10 ms·

EmDrive: Nasa paper has finally passed peer review

87 points by xbmcuser 10y ago

wiz21c 10y ago
FTFA : "The work we're doing is difficult and expensive and the people paying for it don't necessarily want to give it away to the rest of the world, but EmDrive will make a huge impact and a lot of people have thought of a lot of things to apply it to," he said. I hate this world sometimes...
- lutusp 10y ago
  Old-style science is apparently dead. Imagine if Einstein created General Relativity today, but (in keeping with the times and contrary to everything we know about Einstein) realized the commercial potential of the ideas before submitting his paper for publication. Or the quantum theorists of the 1920s -- imagine that they somehow foresaw all the commercial potential of these ideas, before publishing the broad outline of theories that essentially define modern times. This is not to suggest that the EM Drive will necessarily pan out as some of its adherents are claiming, only that the old, pure-research tradition of publishing everything in advance of any consideration of applications seems to be dead.
  - rtpg 10y ago
    The theoretical ideas are still out here. It'd be more if someone figured out a way to do GPS (with relativity issues solved) and decided to keep that secret. Bit of a devil's advocate for patents too. Sure, you can't build the exact same thing for a while, but at least the principles are revealed.
  - davidhyde 10y ago
    Old-style science was not as expensive as new style science. If a team does something for commercial gain then it becomes publically accessible 20 years later when the patents expire. Probably sooner if people ignore the patents or find a way round them. The worst case scenario is that they sit on their invention and do nothing about it. The best case is that they create a new viable industry. Either way, eventually the technology will become available to everyone for free. If there was little incentive to develop these ideas then fewer people would bother and this tech may only have been invented in 100 years time.
    - projct 10y ago
      "it becomes publically accessible 20 years later when the patents expire" I'm about 90% sure this is the opposite of how patents work. You describe the methods in the patent, and in exchange you get to use or license it for the duration of the patent. It's publicly accessible but not usable, which is a useful distinction. Without patents there wouldn't be an incentive to disclose.
  - foobarian 10y ago
    There were many inventors/scientists in that era who developed things in secret or patented the heck out of their work, such as Edison or Tesla. The analogy is not quite right for General Relativity, but this EmDrive thing is not at the same level either.
- pmontra 10y ago
  The approach and the lack of (yet) a convincing theory reminds me of the E-Cat http://www.e-catworld.com/ http://www.e-catworld.com/ In the end what matters most is if they work. For the EmDrive to succeed it's enough to be a better fit for some use cases than other engines.
  - htns 10y ago
    At least E-Cat didn't initially claim to violate any fundamental laws of physics. The unnamed "aerospace company" he says he is working with will never see their money again.
lumberjack 10y ago
OK, I'm officially interested. I'm a physics undergrad. What paper should I be reading that more or less summarizes the mechanism at work?
- rtpg 10y ago
  The EmDrive website (http://www.emdrive.com/ http://www.emdrive.com/) has papers. Quickly flipping through this paper[0], I think it explains the principles. http://www.emdrive.com/FeasibilityStudytechnicalreportissue2.pdf http://www.emdrive.com/FeasibilityStudytechnicalreportissue2...
  - leni536 10y ago
    The theory is simply wrong, it neglects the electromagnetic pressure between the electromagnetic field and the tapered wall of the waveguide, it should produce the missing force component for a net force of 0. It's impossible to arrive at a non-zero net Force with classical electrodynamics. It's theoretically proven that it conserves momentum. Very possible reasons for measuring non-zero force: > Systematic measurement errors. > Leaking EM field carrying momentum. > Energy channel from outside carrying momentum (failing measurements including battery mentioned in comments) Unlikely explanation: All currently used theories of electrodynamics are wrong. But explaining non-zero force from classical ED is simply impossible. Also note that breaking conservation of momentum + relativity means that conservation of energy is broken as well. edit: typo edit 2: I mean the theoretical approach presented in the paper makes obvious mistakes. I'm not arguing that breaking conservation of momentum is impossible (although I think it's really unlikely), I argue that even if it would happen it couldn't be described by classical electrodynamics (or even QED). We would have to come up with better laws for electrodynamics.
    - epicureanideal 10y ago
      This is exactly the kind of comment I would expect to read shortly before some presumed law of the universe were broken. Reminds me of the "maybe in thousands of years people will fly" newspaper comment the same year the Wright brothers flew. I'm not treating it lightly that conservation of energy etc. would be broken. I'm just saying... it's a law until it's discovered that it's not. Or rather, that the law is only applicable within certain conditions, or needs some asterisks on it.
rrggrr 10y ago
Almost as interesting, its reported/discussed that light entering the EmDrive chamber via laser appeared to have travelled superluminally thought to be due to some distortion of the light cone inside the chamber. Thread: http://forum.nasaspaceflight.com/index.php?topic=36313.1860 http://forum.nasaspaceflight.com/index.php?topic=36313.1860
yashinm92 10y ago
