New Test Supports NASA's Controversial EM Drive 480
An anonymous reader writes: Last year, NASA's advanced propulsion research wing made headlines by announcing the successful test of a physics-defying electromagnetic drive, or EM drive. Now, this futuristic engine, which could in theory propel objects to near-relativistic speeds, has been shown to work inside a space-like vacuum. NASA Eagleworks made the announcement quite unassumingly via NASASpaceFlight.com. The EM drive is controversial in that it appears to violate conventional physics and the law of conservation of momentum; the engine, invented by British scientist Roger Sawyer, converts electric power to thrust without the need for any propellant by bouncing microwaves within a closed container. So, with no expulsion of propellant, there’s nothing to balance the change in the spacecraft’s momentum during acceleration.
I want this to be true, but... (Score:5, Insightful)
I want a non-Newtonian drive as much as any other nerd out there, but it's still more probable that (assuming it works) it uses conventional physics, just in ways they haven't figured out yet.
That said, I think this result is the point where NASA, DOD, Lockheed Martin, Boeing et al should turn on the money spigot for research. There's obviously something going on, even if it's just conventional physics in unexpected ways. And on the odd chance it *is* new physics, the results could change the world.
Re: (Score:3, Insightful)
That said, I think this result is the point where NASA, DOD, Lockheed Martin, Boeing et al should turn on the money spigot for research. There's obviously something going on, even if it's just conventional physics in unexpected ways. And on the odd chance it *is* new physics, the results could change the world.
The original "result" would never have made it past peer review and the people pushing it knew it. Their experimental methods had a ton of holes in it (as many people pointed out), and they didn't even have a theoretical basis for why it would work really (the supposed explanation based on White's quantum woo got torn apart by theorists). So they never even tried to publish - the most they did was talk about it at a conference.
This new "result" comes from a post on an internet forum. I'm a bit skeptical
Re: (Score:2)
Well, we know that conventional physics doesn't cover everything, obviously. I'm pretty skeptical of this myself, but I'm reserving my opinion.
Virtual particles are definitely not a fringe understanding of the quantum mechanical realm, but they've always been representative of something... well... virtual. They would be generally expected to cancel out at macro scales. The only example I've heard of where they don't is Hawking radiation, and that's only because of the very specific consequences of anythin
Re:I want this to be true, but... (Score:5, Funny)
In case you haven't seen it yet... [xkcd.com]
Where we need to get to call this real (Score:2)
Before we call this real, we need to put one on some object in orbit, leave it in continuous operation, and use it to raise the orbit by a measurable amount large enough that there would not be argument regarding where it came from. The Space Station would be just fine. It has power for experiments that is probably sufficient and it has a continuing problem of needing to raise its orbit.
And believe me, if this raises the orbit of the Space Station they aren't going to want to disconnect it after the experim
Re: (Score:3)
Before we put it on the ISS, let's start by putting one on a cheap metal box with some dumb sensors and communication equipment on it. I'd rather test this on something that doesn't have somebody living in it.
Re:I want this to be true, but... (Score:5, Interesting)
Re:I want this to be true, but... (Score:5, Informative)
100KW is the theoretical energy that you might be able to make a deep-space craft out of with this drive. The power it's been tested with so far is three orders of magnitude lower.
BS. That most certainly does not "stand to reason". Higher-energy photons have more momentum, not less, yet this thing uses microwaves (much lower energy than visible light) and gets orders of magnitude more thrust than could be explained by the quite-well-understood thrust from EM radiation. Besides, why would there be a net thrust in one direction? The microwaves should escape the cavity in all directions, not just out the back, if they're escaping at all. A light drive has to be open at the back, or the photons would bounce off the rear wall and counter the thrust they imparted to the ship by bouncing off the reflector around the emitter.
Re: (Score:3, Informative)
"After consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China – at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions – the question of where the thrust is coming from deserves serious inquiry."
It produces much more thrust than it should if it were just the effect of shooting microwaves.
Re:I want this to be true, but... (Score:5, Informative)
No, it is a violation of physical law, just not the ones you're thinking of.
