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NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

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Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#31

Post by simonh »

aeleos wrote: post #2

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#32

Post by Sanddancer »

simonh wrote: post #31
aeleos wrote: post #2

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.

Those forces are actually pretty well behaved and can be readily measured and accounted for. Also, light sails have a order of magnitude less power, and the Pioneer Anomaly [1] was smaller yet. Space is probably the best place to test something like this.

[1] https://en.wikipedia.org/wiki/Pioneer_anomaly

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#33

Post by simonh »

Sanddancer wrote: post #32
simonh wrote: post #31

Earlier quoted context omitted.

That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.

Those forces are actually pretty well behaved and can be readily measured and accounted for. Also, light sails have a order of magnitude less power, and the Pioneer Anomaly [1] was smaller yet. Space is probably the best place to test something like this. [1] https://en.wikipedia.org/wiki/Pioneer_anomaly

The Pioneer Anomaly was only detectable over several decades and a journey to the furthest reaches of the solar system. I'd expect a useful propulsion system to produce effects quite a bit more detectable than that.

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.

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#34

Post by the6threplicant »

Fjolsvith wrote: post #19
goodcanadian wrote: post #3

As always, the relevant XKCD: https://xkcd.com/955/ 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.

In case you missed it, the theory behind the EM Drive is also being used to explain galaxy rotation: https://www.researchgate.net/publication/313580454_Low-accel...

Why is it that EM advocates always seem to be dark matter-deniers? There's observational evidence for DM, a lot more than for the EM drive.

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#35

Post by tzs »

simonh wrote: post #31
aeleos wrote: post #2

Seems like the previously leaked 1.2 ± 0.1 mN/kW is true. I look forward to seeing it tested in space to finally see if its real or not.

That's such a tiny thrust it might be quite difficult to measure in space. Orbits are complicated, what with complex gravitational variability of the Earth (mountain ranges, continental shelves, the fact it's not a sphere), the influence of the moon and sun, interaction with the magnetic field, solar winds, and down in low earth orbit even the last vestiges of the atmosphere.

Couldn't many of those effects be accounted for by having a non-operating unit in the same orbit as the test unit, and looking for differences in the motion of the two?

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#36

Post by Cthulhu_ »

SomeStupidPoint wrote: post #20
AndrewDP wrote: post #9

The quote of interest (being able to be tested in months) references another article where nothing has been committed but could be done in 6 months. 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?

Why would you test it in space? I'm not sure I understand the reasoning.

Space is a vacuum and has negligible gravity effects; put it in space, turn on the engine, see what happens. In theory it could propel something to nearly infinite speeds if it checks out.

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#37

Post by FrozenVoid »

Fjolsvith wrote: post #19
goodcanadian wrote: post #3

As always, the relevant XKCD: https://xkcd.com/955/ 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.

In case you missed it, the theory behind the EM Drive is also being used to explain galaxy rotation: https://www.researchgate.net/publication/313580454_Low-accel...

>Hubble-scale Casimir effect Isn't casimir effect very short range phenomenona? Seems like distances involved would reduce it to negligible levels compared with huge EM fields. Its like claiming weak nuclear force is relevant at galactic distances because "all the atoms add up". http://math.ucr.edu/home/baez/physics/Quantum/casimir.html

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#38

Post by phs318u »

the6threplicant wrote: post #34
Fjolsvith wrote: post #19

Earlier quoted context omitted.

In case you missed it, the theory behind the EM Drive is also being used to explain galaxy rotation: https://www.researchgate.net/publication/313580454_Low-accel...

Why is it that EM advocates always seem to be dark matter-deniers? There's observational evidence for DM, a lot more than for the EM drive.

> There's observational evidence for DM

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".

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#39

Post by leni536 »

Fjolsvith wrote: post #19
goodcanadian wrote: post #3

As always, the relevant XKCD: https://xkcd.com/955/ 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.

In case you missed it, the theory behind the EM Drive is also being used to explain galaxy rotation: https://www.researchgate.net/publication/313580454_Low-accel...

I see no connection to the EM drive. The paper you mentioned suggests an alternative inertia formula, however it doesn't break conservation of inertia as far as I can see.

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"?

Re: NASA's Peer-Reviewed EM Drive Paper Has Finally Been Published

#40

Post by Jedd »

NASA has published this paper. These guys presumably know what they're talking about. Moon landing, space shuttle, Voyager, etc. They ran actual experiments on this drive.

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.

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