbertdrive on 16 Jun, 2016 11:13
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..And yet a ping pong ball put above the blower, in the plane of outward flow, can be levitated (not stable but this is beyond the point). This is not changing the fact that the blower device still incurs no net thrust. So where is the reaction to the net action on the ping pong ball ?
The ping pong ball's rest mass is considered, the entire blower device would simply hover lower, right? (by some minute fraction, the surface of the ping pong ball, and it's weight, would press against the blower, even though it is hovering (I think) against gravity, in your scenario. So, the blower device would just simply lower as to equalize the pressure difference (difference in weight, as in a correlation to wind pressure reactions on the surface) right?
Also, if we used nuclear reactors in space, can anyone tell me the energy density difference between that and a massive array of ion thrusters, vs actual rocket fuel, is there a weight/volume comparison to be made?
And, another question, wouldn't a higher energy electromagnetic wave impart more force since it takes more energy to generate? So, a gamma-ray thruster would probably be more efficient in terms of speeding up, but at the expense of massive amounts of energy? Right? What I'm getting at is, light or photons, are a higher level of energy than 2.4 Gigahertz, so something that's trillions of hertz takes more energy to vibrate the photons, how does that vibrational energy density or whatever, translate when talking about expelling light (radio, visible, ultraviolet, etc.) for thrust? Consider, for example, gamma-ray sails, instead of solar sails? Can anyone outline the math behind this for a layman? Thanks if so, if not, cool. Just asking! ^_^
What we generally call "efficiency" for a propellantless device is the thrust divided by energy used by time unit (N/Kw) The gamma photons are more energetic, but the efficiency is exactly the same. a perfectly collimated photonic thruster of 1 Kw has the same thrust if it uses gamma, or infrared.
Also, most of the Sun photonic Energy is infrared, visible, or ultraviolet. You can not get much more by making a solar sail that stops gamma.
And, instead of a solar sail of 1200 M2 that weight 32kg, you would need several centimeters of lead. That means more than 32kg/M2. Even if the sun was providing 1000 times more energy with gamma than with infrared, visible an ultraviolet, it would be useless. We do not need precise calculus to see it has no viability.
About the Nuclear Powerplant, My brother made a few days ago the calculus about the best efficiency.
Supposing fusion of Hydrogen into Helium in a Nuclear Fusion Plant, it makes less than 1% of matter converted into Energy (Heat and radiations)
Supposing a 100% conversion into Eletricity.
Supposing some thrusters that eject helium with converting 100% of electricity generated into Kinetic Energy.
We got an ejection of Helium at less than C/10.
Of course, it does not means it is feasible. But it gives a limit. Even going from Hydrogen to Iron, we do not get much more. And once we get into Iron, we can not get more nuclear Energy.
The SSME send hot gas at 4423 m/s
C/10 means around 30 000 000 m/s
For a device that eject propellant by using the energy of the propellant itself we can define efficiency as thrust divided by massic energy of propellant used by time unit. It allows to compare propellantless devices and Newtonian thrusters.
So our nuclear powered thrusters would be more than 6700 times more efficient than SSME. It also would be around 10 times more efficient than a photonic thruster that only use energy from the powerplant and does not eject the Helium at fast speed, and 10 times less efficient than a photonic thruster fed with antimatter.
Of course, these are limits. It do not pretend that we can approach these results.
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#3192 by Mulletron on 16 Jun, 2016 11:46
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From a notice by rfmwguy... Interesting.
Shell
http://scitation.aip.org/content/aip/journal/adva/6/6/10.1063/1.4953807
On the exhaust of electromagnetic drive
Patrick Grahn1,a), Arto Annila2,3,b) and Erkki Kolehmainen4,c)
Recent reports about propulsion without reaction mass have been met on one hand with enthusiasm and on the other hand with some doubts. Namely, closed metal cavities, when fueled with microwaves, have delivered thrust that could eventually maintain satellites on orbits using solar power. However, the measured thrust appears to be without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster’s cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite phases. At the destructive interference electromagnetic fields cancel. However, the photons themselves do not vanish for nothing but continue in propagation. These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator. By this action momentum is lost from the cavity which, according to the conservation of momentum, gives rise to an equal and opposite reaction. We examine theoretical corollaries and practical concerns that follow from the paired-photon conclusion.
Don't see any motivation to create paired photons, when this is already understood.QuoteDestructive interference destroys the magnetic energy, but
http://puhep1.princeton.edu/~kirkmcd/examples/destructive.pdf
doubles the electric energy.
https://van.physics.illinois.edu/qa/listing.php?id=1891
http://physics.stackexchange.com/questions/55318/where-does-energy-go-in-destructive-interference
http://physics.stackexchange.com/questions/23930/what-happens-to-the-energy-when-waves-perfectly-cancel-each-other
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#3193 by bmcgaffey20 on 16 Jun, 2016 12:23
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..And yet a ping pong ball put above the blower, in the plane of outward flow, can be levitated (not stable but this is beyond the point). This is not changing the fact that the blower device still incurs no net thrust. So where is the reaction to the net action on the ping pong ball ?
