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 Tags EM drive

 22nd November 2016, 09:25 AM #121 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 Originally Posted by RussDill The important aspect here is that the constant force vector is attached to a rotating wheel. Conservation of momentum, angular momentum, and energy are actually really closely linked and the rotating wheel thing is just a simple mental exercise. If you are into low level physics, just imagine an EmDrive in empty space. Energy is applied and it accelerates. Presumably some energy is lost to heat, but some energy is being converted into kinetic energy. Now, imagine some related situations. An EmDrive ship is slowly approaching, it brakes using it's drive to come to a halt. It spent energy in bringing it's kinetic energy to zero. Where did both it's kinetic energy and the energy consumed by the EmDrive go? At the particle level, physics operates the same forwards or backwards once you flip a few signs. Play both tapes in reverse. In the first tape, you have an EmDrive that slows to a stop and converts it's kinetic energy into electrical energy. In the second tape, you have a drive that accelerates away while producing electrical energy. A common problem to these is that whether the kinetic energy of the system is increasing or decreasing depends on the inertial reference frame of the observer. Don't forget that KE = ½mv². So the amount of kinetic energy that's being added (or removed) depends on the relative velocity of your inertial reference frame. The problem gets much worse when you start considering non-inertial reference frames. Thanks, I understand now. __________________ I don't trust atoms. They make up everything.
 22nd November 2016, 09:56 AM #122 phunk Illuminator     Join Date: Aug 2007 Posts: 3,694 Originally Posted by RecoveringYuppy Sure, but I don't see how that relates to BenBurch's statement. Seems pretty straightforward to me. Interaction with the magnetic field can produce thrust, therefore that is one possible source of error that isn't eliminated by putting it in orbit.
 22nd November 2016, 10:02 AM #123 RecoveringYuppy Philosopher   Join Date: Nov 2006 Posts: 7,264 Originally Posted by phunk Seems pretty straightforward to me. Interaction with the magnetic field can produce thrust, therefore that is one possible source of error that isn't eliminated by putting it in orbit. I don't see how. It seems pretty difficult to accidentally attach a very long, highly charged, tether to this mission or to accidentally create anything resembling it. __________________ REJ (Robert E Jones) posting anonymously under my real name for 30 years. Make a fire for a man and you keep him warm for a day. Set him on fire and you keep him warm for the rest of his life.
 22nd November 2016, 10:34 AM #124 phunk Illuminator     Join Date: Aug 2007 Posts: 3,694 Originally Posted by RecoveringYuppy I don't see how. It seems pretty difficult to accidentally attach a very long, highly charged, tether to this mission or to accidentally create anything resembling it. The point was that it's possible to generate thrust off the magnetic field, not that it would be done exactly the same way.
 22nd November 2016, 10:45 AM #125 3point14 Pi     Join Date: Nov 2005 Posts: 14,810 Reading about it all, I ended up here: http://www.projectrho.com/public_htm...nlessdrive.php Which talks about the problems fiction writers will cause themselves if they write in a reactionless drive. While it's talking about such things in reference to works of fiction, there's a lot of, what seems to me, to be decent science in there leading me further and further down the 'it can't and doesn't work' route. I really, really want it to work. I really, really, really don't think it does. __________________ Up the River!
 22nd November 2016, 10:55 AM #126 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 5,818 Originally Posted by RecoveringYuppy I don't see how. It seems pretty difficult to accidentally attach a very long, highly charged, tether to this mission or to accidentally create anything resembling it. For the EM Drive thrust levels, how long would the tether have to be at what charge? I haven't done the math (maybe later) but if you're using a typical small spacecraft 28V power system and you wind up with, say, a 0.3 meter tether to get comparable thrust, then the spacecraft's wire harness will likely have more net thrust than your EM Drive. __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 22nd November 2016, 11:06 AM #127 catsmate No longer the 1     Join Date: Apr 2007 Posts: 19,226 Originally Posted by RecoveringYuppy But is that ever an >escape< from Earth? I meant "out" literally. Do you mean impart enough deltaV to escape Earth orbit, or park at L4 or L5? That would take an enormous amount if energy and remass. __________________ As human right is always something given, it always in reality reduces to the right which men give, "concede," to each other. If the right to existence is conceded to new-born children, then they have the right; if it is not conceded to them, as was the case among the Spartans and ancient Romans, then they do not have it. For only society can give or concede it to them; they themselves cannot take it, or give it to themselves.
