Hello everybody.First of all, thanks to all who have made this discussion possible. I think that some good scientific discussion is being done here and in the other EmDrive thread. I have started lurking in this forum two weeks ago when the buzz about the new tests started, but only now I've decided to register and post some comments.First of all, disclaimer: I am an engineer, not a physicist, but for my degree I had to do several exams to do with electromagnetism and even some quantum-related effects (the ones related to how a semiconductor works). So I have a healthy interest in physics, and I've read more on the matter than just what I studied for the exams, but I am not an expert.I am perplexed by this paragraph in the article:In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant. This model was also met with criticism in the scientific community because the Quantum Vacuum cannot be ionized and is understood to be “frame-less” – meaning you cannot “push” against it, as required for momentum.I'd like to know more about Dr. White's model than just this description, and I don't know enough about the QV in terms of the complicated quantum mechanics maths, but I can wrap my head around virtual particles. I trust in their existence because they are related to black hole Hawking radiation, and we have observed that radiation. We have a model, and it works.From what I understand of the model, though, I think I have a further observation about the model of "pushing against the virtual particles" that could lead to an experiment to disprove it.Suppose you have a fluctuation where a particle-antiparticle couple spawns into existence and then annihilates pretty much immediately, just as in the model for virtual particles; in very simplistic terms (and I'm sure the reality is more complicated) they "borrow" some energy and momentum and "return" it when they annihilate (gah, I know, I'm butchering it, but bear with me). Now suppose that it was possible to "push" that particle-antiparticle pair as reaction mass with some (magic?) apparatus in the time while the pair is briefly in existence. The pair would gain a total momentum p equal and opposite to the apparatus pushing it.Then the pair annihilates - but wait! Now the two particles have more momentum (and energy) than what they "borrowed" to come into existence. Because of CoM, that extra momentum must go somewhere. It can't just disappear. The system would have to transform in such a way that it's conserved.The only way I can see this happening is if it is released as radiation (or other by-product particles). We know that radiation has momentum, so this is possible. In other words, a device using the virtual particles as reaction mass would "shine" with some extra radiation that can't be explained in any other way.This radiation is either massive (i.e. it's made of particles) or massless (i.e. it's light).In the latter case, energy and momentum for radiation are related by the E = pc relation. If we have measured a momentum variation p in our apparatus, and therefore we have an equivalent momentum variation to be radiated, then the energy released as radiation would be pc, which for any meaningful value of momentum would be utterly huge and it would likely destroy the apparatus. Plus, where is the energy coming from?!?In the former case, then this extra stream of particles is radiated from the apparatus in such a way that it must be detectable by some experiment. Granted, it might be difficult (it they're neutrinos, we're basically stuffed) but it must be conceptually possible.We might even be able to estimate a range of bounds for the average total mass generated by this interaction, because for each particle E = mc^2 + pv which can be summed over all the particles, and we know the upper bound of the total E (because of CoE that is at most what energy we pumped into the apparatus as input), the total p (which is equal to the momentum change of the apparatus) and we know that for every massive particle it must be true that 0 <= v < c.So, I would argue that another objection to the "pushing against virtual particles" model is that since we haven't observed a huge amount of gamma rays melting the lab, then some mass must be created somehow from the expended energy. However it has not been explored in the experiments whether this extra mass was produced (and personally I suspect we won't find it, but that's just my opinion).Does this make sense?
The only thing I would add is that it takes a whole lot of energy to produce a tiny amount of mass. The energy needs of the thing would be worse than if you were only producing photons. And you would still burn down your lab with intense radiation.
If you are interested in Dr. White's conjecture regarding the above, see this: https://en.wikipedia.org/wiki/Woodward_effect#Quantum_mechanicsand associated references.
