Quote from: TheTraveller on 09/24/2016 02:27 pmQuote from: Gilbertdrive on 09/24/2016 01:53 pm...On the ship A = F/M rules. The energy / work required to be done on the constant mass of the ship to effect velocity change never varies. The ship doesn't care what some other frame calculates as the necessary energy to cause velocity change.If only the ship cares, why does Shawyer speaks about increase of Kinetic Energy. In the ship referential, Kinetic energy is zero...

Quote from: Gilbertdrive on 09/24/2016 01:53 pm...On the ship A = F/M rules. The energy / work required to be done on the constant mass of the ship to effect velocity change never varies. The ship doesn't care what some other frame calculates as the necessary energy to cause velocity change.

...

Quote from: TheTraveller on 09/24/2016 05:18 am...The Earth's frame only matters if an inbound ship needs to match velocity.However the work needed to be done on the ship's mass to alter the relative velocity to 0, in the ship's frame, stays constant and that is the only effect that is important.You have to chose one reference frame. "alter the relative velocity to 0, in the ship's frame," if you chose the ship's frame the velocity is always zero and there is no relative velocity. That would require a second frame. What you should do is to consider the frame when the ship is at rest; ie: before any acceleration occurs. Then calculate the final kinetic energy added after the acceleration has ended wrt to this rest frame. For any reactionless drive the kinetic energy will eventually become larger than the energy used to accelerate the spacecraft. This is the CoE conundrum all reactionless drives have. Using 2 reference frames incorrectly as you have done just introduces another error. However the equations will never balance with this error so you still have the CoE conundrum.

...The Earth's frame only matters if an inbound ship needs to match velocity.However the work needed to be done on the ship's mass to alter the relative velocity to 0, in the ship's frame, stays constant and that is the only effect that is important.

Quote from: TheTraveller on 09/24/2016 05:18 am...The Earth's frame only matters if an inbound ship needs to match velocity.However the work needed to be done on the ship's mass to alter the relative velocity to 0, in the ship's frame, stays constant and that is the only effect that is important.You have to chose one reference frame. "alter the relative velocity to 0, in the ship's frame," if you chose the ship's frame the velocity is always zero and there is no relative velocity. If you use the ship's frame of reference you are expending energy and not seeing any increase in the kinetic energy. What you should do is to consider the frame when the ship is at rest; ie: before any acceleration occurs. Then calculate the final kinetic energy added after the acceleration has ended wrt to this rest frame. For any reactionless drive the kinetic energy will eventually become larger than the energy used to accelerate the spacecraft. This is the CoE conundrum all reactionless drives have. Using the wrong reference frame just introduces another error. The equations will never balance with this error so you still have the CoE conundrum and sometimes in the opposite sense.

The basic conservation laws are some of the strongest laws we know of governing the actions of systems and particles in our universe and are not thrown out the window when considering the actions of EM propulsion. They don't negate the data we have seen regarding the drives. They need to be used as a guide within the framework of physics in what maybe happening.

Quote from: Gilbertdrive on 09/24/2016 02:53 pmQuote from: TheTraveller on 09/24/2016 02:27 pmQuote from: Gilbertdrive on 09/24/2016 01:53 pm...On the ship A = F/M rules. The energy / work required to be done on the constant mass of the ship to effect velocity change never varies. The ship doesn't care what some other frame calculates as the necessary energy to cause velocity change.If only the ship cares, why does Shawyer speaks about increase of Kinetic Energy. In the ship referential, Kinetic energy is zero...Why will some external frame alter the work needed to be done on the ship's mass by the EmDrive altering A= F/M? The work needed to be done on the ship's mass, to alter velocity, is constant, independent of any external frame.This is almost like the twin paradox where only the local frame is important and frame to frame revelance is variable.

If I look the total Kinetic Energy of the system rocket + propellant, from an earth reference Frame, CoE will always be satisfied. In the earth point of view, the rocket has stolen Kinetic Energy to it's propellant, and there is no paradox.