We're talking about the law of conservation of momentum here. It isn't the microwaves. We know the energy-to-momentum ratio of photons, and the reason using photons for thrust is impractical is that the momentum is far too small for given energy. TFA says this looks far more powerful than a light drive.
A pity that you made no effort to understand what laws of physics it's appearing to break.
To answer my own questions. (Score:3)
I can attest that it is not thermal. It works in a vacuum. It works in a Faraday cage and it works when you reverse the device (the thrust reverses).
Re: (Score:2)
The problem is that the measured thrust is greater than that model would provide. And if that model would need to be revised we'd have a fucking huge problem on our hands :P
But until the experiment have been reproduced by others the safe bet is some measurement/calculation error. Hope I'm wrong though...
Re: (Score:3)
The order of magnitude isn't actually the weird part. It's the "without propellant" part, or the "but the back is closed" (this thing produces infinite orders of magnitude more force than you'd get out of a photon drive with nowhere for the photons to escape, yet the microwaves are emitted into a sealed chamber).
Basically, it appears to be reactionless. All other propulsion systems are reaction based. When walking, your feet push on the ground; ground goes one way and you go the other. When sailing, your sa
inventor? (Score:2)
Re: (Score:3)
[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.
So the recent test was trying to replicate the results in a vacuum to eliminate some unknown other factor as the explanation.
Re: (Score:2)
due to the Quantum Vacuum (the quantum state with the lowest possible energy)
Does the battery look like a melted Tiffany lamp?
Re:inventor? (Score:5, Interesting)
If nobody knows how it works, how did the guy invent it?
Just like penicillin.
Re: (Score:2)
If nobody knows how it works, how did the guy invent it?
LOTS of stuff gets invented without the inventor knowing HOW it works, underlying physics wise. All that's necessary is to notice THAT it works, work out some details of "if you do this much of this you get that much of that", and engineer a practical gadget.
As they say, most fundamental discoveries don't go "Eureka!", they go "That's odd ..."
Conservation of momentum (Score:2)
Re: (Score:3)
Any light bulb and mirror can create momentum, with no propellant expended. SF writers have known for a long time that, in principle, electromagnetic effects like powerful lasers can create thrust.
By expelling photons, which are then acting as a propellant.
--
JimFive
Re: (Score:2)
No, but we do know the momentum of photons having a given energy, and we're talking about a lot more apparent momentum change than can be accounted for by the energy used.
Re:Conservation of momentum (Score:4, Informative)
Leaving aside the fact that light has momentum and therefore is sufficiently "physical" a propellant for this example, and the fact that this thing produces orders of magnitudes more thrust than a few Watts worth of photons could impart, you're still missing a really key problem:
You can impart momentum on a mirror by shining a flashlight on it, but you can't impart momentum on a sealed box by having a lit flashlight *inside* it!
The EmDrive uses a sealed cavity. There's nowhere for any propellant to come out, even if there were any!
A perfect combination (Score:5, Funny)
They say one of the limiting factors (aside from violating the laws of physics) is the political will to launch a large nuclear power plant into space. The solution is obvious: use Cold Fusion to power the EM drive. There is great efficiency here because they can get two Nobel prizes with only one gadget.
A lovely summary from StackExchange (Score:5, Informative)
A lovely summary from the Physics StackExchange which sums up my thoughts:
"The initial tests were at atmospheric pressure. To test the fan hypothesis, an easy way is to vary the pressure, another easy way is to put dust in the air to see the air-currents. The experimenters didn't do any of this (or at least didn't publish it if they did), instead, they ran the device inside a vacuum chamber but at ambient pressure after putting it through a vacuum cycle to simulate space. This is not a vacuum test, but it can mislead one on a first read.
In response to criticism of this faux-vacuum test, they did a second test in a real vacuum. This time, they used a torsion pendulum to find a teeny-tiny thrust of no relation to the first purported thrust. The second run in vacuum has completely different effects, possibly due to interactions between charge building up on the device and metallic components of the torsion pendulum, possibly due to deliberate misreporting by these folks, who didn't bother to explain what was going on in the first experiments they hyped up. Since they didn't bother to do a any systematic analysis of the effect on the first run, to vary air-pressure, look at air flows with dust, whatever, or if they did this they didn't bother to admit their initial error, this is not particularly honest experimental work, and there's not much point in talking about it any more. These folks are simply wasting people's time."
http://physics.stackexchange.com/questions/23725/is-the-emdrive-or-relativity-drive-possible
In conclusion, they did a really really bad experiment and got a bad result. Wow!
