TLDR: Now deleted forum comment by a scientist says that the paper "Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum" has passed peer review and will be published in AIAA Journal of Propulsion and Power. A line of text was included that may be from the paper itself: "Thrust data in mode shape TM212 at less than 8106 Torr environment, from forward, reverse and null tests suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/Kw ()"
Depends on how well does it scale; here is some back of the envelope math:
If we take a Topaz reactor design and build a spacecraft say 10 times bigger than new horizons this gives us a mass of 5000 Kg.
We'll dedicated 2000 of those to the reactor and fuel, and 2000 of those to the instrumentation (this alone is 5 times the dry mass of New Horizons) and 1000 KG for the platform/chassis.
A Topaz reactor weighs around 300KG, let's say ours weights 500 because we want to be able to swap fuel in and out and we want to make sure it generates 5KW of power.
It can operate for about 5 years on 15 KG (12 in the original design) of fuel which in this case is UO2 gas (spent fuel might be used as propellant so we might be able to have a secondary Ion drive cycle to maximize the thrust we get but won't use that in our calculations) this means we have fuel for 100 years.
4 of our 5KW would be dedicated to our propulsion system which would give us a ~4.8N of force which at a mass of 5000KG means we get 0.00000096 m/s2 of acceleration.
Given V=V0 + at after one year or 31622400 seconds accelerating at 0.00000096 m/s2 we'll have a velocity of 30.357504 m/s after 50 years our velocity would be 1517 m/s or about 10% of Voyager 1 and 2.
So yeah not so great unless we can scale it much much better, that said if we do figure out the physics behind it we might be able to design more efficient emitters with considerable better thrust to power ratio.
I've been doing some reading on this recently, and as far as I understand it, this paper is not going to settle the matter one way or the other. IANAP so take these notes with a grain of salt.
There was an experiment done by a Chinese lab a few years ago, which seemed to support the effect, but when they re-did the experiment using an on-board battery instead of a power cable, the effect disappeared.
So far noone has publically replicated this condition (i.e. battery instead of power cable), and either confirmed or disconfirmed this null-result, and I do not think this new paper will report any experiments using this condition either.
There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup.
All in all I think it is going to be years before we know what is what in regards to this technology.
> There are however efforts underway to actually put one of these things into space in the form of a tiny satellite, and see if any thrust is produced there, which seems like the perfect experimental setup.
Wouldn't this have the problem that the object will constantly being hit by particles (and the distribution of particles will not be random) and accelerated by these?
yes but they can use data from pioneer to correct for it, especially if they are far enough from earth, also if the drive can be cycled, they can measure against the condition at rest.
The Cannae Drive is another implementation of the same idea. They say they'll launch a cubesat in a couple of years to demonstrate the drive. Their website doesn't have much information about it but here are some links:
That was the bit that made me really facepalm. It's one thing to compare to something more familiar but it's sorta sad when you need to use Google or something like that to explain what a "moonshot program" is in reference to NASA.
An Stanford/Thurman not Google created the autonomous car. I don't really call commercializing an existing technology innovation. Don't get me wrong introducing an autonomous vehicle to market will be a great achievement but still not "put people on the moon using a government bureaucracy" kind of jaw dropping.
Almost as interesting, its reported/discussed that light entering the EmDrive chamber via laser appeared to have travelled superluminally thought to be due to some distortion of the light cone inside the chamber.
"The work we're doing is difficult and expensive and the people paying for it don't necessarily want to give it away to the rest of the world, but EmDrive will make a huge impact and a lot of people have thought of a lot of things to apply it to," he said.
At least E-Cat didn't initially claim to violate any fundamental laws of physics. The unnamed "aerospace company" he says he is working with will never see their money again.
Old-style science is apparently dead. Imagine if Einstein created General Relativity today, but (in keeping with the times and contrary to everything we know about Einstein) realized the commercial potential of the ideas before submitting his paper for publication.
Or the quantum theorists of the 1920s -- imagine that they somehow foresaw all the commercial potential of these ideas, before publishing the broad outline of theories that essentially define modern times.
This is not to suggest that the EM Drive will necessarily pan out as some of its adherents are claiming, only that the old, pure-research tradition of publishing everything in advance of any consideration of applications seems to be dead.
Old-style science was not as expensive as new style science. If a team does something for commercial gain then it becomes publically accessible 20 years later when the patents expire. Probably sooner if people ignore the patents or find a way round them. The worst case scenario is that they sit on their invention and do nothing about it. The best case is that they create a new viable industry. Either way, eventually the technology will become available to everyone for free. If there was little incentive to develop these ideas then fewer people would bother and this tech may only have been invented in 100 years time.
"it becomes publically accessible 20 years later when the patents expire" I'm about 90% sure this is the opposite of how patents work. You describe the methods in the patent, and in exchange you get to use or license it for the duration of the patent. It's publicly accessible but not usable, which is a useful distinction. Without patents there wouldn't be an incentive to disclose.
The theoretical ideas are still out here. It'd be more if someone figured out a way to do GPS (with relativity issues solved) and decided to keep that secret.
