Quote from: frobnicat on 11/08/2014 12:01 am...more energy to go from 100 to 101 than to go from 0 to 1. Because of the square.100˛ to 101˛ -> needs to add 2010˛ to 1˛ -> needs to add 1Wow, again, seems paradoxical, as this is the same "thing", just seen from a different way...Please, please Frobnicat, you are going too fast for me.- Nobody should add kinetic energy in different reference frames. That's not a paradox, that's plain and classical mechanics. A consequence is that nobody should use trust/power ratio.
...more energy to go from 100 to 101 than to go from 0 to 1. Because of the square.100˛ to 101˛ -> needs to add 2010˛ to 1˛ -> needs to add 1Wow, again, seems paradoxical, as this is the same "thing", just seen from a different way...
- There is no ongoing conspiracy at NASA, only usual business in an agency that consumes 2 billions each years and wants to survive. To survive it needs people support. People enjoy Startrek stuff (I am not joking, I really mean it). So NASA (and Discovery TV, and a handful of SF authors and some NASA consultants) feed people with the stuff they ask. That's a profitable business.
If one want serious science papers, there are many reputable sources. Science journals mostly, not conference papers, not pre-print servers, not self cited papers.I know it may sound harsh, I don't want to be harsh, sorry for my lack of writing gift. This whole thread is going too far, intelligent people see artifacts and meaning where there is none. I am very sorry about that.
To really get to the bottom of the issue of "paradoxical mission profiles" (if they are or not is not unanimous.... in Nasa's defense in both the Brady et al paper and the Human Outer Solar System Exploration via Q-Thruster Technology paper, they play it safe with 0.4 N/kWe) ...
Quote from: Mulletron on 11/08/2014 11:25 amTo really get to the bottom of the issue of "paradoxical mission profiles" (if they are or not is not unanimous.... in Nasa's defense in both the Brady et al paper and the Human Outer Solar System Exploration via Q-Thruster Technology paper, they play it safe with 0.4 N/kWe) ...I don't know if having more (properly accounted) kinetic energy than (properly accounted) spent energy is paradoxical but think there is near unanimity that this is not scientifically correct. This wide unanimous crowd is simply unanimously ignoring those research. I can't let say that 0.4 N/kWe is "playing safe" : first a convincing reproducible experiment showing such stable level for a long duration (say, an hour) is still unreported that I know of, second and most importantly anything above .00000333 N/kW (photon rocket) is not safe as far as energy conservation is concerned.
Quote from: JPLeRouzic on 11/08/2014 07:51 amQuote from: frobnicat on 11/08/2014 12:01 am...more energy to go from 100 to 101 than to go from 0 to 1. Because of the square.100˛ to 101˛ -> needs to add 2010˛ to 1˛ -> needs to add 1Wow, again, seems paradoxical, as this is the same "thing", just seen from a different way...Please, please Frobnicat, you are going too fast for me.- Nobody should add kinetic energy in different reference frames. That's not a paradox, that's plain and classical mechanics. A consequence is that nobody should use trust/power ratio. ...The problem in Appendix A is that there is an error, a huge error, when calculating the Hall thruster in the frame of CMB : the change in kinetic energy is given by initial state minus final state. Which yields a value higher than the spent onboard energy. BUT but but, the change in kinetic energy should be the other way around, final state minus initial !!! Which would yield a negative value, that is obviously less than spent energy. So their calculation is plain wrong, ......
Now, granted, you'd need a serious power plant to power this thing, and you'd probably want to tie a few dozen of them together in a frame of some sort, but it should get you to near relativistic speeds for far less energy cost than a rocket.Unless I'm missing something critical.
But in money terms maybe it's more clear : doing a financial operation where a cash investment of 1000$ (spent energy) makes that your portfolio values (kinetic energy) goes from 100000$ before to 10000$ after you would not say that the change in portfolio value is before-after 100000-10000=90000 and you had 90 over unit gain factor. You would do after-before and see that you have a change of -90000 and lost 90 times the cash invested : this is not really over unit gain.
If you feel they made a mistake, maybe the best is to write to the paper authors...