TLDR: Now deleted forum comment by a scientist says that the paper "Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum" has passed peer review and will be published in AIAA Journal of Propulsion and Power. A line of text was included that may be from the paper itself: "Thrust data in mode shape TM212 at less than 8106 Torr environment, from forward, reverse and null tests suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/Kw ()"
- varjag 10y ago
  We have an ibtimes post referring a deleted comment on NASAspaceflight forum (not affiliated with NASA). Guess it's best to wait for the actual publication.
- pingec 10y ago
  What is a "Kw" ? Must be a typo?
  - Faaak 10y ago
    I suppose kW ?
  - raverbashing 10y ago
    It's obviously a typo
  - dvh 10y ago
    1024 watts
    - jschwartzi 10y ago
      You're thinking of the Kiwi, which is a base-2 measurement of watts.
- mrfusion 10y ago
  Is that good thrust or not? I don't have a point of reference.
simcop2387 10y ago
Can't wait to get a look at this paper. And the results of reproductions of the experiment that are inevitable. If the result is confirmed, i expect a number of people to really start playing with the shape of things to see if we can get the power to thrust ratio up. It'd be awesome if this could make orbit both energy efficient and environmentally friendly.
amelius 10y ago
See also wikipedia [1]. Most interestingly: > Their design principles are not supported by prevailing scientific theories, apparently violating the law of conservation of momentum; as a result they are controversial. [1] https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster
dmichulke 10y ago
An older discussion on HN about an experiment that was unable to replicate the effect when using batteries https://news.ycombinator.com/item?id=12007877 https://news.ycombinator.com/item?id=12007877
- imaginenore 10y ago
  Couldn't you connect the battery by the cable and get the effect back?
jsnathan 10y ago
I've been doing some reading on this recently, and as far as I understand it, this paper is not going to settle the matter one way or the other. IANAP so take these notes with a grain of salt. There was an experiment done by a Chinese lab a few years ago, which seemed to support the effect, but when they re-did the experiment using an on-board battery instead of a power cable, the effect disappeared. So far noone has publically replicated this condition (i.e. battery instead of power cable), and either confirmed or disconfirmed this null-result, and I do not think this new paper will report any experiments using this condition either. There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup. All in all I think it is going to be years before we know what is what in regards to this technology.
- _pmf_ 10y ago
  > There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup. Wouldn't this have the problem that the object will constantly being hit by particles (and the distribution of particles will not be random) and accelerated by these?
  - LoSboccacc 10y ago
    yes but they can use data from pioneer to correct for it, especially if they are far enough from earth, also if the drive can be cycled, they can measure against the condition at rest.
- DanielBMarkham 10y ago
  "...There are however efforts underway to actually put one of these things into space in the form of a tiny satellite..." Neat. Got a link for that?
  - clouddrover 10y ago
    The Cannae Drive is another implementation of the same idea. They say they'll launch a cubesat in a couple of years to demonstrate the drive. Their website doesn't have much information about it but here are some links: 1. http://cannae.com/cannae-is-developing-a-cubesat-thruster/ http://cannae.com/cannae-is-developing-a-cubesat-thruster/ 2. http://cannae.com/press-release-from-cannae/ http://cannae.com/press-release-from-cannae/ 3. http://cannae.com/cubesat/ http://cannae.com/cubesat/
epalmer 10y ago
I went to the article and got one of those bogus your phone has been infected redirect pages. I am on an Android phone.
deleted 10y ago
[deleted]
rubyfan 10y ago
This paragraph made me laugh. > Eagleworks is an experimental lab that is to Nasa essentially what the secretive Google X "moonshot" R&D lab is to Google/Alphabet So Google is the gold standard for R&D now?
- rl3 10y ago
  Not to mention that NASA made the first ever "moonshot" actually happen. A term that's since been cheapened for the purposes of good PR.
  - soylentcola 10y ago
    That was the bit that made me really facepalm. It's one thing to compare to something more familiar but it's sorta sad when you need to use Google or something like that to explain what a "moonshot program" is in reference to NASA.
  - sharemywin 10y ago
    An Stanford/Thurman not Google created the autonomous car. I don't really call commercializing an existing technology innovation. Don't get me wrong introducing an autonomous vehicle to market will be a great achievement but still not "put people on the moon using a government bureaucracy" kind of jaw dropping.
cs702 10y ago
I opened this ibtimes link with Chrome on an Android phone, and my screen was hijacked by a prize offer, asking me to press OK. I couldn't get rid of it -- not even by stopping and restarting the browser. Finally I stopped Chrome and deleted all its stored data. That worked. Has anyone else experienced the same problem with this link?
- soylentcola 10y ago
  Haven't tested it on Chrome (mobile) but now I'm afraid to. Either way, you might want to look for an adblocker. I know that's the basis of a hundred discussions on this site but I find that the relative intrusiveness compared to the more limited resources of a mobile device make ad blocking even more valuable on mobile than on the desktop much of the time.
restalis 10y ago
"People think it's black magic or something, but it's not. Any physicist worth his salt should understand how it works, or if they don't, they should change their profession." This got me thinking about The Emperor's New Clothes. Be it that I'm not that bright to fully grasp how the RFRCT might actually function, the king is still naked to me.

