Argument #1: it violates Newton's Third Law of Motion.
Argument #2: every time they improve the test apparatus, the measured force declines and is "coincidentally" close to the measurement limits of the apparatus.
Argument #3: It was originally designed based on a misunderstanding certain principles of Physics. Now they are trying to find a new explanation for why it works. What are the odds that you misunderstand physics, design something based on that misunderstanding, and that it then works in a barely-detectable way due to "unknown mechanism"?
And don't forget, violating Newton's Third Law of Motion also violates the conservation of energy, linear momentum, angular momentum, and thermodynamics.
Yes, which is why violating a known law isn't automatically disqualifying. But it is highly suggestive, and requires extremely good evidence to surmount. So far, such evidence has not been forthcoming, so this remains a good reason to doubt.
Every so often, something comes along that overturns an established law, like the photoelectric effect or the Michelson–Morley experiment. But the vast majority of the time, the laws remain intact and it's the claim which is somehow flawed. (See the Pioneer anomaly for a recent example where new physics was long considered as a potential explanation, but it ended up being a completely mundane effect.)
This is not the first experiment undertaken by Nasa/Pentagon/Boeing or the DoD. As well as similar measurements confirmed by other research teams (including foreign teams).
I totally agree it requires drastic evidence, but it could be explained by another physical action not necessarily the violation of Newton's laws or effects that supersede those laws like quantum effects
If it's another physical action within known physical laws, then nothing interesting is happening and it's a failure of the experimental setup. Yes, many experiments have been done, and none have conclusively disprove it, but at the same time none of them have conclusively shown that something is going on either. The detected effect remains well within the realm of potential error, so until that uncertainty is resolved, "error" remains a much better bet than "new physics."
>If it's another physical action within known physical laws, then nothing interesting is happening and it's a failure of the experimental setup
I'm not sure what makes you think this. There's no failure in science when an effect is observed and it's explainable within the frame of current theory. If that was the case every experiment I've done would have been a 'failure.'
So, thermal radiation slowed the Pioneer spacecrafts. 'Thermal' is a type of Electromagnetic (EM) radiation, right?
Doesn't that make it an EM Drive?
Why the cone apparatus? What is preventing the intentional design of a spacecraft that uses thermal radiation (or Thermal Recoil Force) similar to the Pioneer spacecraft?
e: The replies indicate the answer is that this could be built but the effect is to weak to be practical. Which I find to be a completely acceptable answer, thanks.
That makes it a photon rocket, which is nothing new. It's a logical consequence of the fact that light carries momentum, which is part of Maxwell's electromagnetic theory from 150 years ago. It's not very practical unless you have an extremely dense power source (nuclear fission won't cut it, you need fusion or antimatter) so it's more of a theoretical toy at this point.
What's interesting about the EmDrive's claims is that it supposedly produces far more thrust for the power that goes into it than would be possible from a photon rocket.
(The Pioneer anomaly wasn't because nobody realized that thermal radiation would act as a photon rocket, but rather that the effect wasn't correctly calculated. The theory is pretty simple, but it gets complex when you apply it to a real spacecraft with complex shapes, non-blackbody materials, and temperature gradients.)
You have to look at it in terms of a barrier. It's not impossible to break it, but it requires a lot of "oompf". The greater the violation, the greater the "oompf" required.
So, because this thing would change basically all Physics books, there's a huge burden on them to prove it beyond any shade of doubt. Forget about flirting with detection error; it should be as clear as the sun rising in the morning.
Please note that relativity, big as is was, was only at a low-to-medium level of "oompf". It didn't change quite everything, far from it.
I would argue relativity was a tectonic shift in how we understand physics. These ideas existed before Einstein in mathematics/ geometry (Grassmann & Reimann). But they were just ideas and not a full-fledged theory.
The arguments against boil down to "Any reactionless drive must by definition violate conservation of momentum." We shouldn't reject any scientific conclusion as unquestionable gospel, of course, but off the top of my head I'm not sure that I can think of any fact about the laws of nature that I consider more firmly established than "momentum is locally conserved". (I'm a physics professor, for the record.) Conservation of momentum is part of the bedrock of everything from relativity to quantum field theory, so if you throw it out, you'll need to come up with entirely different (seriously: entirely different) replacements for those theories that nevertheless manage to reproduce their hundreds of enormously successful predictions (to just as many decimal points). Again, it could be true! Keep an open mind! But if it is, then literally every discovery in (say) particle physics in your lifetime has been a fluke: just dumb luck. You can decide how to balance that likelihood against the evidence presented thus far in favor of the drive.
I'm really not sure what the argument against impossibility is, apart from a fervent longing for something of the sort to be real. (A longing that I share, for what it's worth.) They claim to have some data showing that something really is generating thrust, but as I recall some experiments have shown comparably large results in both the "actual test" and "control" conditions, so I'm not sure what to make of that evidence.
But if it is, then literally every discovery in (say)
particle physics in your lifetime has been a fluke: just
dumb luck.
Why couldn't conservation of momentum, as we understand it, be incomplete, like Newton's Laws, rather than wrong or coincidental?
Note that I'm not grasping at straws wrt the EmDrive. The distinctions between incompleteness and error is far more interesting to me, especially in the context of science. And I'm curious if your statement was more than a rhetorical assertion.
There's a claim that it's just basic physics of microwaves bouncing around. That one's nonsense; from the article, "Woodward likened explaining the results seen at NASA purely in terms of microwave pressure to arguing that you can accelerate a car by getting in the driver’s seat and pushing on the windshield."
As that suggests, the drive would violate conservation of momentum as we currently understand it. It would also violate conservation of energy. Because of relativity, there's no such thing as absolute velocity, so the thrust can't vary by velocity. Since kinetic energy is proportional to the square of the velocity, but the acceleration is constant for a constant energy input, there's some velocity at which you're gaining more energy than you're putting in.
So if it does work, it'd be radically new physics. But there are various ideas for how it might work, like Woodward's, which is derived from general relativity and involves an explanation of inertia; he's been working for decades on reactionless drive experiments based on that idea. We don't currently have a generally-accepted explanation of inertia, so who knows.
If you have an em-drive cubesat, just putting that (battery-powered, closed system) on a balance beam / torsion pendulum in a vacuum chamber is a more rigorous experiment than anything that's been done so far.
Argument #1: it violates Newton's Third Law of Motion.
Argument #2: every time they improve the test apparatus, the measured force declines and is "coincidentally" close to the measurement limits of the apparatus.
Argument #3: It was originally designed based on a misunderstanding certain principles of Physics. Now they are trying to find a new explanation for why it works. What are the odds that you misunderstand physics, design something based on that misunderstanding, and that it then works in a barely-detectable way due to "unknown mechanism"?