Quote from: frobnicat on 11/08/2014 09:53 am...* I wrote about what you stated at 12:01 AM in the server time, it is still quoted above. Your last post (09:53 AM) is about a different issue.* Unfortunately for me physics is not my professional domain, so I don't understand your reasoning (09:53 AM) of a craft that has a speed increasing and a decreasing kinetic energy. (Ef - Ei) < 0 => Ef < Ei.
...
* Anyway I still think the fact kinetic energy can't be added or substracted on different reference frames, applies to what you say in your last point (end-start vs start-end)...The rocket has different speeds at start and end points, so it's different inertial frames.
* If you feel they made a mistake, maybe the best is to write to the paper authors...
It doesn't make sense to me to read that Woodward's electron model is"easy to test", and then read that "if the model is correct", that all HSF would be transformed and enabled, and physics would change, and all that.Shouldn't all this "easy"testing be done first? And then all that transformation?
So in the end this is just "free energy in disguise". Think it's not good to have things in disguise in science, this is not sane. I'm ready to hear that those thrusters emit tachyons (negative energy). I'm ready to hear that quantum vacuum is like criss-crossing asphalt roads at all velocities and you can choose to push on the ones that are slow relative to you, taking at low energy cost (possibly 0) the intrinsic energy from those conveyor belts. That would be crazy but that would be all right : any idea without hidden secrets or "mysteries" or mystifications has a right to be expressed in science. . .
Quote from: frobnicat on 11/07/2014 05:00 pmsomething really outrageous is going on in this Appendix. Second column. Read it well, read it again, check the maths.... this is both gross and subtle.You mean what people call the "kinetic energy paradox"? That kinetic energy is proportional to the square of speed?https://www.physicsforums.com/threads/kinetic-energy-and-frames-of-reference.534883/It is what you already mention as a paradox as well as GoatGuy and it is also used in this linked paper.What physicists say, is that one can't add up kinetic energy in different reference frames (nothing to do with relativity).In my opinion every people using a metric like trust/power for several segments of the same travel, are doing exactly this mistake...adding kinetic energy in different reference frames
something really outrageous is going on in this Appendix. Second column. Read it well, read it again, check the maths.... this is both gross and subtle.
There we are : this is not a paradox or a problem with propellentless schemes, this is a paradox inherent to any spacecraft when energy is accounted for in an inertial frame fast enough relative to those typical delta Vs, because any of those has a Ts such that 1/Ts < high speeds, so surely any spacecraft can (apparently) provide more energy in kinetic form than is spent by the onboard generator. This is not a paradox with Q-thrusters, this is a paradox with relativity of velocities and how kinetic energy is accounted for in different inertial frame (we all know this is a messy business with all this square thing and non additivity...)
On his reading list, Woodward demonstrated this seeming violation occurs with any sort of thruster on a swing arm.
one of the guys over at T-P managed to do the same calc without the GR tools and get the same answer, but this is not to say one ought expect to use the wrong tools and get the right answers.
Quote from: frobnicat on 11/08/2014 12:01 amThere we are : this is not a paradox or a problem with propellentless schemes, this is a paradox inherent to any spacecraft when energy is accounted for in an inertial frame fast enough relative to those typical delta Vs, because any of those has a Ts such that 1/Ts < high speeds, so surely any spacecraft can (apparently) provide more energy in kinetic form than is spent by the onboard generator. This is not a paradox with Q-thrusters, this is a paradox with relativity of velocities and how kinetic energy is accounted for in different inertial frame (we all know this is a messy business with all this square thing and non additivity...) So far as I'm aware, this above is completely correct. On his reading list, Woodward demonstrated this seeming violation occurs with any sort of thruster on a swing arm. And as I said, his solution was to "sum the instantaneous frames of rest" which is some sort of transform used in GR. It was in fact his demonstration that this seeming violation occurs with any thruster that sold me we need a difference in kind to get this kind of performance, and the difference is of course that mass with negative inertia makes an unusual contribution, and can account for the trouble.See Forward's analysis here: http://en.wikipedia.org/wiki/Negative_mass
http://ptp.oxfordjournals.org/content/119/3/351.full.pdf+htmlPeculiar indeed.
In most conventional electromagnetic media, the quantum vacuum inside possesses a universal symmetry and hence has no influence on the motion of the media. However, for a Faraday chiral material,the macroscopically observable mechanical effect, due to the breaking of the universal symmetry of the quantum vacuum may appear