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: for every 1 part copper-doped lead phosphate crystal — pure LK-99 — it makes, it produces 17 parts copper and 5 parts sulfur. These leftovers lead to numerous impurities — especially copper sulfide, which the Korean team reported in its sample.
Jain, a copper-sulfide expert, remembered 104ºC as the temperature at which Cu2S undergoes a phase transition if exposed to air. Below that temperature, Cu2S’s resistivity drops dramatically — a signal almost identical to LK-99’s purported superconducting phase transition. “I was almost in disbelief that they missed it.” Jain published a preprint on the important confounding effect on 7 August.
[...]
“That was the moment where I said, ‘Well, obviously, that’s what made them think this was a superconductor,’” says Fuhrer. “The nail in the coffin was this copper sulfide thing.”
Science is hard. Kudos to everyone involved for trying to replicate it and figuring this puzzle out.
Most PhDs are incredibly specific and don’t necessary indicate broad knowledge of a field as a whole.
Which is why you should be wary of “experts” making overly broad claims about topics within their field but far outside their area of expertise.
Early on during Covid you would see postdoc infectious disease experts on every news channel 3 times daily giving their takes. Some of whom maybe took a 3000 level course in epidemiology when they were 21 and did their PhD on nematode infections in a single population of freshwater clams. Technically an infectious disease expert but I don’t particularly care what they have to say about Covid over a random person on the street either.
There was a B- or C-list physics blogger a few years back whose graduate homework I used to grade. (I still remember this one, so that should tell you something.) He got very angry that I gave him zero credit for one particular question. But he:
- did not use the standard/expected approach to this problem
- did not explain what he was doing well enough for me to find him any partial credit (this is not easy!)
- had a pile of impenetrable unnecessary very complex alien math that I wasn't going to try to cut through given that
- his final answer was very, very wrong
- in fact, it was wrong by 26 orders of magnitude
- and he didn't have the skill to notice something was wrong (and, yes, I was lenient with students who noticed final answers were weird even if they couldn't/didn't fix it up)
- also, he was a major asshole (no surprise given that he's complaining about this "indignity") who was
- somehow still causing #MeToo problems in the 21st century despite being under 30 (seriously??)
So if that's who gets held up as "authorities", even minor ones, forgive me if I don't listen too much. I'll choose who I trust.
Honestly? His mannerisms was all we really needed. He was not well liked in his year, and that takes some doing to achieve these days. The smug "how could I be wrong" when he was, well, 26 orders of magnitude wrong, is special even by entitled scientist standards.
I can't tell if you're being sarcastic or not, but I strongly believe, based on my experiences with really successful people, that being open to being wrong absolutely does count for a lot more than the current truth value of your ideas.
I didn't say authority, and I didn't say trust blindly. I just said I'd trust someone with baseline qualifications over a random (presumably unqualified) person. lmao
My point is that this person has baseline qualifications (Physics PhD!), was accepted by the media as "qualified" to be a blogger, and yet was still a complete god damned moron even in his own field of "specialization".
It wouldn't have made such an impact except that he was getting paid to publicly write about this stuff, at the same time he was privately incompetent. A stellar example of the Gell-Mann Effect (aka Amnesia) if ever there was one.
> Most PhDs are incredibly specific and don’t necessary indicate broad knowledge of a field as a whole
> Which is why you should be wary of “experts” making overly broad claims about topics within their field but far outside their area of expertise.
I mostly agree, but also I think it depends on how strong you are suggesting this and if you also acknowledge that there is high variance between domains as to the variance within the distribution of knowledge. Your last sentence is where I really disagree. There is a big difference.
But I think for the general person, there's 2 things of note: 1) just because you should be wary of an expert talking outside their niche (but inside their broader domain), doesn't mean that their opinion is equal to that of a layman. I'd still trust the mostly-expert over the non-expert any day. The true-expert is often very hard to find tbh. Look for nuance and you'll increase the likelihood of finding the expert. 2) It is easy to confuse expert talk with arrogance or pretentiousness. It is also easy to be that way when talking to a layman as the nature of those conversations will never be between peers, but more akin to a teacher and student. The two parties are not equal, but we're primed to treat any non-academic setting conversation as if we are. The experts often have serious doubts and are far more self-conscious than they appear. You just won't see that unless you're a peer and can speak the language, because experts are also specifically taught to defend their work and speak with confidence. Your hint is how they respond to critiques from other experts (but that's not easy to do accurately as there's probably a lot of nuance you aren't seeing and they are speaking a different language even if you understand all the words).
