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LK-99 isn’t a superconductor

nature.com

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Re: LK-99 isn’t a superconductor

#251

Post by pvg »

Waterluvian wrote: post #50
archepyx wrote: post #31

Earlier quoted context omitted.

HN discussion did not particlarly have "reasonable skepticism". This is probably because people (i) were not aware that there had been many other hypes about RTSC before but less publicly visible all proved to be false, (ii) not being able to accurately judge the technical quality of the initial evidence, (iii) uncritically believing that the data in the initial preprints was proof for superconductivity because their…

I find it perilous to treat an entire community as it if has one voice. Ie. "the HN discussion" as a singular entity with a singular binary state on its skepticism. Someone else could equally claim that the HN community was super pessimistic and skeptical about it, because I certainly saw a lot of that too! While a convenient abstraction, it plays into our biases to notice and remember only some of the discourse. Plu…

it's odd when there's people who treat an optimistic outlook as an error.

It's pretty standard to be skeptical of extraordinary, poorly supported scientific claims and you didn't have to be an expert to find out experts were fairly skeptical of this from the beginning and the reasons for their skepticism. The broad HN sentiment was at odds with what you could find elsewhere. This isn't a moral failing or anything, just a common mode of HN-like forums but to elevate it to some some sort of positive rather than a thing to be cautious about seems backwards.

Re: LK-99 isn’t a superconductor

#253

Post by rubberpoliceman »

deepspace wrote: post #184
vecter wrote: post #14

In their preprint, the Korean authors note one particular temperature at which LK-99’s showed a tenfold drop in resistivity, from about 0.02 ohms per centimetre to 0.002 ohms per cm. “They were very precise about it. 104.8ºC,” says Prashant Jain, a chemist at the University of Illinois Urbana–Champaign. “I was like, wait a minute, I know this temperature.” The reaction that synthesizes LK-99 uses an unbalanced recipe…

When I first saw the quoted resistivity, 0.002 ohms per cm, my thought was "this is not even a conductor, let alone a superconductor". 0.2 Ohms/m is several orders of magnitude less conductive than most metals, and solidly in the semiconductor range.

Resistivity is measured in ohms * meter, so this may be a unit conversion issue…

Re: LK-99 isn’t a superconductor

#254

Post by hedora »

throw-ru-938 wrote: post #98
jcarrano wrote: post #44

Earlier quoted context omitted.

If 20 years of horsing around with a material that does not work did not end their careers, neither will this.

Didn't they only get funding to horse around with that material several years ago?

Well, yes, but their prototype time machine let them put in more years per year than you'd expect.

(Someone anonymously claimed they have a time machine on social media, so it must be true!)

Seriously though, it sounds like the research group is doing interesting work, and also being careful about the claims they make (even if the internet hype cycle is not), so kudos to them.

Re: LK-99 isn’t a superconductor

#256

Post by threeseed »

DarkmSparks wrote: post #169

"The science is settled." Proceeds to quote a guy who studied chemistry at university and now works in finance. Now, Im not saying it is a superconductor. But please, don't insult my intelligence with garbage like that, I'm more inclined to believe that kind of reporting is evidence that serious scientists are not willing to go on record as saying it isn't.

"The science is settled."

- No idea what exactly the original replication process was.

- Limited number of replication attempts globally.

- No comments or samples analysed from the original authors.

Re: LK-99 isn’t a superconductor

#257

Post by pistachiopro »

You can publish an article with a title like this and probably not end up embarrassed. Room temperature and pressure super conductors seem hard enough to find that chances are any given paper claiming to have found one will end up with a more mundane explanation. And I do think the information about the phase change of Cu2S is highly relevant, as it points at a way the original researches my have fooled themselves.

The dismissal of the partial levitation as ferromagnetism, on the other hand, doesn't strike me as especially robust. Ferromagnetism explains the partial levitation of tiny fragments of material generated by people trying to reproduce LK-99. Very light and thin pieces of ferromagnetic material will align themselves with a magnetic field. For example, Andrew McCalip (who streamed himself attempting to reproduce the material in his rocket startup's lab) generated a partially levitating fragment and sent it into USC, where they determined it was ferromagnetic. But bulk pieces of ferromagnetic material will just stick to magnets (or if they are magnetized, they will stick to one side and be unstably repelled from the other).

Ferromagnetism doesn't explain the levitation demonstrated in the videos put out by the original researches, though. Barring fraud, the most likely explanation for that kind of levitation is diamagnetism. The article mentions Derrick van Gennep recreating the partial levitation video with a chunk of pyrolytic graphite (one of the most diamagnetic materials we know of, other than superconductors), supergluing iron filings to a corner of it to anchor it to the magnet. The levitation in that video comes from diamagnetism, not ferromagnetism. LK-99 is primarily made of lead, not graphite, which is 5-10 times denser, so the diamagnetic effect must be at least that much stronger than pure pyrolytic graphite. The thing is, as the rest of the article points out, the supposed main constituents of LK-99 have now been extensively studied, and none of them appear to be especially diamagnetic, so something in those samples the original team recorded must be extremely diamagnetic to make up for it!

Re: LK-99 isn’t a superconductor

#258

Post by redox99 »

Moomoomoo309 wrote: post #25

I found Thunderf00t's video on LK-99 to be funny because he pointed out something no one else did: In almost all applications of superconductors, they don't use high-temperature ones for one simple reason: Material properties. Most high-temp superconductors (including LK-99, he was assuming it was one, since he's not qualified to say one way or the other) are a ceramic. The ones that see use in the LHC, for instance,…

Thunderfoot is more focused on being a contrarian than being accurate and unbiased. See sibling comments that explain why it being a ceramic isn't that relevant.

Re: LK-99 isn’t a superconductor

#259

Post by gabagaul »

thinkingkong wrote: post #2

It’s disappointing news but the excitement and amount of replication on this paper was pretty fun to witness and experience. To me the most interesting part was everyone talking about potential consequences, uses, the order of magnitude improvements we’d see in certain costs or areas. Pumps, MRIs, power grids, chips, etc. Great reminder what materials science can do to some underlying economics.

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