Quote from: frobnicat on 05/05/2015 11:22 pm...Em drives mounted on a rotor turning at 2000m/s tangential velocity (not easy but this is the kind of tangential velocity attained in some energy storage flywheels...). Em drives consuming 1kW microwave, radiating some (all ?) of this power as heat and thrusting at 1N : 1N/kW is in the ballpark of what has been experimentally claimed already. This gives 2000m/s * 1N = 2kW mechanical power to the shaft of the rotor. 2kW mechanical power at the shaft are converted to 1800W DC current by a generator (and 200W radiated as heat). Of this 1800W DC electrical power, 250W are diverted for any use we like. To keep it in line with the topic I put it to good use to power another Em drive but really we are free to use those 250W for whatever (creating mass for instance). The power splitter is not 100% efficient, it radiates 50W of power. 1800-250-50 = 1500W to feed the RF amplifier. The RF amplifier wastes (radiates) 500W as heat and pumps 1000W of clean microwave back into the Em drives on the rotor.The process needs an initial investment in energy (to make rotor move at 2000m/s tangential velocity) but then this is a free energy generator for all practical purpose. If small variations in efficiency make the rotor lose a bit of velocity, just divert a little more power to the RF amplifier : this is just a regulation problem, there is ample margins to adjust and stabilize around the optimal operating point....@frobnicat: how general are the statements above, concerning the hypothesis of constant "propellantless thrust" at constant power ?Do they apply for example, to:1) An idealized military search light used as a photon rocket (assuming, for argument's sake, in a Gedankenmodell that components have an infinite life without degradation, and you operate it an indefinite amount of time with energy supply)
...Em drives mounted on a rotor turning at 2000m/s tangential velocity (not easy but this is the kind of tangential velocity attained in some energy storage flywheels...). Em drives consuming 1kW microwave, radiating some (all ?) of this power as heat and thrusting at 1N : 1N/kW is in the ballpark of what has been experimentally claimed already. This gives 2000m/s * 1N = 2kW mechanical power to the shaft of the rotor. 2kW mechanical power at the shaft are converted to 1800W DC current by a generator (and 200W radiated as heat). Of this 1800W DC electrical power, 250W are diverted for any use we like. To keep it in line with the topic I put it to good use to power another Em drive but really we are free to use those 250W for whatever (creating mass for instance). The power splitter is not 100% efficient, it radiates 50W of power. 1800-250-50 = 1500W to feed the RF amplifier. The RF amplifier wastes (radiates) 500W as heat and pumps 1000W of clean microwave back into the Em drives on the rotor.The process needs an initial investment in energy (to make rotor move at 2000m/s tangential velocity) but then this is a free energy generator for all practical purpose. If small variations in efficiency make the rotor lose a bit of velocity, just divert a little more power to the RF amplifier : this is just a regulation problem, there is ample margins to adjust and stabilize around the optimal operating point....
2) Woodward's propellant-less Mach Effect (assuming, for argument's sake, that Woodward's conjecture is valid, and you can operate it an indefinite amount of time with energy supply)If there are differences that constrain the energy paradox between the above two and the EM Drive, please point out the differences, as it may be instructive for this discussion to unveil these differences regarding what is possible and what is not possible (under conservation of energy and conservation of momentum).Thanks
I'm confused about something ( o.k. many things). I have now read many articles that say this can't work and is all junk science. It violates COM/COE etc.But isn't that taking a Newtonian view of something operating at a quantum level? Tunnel diodes have negative resistance, but they are quantum tunneling diodes after all. We have been making tunnel diodes for 50+ years but the logic that says the emdrive can't work, in my mind, says tunnel diodes can't work either.Am I missing something?
Quote from: LasJayhawk on 05/07/2015 01:29 amI'm confused about something ( o.k. many things). I have now read many articles that say this can't work and is all junk science. It violates COM/COE etc.But isn't that taking a Newtonian view of something operating at a quantum level? Tunnel diodes have negative resistance, but they are quantum tunneling diodes after all. We have been making tunnel diodes for 50+ years but the logic that says the emdrive can't work, in my mind, says tunnel diodes can't work either.Am I missing something?Quantum mechanics and quantum field theory still has conservation of energy-momentum. As mentioned, it is even more explicit there than in classical physics. Tunnel diodes were a straightforward application of known physics and have no relation to this.
....If the QV is a large storage of negative energy, I might only need to put a little in to get a lot out?? I didn't put the same energy in as I got out, I just just my small energy to tap a large pile of stored energy. That wouldn't be a violation of COE, would it?
Trying to make the propellantless drives to comply with apparent COE yields so much inconsistencies that I'm convinced that, if they are for real (which I'm not convinced), they must indeed be energy harvesters, and COE is to be saved by determining what is (silently) harvested. For White this means altering/lowering the ZPF density (which in principle can't be done since it's already a baseline). Could be detected locally. For Woodward this means imparting some entropy (unsure about that one) on the spatio-temporal walls of reality. Would be hard to prove, but experimental proof of apparently unlimited energy generation from a closed box could be indirect evidence.
If true, wouldn't this degrade the universe by using up a finite resource?Perhaps other advanced species figured this out at some point, and hense a solution to the Fermi paradox!
....If true, wouldn't this degrade the universe by using up a finite resource?Perhaps other advanced species figured this out at some point, and hense a solution to the Fermi paradox!
https://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECT
Quote from: Rodal on 05/11/2015 04:53 pmhttps://www.researchgate.net/publication/268804028_NASA%27S_MICROWAVE_PROPELLANT-LESS_THRUSTER_ANOMALOUS_RESULTS_CONSIDERATION_OF_A_THERMO-MECHANICAL_EFFECTAs an observer, I have been taking huge interest in the ongoing discussion for the last couple of weeks. I am deeply convinced that the discovery of even the slightest possibility of feasible and realistic interstellar superluminal travel would profoundly and positively alter our species' trajectory. Thus, I want to thank all of you for investing so much in this slight chance. However, Dr. Rodal's paper seems to effectively end these investigations with respect to the EM Drive, as it makes a lot of sense with a very strong argument.