EmDrive

[Rakaydos]

See the Cubesat project. That’s where it will likely be tested first. If a Cubesat can progressively push its orbital periapsis and apoapsis up, that should be sufficient to prove it. That will be the final proofing stage. Unlike other means of propulsion like the solar sail though, the equipment can be tested on the ground before use, and this doesn’t use toxic materials or have extraordinarily high power requirements (can be tested in the 10-20 W range).

That may be, but for OUR kickstarter'd cubesat, I'd prefer to use proven (if still advanced) technoligies to accomplish new feats, instead of squandering kickstarter's money and potentially a LEO ride on a drive system that may still be a hoax. Ion or Electrotether, if not both.

[CaptainArchmage]

That may be, but for OUR kickstarter'd cubesat, I'd prefer to use proven (if still advanced) technoligies to accomplish new feats, instead of squandering kickstarter's money and potentially a LEO ride on a drive system that may still be a hoax. Ion or Electrotether, if not both.

Probably best post this on the cubesat thingy. That sounds reasonable, though I believe we should consider ground-testing (of all the items, if necessary) - we should also look at what we can make ourselves. Off-the-shelf parts for cubesats carry a hefty mark-up from what I’ve seen.

[Aghanim]

Well, according to nasa's abstract, they are going to do independant verifications and tests at other facilities, and they need to devellop automated control systems (they were using manual control sustems)

So, let's wait & see and let experiments do the talking

If they get positive results, they'll try it in orbit sooner or later

NASA nearly tried their quantum thruster in ISS: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110023492.pdf page 6

Note: If clicking it doesn't work try using download link

[brdavis]

OK, not that this needs another opinion, but… as a PhD in physics, i've got to agree with others here. They, strangely, don't seem to know what they are doing in terms of theory. but that in and of itself doesn't bother me - there are plenty of strange (& useful* effects that have been found by experimentalists and only later did theorist try to figure them out. So that's not a fatal problem.

The fatal problems?

1) This seems to contradict a whole lot of known, well-understood science. Basic, basic science. Like conservation of momentum.

2) A "crippled" test device and a "functioning" test device produced the exact same outcome. If so, it would seem they have no idea what's actually required to make this work (if it does).

3) (and this is the point I didn't find in the previous threads), this NASA test (if that's a fair name for it) was conducted in a vacuum chamber… under ambient conditions. In short, in air. It's hardly surprising that when you pump a bunch of EM energy into a gas that the gas might heat up, expanding, pushing on the device… and generating thrust.

It's a poorly designed experiment, with no good theoretical basis, that would seem to contradict long-standing observations. The only thing they seem to have done right is design the test with a "null case", which seems to prove conclusively that the test is flawed.

Testing this on a CubeSat is even tougher. There's actually a lot of ways to produce small accelerations: heating a thin gas in the chamber would work (put a hot plate on the retrograde side of the CubeSat, and you have a thruster in LEO, due to hot gas molecules bouncing off, same as a classic Crookes radiometer). Gas drag as the upper atmosphere inflates/deflates is very tough to estimate (in fact "watching" a CubeSat de-orbit over time is a good way to get a handle on those forces as they change, so to 'test this by CubeSat' you now need two, one with the Magic Drive and one without, but having the same mass, mass distribution, and external shape; the cost of your test just doubled).

Propellent-less drive? let out a long wire from your CubeSat with a hot anode to boil off electrons at the far end, and solar cells on the CubeSat to provide power. Run it along the wire. Simple, easy, low-thrust acceleration (pro or retrograde) with no propellent. And it still won't work for you between planets.

