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NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published
- aeleos 9y agoSeems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.
- valarauca1 9y agoChina claims their testing a mock up as one of the experiments being conducted on the Tiangong-2
- simonh 9y agoThat's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.
- Sanddancer 9y agoThose forces are actually pretty well behaved and can be readily measured and accounted for. Also, light sails have a order of magnitude less power, and the Pioneer Anomaly [1] was smaller yet. Space is probably the best place to test something like this. [1] https://en.wikipedia.org/wiki/Pioneer_anomaly https://en.wikipedia.org/wiki/Pioneer_anomaly
- simonh 9y agoThe Pioneer Anomaly was only detectable over several decades and a journey to the furthest reaches of the solar system. I'd expect a useful propulsion system to produce effects quite a bit more detectable than that. This effect is about 1/25 the power efficiency of the lowest power ion thrusters. Output at this level over a very long period might be useful at the interplanetary level and maybe at geostationary altitudes, but the low earth orbit environment is actualy highly variable and unpredictable at this scale of effect.
- consp 9y agoWouldn't variations in atmospheric drag negate any possibility of detecting the actual thrust component in leo? The trusts are small, as is the device, but any variation would be extremely hard to detect and measure. Please correct me if my line of thinking is wrong though, I'm not an aerospace engineer.
- tzs 9y agoCouldn't many of those effects be accounted for by having a non-operating unit in the same orbit as the test unit, and looking for differences in the motion of the two?
- simonh 9y agoYes, all I'm saying is the orbital experiment would have to be well designed. It's not necessarily trivial.
- goodcanadian 9y agoAs always, the relevant XKCD: https://xkcd.com/955/ https://xkcd.com/955/ While I don't really believe it, I am intrigued by the possibility. It has been a long time since we learned anything truly new in physics. The recent breakthroughs (Higgs boson, gravitational waves, for example) were satisfying, but not surprising. I would desperately like to be surprised.
- boyhowdy 9y ago1. studies consistently are showing that this seems to produce thrust without expelling any matter 2. we know that can't be possible I think most people are excited about this not because they think we just proved 2 to be wrong, but instead because we know 2 must be true, so what the hell is going on with 1??? Most likely we will find out that we are NOT violating the known laws of the universe, but we're "not violating" them in a very interesting way.
- goodcanadian 9y agoBy far the most likely scenario is that something subtle but utterly mundane is happening and no useful thrust is actually being produced. You say that: 1. studies consistently are showing that this seems to produce thrust without expelling any matter but this is in fact the first peer reviewed study, so we really only have a sample size of one (not to say other experiments are invalid, just that we have no reason to trust them). Even assuming it is down to subtle experimental error, we may still learn something interesting, of course. Far less likely is that this is actually producing useful thrust, and regardless of how it is doing it, that would be extremely interesting, and in all probability, new physics. Even if true, I don't expect it to completely overturn our understanding of physics, but it would be very exciting.
- Fjolsvith 9y agoHere's another article that proposes to explain why it works: http://aip.scitation.org/doi/full/10.1063/1.4953807 http://aip.scitation.org/doi/full/10.1063/1.4953807
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- saagarjha 9y agoPaper listed in article, https://arc.aiaa.org/doi/10.2514/1.B36120 https://arc.aiaa.org/doi/10.2514/1.B36120, appears to cost well over a thousand dollars to access. I found https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170000277.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/201700... online; I think it's the same thing.
- JohnJamesRambo 9y agoThe first link loaded a PDF for me.
- saagarjha 9y agoAhh, it looks like I didn't notice the PDF link. My mistake.
- MPSimmons 9y agoNovember of 2016
- themeddler 9y agoThis was published November 17, 2016. It's been officially published for several months.
- AndrewDP 9y agoThe quote of interest (being able to be tested in months) references another article where nothing has been committed but could be done in 6 months. On one hand it's great that this is being reviewed and tested. The other hand, that it's not getting properly tested in space where it really can make a difference is somewhat saddening. Can anyone point to a committed space trial?
- clxsi 9y agoIt's in the article. Some skepticism is worthwhile though. http://www.sciencealert.com/the-impossible-em-drive-is-about-to-be-tested-in-space http://www.sciencealert.com/the-impossible-em-drive-is-about...
- AndrewDP 9y agoThe 'commitment' from that article is: "No launch date has been set just yet, but it could happen in as soon as six months' time."
- SomeStupidPoint 9y agoWhy would you test it in space? I'm not sure I understand the reasoning.
