Scientists Just Killed the EmDrive (popularmechanics.com) 137
In major international tests, the physics-defying EmDrive has failed to produce the amount of thrust proponents were expecting. In fact, in one test at Germany's Dresden University, it didn't produce any thrust at all. Is this the end of the line for EmDrive? Popular Mechanics: The crux of the EmDrive is if you bounce microwaves around inside the tube, they exert more force in one direction than the other, creating a net thrust without the need for any propellant. And when NASA and a team at Xi'an in China tried this, they actually got a small-but-distinct net force. Now, however, physicists at the Dresden University of Technology (TU Dresden) are saying those promising results showing thrust were all false positives that are explained by outside forces. The scientists recently presented their findings in three papers at Space Propulsion Conference 2020 +1, with titles like "High-Accuracy Thrust Measurements of the EmDrive and Elimination of False-Positive Effects." (Other two studies here and here)
Using a new measuring scale and different suspension points of the same engine, the TU Dresden scientists "were able to reproduce apparent thrust forces similar to those measured by the NASA team, but also to make them disappear by means of a point suspension," researcher Martin Tajmar told the German site GreWi. The verdict: "When power flows into the EmDrive, the engine warms up. This also causes the fastening elements on the scale to warp, causing the scale to move to a new zero point. We were able to prevent that in an improved structure. Our measurements refute all EmDrive claims by at least 3 orders of magnitude."
Using a new measuring scale and different suspension points of the same engine, the TU Dresden scientists "were able to reproduce apparent thrust forces similar to those measured by the NASA team, but also to make them disappear by means of a point suspension," researcher Martin Tajmar told the German site GreWi. The verdict: "When power flows into the EmDrive, the engine warms up. This also causes the fastening elements on the scale to warp, causing the scale to move to a new zero point. We were able to prevent that in an improved structure. Our measurements refute all EmDrive claims by at least 3 orders of magnitude."
Warp Drive (Score:2)
FTW!!!
Reminds me of a comment... (Score:5, Interesting)
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If they had studied electrical engineering, they would have realized that much quicker!
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And if they had studied abstract mathematics they'd have realized that everything is just a set.
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And if they had studied philosphy, they'd have realized
that everything is nothing and nothing is everything!
Or something.
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Actually, It was a Borg-Scientist-Drone that said: (Score:4, Funny)
Resistance is futile!
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10 milli Ohms of futile!
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Resistance is futile!
...At sufficiently low temperatures.
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We have a saying in MRI research: one man's artefact is another man's signal.
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In every tool is a hammer.
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Re:And Every Digital Device is an Analog One (Score:4, Informative)
Everything is a resistor capacitor and inductor
Things that are only one, only exist as abstracts
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Everything is also a capacitor?
Everything is also everything. You make capacitors by putting two sheets of metal close together. A wire is just a small sheet, and since it's nearish to other wires it forms a capacitor with them. Likewise you make an inductor by wrapping a wire around a coil former many times. A straight wire, is like 0.001 turns around a very large coil former. Oh and those metal sheets/wires you made the capacitor out of? They have inductance because they're wires and of course resistance
Well, that's good . . . (Score:5, Funny)
Now we can all move forward.
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What a post about actual science. (Score:5, Insightful)
A negative result is a result. Just as worthy of praise as positive result. Granted it is kinda of a bummer that the emdrive probably cannot happen. But it could save engineers decades of time and resources trying to build one that can be used in production.
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Re:What a post about actual science. (Score:5, Informative)
This isn't just a negative result. They identified the mechanism behind the false positives. It's kind of cool that it's a deformation, so it works in a vacuum too.
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I don't think they'd go to production if it the prototype didn't work
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Lol downmodded. People really love it EM drive!
Rename it the ErrDrive (Score:5, Funny)
It is a drive that generates propulsive force through the skillful (clumsy?) deployment of experimental error. This drive has the advantage that precision, and extreme care in building it and testing it are counterproductive. A more powerful drive is obtained the sloppier and less careful the experimenter is!