[Nuke]

it comes down to the fact that most of these laws were created by observing material objects in space (newton was looking at apples and planets, not weird quantum particles that dont make much sense) and it later turned out that those same laws apply to non-material things as well. conservation of momentum really boils down to conservation of energy.

when thinking about rockets it pays to think in terms of momentum, because its a simplified understanding that works in the material universe. were throwing atoms out the tail pipe to make these other atoms go in the other direction, ignoring the energy that those particles that make up those atoms posses. but if conservation of momentum comes as a result of conservation of energy, then you get all kinds of fringe scenarios where energy from an external source, say a nuclear reactor, can be converted to kinetic energy with magic, and conservation of energy is going on, while making conservation of momentum look broke.

just because correlation is not causation doesn't mean you cant have a correlation so tight that it looks like causation and because the math worked nobody ever questioned it, at least until nasa checks out a quack machine with positive results. its totally possible that the law can be modified without breaking hundreds of years of scientific progress. its also entirely possible that the law is completely correct and does not need to be re-written, and that us humans are just confused about what it means.

either way something to think about. believing in em drive/qdrive/whatever puts me out of my scientific comfort zone, but that doesn't mean its wrong.

and no im not on anything, though i may have missed my meds today and im a little sleep deprived.

Edited August 2, 2014 by Nuke

[ZetaX]

conservation of momentum really boils down to conservation of energy.

No, it does not. If you think otherwise, you will need to give a deduction of that, which I doubt to exist (for example, only one of the two does not uniquely define how two billiard balls fly apart after a collision).

[CaptainArchmage]

No, it does not. If you think otherwise, you will need to give a deduction of that, which I doubt to exist (for example, only one of the two does not uniquely define how two billiard balls fly apart after a collision).

There is conservation of energy and there is conservation of momentum.

In the Quantum Vacuum Plasma Thruster, momentum is conserved as well as energy - it pushes against virtual particle pairs predicted to exist in quantum mechanics.

[ZetaX]

Your answer has nothing to do with my post, which has nothing to do with QMthrusters, but is obviously a response to what I quoted there.

[vger]

3) (and this is the point I didn't find in the previous threads), this NASA test (if that's a fair name for it) was conducted in a vacuum chamber… under ambient conditions. In short, in air. It's hardly surprising that when you pump a bunch of EM energy into a gas that the gas might heat up, expanding, pushing on the device… and generating thrust.

That doesn't make any sense whatsoever. That's a pretty obvious side-effect to account for, so why would anyone be testing it in air? It wasn't even designed for that.

[M Drive]

My 2 cents about the null experiment. I don't think it can be used as an argument of anything until we find out how it was performed. It could be equally possible that they simply didn't try to 'break' it adequately enough, and got thrust anyway because it was still operational in some way, seeing how no one even seems to know what makes it work. Patience is key here.

As for the experiment it was apparently done with a torsion pendulum. Basically this:

The way it works is one of the weights is a counter-weight, and the other the actual EmDrive. If you get the pendulum to rotate you've detected thrust.

My personal opinion is that it seems pretty hard to accidentally beat one of these tests with a non-mechanical 'reactionless' drive where you have mechanical bits flying around in attempt to somehow move the CG. They'll probably be forced to send one up to space sooner or later, as this is probably the best we can do in terms of rigorousness down here on earth.

Edited August 2, 2014 by M Drive

[Z-Man]

ZetaX: Momentum and energy are linked by Lorentz transformations. If you violate momentum conservation for one observer, you automatically violate conservation of energy from the perspective of another observer moving relative to the first one.

M Drive: One way to accidentally detect thrust with a torsion pendulum is if the device produces a torque. Of course, in a vacuum, that is equally impossible in standard theories, but a magnet will do just that in the geomagnetic field. I'm quite sure they eliminated the possibility of that interfering with the result by shielding/countering the field, though.

[Sky_walker]

That doesn't make any sense whatsoever. That's a pretty obvious side-effect to account for, so why would anyone be testing it in air? It wasn't even designed for that.

Just like it doesn't make any sense to write huge headers in news media about "impossible drive working" while in their experiment non-functional metal box produced exactly the same results as the "drive" they were testing.