 22nd November 2016, 11:17 AM #128 RecoveringYuppy Philosopher   Join Date: Nov 2006 Posts: 7,264 Originally Posted by catsmate Do you mean impart enough deltaV to escape Earth orbit, or park at L4 or L5? That would take an enormous amount if energy and remass. Enormous amount of energy? No. Earth orbit to escape velocity is in the neighborhood of 10 kWh per kilogram, obviously depending on specifically what orbit you're starting in. __________________ REJ (Robert E Jones) posting anonymously under my real name for 30 years. Make a fire for a man and you keep him warm for a day. Set him on fire and you keep him warm for the rest of his life.
 22nd November 2016, 11:18 AM #129 ServiceSoon Graduate Poster     Join Date: Oct 2007 Posts: 1,311 Originally Posted by Horatius ...But what they don't get is, real scientists don't think that way.... No true Scotsman.
 22nd November 2016, 11:19 AM #130 RecoveringYuppy Philosopher   Join Date: Nov 2006 Posts: 7,264 Originally Posted by dasmiller For the EM Drive thrust levels, how long would the tether have to be at what charge? I haven't done the math (maybe later) but if you're using a typical small spacecraft 28V power system and you wind up with, say, a 0.3 meter tether to get comparable thrust, then the spacecraft's wire harness will likely have more net thrust than your EM Drive. Even if it did wind up to be that large wouldn't there be trivial ways to negate it? Such as routing the wires appropriately? __________________ REJ (Robert E Jones) posting anonymously under my real name for 30 years. Make a fire for a man and you keep him warm for a day. Set him on fire and you keep him warm for the rest of his life.
 22nd November 2016, 12:27 PM #131 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 5,818 Originally Posted by RecoveringYuppy Even if it did wind up to be that large wouldn't there be trivial ways to negate it? Such as routing the wires appropriately? There would be easy ways to reduce it. Whether that's enough depends on the magnitude of the problem. If a "natural" harness (a harness for which magnetic interaction wasn't a consideration) would cause about the same force as the EM Drive, then we could probably knock the harness effect down by 99% without too much trouble (shielding, twisted pairs, etc). But what if the magnetic effect was 1,000,000X the EM Drive? I suspect the shielding won't be anywhere near that good, and at those levels, there are all sorts of small or transient effects that you won't be able to ignore and will probably have a lot of trouble even measuring. There may be other tricks if you specifically designed your spacecraft to minimize magnetic interaction. It's an interesting problem. I'm not an expert in the field, I'm thinking about it more by analogy to RF shielding problems. And I'm no expert in that, either, but worked around it and I've even had to give a few briefings on the subject. __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 22nd November 2016, 12:54 PM #132 ChristianProgressive Graduate Poster   Join Date: Nov 2014 Posts: 1,608 Originally Posted by Tolls Why do they feel that they need to launch something into space to detect this "thrust"? Why do they think it's easier to see this effect up there than down here in a lab under significantly better controlled conditions? One obvious cause would be gravity If the thrust effect is relatively weak, it would be much easier to detect in microgravity. The science of the EM drive just took a significant step upward in credibility with NASA's paper on the drive effect passing peer-review and being published in the American Institute of Aeronautics and Astronautics (AIAA)’s Journal of Propulsion and Power: http://www.dailygalaxy.com/my_weblog...-hea.html#more Abstract here: http://arc.aiaa.org/doi/10.2514/1.B36120
 22nd November 2016, 01:12 PM #133 RecoveringYuppy Philosopher   Join Date: Nov 2006 Posts: 7,264 Originally Posted by dasmiller But what if the magnetic effect was 1,000,000X the EM Drive? I'm thinking it can't be or we'd be seeing satellites wandering away from Earth due to their current wiring. A million times the numbers being reported by NASA for the EmDrive would be very significant. A million times the numbers being reported by the drive "enthusiasts" would be staggering. Links for the numbers I'm about to cite below. Please poke holes. NASA Eagleworks reports 50 to 100 micro-Newtons [ETA: of thrust for the EmDrive variants]. I don't know the mass of the device they are testing but that seems pretty significant for a small device, especially if you let it operate continuously. The most reliable numbers I can come up for how that thrust might