Everyone should always be skeptical though. That's for certain. But I just want to make sure we don't turn knowledge into a binary setting: expert vs idiot. There's a lot in-between and that matters a lot.
> I'd still trust the mostly-expert over the non-expert any day. The true-expert is often very hard to find tbh.
Right, you can always find somebody more expert than someone else. The level of specificity that some people expect for a variety of problems will leave only a dozen or so people in the world who can call themselves experts.
Oh for sure. Expertise is exceptionally narrow. It's not a super low variance value, as there is spillover (physics/concepts/math/whatever share many similar principles), but most people __vastly__ underestimate the depth and complexity of any given topic, no matter how mundane and simple it may seem. I mean a good example is that you'll find books on o-rings, nails, screws, bolts, etc that are individually over a thousand pages. Hell, The Art of Electronics -- a book this community is probably more familiar with -- is a fucking godsend, but even being over 1k pages and generally a reference manual it is still lacking. Even if you get the second book (X Chapters) with an additional 500 pages!
This is also why experts can often sniff one another out on online forums like this. There's a subtly to the language that is used which conveys an understanding of many deeper nuances than were a novice or even someone with a undergraduate would use to discuss a topic. There's a common misnomer that you don't understand something unless you can explain it to a layman (probably invented by a layman to justify their lack of understanding), but accuracy and complexity are tightly coupled. A concept with x% accuracy has a minimum of y complexity. But also knowing this can help you sniff out experts in fields you aren't also an expert in, but of course your classification accuracy drops since you are introducing more noise. Still, a useful guide if you're trying to figure out who to listen to. Obviously much easier said than done.
You have to (though in general we’re expert on a couple of classes of compounds rather than just one). The literature is just too vast to follow otherwise. Particularly in fashionable fields with loads of funding like high-temperature superconductors, battery materials, PV materials, fuel cells, things like that.
Right but it’s more like someone is an expert in the “async” method. You’d expect them to be expert in whatever language they’re using, so the framing threw me off.
Yeah I get what you mean. Could just be a quirk of the reporting too - like you might write a lot of async python, comment on some hot topic case using that knowledge, GIL removal say, and then get labelled 'async functions expert Darth Avocado' when really you'd never think of yourself that way.
It looks like he doesn't specialize exclusively in copper sulfide. His most cited works are to do with gold, and he has articles on a bunch of different materials:
He's probably a *-sulfide or copper-* expert. Or maybe just a physical chemist that the press is ginning up. Actually, the latter. His page doesn't even mention copper or sulfide; and makes only one mention of conductors.
A number of years back I had an email from a bloke called Elon Musk. I was vaguely aware of who he was but not very.
At the time I was the global expert in a very weird alloy (the market for it was perhaps 5 or 10 tonnes a year. A very weird and minority interest alloy). It was aluminium scandium, which the Russians had developed to compete with Nasa’s use of aluminium lithium. In many ways a better alloy too. And, obviously, there were possible uses in rockets and so on (rather more in something like a Shuttle than in simple rockets though).
OK, so I get this email and it asks me whether this aluminium scandium is worth it, will it make my rockets lighter, asks Musk. No, not really, it’ll make them easier to weld but not lighter particularly. Which was pretty much the end of the exchange.
So, when people ask me whether Musk does tech stuff I would have to say yes. Because he tracked down a one man company that knew the straight answer to the question he needed answering. OK, you might not think that is engineering, preferring to think of it as people using a slide rule to work it all out themselves. But finding the bloke who knows the answer and asking them is engineering to me - it’s still getting to the right answer, isn’t it?
Scandium-aluminium alloy was popular for bicycle frames briefly in the 2000s. On-One made a frame wittily called the Scandal from it. I have a Scandal frame, but it's a second generation one where they dropped the scandium but kept the name!
Some fields are so advanced that people are expert in one single material in very specific settings. There are some really exotic things out there that are barely used/studied
I really wish less people would give pseudo-anon accounts this much credence. Literally no good science has (ever?) been done on Twitter/X, it's mostly just stupid equivocating. Much thanks goes out to the actual scientists out there working in labs and publishing their findings.