A number of recent posts are addressing violation of conservation of momentum and violation of conservation of energy again. The posts have been addressing the propellant-less drive as it would be a closed-system and ignore any interaction with external fields If one would address a gravity assist maneuver with similar arguments, one would arrive at the obviously incorrect conclusion that there is a huge violation of conservation of energy and momentum, as the spaceship involved in a sling shot maneuver apparently gains velocity out of nothing. Obviously to properly consider conservation of mass and energy for a gravity assist maneuver, the spacecraft's effects on the planet must also be taken into consideration. The linear momentum gained by the spaceship is equal in magnitude to that lost by the planet, so the spacecraft gains velocity and the planet loses velocity. The planet's enormous mass compared to the spacecraft makes the resulting change in the planet's speed negligibly small.

Quote from: Rodal on 09/24/2016 04:20 pmA number of recent posts are addressing violation of conservation of momentum and violation of conservation of energy again. The posts have been addressing the propellant-less drive as it would be a closed-system and ignore any interaction with external fields If one would address a gravity assist maneuver with similar arguments, one would arrive at the obviously incorrect conclusion that there is a huge violation of conservation of energy and momentum, as the spaceship involved in a sling shot maneuver apparently gains velocity out of nothing. Obviously to properly consider conservation of mass and energy for a gravity assist maneuver, the spacecraft's effects on the planet must also be taken into consideration. The linear momentum gained by the spaceship is equal in magnitude to that lost by the planet, so the spacecraft gains velocity and the planet loses velocity. The planet's enormous mass compared to the spacecraft makes the resulting change in the planet's speed negligibly small.Thanks for this clarification! I would just like to point out that a gravity assist maneuver would not work in interstellar space (or would have a much smaller effect), while EmDrive is presumed to produce acceleration that does not depend on its position in the universe. Or am I missing something?

Quote from: TheTraveller on 09/24/2016 04:34 am...In the ship's frame, the only one which matters, the energy needed to alter velocity in relation to some desired destination is always the same as the ship's mass does not alter. Well not so much as it matters.All inertial (constant velocity) frames matter, because physics is the same in all inertial frames. This is the fundamental principle of relativity. If you want to jump between frames, then you have to start being careful with transformations, and generally you can't compare energy between frames. Conservation of energy as normally discussed requires you to be talking about a single inertial reference frame. Being in the accelerating frame of the ship requires you to account for non-inertial effects, just like how the Coriolis effect appears if you are in a rotating frame.Quote from: TheTraveller on 09/24/2016 04:34 amBTW Jim Woodward makes a good comment:http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdfQuoteWe routinely hear a criticism of METs based upon an argument that claims: if aMET is operated at constant power input for a sufficiently long time, it will acquireenough kinetic energy to exceed the total input energy of operation. Assuming thisargument to be correct, critcs assert that METs violate energy conservation as the ratio ofthe acquired kinetic energy to total input energy exceeds “unity.”Contrary to this “over-unity” assumption, this argument is based on flawedphysics and, consequently, wrong. The fact that the argument applies to all simplemechanical systems (in addition to METs) should have alerted critics to their mistake.But it didn’t. So, a dumb idea that should have been quickly buried is still with us. Thepurpose of this essay is to carry out a long overdue burial.I hadn't researched Woodward's theories too thoroughly before, but I had the impression he was a general competent physicist, who was poking for (unlikely) loopholes in general relativity. After reading that paper I no longer have that impression.After performing a step of just using the transitive property of equality (if a = b and b = c, then a = c), he says:QuoteNow we have done something stupid and wrong.It is possible he is referring to the first step in that sequence, where the figure of merit is defined, but that figure of merit comes straight out of theories such as Shawyer's. If that is wrong then the theory that it comes from must be wrong.he then remarks:QuoteBut this is the mathematics of those who make the “over unity” energy conservation violation argument about the operation of METs. The real question here is how could anyone, having done this calculation or its equivalent, think that they had made a profound discovery about anything? Simple, the step with defining the figure of merit only applies to METs and the like. Making a single assumption when every other step is valid, and ending up in a contradiction is a common way to disprove the assumption. That is what is done here, but Woodward tries to twist this inside out.The last paragraph of the paper attempts to show the "correct" way of doing this. As part of that he says:QuoteWe know that, starting from t= 0, if we let the integration interval t get very large, the work equation integral will first equal and then exceed the energy calculated by the figure of merit equation. So we require that t be sufficiently small that this obvious violation of energy conservation does not happen. He then tries to get around this limit by continuously jumping into the current rest frame of the device. This causes him to be comparing energy between reference frames which is not valid as Bob012345 has pointed out.The only thing this paper has destroyed for me is the thought that Woodward has any credibility. Unless this paper is some kind of bad joke, or test to see who can find them flaws in it.