affect objects in LEO is station keeping numbers for the ISS. ISS masses 419K Kg. It's station keeping vehicles have, at most, 8000 Newtons of thrust. They operate infrequently, such as a 15-20 minute burn once every 10 to 45 days. If I've done my arithmetic properly that works out to 19 millinewtons per kilogram when the engines are operating. Average over time it then works outs to something around 2 to 10 micro-newtons per kilogram. And that seems to square with some claims I've seen that this device, if real, would make a perfect station keeping engine. So I'm having a hard time understanding why it's certain that a test in space wouldn't be conclusive. It all seems to hinge on whether the test satellite could be in the 10 to ~100 Kg range. And those numbers become more flexible if the test can be conducted at higher altitude. https://en.wikipedia.org/wiki/Intern..._Space_Station https://en.wikipedia.org/wiki/Automa...ansfer_Vehicle https://en.wikipedia.org/wiki/Zvezda_(ISS_module) https://www.nasaspaceflight.com/2012...r-loss-latest/ https://en.wikipedia.org/wiki/RF_res...ics_Laboratory https://en.wikipedia.org/wiki/CubeSat __________________ REJ (Robert E Jones) posting anonymously under my real name for 30 years. Make a fire for a man and you keep him warm for a day. Set him on fire and you keep him warm for the rest of his life. Last edited by RecoveringYuppy; 22nd November 2016 at 01:34 PM.
 22nd November 2016, 02:18 PM #134 dasmiller Just the right amount of cowbell     Join Date: Oct 2008 Location: Well past Hither, looking for Yon Posts: 5,818 Originally Posted by RecoveringYuppy I'm thinking it can't be or we'd be seeing satellites wandering away from Earth due to their current wiring. A million times the numbers being reported by NASA for the EmDrive would be very significant. A million times the numbers being reported by the drive "enthusiasts" would be staggering. Links for the numbers I'm about to cite below. Please poke holes. NASA Eagleworks reports 50 to 100 micro-Newtons [ETA: of thrust for the EmDrive variants]. Fair enough. 1 million times 50 micronewtons would be 50N, and I'm certain that typical spacecraft aren't seeing anything like 50N of magnetic interaction. Or 1N, for that matter. Again, without running the math, I'd guess it's down in the millinewton range. Quote: I don't know the mass of the device they are testing but that seems pretty significant for a small device, especially if you let it operate continuously. The most reliable numbers I can come up for how that thrust might affect objects in LEO is station keeping numbers for the ISS. ISS masses 419K Kg. It's station keeping vehicles have, at most, 8000 Newtons of thrust. They operate infrequently, such as a 15-20 minute burn once every 10 to 45 days. If I've done my arithmetic properly that works out to 19 millinewtons per kilogram when the engines are operating. Average over time it then works outs to something around 2 to 10 micro-newtons per kilogram. And that seems to square with some claims I've seen that this device, if real, would make a perfect station keeping engine. So I'm having a hard time understanding why it's certain that a test in space wouldn't be conclusive. It all seems to hinge on whether the test satellite could be in the 10 to ~100 Kg range. And those numbers become more flexible if the test can be conducted at higher altitude. Bear in mind that in LEO, drag is a significant factor, and it's a proportionately more significant factor on lightweight spacecraft. It's also pretty erratic. ISS is in a relatively high LEO, which helps. But for a very-low-thrust thruster test, I'd definitely want to be at least a few thousand km up. Ideally, I'd want two virtually-identical spacecraft that were starting out in near-identical orbits; each would have an EM Drive and a DummyDrive that consumed the same amount of power and distributed it similarly. I'd have one spacecraft operating the EM Drive and the other running its DummyDrive, and see how the orbits diverged. Then I'd switch 'em, and see it again. etc etc. But that's an expensive test. __________________ "In times of war, we need warriors. But this isn't a war." - Phil Plaitt
 22nd November 2016, 02:44 PM #135 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 Originally Posted by RecoveringYuppy I don't know the mass of the device they are testing but that seems pretty significant for a small device, especially if you let it operate continuously. This seems like something that should be in the published paper, but a quick glance shows that they list the dimensions, but not the mass. __________________ I don't trust atoms. They make up everything.