Re:A lovely summary from StackExchange (Score:5, Informative)
Agreed. Except...that was from 3 years ago.
The new tests from NASA have yet to be satisfactorily explained...
Eddy currents (Score:2, Interesting)
The other thing you get when you generate RF is eddy currents in nearby materials, generating magnetic fields from nearby materials. Nothing to see here, move along...
Where's the loose wire? (Score:2)
This would be really awesome and exciting if it really worked, but, well, it's apparently challenging models of physics which have withstood a tremendously diverse battery of scientific tests. Smart money is on the measurements being a mistake with the experimental apparatus.
Science requires a certain agnosticism (Score:5, Insightful)
Re: (Score:3)
There is an old saying that you should keep your mind open, but not so open that your brains leak out.
When someone claims a violation of very well tested physical laws, AND that violation is not under some new unusual condition, it is very reasonable to be skeptical.
It this was seen with TeV protons at LHC, or in ultra-strong electric fields, or in strong gravity, or other unusual conditions it would be different. Physicists paid attention to the (later dis-proven) FTL neutrinos from CERN because that exper
Would useful fricking links be too much to ask for (Score:2)
Seriously in the links provided there was absolutely nothing that made it possible to evaluate the claims.
Difficult experiment, clearly wrong . (Score:5, Informative)
Its not easy to measure 50 micro-newtons of force when you change a power level by 50 watts.
Currents cause magnetic forces. Things get hot and outgas producing thrust. RF power cables get hot and distort causing a force.
Think about it. The device weighs something like 5Kilos. That is 50 newtons gravitational force. So a 1 micro-radian tilt will cause a 50 micro-newton force. Walking across the lab floor could cause that amount of deflection. If the chamber is 1 meter across, a 0.1 degree temperature change on one side of the chamber (from a nearby power supply) could cause that much tilt.
There of course could be force just from photons - but that is a simple and well understood photon drive - known for at least 50 years now - basically a light-sail.
This is a very difficult experiment to do correctly, and they have not published in enough detail.
Meanwhile: conservation of momentum has been tested under conditions ranging from ultra-cold gas atoms to 100GeV particle collisions, to orbiting neutron stars. The RF fields they use are very modest. At SLAC we run hundreds of megawatts, not 50 watts. We have superconducting cavities where we easily see the deflection caused by the momentum in the microwave fields - operating at many thousands of times higher power than this experiment - we see nothing unexpected.
So: Difficult experiment. No unusual physical conditions. Apparent violation of one of the most carefully tested conservation laws in all of science.
It it literally more likely that the sun will not rise tomorrow (since that is also based on conservation of momentum) than that this experiment was correct.
Re:This again? (Score:4, Funny)
They've gone into plaid?
Re:This again? (Score:5, Funny)
Re: (Score:3, Funny)
Re: (Score:3)
Why do you keep saying this? They aren't giving an answer. They don't understand why it works, they clearly suggest that we should figure out why it does...
You seem to be building a straw man argument so you can rant about the COM.
Re: (Score:2)
There's no 'seem to be' about it. That's exactly what he's doing.
Re: (Score:3)
Well the tests keep showing the damn thing works! Maybe it's just magic.
If it is based on magic, then scientists are ill prepared to detect that. Instead you need a professional magician, who is skilled in the art of deceit and deflection. Is James Randi [wikipedia.org] available?
Re: (Score:2)
I prefer Penn and Teller. Much more entertaining.
Re:This again? (Score:5, Insightful)
Let's see: we can violate conservation of momentum by invoking some sort of vaguely defined quantum woo. Riiiight. Where do I send my check?
The practical result says that it works anyway.
I suspect that there is a balance in physics somewhere... just that no one knows where or what that is yet.
