Room Temperature Superconductor Paper Retracted by Journal Nature | Hacker News Reader

Room Temperature Superconductor Paper Retracted by Journal Nature

wsj.com

142 pointsvoisin29 comments

Note: it is not about LK-99.

To the best of my knowledge no LK-99 paper got retracted simply because it didn't make it to publication.

Its been awhile since I followed this. What was the takeaway? Is this our generations cold fusion?

Yes, the bureau of technology control has debunked it and taken it for internal use. ;-)

The takeaway is: LK-99 is definitely not a superconductor. The apparent observation of zero resistance can be explained due to a well-known phase transition of copper sulfide, combined with sloppy data analysis. The half-levitation seen in images and videos can also be observed in perfectly normal non-superconducting materials.

I think the "99" in LK-99 refers to the year it was first created by the authors of the paper. Were they under the impression that it was a superconductor for the past 24 years, and only found it it was bogus because it attracted worldwide attention this year? If so, that seems strange.

I can see how one might make this compound, do some tests on it, and think "oh it's a superconductor" for a few months, but then surely they would do more tests to explore its properties and discover it's not a superconductor. Did they remain deliberately ignorant for 24 years?

I don't think the inventors actually thought they had samples of a superconductor for 24 years.

My understanding is that they thought they'd detected signs that LK-99 would be superconducting, if they were able to come up with a process to synthesize it with sufficient purity. They spent 24 years (slowly, and without a lot of funding) trying to do that. And over the last couple of years, they started to convince themselves that they had succeeded.

The experimenters fooled themselves by accident, which is a common occurrence in all human endeavours, including science. The scientific method corrects for this via peer review and reproduction of experiment results.

The reproductions showed:

1. The ingredients commercially available have iron impurities. The oven baking process causes the iron to separate out, often towards the edges of the material chunks. Iron is ferromagnetic.

2. The LK99 material itself is strongly diamagnetic, which is interesting in and of itself, but obviously not world-changing.

The result of the combination of the above two is that the iron impurity is attracted to magnets, but the rest of the LK99 material is repelled. This makes samples "stand up", but not hover like a true superconductor would. All of the third-party reproductions showed this effect, none showed samples truly floating.

Similarly, the conductivity tests were zeroed badly. True superconductors have a step-change in conductivity, whereas the graphs measured by the korean team showed a rapid change followed by a slower gradual decrease. The lowest resistance they measured was still very high, comparable to metals, not superconductors.

This is a common issue with fringe research into superconductors: the "signal" they're looking for is a step-change in conductivity because it is easy to measure and rare in most normal materials. However, sudden conductivity changes can occur for all sorts of reasons. It's necessary, but not sufficient for superconductivity to be confirmed.

Fantastic explanation. I appreciate your clarity.

> The scientific method corrects for this via peer review and reproduction of experiment results.

By reproduction, yes. By peer review, no.

https://youtu.be/zl-AgmoZ5mo

I'm not sure what you think this shows. Peers can "review" a study all they like, but observations always trump alleged expertise. Only consistent, failed reproductions can truly refute a paper.

Thankfully the LK99 paper was easy to (try) and reproduce, and it quickly became obvious that it didn't work the way the researchers initially believed.

The same can't be said for the other studies that come out and affect public policy which can't be reproduced. And in some cases we can't even get the data to attempt it!

All things considered I think the publication and refutation of LK99 were triumphs for the scientific community as it showed the process working as it should. Hopefully someone will one day discover a real room temperature superconductor.

> The result of the combination of the above two is that the iron impurity is attracted to magnets, but the rest of the LK99 material is repelled. This makes samples "stand up", but not hover like a true superconductor would. All of the third-party reproductions showed this effect, none showed samples truly floating.

Thanks for the explanation.

But wow, I'm kind of amazed at the simplicity of the error - iron impurities when you are testing for magnetism! I mean, who would have thought this could be a problem, before announcing this to the world?!

To be fair, the team itself wasn't planning on announcing this and still wanted to do more experiments and refining before publishing a paper. I believe it was one of the funders for the team got impatient and leaked it prematurely.

Thanks for explaining. As with most science news coverage, it was hard to understand this context.

> The LK99 material itself is strongly diamagnetic, which is interesting in and of itself, but obviously not world-changing.

How strong is it's diamagnetic constant? Is it way more than pyrolytic carbon so that we can at least create fancy, levitating toys from it?

The most recent developments state that LK-99 should theoretically be a superconductor as of a month ago, but as far as I am aware, no actual physical replication.

https://news.ycombinator.com/item?id=38184750 ("Nature retracts controversial superconductivity paper by embattled physicist (nature.com)", 122 comments)

Remind me of this Youtube video by Veritasium about the problem with science communication. https://youtu.be/czjisEGe5Cw?feature=shared

If/when someone finally does discover room temp superconductivity we're gonna be too exhausted from the previous discovery -> hype -> retraction cycle to notice.

What will happen is something along the lines of explaining that it didn’t actually happen and move the goal post or definition towards some other acceptable criteria.

Your rooms were too cold!

Same as the penis enlarging methods.

https://archive.md/WMliX

Nature - Quick to publish, slow to retract

Not a science journal, see: Proximal Origins

It was fun to dream the first few days this was a thing.

It was the least toxic social media cycle I'd seen in years

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