22nd November 2016, 05:20 PM   #136
RussDill
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Location: Charleston
Posts: 5,426
Great summary. Scott Manley makes all sorts of awesome videos on thrusters.

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__________________
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but i have promises to keep
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And lines to code before I sleep

 22nd November 2016, 08:32 PM #137 Horatius NWO Kitty Wrangler     Join Date: May 2006 Posts: 26,264 Originally Posted by RussDill Great summary. Scott Manley makes all sorts of awesome videos on thrusters. Well, if his Kerbal Space Program videos are anything to go by, I'm convinced! __________________ Obviously, that means cats are indeed evil and that ownership or display of a feline is an overt declaration of one's affiliation with dark forces. - Cl1mh4224rd
 22nd November 2016, 09:36 PM #138 RussDill Philosopher   Join Date: Oct 2003 Location: Charleston Posts: 5,426 Originally Posted by Horatius Well, if his Kerbal Space Program videos are anything to go by, I'm convinced! Check out the science playlist The one about rocking plumbing in particularly interesting. __________________ The woods are lovely, dark and deep but i have promises to keep and lines to code before I sleep And lines to code before I sleep
 23rd November 2016, 01:48 AM #139 Tolls Illuminator   Join Date: Nov 2007 Posts: 3,993 Originally Posted by ChristianProgressive One obvious cause would be gravity If the thrust effect is relatively weak, it would be much easier to detect in microgravity. But you then replace gravity (which is pretty constant down here) with the various other effects we have just been talking about, from drag, to solar rays, to magnetic effects, all of which are nowhere near as constant. Peer review is only the start. It only says "this is not utter garbage"..."there might be something here". Now that it's published we should get to see some interesting reviews, and a better idea of if there is something there.
 23rd November 2016, 03:02 AM #140 Aepervius Non credunt, semper verificare   Join Date: Aug 2003 Location: Sigil, the city of doors Posts: 14,581 Originally Posted by ServiceSoon No true Scotsman. Actually, no. If you go into carrier science, it is to discover new stuff, study the law of nature, and find out more about reality. It is not to nod and agree to old dusty equations. This is really a case where the no true Scotsman is an idiotic fallacy to apply.
 23rd November 2016, 08:08 AM #141 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 So, Eagleworks claim that the drive might work due to pilot-wave theory. I've seen this dismissed as "baloney", but I've not seen any actual counter-arguments. Would anybody who knows more than I do about this like to throw their hat in the ring? __________________ I don't trust atoms. They make up everything.
