NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published(sciencealert.com) |
NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published(sciencealert.com) |
Link: https://www.reddit.com/r/Physics/comments/5ewj86/so_nasas_em...
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)
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.
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.
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?
http://www.sciencealert.com/the-impossible-em-drive-is-about...
I'm not sure I understand the reasoning.
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.
The internet is full of amateurs and they are very very confident about their abilities.
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.
The internet is full of amateurs and they are very very eager to point out when they are not fully grasping something, in one way or another.
AFAIK it is research from their fringe science labs.
Nothing more than a strong believe?
Extraordinary claims need extraordinary proof and the paper doesn't have too much quality regarding the data.
I'm sure even NASA has there fair share of cranks.
Chances are that this is just experimental error. But part of me really wants this to be true. That it's possible some crack pot shoved some microwaves in a tin can and created a device that may reveal a new phenomenon.
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.
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.
Nope, others have been unable to reproduce their results. As for Eagle Works ... their data is crap. The paper consists of 18 data points and large amounts of variance. The largest thrust measurement comes from the middle power setting.
Furthermore, they are measuring (at most!) 120 micro-newtons of thrust. Someone correct me if I am wrong, but that's ~1/100 the weight of a penny[0]. Even if they can produce these tiny amounts of of thrust reliably, they still need to eliminate other sources of error.
Other false-positive results of similar devices have either generated thrust in the null condition or were later retracted after correcting for measurement error.
>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???
The EM drive literally entails perpetual motion. We know that's impossible, yet someone always manages to sell a new version of it every few years.
>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.
There is a reason this is in a journal dedicated to publishing experimental results from aerospace engineers and not a physics journal. Peer review isn't magic, it just means two out of three people signed off on a paper being published.
[0]: Seems crazy small, math may be wacky off due to lack of sleep.
Most likely is still some sort of experimental error. I'd like it to be real but there is still tonnes of room for skepticism.
https://www.researchgate.net/publication/313580454_Low-accel...
The "theory behind the EM drive" [1] is completely based on classical electrodynamics and therefore it's flawed. Classical electrodynamics conserves momentum and energy. It doesn't mean that the EM drive can't work though, it just means that this theory can't work.
[1] I only found this: http://www.emdrive.com/theorypaper9-4.pdf
Is this what you refer as the "theory behind the EM Drive"?
Is there a consensus on this interpretation v. "just adding more dark matter"?
Some of the most sensible comments I've seen here have basically said 'It seems to violate what we know of physics, so hopefully it's right and we have some interesting times ahead'.
It's the dismissal, out of hand, after a relatively extensive amount of research and study -- especially compared to what the armchair critics can supply -- that I find frustrating.
Yeah, sure, I get that it seems implausible, but it transcends hubris to know that it's simply experimental error.
[0]: https://tu-dresden.de/ing/maschinenwesen/ilr/rfs/ressourcen/...
Absolutely, I'd be surprised if it wasn't happening already, within nasa and around the world. I'm guessing they're being a lot more thorough though, controlling for more variables and trying more permutations (different engine sizes, different materials, etc) to try to either isolate the cause or to rule some out. I'd suspect anything less would risk the experimenters being labeled as cranks, that's why we're not seeing direct replication efforts.
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.
Um. Isn't that a contradiction in terms? By definition, DM is stuff whose existence is inferred by observations that contradict what we previously presumed to know. Hence postulate the existence of DM to close the gap between what we observe and what we "know".
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)
But how do you go about distinguishing signal from noise? That's ultimately the reason data say far less, on their own, than they seem to: because interpretation of data is at least as important as how you collect them, but interpretation brings in all the gooey things people really want to wish away. Or put more bluntly, observation can't "beat" theory, because theory is the way you decide which observations to make, how to carry out those observations, and how to understand the products of the observation. Theory and observation are inseparable; in a sense, all observation is at once theoretical, and all theory is at once observational.
But it seems that not all errors have not been taken out of the system
This reminded me of https://xkcd.com/1758/
Well the universe was created, so that seems to imply the energy can be created. We don't know that energy can't be created, just that the current laws of the universe don't allow for it, as far as we know.
Not that I believe this will violate that law in anyway. Even if the drive turns out to be real I suspect it will be something like photon entanglement, where it appears data is travelling faster than light but it's in no way helpful.
The only way it could be Perpetual motion I can see is if I could somehow generate 1KW with that 1.2milinewtons which would be science fiction.
You can create infinite energy by placing a bunch of drives on the spokes of a huge flywheel.
See this paper for a more detailed answer:
> When relativistic effects are taken into account, it is shown that the photon rocket can only reach energy breakeven as the accelerated mass asymptotically approaches the speed of light. Thus, any device with a thrust-to-power ratio greater than the photon rocket would be able to operate as a perpetual motion machine.
A photon rocket is 3.3 μN/kW, thus the EM drive is too efficient.