Given that reactionless thrust is even less plausible on a theoretical basis than superluminal neutrinos, I really hope this doesn't come as much of a surprise to anyone.
> It would have violated our understanding of physics, but it's not like that's never happened before.
I've heard this sentiment a lot when it comes to the EMDrive, but honestly I think it really misunderstands how science progresses in general. For EMDrive to be real, virtually everything we know to be true about physics would have to be false: if you're saying conservation of momentum can be violated, or conservation of energy can be violated, then basically all of modern physics would have to be wrong.
When science, and especially physics, advances, it is very rarely, if ever since Newton's time, that the settled physics is 100% wrong. Instead, the "old" physics tends to be an approximation under most conditions, or there is a new phenomenon that can be explained without really violating the old rules. For example, conservation of momentum still holds under special relativity, it's just that we discovered things without mass can have momentum.
Thus, the only explanation that would really be plausible is if there is "something else" going on with the EMDrive where momentum and energy are still conserved, just that there is something happening beyond our current understanding of "energy" or "momentum". I haven't seen any explanations that even try to postulate what that could be. All I ever have seen is "but the old physics could be wrong!" without an explanation of how it could be wrong.
Not a surprise and not a disappointment either, when it was clear from the start that all results are within measurement error bars, so that there was neither experimental nor theoretical reason to expect to see something.
Reactionless thrust is less plausible, yes, but it is strictly impossible. Not all explanations for it involved reactionless thrust. NASA indicated that pilot wave theory might be involved (where the vacuum acts as the propellant). This research is pretty conclusive: it doesn't work. That being said, just because you don't have any reasonable explanation for an effect does not mean that it does not exist.
Flight would have been considered reactionless thrust before it was understood that air had substance.
Last time I looked it, this EM Drive research was not NASA project. They just gave a NASA engineer a warehouse to pursue his ideas on his own time like good research organization does.
The "Eagleworks Laboratories" or "Advanced Propulsion Physics Laboratory" is just what Harold G. White calls the warehouse. It has no website or staff from NASA.
It was not "NASA" who indicated something, but a couple of guys working for NASA. Also, the "pilot wave theory" stuff is just idle speculation on topics of which the authors did not appear to understand much.
> Given that reactionless thrust is even less plausible on a theoretical basis than superluminal neutrinos, I really hope this doesn't come as much of a surprise to anyone.
You can achieve what looks like reactionless thrust by swimming in spacetime, according to GR:
So I think your statement is only true in the strictest sense using the words literally, but the spirit of the claim is actually false: theory actually predicts the existence of reactionless motion.
No one involved seriously thought it was reactionless. There were plenty of theories, such as a focused catalyst for dark matter decay, that would have made it perfectly compliant with Newton’s third law.
Then you do not know and/or understand the huge body of work around these theories that support them. These are hard to understand for people not familiar with physics. But especially for GR there are experimental confirmations that are absolutely spectacular (Mercury's apsidal precession computed precisely, time delation by gravity measured by placing atomic clocks on mountaintops and airplanes, etc., observed gravitational waves, gravitational lensing...). And noone was so far able to create an experiment that managed to falsify that theory (it is a perfectly falsifiable theory), but not for lack of trying.
Dark matter and energy are irrelevant, no matter what percentage of the "stuff" in the universe are made of them. Greater than 99% of the things you or I experience from day to day are the result of the electromagnetic force. We experience gravity pulling us down all the time, but that's like one continuous note contained within a symphony. Some of our electricity is produced by nuclear power, but that's hard to pick out from anything else. A few people have lived through a nuclear explosion, which probably had a profound emotional impact on them. Perhaps you've seen the glowing, radioactive paint that they used to use on watch-hands to make them glow in the dark (probably from behind glass in a museum, if you have). But everything else, all of the things you can detect with your senses, comes from the interactions between electrons and photons.
Dark matter doesn't interact with either electrons or photons, and neither does dark energy. So they're irrelevant; they can't be used to explain the behavior of the EMDrive, because the EMDrive is made of matter.
Poor title. It is sad to see academic descend into click-baitness. Even the abstract does not tell you the key point of the paper. The most one gets from the abstract is:
Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices.
Reading the paper one can finally get to what we want to know, "Do these thrusters work?" The answer is no and/or can't tell yet.
Under the EMDrive section:
This clearly indicates that the “thrust” is not coming from the EMDrive but from some electromagnetic interaction.