 23rd November 2016, 09:56 AM #142 TubbaBlubba Knave of the Dudes Moderator   Join Date: Jul 2010 Posts: 12,584 Originally Posted by Squeegee Beckenheim So, Eagleworks claim that the drive might work due to pilot-wave theory. I've seen this dismissed as "baloney", but I've not seen any actual counter-arguments. Would anybody who knows more than I do about this like to throw their hat in the ring? It's solid physics, but fringe such. Pilot wave theory is one of many interpretations of quantum theory. Essentially it says that the Schrödinger equations give the equations of motion for a wave carrying a particle, not the particle itself. It's an example of a hidden variable theory that appears to not violate Bell's inequalities. __________________ "The president’s voracious sexual appetite is the elephant that the president rides around on each and every day while pretending that it doesn’t exist." - Bill O'Reilly et al., Killing Kennedy
 23rd November 2016, 11:04 AM #143 RussDill Philosopher   Join Date: Oct 2003 Location: Charleston Posts: 5,426 Originally Posted by Squeegee Beckenheim So, Eagleworks claim that the drive might work due to pilot-wave theory. I've seen this dismissed as "baloney", but I've not seen any actual counter-arguments. Would anybody who knows more than I do about this like to throw their hat in the ring? afaik, all the current interpretations of QM offer no testable predictions to differentiate between them. They all give the same predicted results of all the experiments we currently can run. So saying that there is some solution in pilot wave theory makes me really skeptical because you should be able to have the same solution using any other QM interpretation. Why pilot-wave specifically? Here's a bit of the skinny: https://en.wikipedia.org/wiki/Pilot_wave Quote: The de Broglie–Bohm pilot wave theory is one of several interpretations of quantum mechanics. It uses the same mathematics as other interpretations of quantum mechanics; consequently, it is also supported by the current experimental evidence to the same extent as the other interpretations. __________________ The woods are lovely, dark and deep but i have promises to keep and lines to code before I sleep And lines to code before I sleep
 23rd November 2016, 01:08 PM #144 Jrrarglblarg Guest   Join Date: Nov 2010 Posts: 12,673 Quote: The de Broglie–Bohm pilot wave theory is one of several interpretations of quantum mechanics. It uses the same mathematics as other interpretations of quantum mechanics; consequently, it is also supported by the current experimental evidence to the same extent as the other interpretations. "Sounds a bit wooish to me." I like replicable results. I like falsifiability. If something here is replicable but unexplained, and currently unfalsifiable math models of reality aren't supplying answers in a replicable manner, then they need to be discarded from this problem. Personally, I assert this finally proves the existence of aether.
 23rd November 2016, 02:38 PM #145 Reality Check Penultimate Amazing   Join Date: Mar 2008 Location: New Zealand Posts: 21,659 What I find slightly dubious in Measurement of Impulsive Thrust from a Closed Radio-Frequency Cavity in Vacuum is Figure 19 in the Synopsis of Experimental Results. They measure the forward and reverse thrust at 3 power settings to get 3 points with error bars that almost overlap. They then apply a linear fit. That implies a bit of confirmation bias, i.e. that the effect is real and will increase with increasing power. However it is just as valid to state that the effect levels off at about 90 μN with increasing power from that data. Which in turn is a hint that the effect is not real. Their "push off vacuum" speculation via pilot-wave theory should have a greater push with more power. __________________ NASA Finds Direct Proof of Dark Matter (another observation) (and Abell 520) Electric comets still do not exist!
 24th November 2016, 02:37 AM #146 Roboramma Penultimate Amazing     Join Date: Feb 2005 Location: Shanghai Posts: 10,439 Originally Posted by Jrrarglblarg "Sounds a bit wooish to me." I like replicable results. I like falsifiability. If something here is replicable but unexplained, and currently unfalsifiable math models of reality aren't supplying answers in a replicable manner, then they need to be discarded from this problem. I'm having a hard time understanding you. What "something" is replicable but unexplained? And what unfalsifiable math models are you referring to? You'll note that the only mathematics referred to was the math of QM. As stated in the post you responded to, pilot wave theory is an interpretation of QM, and thus it's mathematics are identical to all other interpretations of QM. __________________ "... when people thought the Earth was flat, they were wrong. When people thought the Earth was spherical they were wrong. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together." Isaac Asimov
 24th November 2016, 03:10 AM #147 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 Originally Posted by RussDill afaik, all the current interpretations of QM offer no testable predictions to differentiate between them. I think the point is that if the EM Drive does work, then pilot wave theory gives it a mechanism by which it could without violating the known laws of physics, which none of the other interpretations do. So, even if the theory is fringe, if there's no evidence contradicting it, and there is as much evidence supporting it as any other interpretation of quantum mechanics, couldn't the working of the EM Drive (were that ever to be demonstrated) actually count as evidence for the theory? And, if there's no evidence against it and it's just not as popular as the Copenhagen interpretation, then by what reasoning can the suggestion be considered "baloney"? So I suppose what I'm asking is is there anything inherent in pilot wave theory that makes the idea of using the virtual particles of the quantum vacuum as a medium through which to generate thrust a nonsense? Is there any actual evidence (mathematical or experimental) against this idea? __________________ I don't trust atoms. They make up everything.