- Malice 9y agoThe effects are small enough that there's some possibility that it's just measurement error. If you produce a drive that actually moves something in space, you have a real effect.
- deleted 9y ago[deleted]
- derrickdirge 9y agoSo you know if it works in space.
- 9y ago
- davesque 9y agoWhat ever happened with the German result that showed no thrust when the device was hooked up to an on-board battery?
- stevendhansen 9y agoThere has been some good discussion on Reddit about how the thrust results shown in the paper are still most likely measurement errors due to thermal effects. It is a shame that they haven't released their actual data for independent analysis. Link: https://www.reddit.com/r/Physics/comments/5ewj86/so_nasas_em_drive_paper_is_officially_published/ https://www.reddit.com/r/Physics/comments/5ewj86/so_nasas_em...
- DanielBMarkham 9y agoI've been following along on reddit on several subs, including the EMDrive sub. This is a fascinating study about the politics and social aspect of science -- i.e., how it's actually done. I'm just a layman, but so far it looks like this is experimental error. I never knew there were so many ways to screw something like this up! Having said that, this is a win either way. It teaches all of us about rigorous science, it allows far-fetched ideas to be taken somewhat seriously as long as there is some sort of experimental evidence, and it provides a forum for practicing scientists and interested laymen to cross-pollinate. It's a really good thing. (Only probably no warp drive involved)
- akvadrako 9y agoI agree this incident has educational value, because it's like a toy research project. The science behind the EM drive and the means to understand why it could never work are accessible to laymen who only have to trust our most well-tested physical laws. If you're curious, you can find an easy to understand theory about why breaking the conservation of momentum lets you build a perpetual-motion machine, creating infinite energy. Then, you can find a paper from the inventor of the EM drive explaining why it won't allow that to happen. His explanation spectacularly violates special relatively in a way we could easily detect.
- DanielBMarkham 9y agoYeah, but it's more than just getting the natural laws out and beating people over the head with them -- there's emotional involvement from the public, and that's terrific. For instance, there are quite a few hobbyests that are building their own rigs. There's discussion about noise control, radiation leakage, resonance, and so forth. For the more theory-minded, there's a great discussion about empirical data versus theory, which you allude to. At the end of the day, of course, if you've got data, you've got data. Once the errors are taken out of the system, observation beats theory hands-down. I know scientists would probably much rather have a conversation around "This is science, dang it, go read a book!" but for us layman schmucks, the really cool part is a conversation around "This is why science is what it is" (Note: I'm not addressing you directly. I've just noticed a lot of mockery and impatience from some of the scientific community, and that's a shame. Better to use this as a teaching moment in my opinion)
- Jedd 9y agoNASA has published this paper. These guys presumably know what they're talking about. Moon landing, space shuttle, Voyager, etc. They ran actual experiments on this drive. Why are half the comments here saying 'They must be wrong' - seemingly based on nothing more than a strong belief that NASA must be wrong.
- dnautics 9y agoI'm skeptically optimistic about the em drive (I think it probably doesn't work but the upside is so great it's worth tinkering with)... NASA has been spectacularly wrong in the past. Arsenic life, for example. In many ways the em drive stuff has the same hallmark "press release-driven" science feel to it.
- f4rker 9y agoThis is the worst part of the internet. Amateurs and 2nd year college students dismissing months/years of hard work by actual professionals. They take all this work and "hand wave" it away in less time than it takes to make coffee. The internet is full of amateurs and they are very very confident about their abilities.
- throwanem 9y agoProfessionals don't always get things right, either, and reactionless thrust doesn't really fit into our best current physical model. That doesn't mean it can't exist - but, given the general usefulness of our current model in predicting how things will behave, there's reasonable cause for extraordinary skepticism in response to claims that one of its "can't happen" conditions is inaccurate. Maybe the paper's conclusion is accurate! Maybe this physical "can't happen" actually can, and the model needs extending to account for that. It wouldn't be the first time. But it also wouldn't be the first time that a "can't happen" really can't happen, and the result suggesting otherwise is an artifact of the way an experiment was run, rather than an accurate description of a previously unsuspected physical phenomenon. Going by past examples, the latter is much more likely than the former. So there's nothing unreasonable, even for people like myself who aren't knowledgeable enough to evaluate the paper on its own merits, in reserving credulity until the result is shown by other experimenters to be reproducible.
- buschtoens 9y agoUgh, science alert. sigh