I am kind of curious though - does it have the acceleration curve of a VASMIR/Ion engine, or can we build something with it that will give greater speed in less time?
(...also, is the acceleration graph linear, curved sharply in either direction, hits a curve at a certain point... what?)
Re:This again? (Score:5, Insightful)
I suspect that there is a balance in physics somewhere... just that no one knows where or what that is yet.
This.
Just because we can't see the balance doesn't mean it isn't there.
Re:This again? (Score:5, Funny)
So it's powered by a typical Comcast bill
Re: (Score:3)
Re: (Score:2)
(...also, is the acceleration graph linear, curved sharply in either direction, hits a curve at a certain point... what?)
As long as you don't change power input, acceleration is always linear.
No idea why you ask this, that is a no brainer.
Re: (Score:2)
Asking because apparently no one knows just yet exactly *why* this thing is putting out, err, 'thrust'. They know how, well, sort of...
Re: (Score:2)
He's asking if 2x the electricity means you get 2x the speed.
Re: (Score:2)
To an outside observer. I don't think it's the same in the inertial frame.
Re: (Score:3, Informative)
There's nothing currently practical about it. It's in the experimental stage. If we had a spacecraft flying around on one of these, I'd be much more confident. The last time an observation violated the laws of physics like this, it turned out to be a loose cable connection.
By Noether's theorem [wikipedia.org], if we're violating the law of conservation of momentum, the laws of physics must vary from place to place in the Universe. (Unfortunately, I don't understand gen
Re: (Score:2)
Nice snark. Explain why they're still seeing observed results in testing then. The latest test in a vacuum chamber is the interesting one as a lot of people expected it to fail as they surmised the other teams were observing thrust from convection. Now that it has succeeded, things look exciting. Obviously it doesn't violate the physical laws of the universe, but it's also apparent nobody knows WHY it works just yet. More study is needed.
Re: (Score:2)
My guess is it's the same sort of testing magic the latest cold fusion dude in italy is peddling.
Re: (Score:3)
Except he in involved with all the tests and sets the parameters. This has been replicated by 3 different teams using their own manufactured cavity chambers and one of those teams works for NASA. Just a wee bit of a difference.
Re: (Score:2)
So NASA didn't build the device, they weren't allowed to control the device, they weren't allowed to check the wires going into the device but assumed that the chamber was emptied to a hard vacuum and that the force sensors worked right?
There's no comparison.
Re: (Score:2)
The inventor knows.
He formulated the theory of the device. And actually it is pretty easy to grasp for a layman. http://en.wikipedia.org/wiki/E... [wikipedia.org]
Can't be so surprising that a scientist draws/imagines a "thing" and engineers build it and: surprise, surprise, it works like the scientist thought it out. (*facepalm*)
The creationists must have done good work in america to destroy the "faith" in science!
Re: (Score:2)
The inventor knows.
He formulated the theory of the device. And actually it is pretty easy to grasp for a layman. http://en.wikipedia.org/wiki/E... [wikipedia.org]
Have you actually read the paper [emdrive.com]? Hint: there's a very, very good reason why it is not in a peer-reviewed journal.
Re: (Score:2)
So, you're limited to, what, 5000 characters and can't/won't/haven't pointed it out?
Stop making vague insults and actually say something meaningful for or against the theory or test. Because you haven't come close to that yet.
Re: (Score:2)
In Dr. White’s model, the propellant ions of the MagnetoHydroDynamics drive are replaced as the fuel source by the virtual particles of the Quantum Vacuum, eliminating the need to carry propellant.
Let's see: we can violate conservation of momentum by invoking some sort of vaguely defined quantum woo. Riiiight. Where do I send my check?
Although I haven't seen the math or read the articles yet, the above sentence makes sense to me. Instead of inputing energy to fuel and kicking out the back, they input the energy to the virtual pairs that are in all space. That gives the drive it's thrust as they are pushing against the virtual pairs which then recombine and cease to exist. However, when they cease to exist, they should still have a higher net energy over free space which would result in EM radiation being released when the virtual particl
Re: (Score:2)
Instead of inputing energy to fuel and kicking out the back, they input the energy to the virtual pairs that are in all space.