...In the ship's frame, the only one which matters, the energy needed to alter velocity in relation to some desired destination is always the same as the ship's mass does not alter. Well not so much as it matters.

BTW Jim Woodward makes a good comment:http://ssi.org/epi/Over-Unity_Argument_&_Mach_Effect_Thrusters.pdfQuoteWe routinely hear a criticism of METs based upon an argument that claims: if aMET is operated at constant power input for a sufficiently long time, it will acquireenough kinetic energy to exceed the total input energy of operation. Assuming thisargument to be correct, critcs assert that METs violate energy conservation as the ratio ofthe acquired kinetic energy to total input energy exceeds “unity.”Contrary to this “over-unity” assumption, this argument is based on flawedphysics and, consequently, wrong. The fact that the argument applies to all simplemechanical systems (in addition to METs) should have alerted critics to their mistake.But it didn’t. So, a dumb idea that should have been quickly buried is still with us. Thepurpose of this essay is to carry out a long overdue burial.

We routinely hear a criticism of METs based upon an argument that claims: if aMET is operated at constant power input for a sufficiently long time, it will acquireenough kinetic energy to exceed the total input energy of operation. Assuming thisargument to be correct, critcs assert that METs violate energy conservation as the ratio ofthe acquired kinetic energy to total input energy exceeds “unity.”Contrary to this “over-unity” assumption, this argument is based on flawedphysics and, consequently, wrong. The fact that the argument applies to all simplemechanical systems (in addition to METs) should have alerted critics to their mistake.But it didn’t. So, a dumb idea that should have been quickly buried is still with us. Thepurpose of this essay is to carry out a long overdue burial.

Now we have done something stupid and wrong.

But this is the mathematics of those who make the “over unity” energy conservation violation argument about the operation of METs. The real question here is how could anyone, having done this calculation or its equivalent, think that they had made a profound discovery about anything?

We know that, starting from t= 0, if we let the integration interval t get very large, the work equation integral will first equal and then exceed the energy calculated by the figure of merit equation. So we require that t be sufficiently small that this obvious violation of energy conservation does not happen.

Welcome back doc.Without you and the other knowledgeable posters here, I'm afraid we would be stuck in 1st year pre-grad physics.