The ping pong ball's rest mass is considered, the entire blower device would simply hover lower, right? (by some minute fraction, the surface of the ping pong ball, and it's weight, would press against the blower, even though it is hovering (I think) against gravity, in your scenario. So, the blower device would just simply lower as to equalize the pressure difference (difference in weight, as in a correlation to wind pressure reactions on the surface) right?
Also, if we used nuclear reactors in space, can anyone tell me the energy density difference between that and a massive array of ion thrusters, vs actual rocket fuel, is there a weight/volume comparison to be made?
And, another question, wouldn't a higher energy electromagnetic wave impart more force since it takes more energy to generate? So, a gamma-ray thruster would probably be more efficient in terms of speeding up, but at the expense of massive amounts of energy? Right? What I'm getting at is, light or photons, are a higher level of energy than 2.4 Gigahertz, so something that's trillions of hertz takes more energy to vibrate the photons, how does that vibrational energy density or whatever, translate when talking about expelling light (radio, visible, ultraviolet, etc.) for thrust? Consider, for example, gamma-ray sails, instead of solar sails? Can anyone outline the math behind this for a layman? Thanks if so, if not, cool. Just asking! ^_^
What we generally call "efficiency" for a propellantless device is the thrust divided by energy used by time unit (N/Kw) The gamma photons are more energetic, but the efficiency is exactly the same. a perfectly collimated photonic thruster of 1 Kw has the same thrust if it uses gamma, or infrared.
Also, most of the Sun photonic Energy is infrared, visible, or ultraviolet. You can not get much more by making a solar sail that stops gamma.
And, instead of a solar sail of 1200 M2 that weight 32kg, you would need several centimeters of lead. That means more than 32kg/M2. Even if the sun was providing 1000 times more energy with gamma than with infrared, visible an ultraviolet, it would be useless. We do not need precise calculus to see it has no viability.
About the Nuclear Powerplant, My brother made a few days ago the calculus about the best efficiency.
Supposing fusion of Hydrogen into Helium in a Nuclear Fusion Plant, it makes less than 1% of matter converted into Energy (Heat and radiations)
Supposing a 100% conversion into Eletricity.
Supposing some thrusters that eject helium with converting 100% of electricity generated into Kinetic Energy.
We got an ejection of Helium at less than C/10.
Of course, it does not means it is feasible. But it gives a limit. Even going from Hydrogen to Iron, we do not get much more. And once we get into Iron, we can not get more nuclear Energy.
The SSME send hot gas at 4423 m/s
C/10 means around 30 000 000 m/s
For a device that eject propellant by using the energy of the propellant itself we can define efficiency as thrust divided by massic energy of propellant used by time unit. It allows to compare propellantless devices and Newtonian thrusters.
So our nuclear powered thrusters would be more than 6700 times more efficient than SSME. It also would be around 10 times more efficient than a photonic thruster that only use energy from the powerplant and does not eject the Helium at fast speed, and 10 times less efficient than a photonic thruster fed with antimatter.
Of course, these are limits. It do not pretend that we can approach these results.
In general, I enjoy reading your posts. You are knowledgeable and well informed. However, this one disappoints me. You are entirely correct on almost everything you said, where you went wrong is saying that a solar sail meant to reflect gamma rays or stop them would not be more efficient due to the need for heavy shielding. While this remains true today, we may one day discover exotic new properties or amplifications of known effects regarding the known realm of existing materials, or maybe a new one entirely. -
#3194 by Mulletron on 16 Jun, 2016 12:26
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Starting to think all the discussion about reported benefits of having phase noise and/or FM modulation:
Quoting @Star-Drive
https://forum.nasaspaceflight.com/index.php?topic=36313.msg1331792#msg1331792QuoteFolks:
In the meantime, lets ask why 60 watts of relatively harmonic free sine-wave RF power at the 1,937.118 MHz AKA the TM212 resonant frequency in this copper frustum cavity, can only generate a paltry ~60uN, whereas the Chinese claimed to have produce 160,000uN using just ~150 watts of 2,450 MHz RF signals from a magnetron? The magnetron RF signal source that is anything but a pure sine-wave generator, that instead has a modulated FM bandwidth of at least +/-30 MHz that is also concurrently amplitude modulated (AM) with thermal electron noise.
And lots of other places, here's another:
https://forum.nasaspaceflight.com/index.php?topic=39004.msg1460244#msg1460244
.....Might be related to jerk, aka the rate of change of acceleration, vice constant acceleration.
http://math.ucr.edu/home/baez/physics/General/jerk.html
http://forum.nasaspaceflight.com/index.php?topic=13020.msg657468#msg657468
http://forum.nasaspaceflight.com/index.php?topic=39772.msg1546803#msg1546803
http://forum.nasaspaceflight.com/index.php?topic=39772.msg1547275#msg1547275
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#3195 by Mulletron on 16 Jun, 2016 13:06
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Over the past couple years, there's been a bunch of different theories of what inertia really is thrown around, because figuring out inertia seemed essential to understanding the EMdrive.
