Thanks for submitting this, love to see feedback from the physicists who hang out around here!
(a) If these models break down somewhere I would expect it to happen under much more extreme conditions and not with a 'table-top' experiment like this one.
(b) As far as I can see, giving up momentum conservation is not a feature that we can simply 'bolt onto' the existing models. It would require a radical rethinking of the very foundations of our current physical models.
So my personal attitude is that extraordinary claims require extraordinary evidence and this paper is not remotely convincing.
This experiment reminds me very much of the faster-than-light neutrinos. The authors of that experiment also seemed careful enough to not overstate their claims but this did not prevent a massive public interest in an ultimately debunked result. I expect the results in this paper to go the same way.
I agree and I'm skeptical myself. But note that models just barely break in this experiment. The deviation from theory (if real) is so small that it's almost unmeasurable. The models might break in a more severe way if extreme conditions are applied in a correct way.
To push back on this kind of thinking a bit, Einstein's breakthrough papers on Brownian motion (which served as evidence of existence of Atoms and Molecules) and the photo electric effect (which demonstrated validity of the Quantum theory of light) were very much "tabletop" effects.
While there's no denying this requires extraordinary proof, I think it's equally important for physicists to prevent themselves being biased by pre-conceived notions.
Yes but they were very well known tabletop effects. What was lacking was the theory to explain them.
What we need now is other physicists to test their own "Q thruster." If no one else detects a thrust, well, fine, chalk it up to weird error and move on. If other people do find a thrust, then we're into "we don't have a theory yet" territory.
They concluded that the force is excerted by coupling the RF-energy from the outside.
If the system is fully self-contained (driven by a battery physically connected to the cavity) there is no thrust to be measured.
It's very sad to see NASA being involved in such shitty research.
[1] https://tu-dresden.de/ing/maschinenwesen/ilr/rfs/ressourcen/...
I believe they are going to put one of these in space, that'll give a definitive answer.
First you have to completely decouple the cavity from it's surrounding environment - especially the RF-field has to be generated by an apparatus fixed to the cavities frame of reference. Also the power has to come from a source connected to this frame of reference.
For me this is Physics 101.
As otherwise your system is not even closed. You are just neglecting that you are pumping LOTS of energy into an open system that you are measuring while assuming it to be closed -> thus leading to wrong conclusions (measuring a change in impulse in one part of the system)
For me this in line with uBeam and the like.
Whacko-science wherever one looks.
In any case, I am not from TU Dresden and have only a passing acquaintance with Tajmar, but I do agree that credit and recognition is not going where it should in this case.
"The nature of the signals observed is still unclear."
They are, clearly, taking the tack of eliminating all sources of measurement error. But they haven't yet achieved that, and as yet a force remains. It seems perfectly reasonable to assume it will be attributed to measurement error, but that is not yet the case:
" Next steps include better magnetic shielding.... We believe that this is a good education project to track down measurement errors..."
NASA would have had the means to eliminate most of those sources of errors. I wouldn't call these measurement errors though -> the measurement is fine - your setup is the source of error.
But they decided not to follow such a line of research.
And yes, they are right "We believe that this is a good education project to track down measurement errors".
The measurement error being the "thrust" that is due to your experimental setup.
But let them waste some more money, time and reputation and build this in space so they can find out it does not actually work.
> NASA would have had the means to eliminate most of those sources of errors.
Yes. NASA as a whole yes. One group researching something that may or may not bear fruit no.
So it's natural they try to eliminate easier errors first. But (as an example) it's one thing to have a good vacuum, another one to have an excellent vacuum for testing. So first you test on the good vacuum.
Yes i did, usually i just let certain topics pass by me and never comment here.
RF-cavities though are the very core to my line of research, so my acceptance for bs is very low in this regard.
If one wants to convince me of a thrust effect: build a prototype where the power source (a battery for example) and the RF-source are strapped onto the cavity, put the whole setup in a vacuum of your choice (i heard NASA has very nice and !large! facilities) and show me a sustained increase in impulse (just let it rotate for a while)
Okay, but they aren't trying to convince you yet.
They're trying to convince themselves that it's worth spending the resources you describe.
> To definitively rule out any residual concerns about thermal error sources, future test campaigns could employ a test apparatus capable of measuring small torques over much larger angular displacements. For example, a Cavendish balance approach properly designed to allow very large rotation angles such as 90, 180, or even 360 deg will not be susceptible to this type of thermal false positive.
The group has been working five years in their own time in this small laboratory with shoestring budget. White has a day job in NASA and he and others are working with this project in their free time. NASA don't seem to be involved in any other way but "NASA Eagleworks Laboratories" makes it sound like official NASA organization.
To be fair, the authors did enlist Tajmar's paper in the state-of-the-art but they do not discuss despite it being the most relevant prior art.
For anyone who knows a little bit Tajmar, if there was a tiny hint of a possibility that this effect could be real, he would definitely have pursued it; after all, his self-admitted goal is nothing else but to discover the warp-drive... That being said, he is no crackpot and the thoroughness of his article confirms it.
Incidentally, in a similar HN story a couple of days ago I shared my suspicion about spurious contributions from thermal drift, and unsurprisingly I see this was also the number 1 suspect for Tajmar. Beside using thermal barrier to mitigate the problem, he also went from electro-magnetic damping to oil damping and found completely different results. Meanwhile, the Eagleworks guys are still using an EM damper, working right next to a strong EM field source.
That being said, I can understand the over-reaction, it is indeed frustrating to see relatively weak articles making front page because they originate from NASA when earlier, more thorough research did not get any attention because their authors were more careful with their claims.
Mind you, I am not saying the Eagleworks paper should not have been published; any data point is good as long as the experiment is sufficiently described for it to be reproduced or disproved, and in that respect I think it is OK. But very good it is not.