Under the Mach-Effect section:
This again indicates that there must be some electromagnetic interaction or thermally induced center of mass shift that is masking any real thrust value.
Edit - I did not read the whole paper but skimmed for these descriptions of if they found any real thrust signal.
Reactionless drives are even "worse" than Epstein drives, since they break conservation of momentum entirely. Epstein drives just have wildly implausible characteristics- while they might break all known laws of, say, material and nuclear science, they don't break conservation laws since they require reaction mass.
If I remember correctly the authors stated it was based off of the theoretical limits of efficiency for a reaction mass drive (e.g. if we could turn mass into acceleration with very little waste energy). Which is a really great conceit in my opinion because it stays hard sci-fi where it matters (e.g. besides the aliens) while still being close enough to our time to be interesting.
Given what appears on screen, the Epstein Drive doesn’t even have that problem. It “only” acts like an electrostatic confinement fusion reactor with a hole in the confinement, slight enough for only the fusion products to escape, where the nozzle points.
(Edit footnote: only seen s1/2, anything surprising in s3 is unknown to me).
I thought when they were "flying teakettle" they were using water as a reaction mass, and the Epstein drive was an unexplained reactionless drive? At least in the books, haven't seen the TV show.
Iirc, there's some mention of pre-Epstein fusion ships that needed even more water.
Damn it. The Epstein drive is a fusion drive. It's far more plausible than this voodoo quackery, the only thing keeping it out of reality is the fact that nothing that size could handle the wattage without becoming a rapidly expanding cloud of plasma.
Everyone that hopes for a bright future would absolutely love a reactionless drive. I'd love it. But it's not real. We've seen lots of very bad methodology and things like researchers ignoring the fact that a null setup still produces the same thrust even though the drive has been modified not to work. With forces of this tiny order of magnitude it's incredibly hard to get accurate readings, and readings within the margin of error of the instrumentation should not be reported to sensationalist media as promising.
This is just another one of those ufo antigravity quacks you see on youtube, but somehow they got their day in court. I can't explain how much I'd love to be proven wrong, but reactionless drives are physically ludicrous in every single way we understand the universe. Is it possible for us to be wrong? Sure. Is it possible that we're wrong about literally every observation we've ever made in the history of physics? I very much doubt it and it's going to take more than a badly set-up experiment featuring a microwave stuffed into a tuba to convince anyone of that.
I want to believe the same way I suspend disbelief when I read S.F. -Its temporally applied. Stop reading the S.F.? no time travel or FTL.
So my wishes aside, I feel like this is very tenuous, and is going to come down to "better measurement isolated an effect causing this" more then "there is now a tractable reactionless drive at scale for big things"
I don't understand how the EMDrive came to be a serious topic.
First, someone proposed a design that violates both conservation of momentum and conservation of energy, but that's cool because you know, fuck physics. Then there was a hoax and yellow journalism and in the end, several experiments failed to confirm/reproduce the effect, but that's cool because we have this awesome theory we are trying to confirm, right?
By the way, I am looking for a team of physicists that will confirm my revolutionary Tooth Fairy Drive(tm).
Testing of propellantless propulsion concepts
requires a highly sophisticated thrust balance that
must be able to reliably detect very small thrust with
a resolution down to the nano-Newton range, block
electromagnetic interactions as much as possible
and limit any balance-vacuum chamber wall
interactions.
The thrust, if any, is so weak it's down in the noise. For a propulsion system, that's a big problem. It's like cold fusion in that way.
Nano-Newtons. For comparison, the tiny rockets used for attitude control on satellites have a thrust of about four Newtons. Falcon 9 booster, about 7,000,000 Newtons. This thing, if it works, maybe 0.00000001 Newton.
The fact that no-one has conclusively disproven this yet gives me hope.
My desperate desire for this to be real has nothing to do with that hope whatsoever.
I feel like, if this is real, it's one of those sci-fi MacGuffin technologies. Literally changes everything.
The tldr for emdrive: having verified that changing the direction of the engine the thrust direction also changed, but when they attenuated the power to just the drive component, which should have changed the thrust, but it did not. Therefore the thrust being seen was not being produced by the drive itself.
For the piezo one the predicted thrust was below the noise threshold in their final tests (specifically below center of mass movements that were also - to my reading - due to the control electronics)
Readit News
I've heard this sentiment a lot when it comes to the EMDrive, but honestly I think it really misunderstands how science progresses in general. For EMDrive to be real, virtually everything we know to be true about physics would have to be false: if you're saying conservation of momentum can be violated, or conservation of energy can be violated, then basically all of modern physics would have to be wrong.
