The laser light excited the pentacene molecules to an energy level known as a metastable state. Then a microwave passing through the crystal triggered the molecules to relax, releasing a cascade of microwaves of the same wavelength.It was the same principle as an optical laser. "The signal that came out of it was huge," says Oxborrow, about a hundred million times as powerful as an existing maser. Alone in his lab, "I swore a lot and walked around the corridor about five times talking to myself".
I wholeheartedly agree with the intention of the smart people around here, helping the rest of us to filter the science from the chaff.Nevertheless, I assume there is going to be a break point: either the Emdrive proves to deliver some anomalous thrust or it doesn't.If it does, such anomaly would maybe go against some of the scientific principles stated here (as very pointedly remarked by frobnicat et al).But such proof by counterexample would need to be really overwhelming and repeatable in order to be accepted. Is that correct?
Quote from: Rodal on 05/11/2015 12:38 pmQuote from: Notsosureofit on 05/11/2015 12:20 pm...Really hadn't thought about it, but at large X, isn't f prop X ? and NT prop X^2/f^3 ??My recollection (from running numerical examples at the time at which you were planning to run experiments with a Gunn diode) is that at large Xmn, with both m~n simultaneously highest, Xmn increases higher than f, so that Xmn (f) ~ f ^y where y>1 Need y>3/2 in order for thrust force to increase with frequency.My recollection is that the thrust force predictions using your formula for the Gunn Diode frequency were much higher than the predictions of Shawyer and McCulloch.EDIT: Also the calculations for Shawyer's Flight Thruster (which I recall was run at higher frequency: 3.85GHz, twice the frequency of NASA's EM Drive tests)Is my memory correct ? (too bad that we don't have a good search function to look for things like that )Can't remember either, that may have been before I did the units check and noticed the 1/f error (typo on post-it notes) in N (number of photons).I should go back and set up a graphing program for these formulas. Cavity dimensions scale as 1/f just to add to the mess. I never did get back to the cylindrical w/ dielectric case. Except for a uniform change, most dielectric surfaces need to include a reflection and you need an iterative program to solve them numerically. (wrote some of these for optical filter companies in the dim dark past) It would be nice to have an integral solution that could be optimized. Just a note: CoM from spacial symmetry is thought to be local from present cosmology, or so I believe, really haven't checked.
Quote from: Notsosureofit on 05/11/2015 12:20 pm...Really hadn't thought about it, but at large X, isn't f prop X ? and NT prop X^2/f^3 ??My recollection (from running numerical examples at the time at which you were planning to run experiments with a Gunn diode) is that at large Xmn, with both m~n simultaneously highest, Xmn increases higher than f, so that Xmn (f) ~ f ^y where y>1 Need y>3/2 in order for thrust force to increase with frequency.My recollection is that the thrust force predictions using your formula for the Gunn Diode frequency were much higher than the predictions of Shawyer and McCulloch.EDIT: Also the calculations for Shawyer's Flight Thruster (which I recall was run at higher frequency: 3.85GHz, twice the frequency of NASA's EM Drive tests)Is my memory correct ? (too bad that we don't have a good search function to look for things like that )
...Really hadn't thought about it, but at large X, isn't f prop X ? and NT prop X^2/f^3 ??
Thanks for the response, and thank to all of you who even bother reading my posts. I'm so privileged to be here talking with minds like yours. I really do want to keep crack-pot and "pseudoscience" to a minimum, but I'm afraid I've not been classically trained. But I do have a passion & (very) open mind. As for the Maser, what about this discovery: http://www.nature.com/news/microwave-laser-fulfills-60-years-of-promise-1.11199Could NASA not handle something like this? I wish I could give NASA the DEA's budget... this is so frustrating.QuoteThe laser light excited the pentacene molecules to an energy level known as a metastable state. Then a microwave passing through the crystal triggered the molecules to relax, releasing a cascade of microwaves of the same wavelength.It was the same principle as an optical laser. "The signal that came out of it was huge," says Oxborrow, about a hundred million times as powerful as an existing maser. Alone in his lab, "I swore a lot and walked around the corridor about five times talking to myself". Seems like the goal, one of them anyway, could be to reduce the input energy? Also, presuming this drive is working as it seems that it does, and the fact that we don't understand it very well or at all, this could be one of those "Hobbyist/Hacker Hunches" (which is all I have to contribute at this time, sorry!).