Here's some copied and pasted from thread 1:
Intrinsic:
Higgs mass +binding energy: Rest mass/energy contribute to inertial mass
Newton: It is intrinsic because it just is.
Extrinsic:
EM ZPF, Haisch et al
Unruh zpf/casimir McCulloch et al
De Brogie Compton resonance Haisch Reuda
Cosmic-Mach
Cosmic-modified by Wheeler/Feynman-Sciama
Causal, moving charged particles Bergman
https://en.wikipedia.org/wiki/Inertia#Source_of_inertia.3B_speculative_theories
Lately, I'm wondering if it's just the minus sign...Lenz's law for gravitoelectromagnetism.
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#3196 by SeeShells on 16 Jun, 2016 14:27
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Please, have someone the link of the scheduled interview with Dr. McCulloch? It was supposed to be this 17th June in an online web video...
Thanks
http://www.thespaceshow.com/show/17-jun-2016/broadcast-2722-em-drive -
#3197 by Notsosureofit on 16 Jun, 2016 14:46
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Re: Reports of my demise have been greatly exaggerated...
Just wanted to pop in while I have a rare moment between all the activity going on on this end....
I'm still trying to integrate the entropy relation between the small nmp states in the frustum vs those of a pseudo-cylindrical cavity (ie the frustum under acceleration) ....at very high mode numbers the difference goes to zero for chambers of the same volume.
Needless to state, any information of exact solutions, even of other shapes, is extremely valuable.
Thanks..
PS: http://news.mit.edu/2016/second-time-ligo-detects-gravitational-waves-0615
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#3198 by SeeShells on 16 Jun, 2016 14:47
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You've very correct. I just thought it was interesting and wanted to bring it up here. It in no way eludes that I accept the article.From a notice by rfmwguy... Interesting.
Shell
http://scitation.aip.org/content/aip/journal/adva/6/6/10.1063/1.4953807
On the exhaust of electromagnetic drive
Patrick Grahn1,a), Arto Annila2,3,b) and Erkki Kolehmainen4,c)
Recent reports about propulsion without reaction mass have been met on one hand with enthusiasm and on the other hand with some doubts. Namely, closed metal cavities, when fueled with microwaves, have delivered thrust that could eventually maintain satellites on orbits using solar power. However, the measured thrust appears to be without any apparent exhaust. Thus the Law of Action-Reaction seems to have been violated. We consider the possibility that the exhaust is in a form that has so far escaped both experimental detection and theoretical attention. In the thruster’s cavity microwaves interfere with each other and invariably some photons will also end up co-propagating with opposite phases. At the destructive interference electromagnetic fields cancel. However, the photons themselves do not vanish for nothing but continue in propagation. These photon pairs without net electromagnetic field do not reflect back from the metal walls but escape from the resonator. By this action momentum is lost from the cavity which, according to the conservation of momentum, gives rise to an equal and opposite reaction. We examine theoretical corollaries and practical concerns that follow from the paired-photon conclusion.
Don't see any motivation to create paired photons, when this is already understood.QuoteDestructive interference destroys the magnetic energy, but
http://puhep1.princeton.edu/~kirkmcd/examples/destructive.pdf
doubles the electric energy.
https://van.physics.illinois.edu/qa/listing.php?id=1891
http://physics.stackexchange.com/questions/55318/where-does-energy-go-in-destructive-interference
http://physics.stackexchange.com/questions/23930/what-happens-to-the-energy-when-waves-perfectly-cancel-each-other
It is so close to Dr. Sonny White's theory of the QV VPs it's scary.
Got work to do today and sorry if I'm quiet but only so many hours in a day. I'm up at 4AM to read and keep updated and normally don't stop till late at night. I wish I had a virtual pair... of me. Maybe if I stuck the EMDrive on my head like a hat I'd get a virtual pair. 
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#3199 by Rodal on 16 Jun, 2016 15:05
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Re: Reports of my demise have been greatly exaggerated...
Just wanted to pop in while I have a rare moment between all the activity going on on this end....
I'm still trying to integrate the entropy relation between the small nmp states in the frustum vs those of a pseudo-cylindrical cavity (ie the frustum under acceleration) ....at very high mode numbers the difference goes to zero for chambers of the same volume.
Needless to state, any information of exact solutions, even of other shapes, is extremely valuable.
Thanks..
PS: http://news.mit.edu/2016/second-time-ligo-detects-gravitational-waves-0615
Can you explicitly provide the equation that you are trying to integrate?
Suggestion: given the lack of mathematical fonts in this site, you could write the equation in a piece of paper, scan it or take a picture and post the image
PS: further info on the 2nd detection of gravitational waves here: http://forum.nasaspaceflight.com/index.php?topic=39297.msg1550321#msg1550321
This event was much smaller than the first detection: The first event involved black holes that were 29 and 36 times as massive as the sun, while this new collision, which took place 1.4 billion years ago, brought together black holes of 8 and 14 solar masses. While the first detection “jumped out” from the data, the researchers say, the second one was only noticed thanks to the analysis of specially developed software.
