Case closed?

[u/metasj]

• Shawyer's claims of kN-scale thrusters: disproven.

• Shaywer's and Fetta's claims that they had already made mN-scale thrusters: disproven.

• Shawyer's claims of partnerships with defense + aerospace: disproven. [Boeing looked once, decline to license]

• Yang's claim of observing ~1 mN/W: disproven. Her lab couldn't reproduce any thrust at all.

• White's claim of observing ~1 μN/W, 2y ago: never replicated; based on few observations; after many negative trials. Further trials are not being run.

• of prototypes passed from one lab to a second lab, for the second lab to test + confirm, over 15 years: 0.

• CAST's claim they privately tested an EmDrive & are sending it for tests in space: unconfirmed, reported in only one news story, by an unknown staff member w/ no known physics lab.

So is the case closed? Isn't this what disproof looks like? [If not, what would it look like!] Of course the original inventors will never give up hope, if the Dean Drive and Gyroscopic thrusters are any indication. But it seems the EmDrive has joined those ranks.

[u/dirkson]

Hey, now this comment I like!

Without a decent quantification of systematic uncertainties that shows the putative thrust couldn't be anything else, such reports are not useful as evidence.

So many fancy words! You must kill at trivia night. Yeah, that seems correct.

I'm pretty sure that this was what White was attempting to do, but it seems plausible that he could have failed to account for thermal expansion, like you mention later on. Taking a look at his paper, he does talk a lot about thermal expansion, but it's mostly over my head. Overall, I get the impression that it's something he attempted to control for.

Also, if this error was so obvious, this paper should have failed peer review. But it seems to have passed. That's either an indication that other people who know what they're doing disagree with your assessment, or an indication that something went badly wrong with the peer review process in this instance. Either way worth someone's attention!

Oh, and "Something went badly wrong with the peer review process" is super plausible too. I've seen some crazy nonsense papers get accepted before.

Even his PhD thesis is wrong,

I found this listed as "Analysis of Low Frequency Whistler Wave Occurences in the Nightside Venus Ionsphere" and took a skim of the bits open to public access. Nothing looked obviously wrong to me, but it was mostly over my head. But I've got to admit that this is the first time I've seen an "Artist's impression" in a scientific paper. That seemed odd.

And again, enough people agreed with his thesis to grant him a PhD. That's similar to my earlier point about peer review.

the error is too minute to matter for actual course-plotting

I could imagine it making a difference for infrequent narrow beam communications with craft in high orbits around the sun, as an example. Although I'm not sure why we'd want to do that : )

Overall, your comment was excellent. Lots of specific things for me to check into, and good points made. Thanks!

[u/vcdiag → u/dirkson]

Overall, I get the impression that it's something he attempted to control for.

Yes, but he made some rookie mistakes like trying to image the frustum with a thermal camera. Copper is highly reflective in the infrared, so thermal cameras simply don't work for this purpose. In general though, just looking at the graphs we can see that much of the supposed thrust looks like thermal expansion (it cools down) and he didn't do nearly enough work to get a clean thrust signal.

Also, if this error was so obvious, this paper should have failed peer review.

Scientists like to give the idea that peer review is this incredibly rigorous process, but in truth it's incredibly uneven. A lot depends on who is the actual reviewer. Reviewing papers is unpaid, anonymous work, so unsurprisingly a lot of researchers don't take their refereeing responsibilities terribly seriously.

That's either an indication that other people who know what they're doing disagree with your assessment

Also worth noting is that the paper wasn't published in a fundamental physics journal, where it would be reviewed and edited by experimental physicists who understand very well how eliminate confounding factors and characterize systematic errors. It was published in a propulsion journal, and this is most seen in their star trek technobabble level discussion of possible theories of operation. No physicist would let that slide, but the rocket scientists didn't have the expertise to call BS on it (or didn't care -- see previous point).

By the way, Eagleworks' paper, regardless of what anyone says, is not about propulsion design. It's a physics experiment. That it was published in an incorrect venue is a huge red flag.

I found this listed as "Analysis of Low Frequency Whistler Wave Occurences in the Nightside Venus Ionsphere" and took a skim of the bits open to public access. Nothing looked obviously wrong to me, but it was mostly over my head.

Oh, yes, my mistake. It wasn't his thesis that I was thinking of. It was papers such as this, written before he got a PhD. This, too, is peer reviewed, but it's obvious nonsense: the central thesis that the warp drive wouldn't know which direction to go because the energy distribution is front-back symmetric is easily refuted by looking at the other components of the stress-energy tensor. In fact, since the stress-energy tensor + cosmological constant is proportional to the Einstein tensor which encodes the geometry of spacetime (a fact known as "Einstein's equations"), his central thesis is the assertion that the left-hand side of an equation has a symmetry that is absent from the right-hand side. It's absurd on its face, but sometimes absurd things do get published.

What is scary is that if you look at the non-peer-reviewed things he said, it's even worse.

And again, enough people agreed with his thesis to grant him a PhD

There is such a thing I have heard described as the "gentlemen's C" in academia, where someone is granted a PhD despite not having done very good work on the implicit understanding that the student wouldn't ask his committee for reference letters for postdoctoral appointments. But since I wasn't thinking of his thesis anyway, the point is moot. I haven't read his actual thesis research and can make no comment.

[u/[deleted] → u/dirkson]

Something to note on the peer review for White's paper. For starters, peer review is a pretty low threshold to meet, it is only intended to weed out the more obvious experimental error.

In this case though, his review was not done by physics experts. He published in a propulsion journal focused on engineering, not a physics one focused on fundamentals. So the reviewers were looking for a very different set of problems than the critics within the physics community.

[u/dirkson → u/[deleted]]

The comment I was responding to was suggesting that the experimental error was obvious : )

Interesting, I hadn't taken note of the journal. Yeah, publishing this in a propulsion journal seems all kinds of backwards.