Bit of a devil's advocate for patents too. Sure, you can't build the exact same thing for a while, but at least the principles are revealed.
"People think it's black magic or something, but it's not. Any physicist worth his salt should understand how it works, or if they don't, they should change their profession."
This got me thinking about The Emperor's New Clothes. Be it that I'm not that bright to fully grasp how the RFRCT might actually function, the king is still naked to me.
> Their design principles are not supported by prevailing scientific theories, apparently violating the law of conservation of momentum; as a result they are controversial.
Can't wait to get a look at this paper. And the results of reproductions of the experiment that are inevitable. If the result is confirmed, i expect a number of people to really start playing with the shape of things to see if we can get the power to thrust ratio up. It'd be awesome if this could make orbit both energy efficient and environmentally friendly.
I opened this ibtimes link with Chrome on an Android phone, and my screen was hijacked by a prize offer, asking me to press OK. I couldn't get rid of it -- not even by stopping and restarting the browser. Finally I stopped Chrome and deleted all its stored data. That worked.
Has anyone else experienced the same problem with this link?
Haven't tested it on Chrome (mobile) but now I'm afraid to. Either way, you might want to look for an adblocker. I know that's the basis of a hundred discussions on this site but I find that the relative intrusiveness compared to the more limited resources of a mobile device make ad blocking even more valuable on mobile than on the desktop much of the time.
I've followed the topic on Reddit for quite a while. You won't find the mechanism because no real working theory exists why this effect might be real. There are a few theories floating, but none of the stood the test of scientific inquiry.
Current state is still at the stage to prove without doubt that the effect is real. Nobody demonstrated it so far with high enough signal to noise ratio.
The EmDrive is not a real thing with a high certainty.
> What paper should I be reading that more or less summarizes the mechanism at work?
As to the NASA paper, it's yet to be published according to the linked article, but publication is imminent. And the mechanism is not clear, only the measurement (which remains a topic of debate).
The possibility remains, because of the small size of the effect being measured, that it has a pedestrian explanation, not new physics. It's essential to keep this in mind.
The theory is simply wrong, it neglects the electromagnetic pressure between the electromagnetic field and the tapered wall of the waveguide, it should produce the missing force component for a net force of 0.
It's impossible to arrive at a non-zero net Force with classical electrodynamics. It's theoretically proven that it conserves momentum.
Very possible reasons for measuring non-zero force:
> Systematic measurement errors.
> Leaking EM field carrying momentum.
> Energy channel from outside carrying momentum (failing measurements including battery mentioned in comments)
Unlikely explanation: All currently used theories of electrodynamics are wrong.
But explaining non-zero force from classical ED is simply impossible.
Also note that breaking conservation of momentum + relativity means that conservation of energy is broken as well.
edit: typo
edit 2:
I mean the theoretical approach presented in the paper makes obvious mistakes. I'm not arguing that breaking conservation of momentum is impossible (although I think it's really unlikely), I argue that even if it would happen it couldn't be described by classical electrodynamics (or even QED). We would have to come up with better laws for electrodynamics.
This is exactly the kind of comment I would expect to read shortly before some presumed law of the universe were broken. Reminds me of the "maybe in thousands of years people will fly" newspaper comment the same year the Wright brothers flew.
I'm not treating it lightly that conservation of energy etc. would be broken. I'm just saying... it's a law until it's discovered that it's not. Or rather, that the law is only applicable within certain conditions, or needs some asterisks on it.
Maybe that's how the universe came into existence at all, is "breaking the law" of conservation of energy? I'm not even arguing this, I'm just saying maybe we haven't been looking at things the right way or the proof will be obvious after we know about a new effect.
That's not what the comment addresses. Could the current theory be wrong? Sure. But any explanation within the current theory is someone doing math incorrectly.
There were a fuckton of people who thought heavier than air flight was not possible until it was done. Not sure how they reconciled birds, but that was a common opinion even among scientists at the time
The fact that several teams of very highly qualified physicists bothered to look at it makes me believe the physics involved is non-obvious and can't be written off with a simple "the theory is simply wrong". Dismissing it out of hand does a disservice to all those people.
That's not to say it'll prove to be true, I doubt it will, but this is something that has so much potential it's worth investigating the tiny possibility that it's real, and "all currently used theories of electrodynamics are wrong", just in case.
If the waveguide boils at a certain rate at certain power levels, then it should be possible to estimate how much force this would produce. If that force is on the same order, then it's likely the reason for what we're seeing.
> Dismissing it out of hand does a disservice to all those people.
Or maybe they all know its impossible, but continue because they are perfectly happy with the amount of funding thrown at them. Not saying it's true, but it's the other side of the coin.
Has anyone bothered to write your counterargument in more detail?
I think I understand your argument but I wonder if anyone's really done the calculation... though I suppose the conservation of momentum itself a theoretical proof that the "other forces" have to cancel out.
Is it possible that classic electrodynamics are not wrong, but there's some other fundamental thing in play here? I'd be a bit surprised, given that this just seems to be such a simple setup, but maybe? One can dream....
i'm waiting for a cubesat(-ish craft) with the device attached so NORAD or whoever can measure how orbital elements change over time, or more likely not.