 24th November 2016, 03:50 AM #148 Roboramma Penultimate Amazing     Join Date: Feb 2005 Location: Shanghai Posts: 10,439 Originally Posted by Squeegee Beckenheim So I suppose what I'm asking is is there anything inherent in pilot wave theory that makes the idea of using the virtual particles of the quantum vacuum as a medium through which to generate thrust a nonsense? Is there any actual evidence (mathematical or experimental) against this idea? It seems to me that the virtual particles that one used to generate thrust would, by virtue of that interaction, become real particles with energy and momentum. Your spacecraft would simply be emitting particles (probably photons?). In which case you've just got a photon drive, not a reaction-less drive. You'd be able to detect the photons (or whatever particles) thus emitted. __________________ "... when people thought the Earth was flat, they were wrong. When people thought the Earth was spherical they were wrong. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together." Isaac Asimov
 24th November 2016, 04:09 AM #149 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 Originally Posted by Roboramma It seems to me that the virtual particles that one used to generate thrust would, by virtue of that interaction, become real particles with energy and momentum. Your spacecraft would simply be emitting particles (probably photons?). In which case you've just got a photon drive, not a reaction-less drive. You'd be able to detect the photons (or whatever particles) thus emitted. Okay, so it seems like it'd be worth them coming up with a protocol to test whether or not it actually does emit particles of some sort. That would go some way towards confirming their hypothesis as to method of action. __________________ I don't trust atoms. They make up everything.
 24th November 2016, 08:03 AM #150 RecoveringYuppy Philosopher   Join Date: Nov 2006 Posts: 7,264 I thought photons had already been eliminated as a possible thrust based on performance being "better" than expected. __________________ REJ (Robert E Jones) posting anonymously under my real name for 30 years. Make a fire for a man and you keep him warm for a day. Set him on fire and you keep him warm for the rest of his life.
 25th November 2016, 06:36 AM #151 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 __________________ I don't trust atoms. They make up everything.
 25th November 2016, 10:17 AM #152 jimbob Uncritical "thinker"     Join Date: Jan 2007 Location: UK Posts: 17,611 Originally Posted by Roboramma It seems to me that the virtual particles that one used to generate thrust would, by virtue of that interaction, become real particles with energy and momentum. Your spacecraft would simply be emitting particles (probably photons?). In which case you've just got a photon drive, not a reaction-less drive. You'd be able to detect the photons (or whatever particles) thus emitted. Yes, and of course, if you are going to use photons, you wouldn't want microwave photons. __________________ OECD healthcare spending Expenditure on healthcare http://www.oecd.org/els/health-systems/health-data.htm link is 2015 data (2013 Data below): UK 8.5% of GDP of which 83.3% is public expenditure - 7.1% of GDP is public spending US 16.4% of GDP of which 48.2% is public expenditure - 7.9% of GDP is public spending
 25th November 2016, 12:55 PM #153 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 I think the idea is that the virtual particles exist long enough to generate thrust before disappearing again. It's a little hard to tell, as even quantum physicists seem to not quite be able to get their heads around what the claim is exactly. __________________ I don't trust atoms. They make up everything.
 25th November 2016, 01:57 PM #154 jimbob Uncritical "thinker"     Join Date: Jan 2007 Location: UK Posts: 17,611 Originally Posted by Squeegee Beckenheim I think the idea is that the virtual particles exist long enough to generate thrust before disappearing again. It's a little hard to tell, as even quantum physicists seem to not quite be able to get their heads around what the claim is exactly. The Casmir effect is real and pretty weird __________________ OECD healthcare spending Expenditure on healthcare http://www.oecd.org/els/health-systems/health-data.htm link is 2015 data (2013 Data below): UK 8.5% of GDP of which 83.3% is public expenditure - 7.1% of GDP is public spending US 16.4% of GDP of which 48.2% is public expenditure - 7.9% of GDP is public spending
 25th November 2016, 02:07 PM #155 Squeegee Beckenheim Penultimate Amazing     Join Date: Dec 2010 Posts: 19,390 I'm pretty sure that it's been shown that the Casmir effect can't actually be responsible for the thrust, although some people certainly claim that it is. I mean, of course, all of this is putting the cart before the horse, rather, since it's not yet been demonstrated that there is any thrust to explain. __________________ I don't trust atoms. They make up everything.