The academic/publishing process is far from perfect already (conflicts of interest, funding, political pressure, institutional pressure, personal pride), now imagine throwing a "Catgirl Girlfriend" (that trolls on an anonymous social media account) into the mix.
Free speech is fine, it's the listeners I have a problem with.
This is a bad counter-argument. What do you think is the overwhelming product of ranting and raving of anime-picture "scientists" on Twitter: scientific muddying of waters that confuse laypeople and promulgate disinformation, or actual theorem-solving?
Anonymization is the only completely sane response to the completely crazy reach-impact spiral of data mining data broker platform TOS. Online persona(s) are private brands of built up real public social value over time and just because there is no officiated imprimatur's stamp of approval, doesn't mean you can exclude them without other cause from the real conversation walled off in ivory corporate towers of group think apprentice effected idea cloning orthodoxy.
I know of a 3D graphics format interop workgroup at an official Standard Setting Organization where some of the main contributors are MAdjDuckSauce type handles and its caused no lack of backflipping through hoops to get their input codified because of ISO 9000 prescribed forms that still want your employer organization's fax number listed.
In fact, how this whole story played out on arXiv is a great example of the power of all hands on deck crowdsourced global fact checking in the broad noisy open realtime light of day. More claims should be subject to this kind of wide net scrutiny not less.
(*Correction to post above it should read "ethnically Soviet" as pointed out below)
Ad Hominem attacks like this are what make me follow people like Iris more. I've both published and peer-reviewed research, and I've seen some hot garbage come from academics.
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.
Right? That's what's not clear to me either. If they got readings for superconductivity and Cu2S impurities were the cause then fantastic, Cu2S is the room temperature superconductor? Just get a load of that instead then.
Or perhaps the way they measured the whole experiment was completely inane from the start if a simple conductor passes with flying colours. With that and them presenting ferromagnetism as the Messner effect makes me kind of question the competence of the entire analysis.
So they saw a large change in resistivity at 104C but what's not clear from this excerpt is why the Cu2S was a confounding factor, or isnt interesting.
Is it that LK99 had impurities of Cu2S and the properties of Cu2S dominated but we already know things about Cu2S?
Per the article, CU2S was well-characterised in the 50s.
The CU2S was a confounding factor because 104C is where it undergoes phase changes, which drastically change its resistivity. So the change in resistivity was from the CU2S impurities, not the LK99 itself. As the tail end of the article notes, when researchers grew a completely pure crystal of LK99 they got a strong insulator (in the mega-ohms).
And as a nearby commenter notes, neither 0.02 ohm-cm nor 0.002 ohm-cm is even a good conductor: typical conductor metals (gold, copper, silver, aluminum) are under 3e-6.
Their family would be miserable, their kids would swear to never become a material science expert, and they'd all be missing on the cross discussions with other fields and inspirations coming from outside the material science world ?
Not really trying to be flippant, but that pretty much feels like a James Bond villain fantasy, and only a few select people would probably enjoy the setting.
We kinda have a real world equivalent with people working on the LHC by the way.
Maybe someone with a billion dollars could re-locate them and their families onto some posh island all expenses paid. If Elon had instead invested 40B into this and other tactical science projects rather than dump it into Twitter, imagine the possibilities lol.
The reaction that synthesizes LK-99 uses an unbalanced recipe: for every 1 part copper-doped lead phosphate crystal — pure LK-99 — it makes, it produces 17 parts copper and 5 parts sulfur. These leftovers lead to numerous impurities — especially copper sulfide, which the Korean team reported in its sample.
Jain, a copper-sulfide expert, remembered 104ºC as the temperature at which Cu2S undergoes a phase transition if exposed to air. Below that temperature, Cu2S’s resistivity drops dramatically — a signal almost identical to LK-99’s purported superconducting phase transition. “I was almost in disbelief that they missed it.” Jain published a preprint on the important confounding effect on 7 August.
[...]
“That was the moment where I said, ‘Well, obviously, that’s what made them think this was a superconductor,’” says Fuhrer. “The nail in the coffin was this copper sulfide thing.”
Science is hard. Kudos to everyone involved for trying to replicate it and figuring this puzzle out.