"Impulse Drives" don't work by pushing "against something".
Re:This again? (Score:5, Insightful)
This might be another Cold Fusion moment. Or, it might be the start of something very interesting.
When an experiment contradicts a theory, there are two possibilities: (1) there's something wrong with the experiment; or (2) there's something wrong with the theory. If the correct answer is (1), then it's par for the course: mistakes happen, and the process of science corrects them eventually. But if the correct answer is (2) then it's cork-popping time, because you have discovered new science.
Re:This again? (Score:5, Informative)
Note that this is the fifth experiment so far that has reproduced the effect (and every new experiment tries to account for some explanation that could possibly invalidate the previous one; e.g. for the last one, they ran it in vacuum).
Re:This again? (Score:5, Insightful)
And BTW: those things are already happening. Other scientists are critiquing (constructively rather than your sort of nonsense) and others are carrying out new experiments in the same and novel situations to eliminate confounds. You know, the scientific world doing what they do.
What I find absolutely amazing here (apart from the *potential* discovery) is how everyone is more interested in bagging on the science than commenting on how this might be a major breakthrough after NASA (FFS) has been confirming the results.
Yes, it may not be as it is. But it is also WAAY too early to cry foul.
Some days the internet its like watching a tribe of chimps...
Re: (Score:2)
Everybody's busy bagging on the science because reactionless space drives are known to be impossible, and if it turns out this is actually one, it's going to be a real interesting time to be a physicist because some really basic assumptions are going to have to be replaced.
The chance that this is due to some systemic experimental effect that nobody's noticed yet is still way higher than the chance that this actually works as advertised, so it's WAAY too early to cry fair either.
Re: (Score:2)
For the physics you can google yourself. /. since 3 or 4 years, and the physics is published since at least 2000, which was 15 years ago if you are bad in math, it should not be difficult for you to figure how the drive is "supposed" to work.
As articles about the EM drive are showing up on
How exactly do you want to be spoon fed? If you have not even read up the basics, what exactly do you ask me to tell you about it?
When somebody sounds like a total fucking crackpot, they almost always are.
Did not know tha
Re:This again? (Score:5, Informative)
If I were to peer-review a paper on this, I would insist on a plausible physical explanation for the claimed measurement. The burden of proof is on them: they are making a truly extraordinary claim, one that, if true, would entail revising all of physics from its very foundation.
When somebody sounds like a total fucking crackpot, they almost always are.
You might have missed high temp super conductivity entirely then. The phenomenon was measured and replicated in many labs - but it was at least a few years before any plausible theory came out - and 20 years on we do not have firm agreement on the cause.
Re: (Score:3)
Re: (Score:2)
There is already a proposed mechanism that doesn't require "revising all of physics from its very foundation".
Re: (Score:2)
Re: (Score:3)
"If I were to peer-review a paper on this, I would insist on a plausible physical explanation for the claimed measurement." That's stupid. Providing proof that something interesting is happening and repeatable is viable science all on its own.
If they simply wrote a paper saying "we noticed an anomalous force in this experimental setup, and we don't understand why", then nobody would have a problem with it. They're not doing that. They are claiming that it can be used as a reactionless propulsion system, a claim which is entirely incredible without a solid physical theory to justify it.
Re: (Score:3)
"If I were to peer-review a paper on this, I would insist on a plausible physical explanation for the claimed measurement." That's stupid. Providing proof that something interesting is happening and repeatable is viable science all on its own. I've read quite a lot of highly-respected papers from highly-respected people in highly-respected journals which did nothing other than document a pattern of behavior without explanation. In fact, most scientists I know will say they rarely ever really think they know *why* something happened, but that doesn't stop them from wanting to know. Some things get thousands of perfectly cromulent papers written prior to anyone really having a firm grasp on the "why" - hell, if you have the "why" then you probably have the last paper that will ever need to be written on the subject. Even farking *gravity* is still a bit of a mystery. We're pretty good on exactly *how* it works, but the *why* that you insist is necessary, for even something we all pretend to understand, isn't really yet known.