Expected outcome, but useful (Score:4, Insightful)
This was always the expected outcome, since any positive result required some very unlikely new mechanisms, but you always look because the effort itself often yields something new.
From TFA -- "Unfortunately, we werenâ(TM)t able to verify any of the drive concepts, but we were able to greatly improve our measurement technology as a result, so that we can of course continue researching in this science area and perhaps discover something new."
roflmao (Score:2)
"Mike McCulloch, a lecturer in geomatics at the University of Plymouth, U.K., and leader behind DARPA's EmDrive project..."
Geomatics is not a new branch of physics; it's informatics about geographical data. There's a very good reason why no tenured particle physicist was interested in leading this group.
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> There's a very good reason why no tenured particle physicist was interested in leading this group.
Yup, it's bad for tenure. Fucking around with math for the past 40 years, or whenever the cancellation problem was solved, has been good for physicists' tenure and bad for everybody else.
At least the experimentalists are moving society forward.
Exploring the bounds of the possible is how we've made most real advances. Falsifying a hypothesis is a wonderful result but most University PR departments won't e
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this, of course, would be more convincing if the emdrive had worked...
at any rate, it wasn't an "experiment," it was a crackpot invention from start to ignoble finish.
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also, this would not be "bad for tenure". sure it's crackpottery but it's for NASA/DARPA so whatever; it could even count as service. the only things really bad for tenure once you have it are: being vocal against the cause du jour, straight-up just not doing anything at all for years, and fucking a student.
it would be bad for his career in other ways, but it wouldn't be a threat to his tenure on its own.
Argument fails (Score:2)
Yup, it's bad for tenure.
"Tenured" means that they already have tenure otherwise it is tenure-track. However, the concept of tenure largely no longer exists in the UK where lecturers are hired on 5-year renewable contracts.
So I am completely unsure what the OP's argument was supposed to be. Someone with tenure would be protected from being fired over something like this and yet the person who did the study lacked tenure and could technically be fired and so were taking more of a risk.
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Exploring the bounds of the possible is how we've made most real advances. Falsifying a hypothesis is a wonderful result but most University PR departments won't even bother writing a release.
What if the "hypothesis" is that perpetual motion machines exist? Do you really want universities falsifying that again and again and again? The thing is the EM drive is equivalent to a perpetual motion machine: you just need to add a couple of components.
So all they've done is yet again prove some inventor's crazy per
Bad headline (Score:2)
Should probably read Science Killed the EmDrive.
The way it reads, I was expecting to at least find a meme TikTok with a bunch of soot-faced lab-coat wearing stooges standing over an incinerated EmDrive, wearing shit-eating grins.
EmDrive was science illiteracy (Score:3)
The claimed amounts of thrust were entirely within the bounds of the expected amount of radiation pressure/antenna thrust from the claimed amount of emitted RF power.
The formula for antenna thrust or radiation pressure is P/c for a perfectly directional antenna. 100W/3e8 = .33 uN in a vacuum. If you're radiating into a metal test chamber wall, you may build up a higher power density in some spots and get more "thrust" if you keep the cavity from moving.
In short, this whole thing was an example of "something I didn't understand happened" + "quantum" therefore ghosts and aliens.
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The claimed amounts of thrust were entirely within the bounds of the expected amount of radiation pressure/antenna thrust from the claimed amount of emitted RF power.
Yep. But it didn't emit radiation. The microwaves were all inside the cavity; they didn't radiate out.
That was the very first thing they checked for, whether it was producing thrust from energy leaking out.
Re: EmDrive was science illiteracy (Score:2)
1. That's not possible. Every RF circuit leaks energy somewhere, and if you're pumping 100W in, it's going to get out somehow.
2. Let's assume that it was a perfectly sealed RF sink. What that would mean is that you've got a metal cavity with ever more power being put into it and ever larger electromagnetic fields bouncing around inside it. Since the cavity is not a superconductor, those fields will cause eddy currents inside the inner surface of the cavity, causing it to heat up.
