NASA's EmDrive actually works

[Cerebrum123]

I'm open for most things, right now though I suspect that there's a subtle error in their setup which they haven't detected. My other bet was that it was somehow a photon rocket... if it emits microwaves more in one direction than another, that too would produce net thrust.

I've heard about this thing before. Supposedly it's been duplicated at multiple labs around the world. Would be very weird if all the labs had the same error IMO.

[Leonhard]

I've heard about this thing before. Supposedly it's been duplicated at multiple labs around the world. Would be very weird if all the labs had the same error IMO.

For really tiny and hard to measure effects with a lot of media hype surrounding it, that does happen occasionally. The infamous case was Fleischmann nad Pons claim of having caused hydrogen fusion in a simple chemical setup with a Palladium electrode. In their claim it was enough to boil the water in their setup.

Initially there was a flurry of results coming out demonstrating 'anomalous energy production'. Yet various other expected effects were absent: no gamma radiation, and no production of helium-3 isotopes. Eventually the cause of the anomalous energy production was tracked down as being a chemical reaction in the metal, and not a nuclear reaction of the hydrogen.

[rwatts]

It is basically the equivalent of being on a sailboat with a fan blowing into the sail and having it actually work.

It bounces microwaves around in a closed chamber and produces propulsion.

http://www.nasaspaceflight.com/2015/...stic-em-drive/
A group at NASA’s Johnson Space Center has successfully tested an electromagnetic (EM) propulsion drive in a vacuum – a major breakthrough for a multi-year international effort comprising several competing research teams. Thrust measurements of the EM Drive defy classical physics’ expectations that such a closed (microwave) cavity should be unusable for space propulsion because of the law of conservation of momentum.

[ATTACH=CONFIG]6106[/ATTACH]

I love this kind of stuff. Things that sit on the edge and seemingly defy what we think we know. "Electric universe" is another of those ideas that is strangely attractive and would be great if they could defy the odds and prove it.

Does this mean that "Star Wreck" might finally become a reality?

[oxmixmudd]

For really tiny and hard to measure effects with a lot of media hype surrounding it, that does happen occasionally. The infamous case was Fleischmann nad Pons claim of having caused hydrogen fusion in a simple chemical setup with a Palladium electrode. In their claim it was enough to boil the water in their setup.

Initially there was a flurry of results coming out demonstrating 'anomalous energy production'. Yet various other expected effects were absent: no gamma radiation, and no production of helium-3 isotopes. Eventually the cause of the anomalous energy production was tracked down as being a chemical reaction in the metal, and not a nuclear reaction of the hydrogen.

As Cerebrum 123 pointed out, this has been replicated, and now we know whatever they are measuring is not related to being in an atmosphere. And it is NASA and not some guy in a garage doing the experiments. That helps at least provide a margin of legitimacy to the results, at least in my mind. If it works it will lead to more discoveries. But more than that, we need to be willing to give it a chance to be proven one way or the other and not dismiss it because on the surface it doesn't seem possible. I agree though that 'seem' is the operative word. Proposing it works by violating conservation of momentum is silly and should have been the last potential explanation. I don't know why people do silly stuff like that. See if works, then figure out why it works, and only when that is fairly well understood and the violation clearly established do you propose it as a consequence.


Jim

[Leonhard]

As Cerebrum 123 pointed out, this has been replicated, and now we know whatever they are measuring is not related to being in an atmosphere. And it is NASA and not some guy in a garage doing the experiments.

I have not questioned the competancy of NASA in this, but I did say that right now there's a lot of media hype where there should be critical focus. I mean articles are already coming out with designs for spaceships based on drives with this stuff, that's just a little bit premature.

During the Cold Fusion hype, there was a lot of replication, even apparently of isotope production, only later was it determined that there was no cold fusion going on at all, which was already highly unlikely on theoretical grounds. So there's a historical precedens for this.

If it works it will lead to more discoveries.

Lets not be coy. If this thing works, it'll overturn physics as we know it. We can't handwave it away that it somehow pushes against the quantum vacuum (as physically impossible as conservation of momentum violation) It might actually, in fact be the case. If it is, its so earth-shattering, that we ought to be extra careful that something else isn't causing a subtle error.

