Reactionless spacedrives... for real?

[Cyborg Girl]

... maybe there is a God.

http://www.wired.co.uk/news/archive/201 ... pace-drive

If this really does pan out, the Universe just got much stranger.

Conservation of momentum is supposed to reflect the invariance of physical laws with respect to space. If you can violate conservation of momentum, that necessitates that physics is not invariant with respect to space.

If this thing actually works, it represents the kind of physics revolution I never dreamed of happening during my lifetime. Oh, and also incidentally a way to colonize the solar system.

I know, I know... Too good to be true. The media is all over it. But still: reproducible, detectable thrust. This could be absolutely amazing.

[SciFiFisher]

Strangely, one of my first thoughts after "Cool Space Drive!!!" was "what would happen if we could get this technology to work in cars, electricity generation, and other power applications." Say goodbye to world dependence on oil.

And hello to a new breed of energy barons. (yes, FZ that's for you )

[Sigma_Orionis]

I'll wait till some engineer produces a practical working prototype (that means one that actually can transport say.... cats) before celebrating, but definitely looks significant.

[The Supreme Canuck]

Yeah, no. I wish it were true, but no. They got thrust out of the test article, sure... but they also got thrust out of a test article modified to not produce thrust.

Smart money's on errors produced by the equipment.

[FZR1KG]

Yeah, no. I wish it were true, but no. They got thrust out of the test article, sure... but they also got thrust out of a test article modified to not produce thrust.

Smart money's on errors produced by the equipment.

rofl

The one thing that is trending the wrong way is error analysis.
I understand sometimes it's hard to do but some of the stuff I've seen hardly mentions errors at all.
Other times the error analysis wouldn't pass a first year physics lab submission.

Instead of putting it on equipment error, I'd throw it back and say the error analysis was incorrect.
One blames an object whose parameters are known and can be factored.
The other blames the person who failed to factor those errors correctly.
And, as everyone knows, all equipment has errors.
No if's or but's. They just need to be calculated correctly, before publishing the results.

[The Supreme Canuck]

Ah, well, that's the other thing - this isn't published research. It's a conference paper, not a peer-reviewed paper. It's just kind of a progress report. More of a "we're working on looking at this thing" than a "we've made a discovery." They're not to the stage where they do rigorous testing and accounting for errors yet.

But try to tell the media that.

[FZR1KG]

Then it isn't even news worthy.
It's junk.

Might as well start reporting stuff about perpetual motion machines because it appears to generate power but we aren't sure because we haven't actually tested it yet...oh wait. Been there done that too. lol

[The Supreme Canuck]

Then it isn't even news worthy.
It's junk.

Exactly. But it's sensational junk - which means it's junk that gets web-hits.

Why post actual news when junk's where the money's at?

[Sigma_Orionis]

Why do I rob banks?

Because that's where they keep the money

And to make it more poignant, it's an apocryphical quote, but it's just too good not to repeat

[SciFiFisher]

But I want my cheap limitless power source now damn it!

[Cyborg Girl]

But I want my cheap limitless power source now damn it!

Umm no. Violating conservation of momentum is crazy, but it's not anywhere in the same league as violating the second law of thermodynamics. One would unseat the foundations of physics, the other would unseat those of statistics.

Edit: NB I am being completely serious here. The first case, reactionless motion, is probably physically impossible. The second case, perpetual motion, is AFAIK mathematically impossible - it's what you automatically get when you have enough particles bouncing around, and overall mass/energy is conserved.

Edit 2: oh wait I see what you did there - throwing out one conservation law (conservation of momentum) puts them all in jeapardy, right?

In any case I'm going to wait before dismissing it immediately because I am not a physicist, and the Universe does have a tendency to throw weird curveballs at us.

[SciFiFisher]

But I want my cheap limitless power source now damn it!

Edit 2: oh wait I see what you did there - throwing out one conservation law (conservation of momentum) puts them all in jeapardy, right?

I see no reason not to throw them all out.

[Sigma_Orionis]

Just click your heels together three times and say..." There's no place like home".

[Swift]

There is a technical discussion about it over at CQ, but the consensus is, as stated here, that it is garbage.

[Cyborg Girl]

Almost a year later:

http://io9.com/new-test-suggests-nasas- ... 1701188933

[T]he EM Drive’s thrust was due to the Quantum Vacuum (the quantum state with the lowest possible energy) behaving like propellant ions behave in a MagnetoHydroDynamics drive (a method electrifying propellant and then directing it with magnetic fields to push a spacecraft in the opposite direction) for spacecraft propulsion.

I'm confused. The claim seems to be that it's yanking virtual particles out of the vacuum, putting in enough energy to make them real, and spewing them out behind. But where would the energy come from? E=mc^2. Microwaves should be a bit weak for doing that, no? And if it were doing that, couldn't they stick a Geiger counter behind it and notice all the little leptons flying around?

[Cyborg Girl]

Update - much better article here:

http://www.nasaspaceflight.com/2015/04/ ... -em-drive/

The simulation for the 100 Watts input power (as used in the latest tests at NASA) predicted only ~50 microNewtons (in agreement with the experiments) using the HDPE dielectric insert, while the 10 kiloWatts simulation (without a dielectric) predicted a thrust level of ~6.0 Newtons. At 100 kiloWatts the prediction is ~1300 Newton thrust.

WTF? Where does all that come from?

[Sigma_Orionis]

Would be nice if they produced an actual Scientific Paper.....

[Swift]

The CQ thread has multiple explanations that I'm not going to bother repeating here.

http://cosmoquest.org/forum/showthread.php?156753-Is-the-EM-Drive-a-warp-bubble-drive&p=2287670#post2287670

Bottom line.. it is still a crock.

[Cyborg Girl]

Well, the paper has arrived, but I'm not seeing it talked about anywhere more credible than Forbes or Medium. (I'm guessing there's a good reason for that.)

https://medium.com/starts-with-a-bang/n ... .ph69uds7x