Metal conducts heat. And eve
the very first thing they checked [Re: EmDrive...] (Score:2)
And, as I said: this is the very first thing they checked for.
Re: the very first thing they checked [Re: EmDrive (Score:4, Informative)
You show no evidence of knowing anything about the subject or having paid any attention to the subject prior to an hour ago. You didn't even read the summary we are discussing, or you would have seen that the measurement error was not photon momentum, which is a very well known effect, but the fact that heat caused the fastening elements on the scale to warp, which moved the scale to move to a new zero point.
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You are exaggerating.
The math behind it is pretty solid. Hence several Universities and other research labs tried it out.
Or do you really think a German University and his professor in that topic has nothin better to do than "proving an idiot wrong"?
If it would have been obvious, that it can not work: no University had tried it. Waste of time and resources.
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Look I hate to agree with Mr. rightwingnutjob because I generally think he's a prat, but he is absolutely, unequivocally 100% right on the money with his assessment.
The math behind it is pretty solid.
They "derived" the result using relativity initially. Unfortunately relativity is proven to be momentum conservative. So either maths is inconsistent or there was an error in their working. funnily enough it turned out the be the latter. Then they switched over to "uhhhh virtual particles", invoking quantum woo
This stupidity is still around? (Score:2)
Very illustrative of how many people cannot distinguish between wishful thinking and actual reality.
Re:This stupidity is still around? (Score:4, Insightful)
With the knowledge we gained here we're better at faster and efficiently debunking more nonsense in the future.
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We won't unfortunately.
People who believe in bunk will keep believing it out of wishful thinking. The next level of bunk will claim to have smaller effects juusstt at the edge of what is practical to measure (just like this one) and will take just as much effort to measure.
Even showing people how to turn one into a perpetual motion machine didn't help. All that resulted was anger and downmods.
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The Michelson-Morley experiment is also still repeated with ever higher precision, but again and again, all that it proves is that there's no prove for a luminiferous aether.
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Indeed. But it is an universal problem and wishful thinking on the form of religion is just one indicator.
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Bear in mind that 47% of Americans are Church/Mosque/Temple members. So it is a land full of wishful thinkers. Free thinkers are really a scarce commodity.
That you posted this comment is rather astounding evidence that you yourself are no more "free-thinking" than those you decry.
Conviction that something does not exist is logically indistinguishable from conviction that it does.
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And fail. Nobody tried to prove that God does not exist. It was just pointed out that believing God does exist without extraordinary proof is an immature thing and a belief in a fantasy. And that way your complete pseudo-"argument" goes out the window.
Flat Earth (Score:2)
Thanks (Score:5, Funny)
if you bounce microwaves around inside the tube, they exert more force in one direction than the other
This must be why my microwave oven keeps sliding around on the counter. Not me slamming the door, as my wife claims.
Shame, I would have loved it to be a real effect (Score:2)
it would have been really useful in helping us get to the stars. It broke the rules as I understood them so I am not surprised that it did not check out. However I still have a twinge of sadness.
aww nuts! (Score:3)
Scientists just killed the EmDrive (Score:3)
Did they really? Did they do any research at all that proves it was alive in the first place?
Meanwhile,... (Score:2)
Fuckin' Germans (Score:2)
This is why we have physics (Score:2)
so you can predict what will happen before you start on a decades long waste of time.
Online conference with inventor tomorrow (Score:2)
Normal way ideas a filtered (Score:2)
This was the expected outcome of this idea. The original claim was extremely unlikely to be true since it violated some our foundational understanding of how light and matter interact. See earlier /. discussions for details. But it is good to check carefully and verify how and if our current understanding applies in a new case that shows something odd.