 25th November 2016, 02:25 PM #156 jimbob Uncritical "thinker"     Join Date: Jan 2007 Location: UK Posts: 17,611 Originally Posted by Squeegee Beckenheim I'm pretty sure that it's been shown that the Casmir effect can't actually be responsible for the thrust, although some people certainly claim that it is. I mean, of course, all of this is putting the cart before the horse, rather, since it's not yet been demonstrated that there is any thrust to explain. It doesn't seem to be like the Casmir effect - and indeed, it seems to try violating conservation of momentum, so I doubt there's anything except experimental error __________________ OECD healthcare spending Expenditure on healthcare http://www.oecd.org/els/health-systems/health-data.htm link is 2015 data (2013 Data below): UK 8.5% of GDP of which 83.3% is public expenditure - 7.1% of GDP is public spending US 16.4% of GDP of which 48.2% is public expenditure - 7.9% of GDP is public spending
25th November 2016, 04:19 PM   #157
rjh01
Gentleman of leisure
Tagger

Join Date: May 2005
Location: Flying around in the sky
Posts: 23,599
SciShow Space have just published a youtube that explains all of this in a simple way. Some of it is a repeat of what is in this thread. I think it is well worth a watch.

You need only watch the first 2:30 minutes of it. The rest is on another, equally interesting, subject.

 YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website. I AGREE

 25th November 2016, 04:24 PM #158 RussDill Philosopher   Join Date: Oct 2003 Location: Charleston Posts: 5,426 Originally Posted by Squeegee Beckenheim I think the idea is that the virtual particles exist long enough to generate thrust before disappearing again. It's a little hard to tell, as even quantum physicists seem to not quite be able to get their heads around what the claim is exactly. If that's true, You'd need to be giving them enough energy so that when they recombine, they would emit a pair of photons. These photons would then be the carriers of momentum and you'd likely be at worse efficiency than just a straight photon drive. At least to me, any explanation needs to first explain in what way this is not a free energy device. __________________ The woods are lovely, dark and deep but i have promises to keep and lines to code before I sleep And lines to code before I sleep
25th November 2016, 09:10 PM   #159
Fudbucker
Philosopher

Join Date: Jul 2012
Posts: 7,613
Originally Posted by rjh01
SciShow Space have just published a youtube that explains all of this in a simple way. Some of it is a repeat of what is in this thread. I think it is well worth a watch.

You need only watch the first 2:30 minutes of it. The rest is on another, equally interesting, subject.

 YouTube Video This video is not hosted by the ISF. The ISF can not be held responsible for the suitability or legality of this material. By clicking the link below you agree to view content from an external website. I AGREE
SciShow says "it looks like the technology is legit". I don't remember them as being particularly "out there". Are they right? Is the EM drive actually looking like it might work?

 26th November 2016, 12:45 AM #160 RussDill Philosopher   Join Date: Oct 2003 Location: Charleston Posts: 5,426 Originally Posted by Fudbucker SciShow says "it looks like the technology is legit". I don't remember them as being particularly "out there". Are they right? Is the EM drive actually looking like it might work? This thread holds people with views all across the spectrum. I really think the video gave the whole thing the kid's gloves treatment in order to hop on the hype train. I certainly don't think the majority view of the scientific community is that it's legit. The "maybe pilot wave" thing just raises a whole bunch of red flags with me. It shouldn't matter what QM interpretation you use. If you can get a result with pilot wave theory, you should be able to get the same result with copenhagen. __________________ The woods are lovely, dark and deep but i have promises to keep and lines to code before I sleep And lines to code before I sleep

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