Quote from: Star One on 05/23/2015 06:43 pmQuote from: txdrive on 05/23/2015 06:26 pmWell, I'm in the following group:1: Shawyer's paper is completely confused. Right at the start he attributes the force to a greater radiation pressure upon the wide end, yet it pushes itself small end forward; this is based upon a completely confused discussion of reaction forces and thrust. This notion that there would be no force on the side walls "according to Maxwell's equations" is simply flat-out wrong. Maxwell's equations, as applied, yield zero thrust; the force on the side walls precisely balances out the pressure difference between the ends. (They're also Lorentz invariant so there's no special relativity corrections to be made)2: All explanations where the measured force is impacted upon the cavity walls by incident electromagnetic radiation are likewise wrong, whenever they involve speculations about the quantum vacuum or not. The measured force corresponds to the incident electromagnetic radiation deviating from conventional predictions by >50% (Shawyer, Chinese results), or >2.5% (EW results), which is in gross contradiction to experiments that measure electromagnetic radiation directly (many are precise to parts per billion or better).3: Regarding EW's experiments, their readings contradict each other (when flipped 180 degrees). Other experiments are substantially worse still, with high voltage wires, stiff waveguides being heated, etc. pushing the cavity mechanically. What results do you expect to get if there's no thrust but you got a bunch of high voltage wires, substantial heat, electrical current in the wires, and vibration? You can't seriously expect to get a literal zero.And you think the professional experimenters, not talking about the DIY versions here, haven't already considered this. You put forward an argument as if this was the first time anyone had thought of these issues. A greater part of the last thread was examining such issues amongst other things.I don't think many competent physicists have any interest in Shawyer's theories. What he's writing is so wrong it is painful to read. Experimental physics requires, at least, good knowledge of mechanics, and the glaring bit about the pressure puts anyone with such knowledge off.
Quote from: txdrive on 05/23/2015 06:26 pmWell, I'm in the following group:1: Shawyer's paper is completely confused. Right at the start he attributes the force to a greater radiation pressure upon the wide end, yet it pushes itself small end forward; this is based upon a completely confused discussion of reaction forces and thrust. This notion that there would be no force on the side walls "according to Maxwell's equations" is simply flat-out wrong. Maxwell's equations, as applied, yield zero thrust; the force on the side walls precisely balances out the pressure difference between the ends. (They're also Lorentz invariant so there's no special relativity corrections to be made)2: All explanations where the measured force is impacted upon the cavity walls by incident electromagnetic radiation are likewise wrong, whenever they involve speculations about the quantum vacuum or not. The measured force corresponds to the incident electromagnetic radiation deviating from conventional predictions by >50% (Shawyer, Chinese results), or >2.5% (EW results), which is in gross contradiction to experiments that measure electromagnetic radiation directly (many are precise to parts per billion or better).3: Regarding EW's experiments, their readings contradict each other (when flipped 180 degrees). Other experiments are substantially worse still, with high voltage wires, stiff waveguides being heated, etc. pushing the cavity mechanically. What results do you expect to get if there's no thrust but you got a bunch of high voltage wires, substantial heat, electrical current in the wires, and vibration? You can't seriously expect to get a literal zero.And you think the professional experimenters, not talking about the DIY versions here, haven't already considered this. You put forward an argument as if this was the first time anyone had thought of these issues. A greater part of the last thread was examining such issues amongst other things.
Well, I'm in the following group:1: Shawyer's paper is completely confused. Right at the start he attributes the force to a greater radiation pressure upon the wide end, yet it pushes itself small end forward; this is based upon a completely confused discussion of reaction forces and thrust. This notion that there would be no force on the side walls "according to Maxwell's equations" is simply flat-out wrong. Maxwell's equations, as applied, yield zero thrust; the force on the side walls precisely balances out the pressure difference between the ends. (They're also Lorentz invariant so there's no special relativity corrections to be made)2: All explanations where the measured force is impacted upon the cavity walls by incident electromagnetic radiation are likewise wrong, whenever they involve speculations about the quantum vacuum or not. The measured force corresponds to the incident electromagnetic radiation deviating from conventional predictions by >50% (Shawyer, Chinese results), or >2.5% (EW results), which is in gross contradiction to experiments that measure electromagnetic radiation directly (many are precise to parts per billion or better).3: Regarding EW's experiments, their readings contradict each other (when flipped 180 degrees). Other experiments are substantially worse still, with high voltage wires, stiff waveguides being heated, etc. pushing the cavity mechanically. What results do you expect to get if there's no thrust but you got a bunch of high voltage wires, substantial heat, electrical current in the wires, and vibration? You can't seriously expect to get a literal zero.
Brand new. Interview with the inventor of EmDrive. Good info in there.
What the EmDrive thruster does is to produce a force, which we call the thrust, in one direction. This is a force that you can measure. If you put your hand against the end plate that's producing the thrust you'll feel it pushing against you. And, as with all machines that follow Newton's principles, it will therefore accelerate in the opposite direction. So this is not a reactionless thruster, because those things just don't exist outside of science fiction, but it is a propellantless thruster.
This is what happens when a smart person is faced with data that is irreconcilable with known physics. They know that they are expected to explain it, and they also know that they cannot. In this case Shawyer simply babbles nonsense (and I'm putting that as kindly as I can without resorting to insult). It's cognitive dissonance in the flesh.
not even wrong
(...)Reaction - Thrust =0 (essentially Shawyer shows a Free-Body-Diagram where the forces sum up to zero)(...)