87 points by xbmcuser 10y ago

FTFA : "The work we're doing is difficult and expensive and the people paying for it don't necessarily want to give it away to the rest of the world, but EmDrive will make a huge impact and a lot of people have thought of a lot of things to apply it to," he said. I hate this world sometimes...

lutusp 10y ago
Old-style science is apparently dead. Imagine if Einstein created General Relativity today, but (in keeping with the times and contrary to everything we know about Einstein) realized the commercial potential of the ideas before submitting his paper for publication. Or the quantum theorists of the 1920s -- imagine that they somehow foresaw all the commercial potential of these ideas, before publishing the broad outline of theories that essentially define modern times. This is not to suggest that the EM Drive will necessarily pan out as some of its adherents are claiming, only that the old, pure-research tradition of publishing everything in advance of any consideration of applications seems to be dead.
- rtpg 10y ago
  The theoretical ideas are still out here. It'd be more if someone figured out a way to do GPS (with relativity issues solved) and decided to keep that secret. Bit of a devil's advocate for patents too. Sure, you can't build the exact same thing for a while, but at least the principles are revealed.
- davidhyde 10y ago
  Old-style science was not as expensive as new style science. If a team does something for commercial gain then it becomes publically accessible 20 years later when the patents expire. Probably sooner if people ignore the patents or find a way round them. The worst case scenario is that they sit on their invention and do nothing about it. The best case is that they create a new viable industry. Either way, eventually the technology will become available to everyone for free. If there was little incentive to develop these ideas then fewer people would bother and this tech may only have been invented in 100 years time.
  - projct 10y ago
    "it becomes publically accessible 20 years later when the patents expire" I'm about 90% sure this is the opposite of how patents work. You describe the methods in the patent, and in exchange you get to use or license it for the duration of the patent. It's publicly accessible but not usable, which is a useful distinction. Without patents there wouldn't be an incentive to disclose.
- foobarian 10y ago
  There were many inventors/scientists in that era who developed things in secret or patented the heck out of their work, such as Edison or Tesla. The analogy is not quite right for General Relativity, but this EmDrive thing is not at the same level either.
pmontra 10y ago
The approach and the lack of (yet) a convincing theory reminds me of the E-Cat http://www.e-catworld.com/ http://www.e-catworld.com/ In the end what matters most is if they work. For the EmDrive to succeed it's enough to be a better fit for some use cases than other engines.
- htns 10y ago
  At least E-Cat didn't initially claim to violate any fundamental laws of physics. The unnamed "aerospace company" he says he is working with will never see their money again.