There is a lesson here that many would benefit from. People really want there to be breakdowns in existing physics theories that will make amazing new t
Oh well (Score:2)
It was kind of exciting wondering if something that we know to be impossible could, maybe somehow, actually be possible. Disappointing if unsurprising.
Moment of reckoning for physics (Score:2)
At some point, you just have to actually take into account the whole system, warps and all, and not just take the maths for granted.
"physics-defying" (Score:3)
Never a good sign when they attach "physics-defying" to your project.
OMG, they killed the EmDrive! (Score:2)
The Bastards!
Not the end (Score:2)
I'm pretty sure the emdrive can produce plenty of thrust if only from the expending of immense religious fervor.
Re: If such phenomenon could work (Score:4, Insightful)
Re: If such phenomenon could work (Score:5, Informative)
Lasers were also never seen in nature.
Ehm... [laserfocusworld.com]
Re: If such phenomenon could work (Score:2)
Well, to be fair... (Score:2)
"...but I can not think of a phenomena that is exclusively the domain of laboratories which does not math out or have observable examples in nature."
Every birthday my family slices up a phenomena that does not occur in nature. I pour a small amount of whipping cream on mine.
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That's neat, but I think the point was that we developed the laser without first observing one in nature.
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Yes, Saloomy's claim can be reduced to "if something is possible, it has already been observed in nature". (The obvious corollary being "if we haven't already observed something in nature, it is not possible", which is absurd.)
Ake Malmgren's laser example was supposed to contradict that. The laser, after all, was developed long before we observed one in nature. That we later observed one is interesting, but it doesn't do anything to support Saloomy's claim.
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That's being a bit obtuse. I think it's fairly obvious that "observed" in this context does not just mean seen, but also recognized for what it actually is.
Re: If such phenomenon could work (Score:2)
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It's not a very convincing argument.
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To be fair, we needed to figure out what a laser was before anybody knew to look for laser emission lines, and then it still apparently took 25 years before we found something.
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IIUC, we had a theoretical prediction of lasers over a decade before someone figured out that they could actually build one with a supercooled ruby. There was this mathematical result that predicted them, but didn't say how it would be possible to build them.
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IIRC Einstein predicted stimulated emission. But before he did, if you looked at the gas cloud in the story the OP linked, you'd just see the emission lines you expected. It wasn't until we understood what stimulated emission was, and quite a few other details, that we could look at that cloud and say that one of those emission lines is brighter than it should be.
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Lasers aren't about the light, they're about how it's produced.
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Laws of Physics the Same (Score:2)
Why?
Simply because the law of conservation of momentum, which this drive would violate, comes from the symmetry that the laws of physics are the same everywhere in the universe. So we do not need fancy lasers or microwaves, simply the fact that we have seen no difference in the laws of physics anywhere suggested that this drive was extremely unlikely to work.
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But you do know the drive was not even supposed to use momentum for acceleration, right?
Your argument makes no sense, as it has no relation to the supposed why the drive "should have worked" - if it had worked.
That's why it broke momentum conservation (Score:2)
But you do know the drive was not even supposed to use momentum for acceleration, right?
Yes, I do know that because this is exactly why it broke the law of conservation of momentum. If you can accelerate i.e. gain momentum in one direction without imparting an equal and opposite momentum to something else heading in the opposite direction then you have violated conservation of momentum.
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The drive was supposed to use a special kind of "unrue energy", perhaps you want to read it up.
As I said before: when dozens of research centers try to research that thing: they they certainly know more about it than you do.
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:facepalm:
It also violates conservation of energy. If you had one that worked you could make a perpetual motion machine.
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You should check out the Austin Powers documentary, it is rumored some sharks do carry a laser :p
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I would never even have bothered testing the emdrive but i suppose once there is a critical mass of people believing in it there is value in taking it seriously and debunking it.
Re: If such phenomenon could work (Score:2)
It would have either one of two outcomes: we discover a wonderful new phenomenon, OR we learn how to test better.