Where is the calculation for a photon rocket comparison? When calculating the photon rocket thrust was the input power used, or the input power multiplied by the Q? I don't think I've seen that yet. I seriously need to start keeping a spreadsheet of data, tests, results and discussions. It's too much to keep track of in my head.
If it works as a maser then it must have a reasonably high index at those frequencies (or it was in some sort of cavity) Too bad it wasn't frustrum shaped.OK so it was inside a tuned cavity.
Quote from: Rodal on 05/11/2015 07:09 pmQuote from: WarpTech on 05/11/2015 07:02 pm...At the "instantaneous scale" there are collisions between photons and atoms where momentum is transferred and it generates heat but not thrust. When the photons are injected their momentum is p1 and energy is E1. It can only conserve NET momentum if there is a 50/50 probability that momentum is absorbed in each direction, without generating ANY heat at all. As soon as things start getting hot, the probability is not 50/50 anymore, then some of the momentum is not being absorbed as thrust, but rather to heat up the metal. Therefore, the NET momentum in either direction will depend on the difference in the dissipation and attenuation, in each direction. Todd D.Yes, the problem is, however, how would this, quantitatively, result in a more efficient (thrust/PowerInput) propellant-less drive than a perfectly-collimated photon rocket.Another fascinating observation that @frobnicat made early on, is that for photons (whether tunneling, dissipation or another mechanism) to end up producing a more efficient drive than a photon rocket, the photons would have to escape the EM Drive as tachyons, superluminally.Where is the calculation for a photon rocket comparison? When calculating the photon rocket thrust was the input power used, or the input power multiplied by the Q? I don't think I've seen that yet. I seriously need to start keeping a spreadsheet of data, tests, results and discussions. It's too much to keep track of in my head.
Quote from: WarpTech on 05/11/2015 07:02 pm...At the "instantaneous scale" there are collisions between photons and atoms where momentum is transferred and it generates heat but not thrust. When the photons are injected their momentum is p1 and energy is E1. It can only conserve NET momentum if there is a 50/50 probability that momentum is absorbed in each direction, without generating ANY heat at all. As soon as things start getting hot, the probability is not 50/50 anymore, then some of the momentum is not being absorbed as thrust, but rather to heat up the metal. Therefore, the NET momentum in either direction will depend on the difference in the dissipation and attenuation, in each direction. Todd D.Yes, the problem is, however, how would this, quantitatively, result in a more efficient (thrust/PowerInput) propellant-less drive than a perfectly-collimated photon rocket.Another fascinating observation that @frobnicat made early on, is that for photons (whether tunneling, dissipation or another mechanism) to end up producing a more efficient drive than a photon rocket, the photons would have to escape the EM Drive as tachyons, superluminally.
...At the "instantaneous scale" there are collisions between photons and atoms where momentum is transferred and it generates heat but not thrust. When the photons are injected their momentum is p1 and energy is E1. It can only conserve NET momentum if there is a 50/50 probability that momentum is absorbed in each direction, without generating ANY heat at all. As soon as things start getting hot, the probability is not 50/50 anymore, then some of the momentum is not being absorbed as thrust, but rather to heat up the metal. Therefore, the NET momentum in either direction will depend on the difference in the dissipation and attenuation, in each direction. Todd D.
Quote from: Notsosureofit on 05/11/2015 08:50 pmIf it works as a maser then it must have a reasonably high index at those frequencies (or it was in some sort of cavity) Too bad it wasn't frustrum shaped.OK so it was inside a tuned cavity.The tuned cavity being a cube, correct? Like the attached image? Would feeding the output of the maser into a frustrum change Shawyer's findings? Would it have an effect on the perceived thrust at all? Would it be better to make the maser in a frustrum rather than feed the output into the resonant cavity?
Is there any reason this should not be further investigated in regards to an EM Drive?
