
EmDrive: Nasa paper has finally passed peer review - xbmcuser
http://www.ibtimes.co.uk/emdrive-nasa-eagleworks-paper-has-finally-passed-peer-review-says-scientist-know-1578716
======
yashinm92
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 ()"

~~~
pingec
What is a "Kw" ? Must be a typo?

~~~
dvh
1024 watts

~~~
jschwartzi
You're thinking of the Kiwi, which is a base-2 measurement of watts.

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jsnathan
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_
> 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
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.

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rubyfan
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
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
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.

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dmichulke
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
Couldn't you connect the battery by the cable and get the effect back?

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rrggrr
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)

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wiz21c
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
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.

~~~
davidhyde
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
"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.

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restalis
_" 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.

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amelius
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)

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simcop2387
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.

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cs702
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
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.

------
lumberjack
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
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...](http://www.emdrive.com/FeasibilityStudytechnicalreportissue2.pdf)

~~~
leni536
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
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.

~~~
JonnieCache
I think the issue is that if it were possible to break conservation laws using
such setups, we would have seen nature doing it by now.

~~~
estefan
Perhaps we have:
[https://en.wikipedia.org/wiki/Flyby_anomaly](https://en.wikipedia.org/wiki/Flyby_anomaly)

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