Dr. Schweitzer will tell you the same thing. She found what looked like soft tissue in a T-Rex bone back in 1993 and published her results, in shock herself and knowing that it was impossible to really be that. She checked and rechecked to rule out contamination and other causes, never finding one. The entire scientific community though refused the possibility it was soft tissue because Schweitzer couldn't explain how it could be preserved. By the year 2000 though she'd found the same results from enough ot
Where to send check? (Score:2)
Re: (Score:2, Funny)
https://xkcd.com/1404/
ion engine compare? [Re:This again?] (Score:2)
What are we calling "propellant"? It requires power to generate the radiation. How is this diff than say an ion engine? It needs SOME energy source, just not necessarily traditional sources such as flammable chemicals.
And as the radiation bounces around inside the Gumby-head-shaped chamber, it does lose some energy on each bounce such that the radiation generator has keep doin
Re: (Score:2)
Ion Engines throw ions out the back at very high speeds. Those ions (matter) are the propellant, like xenon. This means you gotta accelerate all the fuel that you're bringing with you - and that it's possible to run out of fuel.
If this device works as claimed, you could conceivably convert any energy source (nuclear, solar panels, whatever) and turn that directly into acceleration, even in the void of deep space.
Re: (Score:2)
Send it to Larry Niven. I always wondered how his "reactionless drives" worked, and now I finally und-- actually, no, I don't understand how this works at all.
Re: (Score:3)
I see you like to comment on something without reading it.... try taking a look at the article... it says specifically that conservation of momentum is NOT violated...
Well, the article says it, so it must be true.
If you're not throwing anything out of the back of the rocket, you're violating conservation of momentum.
Re: (Score:2)
I see you like to comment on something without reading it.... try taking a look at the article... it says specifically that conservation of momentum is NOT violated...
Well, the article says it, so it must be true.
If you're not throwing anything out of the back of the rocket, you're violating conservation of momentum.
So... You're now arguing that you can violate the conservation of momentum. Interesting.
Re:This again? (Score:5, Informative)
You might want to look at this nice summary from Reddit of all the experiments performed in China and at NASA about these drives:
The FACTS as we currently know them about the EmDrive and Cannae Drive [reddit.com]
Re:This again? (Score:5, Funny)
If two magnets get close enough and snap together are they violating conservation of momentum when forces are acting on them to accelerate toward each other?
Of course not. The total momentum of the system stays zero.
When I was a kid, I tried to make a self-propelled car by putting magnets on the back and front bumpers of a toy car, reasoning that the front magnet would attract the back one, and therefore produce thrust. When I built it, I learned a valuable lesson: it doesn't work. Because the force pulling the back magnet forward is exactly counterbalanced by the force pulling the front magnet backward.
The EM drive is closely analagous to this idea. Except that they didn't figure out when they were eight that this will never work.
Re:This again? (Score:5, Insightful)
More like tests keep showing that it IS working, and nobody is sure why. Either the problem is with the test, or there's something else happening that we don't understand, but either way, nobody is sure yet what's going on.
I think it's likely that the test is faulty, but they need to figure out why or how the test is faulty.
Re: (Score:2)
They power up the device, and apparently it works by providing thrust somehow. What fault? I really need one of those for my car ASAP.
Re:This again? (Score:5, Funny)
Re:This again? (Score:5, Funny)
Area man refuses to accept that something was demonstrated by a scientific experiment can possibly be true - insists that his knowledge of science as an 8 year old was more advanced than that of actual actual specialized scientists.
Re:This again? (Score:4, Insightful)
Difference:
Pons and Fleischmann announce, others try to reproduce, fail.
vs.
British engineer announces, China tries to reproduce and succeeds, NASA tries to reproduce and succeeds. Supposedly BAE Systems, EADS Astrium, Siemens and the IEE have also gotten positive results.
Of course, there is still a lot of work to be done to see if it isn't some other effect contaminating the data.
Re: (Score:3)
The more reproductions without someone figuring out what's wrong with the test the more likely it is that it's not the test that's wrong.