Hype in media and on a forums over this whole thing went waaaay over the board.

Edited August 3, 2014 by Sky_walker

[KerikBalm]

It reminds me of the "Arsenic Life" paper - it sounds amazing and like it comes from a reliable source, then once you look carefully at it, you see really shoddy work and no good evidence of the claim.

[vger]

Just like it doesn't make any sense to write huge headers in news media about "impossible drive working" while in their experiment non-functional metal box produced exactly the same results as the "drive" they were testing.

That both labs have gotten the same results now is just bizarre though.

Cold Fusion at least only 'happened' once.

And "non-functional metal box" is probably far too simplified for the control experiment.

Either way I hope this doesn't end up being something we have to wait years for to hear of further tests. The media probably won't even peep about it again, like with the Alcubierre even though more results have come in.

[Nibb31]

It reminds me of the "Arsenic Life" paper - it sounds amazing and like it comes from a reliable source, then once you look carefully at it, you see really shoddy work and no good evidence of the claim.

This seems to be a disturbing trend emerging at NASA these days.

[Albert VDS]

So because it's NASA they can't be allowed to be wrong about new discoveries?

[KerikBalm]

No, because its NASA, we expect proper controls, and the scientific method, not leaping to unfounded conclusions.

Extraordinary claims with extraordinarily bad evidence.

[ZetaX]

You are confusing NASA with journalists.

[jfull]

No, because its NASA, we expect proper controls, and the scientific method, not leaping to unfounded conclusions.

Extraordinary claims with extraordinarily bad evidence.

We aren't really talking about the entire NASA organization here, just a team of researchers under their jurisdiction.

[Wanderfound]

That both labs have gotten the same results now is just bizarre though.

They didn't, though. The thrust reported by the NASA team is much lower than the original version.

My money's on an experimental cockup (for NASA; I wouldn't be shocked to hear that the original was straight up fraud). The dubious result from the control should have been enough to kill any publication at least until it was replicated properly. Science by press release is immensely dodgy; the NASA crew should shortly be receiving a well-deserved spanking.

[Borklund]

This seems to be a disturbing trend emerging at NASA these days.

Two examples in 4 years do not a trend make.

[crazyewok]

No but such a renowned institution should not be jumping the gun. Not on something this controversial.

If it does work then great. Hell I would laugh my butt off.

But likely its a screw up and NASA will just look like fools. And NASA cant afford to look like fools. If they look like imbeciles then funding can get cut.

[Z-Man]

Science by press release is immensely dodgy; the NASA crew should shortly be receiving a well-deserved spanking.

This one not a press release (The arsenic life one was). It's not even a scientific publication. It's a conference paper. Blowing it out of proportion is entirely the fault of the press and enthusiast community.

[Sky_walker]

That both labs have gotten the same results now is just bizarre though.

They did not. One lab registered magnitude(s?) higher "thrust" than the other.

And "non-functional metal box" is probably far too simplified for the control experiment.

They didn't describe the reference device, so it might have been everything: from a metal box with identical size and weight down to the exact same device only with no power applied.

And if that's the case than NASA just discovered an ultimate drive: no power required and yet: produces thrust! Now that's something! Why there's no hype on that?! Cause people don't read and they blindly believe that there is a reason to hype EmDrive.

Either way I hope this doesn't end up being something we have to wait years for to hear of further tests.

I'm afraid we will, cause I very much doubt they'll fund further studies any time soon based on the results of this experiment.

Edited August 4, 2014 by Sky_walker

[Nuke]

No but such a renowned institution should not be jumping the gun. Not on something this controversial.

If it does work then great. Hell I would laugh my butt off.

But likely its a screw up and NASA will just look like fools. And NASA cant afford to look like fools. If they look like imbeciles then funding can get cut.

its a government thing. if nasa spent all its money trying put a giant ball of twine into orbit and only managed to blow it to bits, it would still look less stupid than the rest of the government.