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New NASA Emdrive paper shows force of 1.2 millinewtons per kilowatt in a Vacuum
- grzm 10y agoI am going to be very happy when I come across an explanation to this that makes sense to me. Certainly interesting stuff, regardless of whether it works. We're going to learn something either way. Yeah, science! </pinkman>
- gaur 10y agoYeah, we're going to learn that some experimenters are sloppy.
- dhdhchdjsnx 10y agoHow many times do these results need to be replicated before you'll believe them? So far the thrust results have been replicated more than the majority of economics and social science research (i.e. more than zero times).
- gilgoomesh 10y agoThe paper itself details a range of mundane error sources (including thermal expansion) that still haven't been ruled out as the cause of the observed thrust.
- witty_username 10y agoIt violates the conservation of momentum; so it needs to replicated many many times.
- StanislavPetrov 10y agoWhat tablet did god write this law on?
- maverick_iceman 10y agoThat is a pretty moronic comment. Go sit in a Physics 101 classroom.
- StanislavPetrov 10y agoThanks for proving my point.
- zeroer 10y agoWell, you're right that it's not a mathematical certainty that momentum is always conserved. But there's such a mountain of evidence for it that we should have a very high bar for claims that it's violated. Thermal effects and measurement error are both likely sources of the discrepancy. But another reason to be skeptical is that Noether's Theorem tells us that a violation of conservation of momentum is only possible if the laws of physics are not translation invariant, and we should be able to use the violation of conservation of momentum to illustrate a specific instance where physical laws are not translation invariant. That would be Earth-shattering. (But not, strictly speaking, impossible)
- out_of_protocol 10y ago... or the law was bypassed, somehow. Also huge news if confirmed
- thescribe 10y agoIt seems to be that extraordinary claims require extraordinary evidence.
- Oletros 10y agoIn a tablet way more powerful than the weak evidence that this drive shows
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- duckingtest 10y agoHow do you know that? Consider a pretty simple and obviously correct device: an electric engine with an internal rotating shaft + a solar panel to power it, floating in space. The faster it rotates, the higher its acceleration in the gravitational field.
- witty_username 10y agoThe engine would spin, but it would have 0 velocity unless it sent out something as exhaust.
- duckingtest 10y agoThat's not how general relativity works. Spinning would increase its energy, hence increasing its gravitational pull, hence accelerating faster.
- witty_username 10y agoBut momentum conservation holds in GR. I don't know GR, but approximately the Earth would also accelerate faster.
- duckingtest 10y agoConservation of momentum only works because the gravitational field itself is supposed to have momentum. Similar to how momentum is conserved for an accelerating paddling boat only if you include the sea. Sea analogy is a good one I think, especially because the gravitational field interacts with itself, like water, contrary to electromagnetic fields. Conservation laws in general are a quirky thing in GR, see: http://people.bu.edu/gorelik/ES_GG_Conservation_Laws.pdf http://people.bu.edu/gorelik/ES_GG_Conservation_Laws.pdf or http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/ http://www.preposterousuniverse.com/blog/2010/02/22/energy-i... for a shorter read >but approximately the Earth would also accelerate faster. Well yes, Earth has a stronger gravitational pull because of rotation. On smaller distances rotation effects become even more interesting: https://en.wikipedia.org/wiki/Frame-dragging https://en.wikipedia.org/wiki/Frame-dragging
- maverick_iceman 10y agoWhile I agree with your statement I derive the opposite conclusion from it. (I.e. these results are certainly false and you can see what that implies about economics and social science.)
- Oletros 10y ago> So far the thrust results have been replicated more than the majority of economics and social science research (i.e. more than zero times). No, they haven't
- StanislavPetrov 10y agoIts amazing to me how many people who purportedly believe in science act more like priests than scientists. Science is about drawing conclusions from empirical data, not ignoring empirical data that doesn't jive with your predetermined conclusions.
- maverick_iceman 10y agoThe science is pretty settled here. No such thing can exist by laws of physics. You might as well try making a perpetual motion machine or homeopathic medicine.
- StanislavPetrov 10y ago>The science is pretty settled here. No such thing can exist... Thanks, this more neatly sums up the attitude I was attempting to describe then anything I could come up with. The hubris that is endemic in much of the "scientific" community is simply amazing. Another glaring example of the gap between education and intelligence.
- Oletros 10y agoExtraordinary claims need extraordinary proof and until now there is no single proof or theory. so yes, it is not hubris, it is science. > Another glaring example of the gap between education and intelligence. Pot kettle?
- EvgeniyZh 10y agoScientific method say that if observation contradicts your theory, then your theory is wrong.
- gus_massa 10y agoOne of the more important things that you learn in a laboratory is that experimental science is hard. There are many source of experimental errors. So it's not enough to have an experimental result, it's necessary to check very carefully the details to be convinced that it breaks the theory. In this case, the problem is that they are measuring a very small force, and many things can cause small forces. So you must be sure that all the other possible small forces sources are under check and that the force you are measuring is created by the method you are trying to measure. In this case, the most obvious candidates for errors are: * Thermal: The device gets very hot, so there may be some thermal expansions and some thermal air currents. * Electromagnetic: They use a lot of current, so the wires that connect the device may be acting as an electromagnet or something. They try to bound this error, but it's very hard to estimated correctly how big each one of them are, and prove that they are smaller than the force they see in the experiment.
- apsec112 10y agoBefore anyone gets too excited, remember that there are hundreds of papers "proving" that humans have psychic powers. http://www.news.cornell.edu/stories/2010/12/study-looks-brains-ability-see-future http://www.news.cornell.edu/stories/2010/12/study-looks-brai...
- EvgeniyZh 10y agoNot by NASA
- Pfhreak 10y agoThe file name is: Q-Thruster In-Vacuum Fall 2015 Test Report.pdf That hardly suggests that there's a new Emdrive paper, and the linked blog doesn't have sufficient detail about the paper to suggest that the paper is new either.
- EvgeniyZh 10y agoThere is PDF file. You can read and check if it's new or not.
- maverick_iceman 10y agoAh, not this again. Just because they are NASA doesn't mean they are immune from pseudoscience.[1][2] [1] http://www.preposterousuniverse.com/blog/2015/05/26/warp-drives-and-scientific-reasoning/ http://www.preposterousuniverse.com/blog/2015/05/26/warp-dri... [2] http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-validate-imposible-space-drive-word/#.VCYphStdU3c http://blogs.discovermagazine.com/outthere/2014/08/06/nasa-v...
- vorotato 10y agoFirstly, warpdrives aren't pseudoscience. The author is not claiming that they presently have a warp-drive. They are merely claiming they have some evidence that one might be theoretically possible. This isn't that inconceivable, sure it might take a thousand years before we could actually implement it. Finally about the "EMDrive" there's no reason to believe that energy isn't escaping it, but that it's doing so in a way that something might be learned outside of imprecise measurements.
- zde 10y agoIt works in practice, but does it work in theory?