This engine is interesting on many fronts, the most important of which is it appears to violate what we know about conservation of momentum and IF it does it's going to actually point to some fundamental constant or principle of the universe that we've missed as long as it's not an experimental error. This is a big hurdle to take so it's going to take a LOT of evidence the
Re:This again? (Score:5, Insightful)
That's just silly. The people reporting this observable phenomenon do not claim to understand why this happens - in fact the point of the article is that we should strive to understand why this works.
Just because YOU don't understand why this works doesn't mean that they are claiming to be violating the conservation of momentum - especially since they are not. Most especially because there's a clear expenditure of input energy - a grossly inefficient (it would seem) one.
Re: (Score:2, Troll)
That's just silly. The people reporting this observable phenomenon do not claim to understand why this happens - in fact the point of the article is that we should strive to understand why this works.
They're measuring an anomalous force in an electromagnetic cavity. That's a measurement, a concrete fact. They're claiming that they'll be able to make a starship with it. That's beyond any credibility. It's totally delusional.
Re: (Score:3)
"They" are many different people here. The experiment has been reproduced by, what, five different teams all across the world by now? As I understand, only the guy with the original idea is making outlandish claims; everyone else is just trying to figure out what the hell is going on.
One observation that the other teams did make is that the observed output seems to be scaling nonlinearly with input, which implies that there's a peak of efficiency. They have a model that tries to guess what that is, which se
Re: (Score:3)
First of all, you need to be careful of your pronouns. "They" the inventor of the device is mostly just saying it can be used to replace satellite thrusters, which would be a huge weight saving (no need for maneuvering or stationkeeping fuel). "They" NASA are saying that, *if* it scales up the way their current model says (yes, they have one), then after a lot of refinement and with a nuclear reactor powering it, this thing could produce hundreds of Newtons of thrust at a scale that would be feasible for sp
Re: (Score:2)
Haha, my concept as a child was to have a buoyant container on wheels in a tube full of water that would rise up, roll down a ramp on the other side, and re-enter the tube through an airlock on the bottom.
Wish my dad had taken the time to tell me why it wouldn't work rather than just saying "perpetual motion is impossible".
Re:This again? (Score:5, Insightful)
Or, rather than all of physics being wrong, maybe they have an erroneous measurement setup.
That doesn't mean you shouldn't investigate anomalous measurements. But at this stage you shouldn't be writing fluff pieces with page after page of how much your new technology will change spaceflight. You should be publishing a paper with a name like "Measurement of anomalous thrust in a microwave apparatus operated in a hard vacuum" and trying to avoid the media insomuch as possible - and when you need to talk with them, trying to explain "we don't know what's going on... we have some theories but they're controversial... we need to do more testing." etc.
Re:This again? (Score:5, Insightful)
That is pretty close to what is going on.
There are now several experiments which confirm the production of thrust, many efforts to falsify the results, and a few efforts to come up with a theory which explains what we are seeing. There may be another test or two on the ground, but the first real space trial is likely coming soon. The only real way to be sure is to launch one and measure the dv.
I had the same thought they did initially, which is that convection of air was responsible for their thrust. That will not happen in vacuum, so that idea is right out.
This is a very promising experimental result, following several other very promising experimental results from different labs. I would say there is now serious evidence that this works, or at least that there is more to it than we can easily explain given our current understanding of physics.
Re:This again? (Score:5, Informative)
There are several medications doctors prescribe although they and even the researchers that invented them don't how or why they work.
Re: (Score:3)
It is very hard to believe that they are going to send a propulsion system into space without a clear understanding of how it works.
We send drivers on the road every day who don't have a clear idea how cars work.
Knowing how something works is nice, but not knowing how it works won't diminish its utility, so long as it *does*.
We use gravity daily to generate hydroelectric power. Ask a group of physicists how gravity works. We have the math for it, but we don't have the story of it. Either way, the lights come on when the water weight is converted from potential to kinetic energy, and we are still damned if we know the mechanism of con
Re: This again? (Score:5, Insightful)
So you're one of the swags that believes all physics is right? Puh-leeze lets make up some more shit like dark matter an dark energy to make it so!