Quote from: Bob012345 on 09/22/2016 10:00 pmEach delta v requires the same burn, not more to account for the fact that future fuel is more effective. The reason we don't see more paradoxes with rockets is that they require so much mass that they run out before that point would be reached and they are so very inefficient so most kinetic energy is wasted.Also, I don't consider the energy issue a paradox if you use the work-energy theorem. It's the mechanical power times the time that always equates to the kinetic energy change in every observer frame. So there is no paradox. There is just a mixing of energy from different frames that confuses people.I think I have the right solution for this paradox that completes the answer that Meberbs did.I shall first formulate the paradox a very clear way.For classical rockets, unlike a car pushing against a road, the Delta V is the same for each burn.So, in the earth reference frame, the faster the rocket is, the more Kinetic Energy gained, for the same amount of energy spent.So, at a certain speed, the rocket gains more Kinetic Energy in the earth reference frame that the energy it has spent.My solution of the paradox is.Yes, it is true that in earth referential the rocket gains more Kinetic Energy that it has spent. But the rocket is not alone. The propellant that was expulsed at the opposite direction has now less Kinetic Energy in a earth reference frame. And the faster the rocket was, the more Kinetic Energy it has lost. It compensates the fact that the ship has gained more Kinetic Energy.If I look the total Kinetic Energy of the system rocket + propellant, from an earth reference Frame, CoE will always be satisfied. In the earth point of view, the rocket has stolen Kinetic Energy to it's propellant, and there is no paradox.In fact several messages already explicited that, but maybe another formulation can help. Tellmeagain and Meberbs have already made very good explanations.

Each delta v requires the same burn, not more to account for the fact that future fuel is more effective. The reason we don't see more paradoxes with rockets is that they require so much mass that they run out before that point would be reached and they are so very inefficient so most kinetic energy is wasted.Also, I don't consider the energy issue a paradox if you use the work-energy theorem. It's the mechanical power times the time that always equates to the kinetic energy change in every observer frame. So there is no paradox. There is just a mixing of energy from different frames that confuses people.

The figure of merit itself is not a mistake, it's how people use it to prove a constant force basically does not cause a constant acceleration which is implicit in the criticisms.

As I understand Woodward's comments, he's saying one can think of that supposed break even limit as an interval. After that interval, reset or re-guage the problem. Think of a rocket doing a long series of small burns. One ends up with a series of frames, in each energy was not violated but it's a simple undeniable fact of nature that the devices velocity in the last frame is the linear sum of all the frames yet the kinetic energy is different in each frame and far exceeds the sum of input energies in the last frame. But it's not a paradox at all. It's just how nature works and has always been built into classical mechanics. Woodward's argument is reasonable.

P.S. If someone still insists it can't work because 'momentum isn't conserved' assume it is, and assume however it is, the ship is just borrowing additional kinetic energy from the 'exhaust' of the universe just as it is in a rocket.

Everything you said about the rocket is true, however, if you let the rocket burn long enough (unfortunately, you can't because of practical mass limits), even accounting the exhaust energy balance, you would run into the same problem as with the EmDrive.

There is no error when only the ship's frame is considered. In that frame A = F/M rules and a constant amount of work on the ship's mass results in a constant acceleration and velocity change.A EmDrive powered ship, desiring to match a destination velocity, needs only to engage a known amount of work on the ship's mass to effect zero relative velocity.External KE frames are not involved. Only relative velocity differences between the ship and destination are important and those velocity differences relate to the necessary work needed to be done on the ship's mass to effect the desired velocity change.

.... When you do that CoE is violated and of course momentum is not conserved. This is true for any reactionless drive. I don't consider planetary assist to be reactionless propulsion because the planet is pulling the spacecraft and momentum is tranferred using gravity.

At the Estes Park Breakthrough Propulsion Workshop, Dr. Jean-Philippe Montillet of the École Polytechnique Fédérale de Lausanne, Switzerland, presented a paper titled "Model of the EM Drive with the EMG coupling" (that mathematically and physically) explains the EM Drive as a capacitor, where:* Surface currents propagate inside the cavity on the conic wall (between the two end plates)* electromagnetic resonant modes create electric charges on each end plate* Mach/Woodward effect is triggered by Lorentz force from surface currents on the conic wall * acceleration of RF cavity as due to the variation of Electro Magnetic density from evanescent waves inside the skin layer

P.S. I saw HMXHMX say the videographers have to do some editing. Honestly, given the nirvana I imagine going on at this conference I would rather watch those videos unedited.