
NASA: EM Drive really does work - finenad
http://www.sciencealert.com/leaked-nasa-paper-shows-the-impossible-em-drive-really-does-work
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thearn4
I'm a researcher working in propulsion technologies at NASA. For what it's
worth, the "Eagleworks" guys at JSC are basically doing their own thing that,
as far as I can tell, is outside of any peer review process. For the life of
me I can't imagine a team at one of the research centers (GRC, LaRC, ARC,
GSFC, JPL) getting away with that.

I'm guessing that they're running off of resources from center-level micro
seedling funding.

On one hand, the effort is probably costing next to nothing in terms of FTE
and procurement. On the other hand, they're giving the public warp-drive level
expectations, when the agency can barely afford to keep the lights on for a
manned spaceflight program.

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kylebenzle
This must mean we are on the verge of a paradigm shift in physics to explain
this wizard free energy bull-shit then.

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lucozade
As far as i understand it, there no free energy being claimed i.e. they still
need to power the drive.

What's being claimed is a drive that creates thrust without a reaction (in the
Newtonian sense). If true, from a physics point of view, this is huge. Less
clear about its immediate practical implications other than it may make a
useful thruster for spacecraft.

To put it in its historical context, its hardly unprecedented that we pass the
bounds where Newtonian physics is an adequate model. It's definitely not the
equivalent of a perpetual motion machine.

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leephillips
Energy-momentum conservation is more fundamental than Newtonian physics. It's
part of the structure of spacetime.

[http://arstechnica.com/science/2015/05/the-female-
mathematic...](http://arstechnica.com/science/2015/05/the-female-
mathematician-who-changed-the-course-of-physics-but-couldnt-get-a-job/)

~~~
lucozade
There's possibly another, more subtle, interpretation.

It may be that the structure of spacetime does not necessarily exhibit this
conservation. However, all scientifically observable phenomenon must, by
definition, exhibit space, time and rotational invariants. Otherwise they
can't be scientifically observable i.e. by repeatable experiments.

From Noether's theorem, this means that the scientifically observable
phenomena must exhibit at least energy, momentum and angular momentum
conservation. Either in the laws that govern the phenomena or the consequences
of a, potentially violating, law that do conserve.

It's an interesting take on the duality, at least it is to me.

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leephillips
I think there are some interesting ideas here, thanks.

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Rooster61
At this point, if the prototypes that are being tested in space really do
produce useful thrust, I couldn't care less what the physics behind it are.

Propellantless propulsion would be a HUGE boon for space travel.

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todd8
A few years ago, before this news of the EM Drive started to appear, I was
contacted by a friend who wanted to introduce me to an "inventor".

This young inventor that had not taken any courses in physics, but believed
that he had invented a mechanical inertial drive mechanism that worked with
rotating wheels and moving rods and weights. He was looking for investors to
fund the construction of the mechanism. I tried to explain that _conservation
of momentum_ meant that his "drive" could not generate any net motion, but he
never accepted my assessment; he kept asking me to explain in detail why this
or that force combined with a rotating pair or arms wouldn't propel a vehicle
forward. I told him that the laws of Newtonian physics would have to be tossed
out if his invention indeed worked; he responded by saying that this is how
scientific revolutions happened.

It was all quite frustrating for both of us and reminded me of seeing a report
on a national news program (NBC) perhaps twenty years ago of a farmer in the
US that had inventing a perpetual motion machine. They showed the complex
machine turning a wheel in the farmer's barn. The reporter was quite excited
by the possibility that this would be the answer to unlimited energy.
Seriously!

Now there is this EM Drive, of which I am naturally skeptical, and no one
seems to be able to explain the experimental results. It's ironic.

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stevarino
"But the team does acknowledge that more research is needed to eliminate the
possibility that thermal expansion could be somehow skewing the results."

So maybe it doesn't really work? I don't see anything substantially new in
this article that the EM Drive community didn't already know.

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andygates
It's another resounding "meh!" as far as measurement goes. And publishing in a
low-impact engineering journal is a bit of a warning flag when they're
proposing exotic new physics.

Prediction: When it's actually published, it's going to be torn apart.

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petters
It would require impressive evidence in order to disprove conservation of
momentum.

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cloudsloth
Forgive me if I'm being obtuse, but can't someone just put am EM drive in
space and see if it goes?

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andygates
Lightsail (which uses regular physics) is doing that, launching a breadbox
sail and a second proximity measuring cubesat along with it.

So there's the challenge of building the space-rated devices, with all the
testing. It's got to have independent power, have a set of tests defining "it
goes" and not, and you've got to consider that LEO isn't really space, it's
freefall in a gravity well and magnetic field with tenuous atmosphere. And
it's expensive!

That will all take a lot of bench testing. So the project needs access to
shielded, vacuum rated facilities, and so on. Testing satellite engine
concepts with a 2D model (effectively a huge air hockey table) is also common.
This would all be done to both build the satellite and to prove the concept.
So they need to do the bench work first.

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Rooster61
> it's freefall in a gravity well

Bit of a nitpick, but this is true of any object in "space", at least on sub-
galactic scales. If it wasn't in freefall around Earth, it would be in
freefall around the Sun, and if not that, the Milky Way.

You are correct about the magnetic field and magnetosphere however.

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Mythanar
The paper the article links to is from 2015. There is no new information here.