When science, and especially physics, advances, it is very rarely, if ever since Newton's time, that the settled physics is 100% wrong. Instead, the "old" physics tends to be an approximation under most conditions, or there is a new phenomenon that can be explained without really violating the old rules. For example, conservation of momentum still holds under special relativity, it's just that we discovered things without mass can have momentum.
Thus, the only explanation that would really be plausible is if there is "something else" going on with the EMDrive where momentum and energy are still conserved, just that there is something happening beyond our current understanding of "energy" or "momentum". I haven't seen any explanations that even try to postulate what that could be. All I ever have seen is "but the old physics could be wrong!" without an explanation of how it could be wrong.
A lot of these things are often scams, but in this case i think everyone involved was genuine and believed they had found something great.
Flight would have been considered reactionless thrust before it was understood that air had substance.
Last time I looked it, this EM Drive research was not NASA project. They just gave a NASA engineer a warehouse to pursue his ideas on his own time like good research organization does.
The "Eagleworks Laboratories" or "Advanced Propulsion Physics Laboratory" is just what Harold G. White calls the warehouse. It has no website or staff from NASA.
You can achieve what looks like reactionless thrust by swimming in spacetime, according to GR:
http://science.sciencemag.org/content/299/5614/1865.full
So I think your statement is only true in the strictest sense using the words literally, but the spirit of the claim is actually false: theory actually predicts the existence of reactionless motion.
"Theoretically" 95% of the universe is made of invisible, unexplained stuff...
Dark matter doesn't interact with either electrons or photons, and neither does dark energy. So they're irrelevant; they can't be used to explain the behavior of the EMDrive, because the EMDrive is made of matter.
Our results show that the magnetic interaction from not sufficiently shielded cables or thrusters are a major factor that needs to be taken into account for proper µN thrust measurements for these type of devices.
Reading the paper one can finally get to what we want to know, "Do these thrusters work?" The answer is no and/or can't tell yet.
Under the EMDrive section:
This clearly indicates that the “thrust” is not coming from the EMDrive but from some electromagnetic interaction.
Under the Mach-Effect section:
This again indicates that there must be some electromagnetic interaction or thermally induced center of mass shift that is masking any real thrust value.
Edit - I did not read the whole paper but skimmed for these descriptions of if they found any real thrust signal.
(Edit footnote: only seen s1/2, anything surprising in s3 is unknown to me).
Iirc, there's some mention of pre-Epstein fusion ships that needed even more water.
Dead Comment
Everyone that hopes for a bright future would absolutely love a reactionless drive. I'd love it. But it's not real. We've seen lots of very bad methodology and things like researchers ignoring the fact that a null setup still produces the same thrust even though the drive has been modified not to work. With forces of this tiny order of magnitude it's incredibly hard to get accurate readings, and readings within the margin of error of the instrumentation should not be reported to sensationalist media as promising.
This is just another one of those ufo antigravity quacks you see on youtube, but somehow they got their day in court. I can't explain how much I'd love to be proven wrong, but reactionless drives are physically ludicrous in every single way we understand the universe. Is it possible for us to be wrong? Sure. Is it possible that we're wrong about literally every observation we've ever made in the history of physics? I very much doubt it and it's going to take more than a badly set-up experiment featuring a microwave stuffed into a tuba to convince anyone of that.
Dead Comment
So my wishes aside, I feel like this is very tenuous, and is going to come down to "better measurement isolated an effect causing this" more then "there is now a tractable reactionless drive at scale for big things"
First, someone proposed a design that violates both conservation of momentum and conservation of energy, but that's cool because you know, fuck physics. Then there was a hoax and yellow journalism and in the end, several experiments failed to confirm/reproduce the effect, but that's cool because we have this awesome theory we are trying to confirm, right?
By the way, I am looking for a team of physicists that will confirm my revolutionary Tooth Fairy Drive(tm).
The thrust, if any, is so weak it's down in the noise. For a propulsion system, that's a big problem. It's like cold fusion in that way.
I feel like, if this is real, it's one of those sci-fi MacGuffin technologies. Literally changes everything.
For the piezo one the predicted thrust was below the noise threshold in their final tests (specifically below center of mass movements that were also - to my reading - due to the control electronics)