(...)therefore:massReaction = - massThrustin other words, for what Shawyer claims that happens to happen, one must have the mass associated with the Thrust force to be negative massAccording to his theory, separating the EM Drive into two distinct waveguides (instead of one closed cavity), one waveguide is associated with the Big End and the other waveguide is associated with the Small End. Then for the small end to accelerate with the Reaction Force, that means that the portion of the total mass associated with the Thrust force, the mass of the Big End waveguide, must have negative mass.and the total mass of the EM Drive must be zero:massReaction + massThrust = total mass = 0Again:1) Mass of waveguide associated with the Small End is positive, normal mass2) Mass of waveguide associated with the Big End is negative, exotic mass3) Total mass of EM Drive cavity is zero.Conclusion: unless the total mass of the EM Drives being experimented by Shawyer is zero, and a portion of their mass (associated with the Big End) is negative, exotic mass, his theory cannot explain what is being claimed Quote from: Wolfgang Paulinot even wrong
1) Mass of waveguide associated with the Small End is positive, normal mass2) Mass of waveguide associated with the Big End is negative, exotic mass...Quote from: Wolfgang Paulinot even wrong
Quote from: txdriveI don't think many competent physicists have any interest in Shawyer's theories. What he's writing is so wrong it is painful to read. Experimental physics requires, at least, good knowledge of mechanics, and the glaring bit about the pressure puts anyone with such knowledge off.Yet both Shawyer and the Chinese claim their theories closely calculate the value of their measured thrust? Surely that must open the possibility of their unconventional application of classic theory being correct and that no new physics is involved nor needed?
I don't think many competent physicists have any interest in Shawyer's theories. What he's writing is so wrong it is painful to read. Experimental physics requires, at least, good knowledge of mechanics, and the glaring bit about the pressure puts anyone with such knowledge off.
...The equation should be Reaction + Thrust = 0 , under the premise that anyone even gives a darn about conventions anymore.
The other way to put it - we can actually set up a situation where radiation pressure upon the big end is greater than that upon the little end. In space, put a flashlight inside the cavity, pointed upon the big end (which is not perfectly reflective). The radiation pressure upon the big end will be greater than that upon the small end, and the cavity will accelerate big end forward. (The flashlight, if unsupported, will move in the opposite direction, like a photon rocket, but it could in principle be held in place, e.g. using magnetic levitation)
Quote from: CW on 05/23/2015 09:03 pm...The equation should be Reaction + Thrust = 0 , under the premise that anyone even gives a darn about conventions anymore.I'm using D'Alembert's principle looking at Shawyer's diagram. His force convention does not follow any of the books I have in Mechanics (the fact that he has these two equal an opposite forces which should result in a body in equilibrium, hence having no acceleration).Let's say that we instead interpret Shawyer as you suggest. Then work out the bullet/gun split: one comes up with the accelerations having different signs which I agree is a more conventional view. If one consistently follows the same convention all the way through, for the bullet and the gun to both have real positive masses, then one ends up with the same result I have above that the mass of the Big End is the negative of the mass of the Small End and that the Total Mass of the EM Drive must be zero, according to Shawyer.
Quote from: Rodal on 05/23/2015 09:37 pmQuote from: CW on 05/23/2015 09:03 pm...The equation should be Reaction + Thrust = 0 , under the premise that anyone even gives a darn about conventions anymore.I'm using D'Alembert's principle looking at Shawyer's diagram. His force convention does not follow any of the books I have in Mechanics (the fact that he has these two equal an opposite forces which should result in a body in equilibrium, hence having no acceleration).Let's say that we instead interpret Shawyer as you suggest. Then work out the bullet/gun split: one comes up with the accelerations having different signs which I agree is a more conventional view. If one consistently follows the same convention all the way through, for the bullet and the gun to both have real positive masses, then one ends up with the same result I have above that the mass of the Big End is the negative of the mass of the Small End and that the Total Mass of the EM Drive must be zero, according to Shawyer.I fear that the available documents from Mr. Shawyer are unusable for any reasonable discussion. Judging by the available reports of a number of groups telling that something seems to or is going on, I feel that Mr. Shawyer might have found something by sheer coincidence. It reminds me of the logical implication that tells us that starting from a wrong premise, any conclusion is possible - even the right one.
(...)So, Shawyer has two forces that he says follow Newton's 3rd law, and Shawyer says that he follows MaxwellReaction = - Thrustassign a portion of the mass of the truncated cone to the Reaction force and the other portion to the Thrust forcemassReaction + massThrust =total massthenmassReaction*accelerationReaction = massThrust*accelerationThrust(...)
Quote from: Rodal on 05/23/2015 09:59 pm(...)So, Shawyer has two forces that he says follow Newton's 3rd law, and Shawyer says that he follows MaxwellReaction = - Thrustassign a portion of the mass of the truncated cone to the Reaction force and the other portion to the Thrust forcemassReaction + massThrust =total massthenmassReaction*accelerationReaction = massThrust*accelerationThrust(...)Dear Dr. Rodal,I believe your're introducing a sign error in your considerations. It looks to me as if you only take the absolute values or norm of 'accelerationReaction' and 'accelerationThrust' and equate them. If Newton's 3rd law is correctly applied, then it is IMHO writtenmassReaction*accelerationReaction + massThrust*accelerationThrust = 0, ormassReaction*accelerationReaction = -massThrust*accelerationThrustOr is there a reason to ignore the vector directions that eludes me? Otherwise I can easily see, why negative mass seemingly arises. If the EM-drive accelerates, it can't have anything to do with Newton's 3rd law. At least not in our measly 3+1 space, IMHO.