lumberjack 10y ago

OK, I'm officially interested. I'm a physics undergrad. What paper should I be reading that more or less summarizes the mechanism at work?

rtpg 10y ago
The EmDrive website (http://www.emdrive.com/ http://www.emdrive.com/) has papers. Quickly flipping through this paper[0], I think it explains the principles. http://www.emdrive.com/FeasibilityStudytechnicalreportissue2.pdf http://www.emdrive.com/FeasibilityStudytechnicalreportissue2...
- leni536 10y ago
  The theory is simply wrong, it neglects the electromagnetic pressure between the electromagnetic field and the tapered wall of the waveguide, it should produce the missing force component for a net force of 0. It's impossible to arrive at a non-zero net Force with classical electrodynamics. It's theoretically proven that it conserves momentum. Very possible reasons for measuring non-zero force: > Systematic measurement errors. > Leaking EM field carrying momentum. > Energy channel from outside carrying momentum (failing measurements including battery mentioned in comments) Unlikely explanation: All currently used theories of electrodynamics are wrong. But explaining non-zero force from classical ED is simply impossible. Also note that breaking conservation of momentum + relativity means that conservation of energy is broken as well. edit: typo edit 2: I mean the theoretical approach presented in the paper makes obvious mistakes. I'm not arguing that breaking conservation of momentum is impossible (although I think it's really unlikely), I argue that even if it would happen it couldn't be described by classical electrodynamics (or even QED). We would have to come up with better laws for electrodynamics.
  - epicureanideal 10y ago
    This is exactly the kind of comment I would expect to read shortly before some presumed law of the universe were broken. Reminds me of the "maybe in thousands of years people will fly" newspaper comment the same year the Wright brothers flew. I'm not treating it lightly that conservation of energy etc. would be broken. I'm just saying... it's a law until it's discovered that it's not. Or rather, that the law is only applicable within certain conditions, or needs some asterisks on it.

rrggrr 10y ago

Almost as interesting, its reported/discussed that light entering the EmDrive chamber via laser appeared to have travelled superluminally thought to be due to some distortion of the light cone inside the chamber. Thread: http://forum.nasaspaceflight.com/index.php?topic=36313.1860 http://forum.nasaspaceflight.com/index.php?topic=36313.1860

yashinm92 10y ago

TLDR: Now deleted forum comment by a scientist says that the paper "Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum" has passed peer review and will be published in AIAA Journal of Propulsion and Power. A line of text was included that may be from the paper itself: "Thrust data in mode shape TM212 at less than 8106 Torr environment, from forward, reverse and null tests suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/Kw ()"

varjag 10y ago
We have an ibtimes post referring a deleted comment on NASAspaceflight forum (not affiliated with NASA). Guess it's best to wait for the actual publication.
pingec 10y ago
What is a "Kw" ? Must be a typo?
- Faaak 10y ago
  I suppose kW ?
- raverbashing 10y ago
  It's obviously a typo
- dvh 10y ago
  1024 watts
  - jschwartzi 10y ago
    You're thinking of the Kiwi, which is a base-2 measurement of watts.
mrfusion 10y ago
Is that good thrust or not? I don't have a point of reference.

simcop2387 10y ago

Can't wait to get a look at this paper. And the results of reproductions of the experiment that are inevitable. If the result is confirmed, i expect a number of people to really start playing with the shape of things to see if we can get the power to thrust ratio up. It'd be awesome if this could make orbit both energy efficient and environmentally friendly.