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Not all claims are worth investigating in the same way. You can't go by 'everything has equal right to be investigated'. A useful distinction to start with is between a 'new phenomenon not covered by any existing models' and a 'new behaviour from an existing mathematical model'. If someone creates a mechanical setup and says 'it still needs some tuning but it will end up going round and round by itself forever' then this person is claiming new behaviour of a system which has a satisfactory mathematical mode
Re:Doh (Score:5, Insightful)
This is really a facepalm moment for everyone that received a positive result. Why the hell did we think this would even work? It's worrying that NASA didn't ask themselves after getting a positive result, what are we doing wrong that we have received a positive result.
Pretty much everybody at NASA was saying "it's very unlikely that this is real; it's much more likely that it is some form of measurement error we haven't yet found."
But you have to track down that error, because of the unlikely possibility that there actually is something real being observed.
Re:Doh (Score:5, Insightful)
But you have to track down that error, because of the unlikely possibility that there actually is something real being observed.
Plus, it's helpful to know about that particular mechanism of error as a potential reason for unexpected results in other experiments.
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Then why did they spend a million dollars to test it?
They didn't: the they in question being NASA. The link is for DARPA. Either way, who knows? They funded an attempt at a perpetual motion machine[*], they ought to feel pretty dumb.
[*]I know you know, but I've had a lot of arguments here, and many people don't realise you could build a perpetual motion machine out of an EM drive if the EM drive actually worked.
We now know for certain that it does not work but how many things are we not going to learn now
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[*]I know you know, but I've had a lot of arguments here, and many people don't realise you could build a perpetual motion machine out of an EM drive if the EM drive actually worked.
Yes... and no.
To make that claim, you made assumptions how the EM drive works. If the EM drive produces fixed force independent of its state of motion: yes, it's a perpetual motion machine of the first kind. This is trivial to see: power equals force times velocity, so if it's moving, a constant force produces power. Or, if you prefer a relativistic explanation, the EM drive produces force, and force is momentum per unit time. So, since relativistically, momentum is just one component of the energy-momentu
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But to make that analysis you assumed that the EM drive force is independent of velocity. You say, "but that's just the postulate of relativity", but, no: reference frames are not completely independent of velocity unless you are in field-free empty space. But the device is not: it is in a lab, on the surface of the Earth. There could be some as-yet unknown way in which it is referenced to the rest frame of the lab and/or interacts with the environment.
Yes...
I mean it could basically interact with the earth
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Funny thing is they derived the "theory" for this device before it was made. And they used relativity which is provably conservative. Then when they eventually found the error in their working, they switched over to quantum woo as the explanation (also a momentum conservative theory).
Yep. Their theories don't make any sense to me.
But if the device doesn't actually work, it's irrelevant whether the theories make any sense or not.
DARPA, not NASA [Re:Irresponsible use of Funds] (Score:2)
A million dollars to NASA is like a penny to you.
And more to the point, that was DARPA, not NASA.
Tracking down anomalies is science. Yes, most likely this is measurement error, but on the chance that it is actually new physics, there is value actually doing the work to confirm that yes, it wasmeasurement error, and here is the explanation of why the particular measurement made was not right.
Most of the time, tracking down a measurement error is just the unsung brickwork of science. Every now and then, tracking down a measurement error is a Nobel Prize.
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People thought it would work because there was a dedicated core of scammers popularizing the idea
That is wrong. The people coming up with the idea are PhDs in physics. And the math was solid, otherwise no other Physicist had tried to build one.
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And the math was solid
Talking out of your arse again, I see.
The maths was not solid. Any maths that purports to break the 2nd law of thermodynamics is most likely wrong, regardless of how many PhDs looked into it. The maths was too alluring and some PhDs got caught up in it, forgetting that no mathematical model will ever be complete.
Likewise, many PhDs also got caught up in the superluminal neutrinos. PhDs are no antidote to wishful thinking, scientists are no substitute for science.
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Why do you not simply look on the wikipedia page instead of insulting people who know more about the topic than you?