Any time you have an assumption based on physical laws, it must be able to be tested and measured and accounted for and predicted, and if the prediction based on those physical "laws" differs from what is observed, one must first, check their math for errors, check their method of measurement and if all of that checks out to be accurate to ask questions along the lines of: "What are the implications of what we have observed and measured and verified here?" or as Einstein asked "What would the universe be like if it operates the way we have observed it to here?" This is what allows science to side step conundrums based on incorrect assumptions and asking poorly worded questions that lead research astray and into asking the "Wrong questions". Before Einstein, the question was "Why does light always seem to be moving the same speed regardless of the point of view or movement of the observer with respect to that light, when we know that it can't?" That is a poorly worded question, because it assumes that what we know, but that we are unable to use to explain what we observe is correct, when it is likely it is not correct. This is why I hate the term "Laws of Physics" because it implies that they way we understand the universe is the way it operates, when these "Laws" are just our shorthand for documenting and understanding what we observe. This is also not to imply that when someone says "This breaks the laws of physics!" that they are pulling a James Dean, rebel attitude and getting something for nothing, it really, most likely means someone does not fully understand the thing they are dealing with and some corrections will be needed to science books of the future. As HAL9000 said in 2001, A Space Odyssey, "The problem can only be attributable to human error."
Re: (Score:3)
Their measured force is far greater than radiation pressure could explain (around 1 newton /kW now, expected to be 500-1000 newtons per kW with some refinement if their current theories are correct), and it was not tested in sunlight as far as I know.
It cannot be simple radiation pressure, of this NASA is certain.
Re:This again? (Score:5, Informative)
Wrong.
Conservation of linear momentum is most certainly NOT derived from Thermodynamics.
Conservation of linear momentum is a mathematical consequence of translational symmetry - in other words, momentum is conserved if the laws of physics are invariant in space. Similarly, angular momentum is conserved if the laws of physics are invariant by rotation.
Re:This again? (Score:4, Informative)
Conservation of linear momentum is a mathematical consequence of translational symmetry - in other words, momentum is conserved if the laws of physics are invariant in space. Similarly, angular momentum is conserved if the laws of physics are invariant by rotation.
And energy is conserved if the system is invariant over a translation in time.
Hooray for Emmy Noether. [wikipedia.org]
Re: (Score:2)
When it spends 99% of its launch mass lifting itself to orbit, you have a bad system. Nice to see people trying to think outside the box.
Technically, they're keeping it all in the box.
Re: (Score:3)
It is the same as if you are locked in a cage and bump yourself against the wall - the cage eventually moves. yet nothing is expelled outside of the cage.
Doesn't that only work because of static friction though? Bump hard enough to break the static friction and scoot across the floor, then move slowly when reversing such that you don't break the static friction on the way back.
I'm not holding my breath waiting for superluminal (Score:2)
this gem ... hidden in the article:
"... whether it is possible for a spacecraft traveling at conventional speeds to achieve effective superluminal speed by contracting space in front of it and expanding space behind it. ..."
They've been playing at that for a while. It would allegedly work by creating a condition of cosmic expansion behind the craft and its converse in front of it, so the spacecraft is in a bubble where it's running slower than lightspeed (i.e. stopped) but the cosmic expansion and contrac
Re:Why are people posting this nonsense? (Score:4, Insightful)
Nope, they're not. It's generating three orders of magnitude more thrust than would be generated merely by the momentum of emitted microwaves.
This is not a photon drive (Score:4, Informative)
The expulsion (should that not be expulsion or something?) are micro waves ...
hence the name: EM drive.
What you are describing is a photon drive where photons are the propellant. But the fine article explains:
After consistent reports of thrust measurements from EM Drive experiments in the US, UK, and China -- at thrust levels several thousand times in excess of a photon rocket, and now under hard vacuum conditions -- the question of where the thrust is coming from deserves serious inquiry.
The reason I don't believe it is real is the same reason I don't believe cold fusion is real. They put in metric ton-loads of energy and measure a very small effect. They say they will need to increase the efficiency by many orders of magnitude to create a practical device. I say they probably made a mistake somewhere and the tiny effect they measured is either noise or due to something else they haven't yet accounted for.