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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059
Hi.. The lack of reliable replications by reputable scientists suggests to me that the whole thing could unfortunately be measurement error combined with wishful thinking.
Certainly there are a lot of people working on this, but if the effect was this obvious it would have side effects such as affecting inertia locally which simply has not been observed. Also there seems to be no coherent theory on why a simple resonant chamber should have any anomalous thrust, the scaling effect with chamber Q factor is also very suspicious as it would lead to large jumps in efficiency inconsistent with basic thermodynamics and have other detectable side effects we would have detected already.
I do feel sorry for the people who have wasted their time and money on this, but it does suggest that a basic understanding of fundamental laws of physics is evident. A simple balance of forces analysis proves that there is no possibility of generating thrust without reaction mass being expended.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
It's 'technically' already been peer reviewed in Actua Physica which is a Chinese periodical, but it has an impact factor of about 2, so it's not exactly prestigious, and probably not the best peer review in the world.
But yeah, it's very, very likely to be experimental error(s).
It's probably similar to the CERN experiment where they were apparently getting transluminal neutrinos, till they figured out they'd just left the timing cable unplugged slightly.
The thing to look for is when the effect gets stronger with more accurate experiments. With the NASA experiment, the apparent signal strength went down relative to previous experiments.
If the effect was real, the effect should have been much stronger and more obvious with more sensitive experiments.
Right now, it's looking more like pathological science.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
As I understand it, and I don't think the write ups ever offered any real explanation, it's supposed to absorb EM radiation, of many different wavelengths, and 'warm up', then emit 'black body radiation', more in one direction than in others, doe to it's 'waveguide' shape.
Surely we should also consider the basic idea itself, and whether this is possible, and if so, how to construct a 'better designed apparatus' for this purpose?
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
we already have the technology to emit a collimated beam of photons, in whatever direction we want, at high powers, basically a photon rocket. Emitting back body radiation, in one direction, would not improve on that.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
Ash Small wrote ...
As I understand it, and I don't think the write ups ever offered any real explanation, it's supposed to absorb EM radiation, of many different wavelengths, and 'warm up', then emit 'black body radiation', more in one direction than in others, doe to it's 'waveguide' shape.
No, that would be a type of photon rocket; it supposedly wayyyy outperforms a photon rocket.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Well, I think everyone agrees the results aren't accurate. NASA even said there were problems with their setup, but didn't bother to investigate further.
Surely a 'proton rocket' would be worth pursuing anyway, if it's powered by background EM waves in space it will still keep accelerating indefinitely........?
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Ash Small wrote ...
Surely a 'proton rocket' would be worth pursuing anyway, if it's powered by background EM waves in space it will still keep accelerating indefinitely........?
We've already got proton rockets (OK, you need a few neutrons as well to keep the clumps of them stable, and some electrons to keep them overall neutral) and they have a good specific impulse, but the problem is you need a tank of them. Harvesting them from the interstellar medium so you don't need to carry them with you has often been mooted, but it's only pie in the sky at the moment.
We can easily make photon rockets, but their specific impulse is $hite. Shining a LED or a laser out of the back is a lot more practical than heating a conic frustrum waveguide with waste heat and hoping the black body radiation comes out anisotropically. A solar sail gets two momentum exchanges for each photon, and doesn't have to fiddle about with all that energy conversion, but you can't sail into the wind, so to speak.
The EM drive was to improve over the specific impulse of photons by orders of magnitude, it would not have been worth it otherwise.
The EM drive was only ever to be powered by an on-board supply, RTG or PV. Once you are asking to harvest the background EM of space, then we are even deeper into tin-foil-hat territory than the EM drive itself. Keep a grip! Mechanism creep is a sure sign of dodgy methodology.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I still argue that in order to travel any 'significant' distance in space, it doesn't make any sense trying to carry enough fuel fo the whole journey, and that you need to harvest energy on the way. Background radiation, of one sort or another, is there in abundance.
Of course, time scales will be far longer than we can imagine, but they would be in order to travel any 'significant' distance in space, anyway.
Registered Member #2529
Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600
Dr. Slack wrote ...
Ash Small wrote ...
Surely a 'proton rocket' would be worth pursuing anyway, if it's powered by background EM waves in space it will still keep accelerating indefinitely........?
We've already got proton rockets (OK, you need a few neutrons as well to keep the clumps of them stable, and some electrons to keep them overall neutral) and they have a good specific impulse, but the problem is you need a tank of them. Harvesting them from the interstellar medium so you don't need to carry them with you has often been mooted, but it's only pie in the sky at the moment... Once you are asking to harvest the background EM of space, then we are even deeper into tin-foil-hat territory than the EM drive itself. Keep a grip! Mechanism creep is a sure sign of dodgy methodology.
Actually, that's how some current drives work.
They harvest EM fields for energy and then electromagnetically emit protons and neutrons at extremely high speed to get good specific impulse.
They're called ion drives, and the device for harvesting EM fields is called a 'solar panel'
Neat, huh? ;)
Trouble is, the EM fields become very rarified in the interstellar medium.
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Is EmDrive actually just gibberish?