Quote from: WarpTech on 05/11/2015 07:31 pmQuote from: Rodal on 05/11/2015 07:09 pmQuote from: WarpTech on 05/11/2015 07:02 pm...At the "instantaneous scale" there are collisions between photons and atoms where momentum is transferred and it generates heat but not thrust. When the photons are injected their momentum is p1 and energy is E1. It can only conserve NET momentum if there is a 50/50 probability that momentum is absorbed in each direction, without generating ANY heat at all. As soon as things start getting hot, the probability is not 50/50 anymore, then some of the momentum is not being absorbed as thrust, but rather to heat up the metal. Therefore, the NET momentum in either direction will depend on the difference in the dissipation and attenuation, in each direction. Todd D.Yes, the problem is, however, how would this, quantitatively, result in a more efficient (thrust/PowerInput) propellant-less drive than a perfectly-collimated photon rocket.Another fascinating observation that @frobnicat made early on, is that for photons (whether tunneling, dissipation or another mechanism) to end up producing a more efficient drive than a photon rocket, the photons would have to escape the EM Drive as tachyons, superluminally.Where is the calculation for a photon rocket comparison? When calculating the photon rocket thrust was the input power used, or the input power multiplied by the Q? I don't think I've seen that yet. I seriously need to start keeping a spreadsheet of data, tests, results and discussions. It's too much to keep track of in my head.There is, in classical interpretation of SR, no reason to multiply the thrust of a photon rocket by Q as the number of time a quantum of momentum carrier bounced around before leaving the rocket for good and living its own trajectory (by definition : as a real particle) is irrelevant. Only the momentum "lost" by a leaving particle in a direction is a "gained" momentum in the opposite direction for a spacecraft.For a classical SR interpretation of what is possible for a deep space craft assuming no field/bath/mutable_vacuum to swallow and/or push on, see second half of this fascinating post ( 3/ ... ) And the other way around, if a cavity is receiving a flux of particles, there is no way (classically) it can recover more nor less momentum than the initial amount entering the boundary, no matter the path and number and modality of interactions of particles with said cavity, if they are to end their lives within. And not only that would make the emitting system to transfer momentum with no more efficiency than using the equivalent of a photon rocket thrust to blow on a sail (unless it is sending tachyons), but if the sender of the flux is attached to the receiving cavity then the net momentum delta of the whole process is 0 (assuming nothing leaves).Only between two different systems exchanging photons back and forth many times a transfer of momentum more efficient (by a factor Q) than the photon rocket limit can occur. This could be used to "beam" a force from system A to system B. But again, if system A and B are rigidly linked within a same craft, this is just a static force within the craft, so the Q factor won't amplify nothing useful. EM internal pressure inside a resonating cavity is proportional to Q but does not help to create net imbalance. And as soon as photons leave (if they leave), there can be net imbalance, but Q is not an amplifying factor of efficiency, there are not more photons leaving (for a given energy input) because they bounced many times before leaving.I've scratched my head for 15 minutes trying to understand the points made in your previous post about asymmetric dissipation but this is not making sense for me so far, even trying hard to think "out of the box". Will try to address and ask for clarifications when time permits.edit: blowing on a reflective sail a flux of photon actually allows the emitter to "transmit a force", for a given power, twice that of a photon rocket thrust (best case). Still irrelevant if emitter is rigidly linked to sail : perfectly absorbing sail -> 0 net thrust, perfectly reflecting and collimating sail -> thrust/power=1/c
...Frankly, if you had a source of microwaves equal to Q*100W, that photon rocket would probably be more efficient than a frustum at exerting thrust because there are fewer losses.Todd
Quote from: deltaMass on 05/11/2015 10:03 pm@frobnicat:I totally agree that "Q*(photon rocket thrust)" is a nonsense piece of physics on the face of it, for the same reasons you elaborate. However, I was just pointing out that it simply seems to be a good experimental thrust predictor.Which, of course, is completely weird if you take the thrust measurements as largely unflawed. And no, I don't know what it points to.As you calculated, the internal energy is proportional to Q. The internal energy is dissipated into heat. So that again points toward a thermal effect. Vacuum someone says? Let's look at outgassing from the heated FR4
@frobnicat:I totally agree that "Q*(photon rocket thrust)" is a nonsense piece of physics on the face of it, for the same reasons you elaborate. However, I was just pointing out that it simply seems to be a good experimental thrust predictor.Which, of course, is completely weird if you take the thrust measurements as largely unflawed. And no, I don't know what it points to.
...There seems to be confusion here. No question internal energy is proportional to Q, for a given net power input. But this net power input is not clear...
...I should go back and set up a graphing program for these formulas. Cavity dimensions scale as 1/f just to add to the mess. ...
As yet I haven't dipped my toe into the doubtless tasty maths of frustum mode frequencies as a function of frustum dimensions. It would seem best to use the most successful mode from an experimental POV. This would be the so-called TE2012 of EW? or something else? I'm talking about max thrust, which is really the only interesting metric at this stage.
The more that Br'er Rabbit fights the Tar-Baby, the more entangled he becomes