amelius 10y ago

See also wikipedia [1]. Most interestingly: > Their design principles are not supported by prevailing scientific theories, apparently violating the law of conservation of momentum; as a result they are controversial. [1] https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster https://en.wikipedia.org/wiki/RF_resonant_cavity_thruster

dmichulke 10y ago

An older discussion on HN about an experiment that was unable to replicate the effect when using batteries https://news.ycombinator.com/item?id=12007877 https://news.ycombinator.com/item?id=12007877

imaginenore 10y ago
Couldn't you connect the battery by the cable and get the effect back?

jsnathan 10y ago

I've been doing some reading on this recently, and as far as I understand it, this paper is not going to settle the matter one way or the other. IANAP so take these notes with a grain of salt. There was an experiment done by a Chinese lab a few years ago, which seemed to support the effect, but when they re-did the experiment using an on-board battery instead of a power cable, the effect disappeared. So far noone has publically replicated this condition (i.e. battery instead of power cable), and either confirmed or disconfirmed this null-result, and I do not think this new paper will report any experiments using this condition either. There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup. All in all I think it is going to be years before we know what is what in regards to this technology.

_pmf_ 10y ago
> There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup. Wouldn't this have the problem that the object will constantly being hit by particles (and the distribution of particles will not be random) and accelerated by these?
- LoSboccacc 10y ago
  yes but they can use data from pioneer to correct for it, especially if they are far enough from earth, also if the drive can be cycled, they can measure against the condition at rest.
DanielBMarkham 10y ago
"...There are however efforts underway to actually put one of these things into space in the form of a tiny satellite..." Neat. Got a link for that?
- clouddrover 10y ago
  The Cannae Drive is another implementation of the same idea. They say they'll launch a cubesat in a couple of years to demonstrate the drive. Their website doesn't have much information about it but here are some links: 1. http://cannae.com/cannae-is-developing-a-cubesat-thruster/ http://cannae.com/cannae-is-developing-a-cubesat-thruster/ 2. http://cannae.com/press-release-from-cannae/ http://cannae.com/press-release-from-cannae/ 3. http://cannae.com/cubesat/ http://cannae.com/cubesat/

epalmer 10y ago

I went to the article and got one of those bogus your phone has been infected redirect pages. I am on an Android phone.

deleted 10y ago

[deleted]

rubyfan 10y ago

This paragraph made me laugh. > Eagleworks is an experimental lab that is to Nasa essentially what the secretive Google X "moonshot" R&D lab is to Google/Alphabet So Google is the gold standard for R&D now?

rl3 10y ago
Not to mention that NASA made the first ever "moonshot" actually happen. A term that's since been cheapened for the purposes of good PR.
- soylentcola 10y ago
  That was the bit that made me really facepalm. It's one thing to compare to something more familiar but it's sorta sad when you need to use Google or something like that to explain what a "moonshot program" is in reference to NASA.
- sharemywin 10y ago
  An Stanford/Thurman not Google created the autonomous car. I don't really call commercializing an existing technology innovation. Don't get me wrong introducing an autonomous vehicle to market will be a great achievement but still not "put people on the moon using a government bureaucracy" kind of jaw dropping.

cs702 10y ago

I opened this ibtimes link with Chrome on an Android phone, and my screen was hijacked by a prize offer, asking me to press OK. I couldn't get rid of it -- not even by stopping and restarting the browser. Finally I stopped Chrome and deleted all its stored data. That worked. Has anyone else experienced the same problem with this link?

soylentcola 10y ago
Haven't tested it on Chrome (mobile) but now I'm afraid to. Either way, you might want to look for an adblocker. I know that's the basis of a hundred discussions on this site but I find that the relative intrusiveness compared to the more limited resources of a mobile device make ad blocking even more valuable on mobile than on the desktop much of the time.

restalis 10y ago

"People think it's black magic or something, but it's not. Any physicist worth his salt should understand how it works, or if they don't, they should change their profession." This got me thinking about The Emperor's New Clothes. Be it that I'm not that bright to fully grasp how the RFRCT might actually function, the king is still naked to me.