[Kbertsche]

As Cerebrum 123 pointed out, this has been replicated, and now we know whatever they are measuring is not related to being in an atmosphere. And it is NASA and not some guy in a garage doing the experiments. That helps at least provide a margin of legitimacy to the results, at least in my mind. If it works it will lead to more discoveries. But more than that, we need to be willing to give it a chance to be proven one way or the other and not dismiss it because on the surface it doesn't seem possible. I agree though that 'seem' is the operative word. Proposing it works by violating conservation of momentum is silly and should have been the last potential explanation. I don't know why people do silly stuff like that. See if works, then figure out why it works, and only when that is fairly well understood and the violation clearly established do you propose it as a consequence.


Jim

This sounds intriguing, but I'll bet it ends up having a simple explanation based on classical physics. I am quite sure that it will be found not to violate the conservation of momentum and not to rely on some sort of strange interaction with the quantum vacuum.

Note that it requires a lot of power for a small amount of thrust; it's nowhere close to a "free lunch". I suspect that ion drives would be more practical.

[Truthseeker]

Note that it requires a lot of power for a small amount of thrust; it's nowhere close to a "free lunch".

Nuclear power, e.g., pressurized water reactors?

[Teallaura]

Big hamster wheels for little kids - that'd be enough power for anything!

[Irate Canadian]

Big hamster wheels for little kids - that'd be enough power for anything!

Can they generate 1.21 Gigawatts?

[Pytharchimedes]

Can they generate 1.21 Gigawatts?

Where we are going, we don't need roads.

(metaphorically and allegorically speaking, of course.)

In parentheses, for good measure.

[Teallaura]

Can they generate 1.21 Gigawatts?

You've never been left alone with a few five year olds, have you?

[Leonhard]

Nasa scientists have started to tone the news on this down a bit.

"The reason it's controversial is, it violates Newton's Third Law," Brian Koberlein, an astrophysicist who studies general relativity and computational astrophysics, told Space.com.

It's possible that electromagnetic leaks in the chamber or coupling with Earth's magnetic field are responsible for the supposedly impossible result, said Koberlein, who is based at the Rochester Institute of Technology. But the recent test in the vacuum chamber, if it is indeed valid, does rule out another prosaic explanation — that the engine was pushing against Earth's atmosphere in some way, he added.

...

It's unclear from these forum posts if the prototype propulsion system actually generated any thrust during the recent tests, said Ethan Siegel, a physics and astronomy professor at Lewis & Clark College in Portland, Oregon. Siegel also wrote about the EmDrive in Forbes Magazine, to which he regularly contributes.

Siegel said he is seeing claims of thrust happening just a few times over many tests, with a frequency that is "not inconsistent with random chance." Further, the thrust that was produced in these rare instances was apparently just above the margin of error for measurement, he added. [Gallery: Visions of Interstellar Starship Travel]

"It's tens of micronewtons, less than the weight of a snowflake," Siegel told Space.com. Specifically, Siegel said he is seeing reports of anywhere between 50 and 70 micronewtons. The error bar of measurement, however, is reported as between 15 and 30 micronewtons.

(src: http://www.space.com/29363-impossibl...gine-nasa.html)

[Paprika]

Nasa scientists have started to tone the news on this down a bit.

Looks like another arsenic DNA bacteria.

It's almost as if peer-review isn't important anymore.

[Truthseeker]

Nasa scientists have started to tone the news on this down a bit.


(src: http://www.space.com/29363-impossibl...gine-nasa.html)

The third law is not valid in electrodynamics, a fact that Einstein discussed in Zur Elektrodynamik bewegter Körper
Umm . . . maybe I should rather say that it is not valid in Relativity.

[Leonhard]

The third law is not valid in electrodynamics, a fact that Einstein discussed in Zur Elektrodynamik bewegter Körper
Umm . . . maybe I should rather say that it is not valid in Relativity.

First of all, here a link to an english translation of Eintein's 1905 paper "On The Electrodynamics of Moving Bodies" As anyone can read for themselves, Einstein never proposes that the third law is invalid in Electrodynamics.

Thirdly, momentum is conserved locally (and globally) in the special theory of relativity.