LK-99 isn’t a superconductor — how science sleuths solved the mystery
LK-99 isn’t a superconductor — how science sleuths solved the mystery
Replications pieced together the puzzle of why the material displayed superconducting-like behaviours.
[...] the same edge of the sample seemed to stick to the magnet, and it seemed delicately balanced. By contrast, superconductors that levitate over magnets can be spun and even held upside-down.
[...] more likely the result of ferromagnetism. So he constructed a pellet of compressed graphite shavings with iron filings glued to it [...] his disc — made of non-superconducting, ferromagnetic materials — mimicked LK-99’s behaviour.
[...] 104ºC as the temperature at which Cu2S undergoes a phase transition. Below that temperature, the resistivity of air-exposed Cu2S drops dramatically — a signal almost identical to LK-99’s purported superconducting phase transition.
[...] Separated from [Cu2S] impurities, LK-99 is not a superconductor, but an insulator with a resistance in the millions of ohms — too high to run a standard conductivity test. It shows minor ferromagnetism and diamagnetism, but not enough for even partial levitation. “We therefore rule out the presence of superconductivity,” the team concluded.
[...] old, often overlooked data — the crucial measurements that he relied on for the resistivity of Cu2S were published in 1951.
A rare opportunity for a scientific story to have a proper beginning middle and end. I liked it even if it's too bad LK-99 isn't a superconductor, I was hopeful because of the relative ease of synthesis the result could be better checked.
Yea ... this is a good ending though ... for those paying attention and keen to learn something about science. It was collaboration and multiple perspectives and expertises that got to the truth ... it was a mystery with a non-obvious answer that required hard to predict insight and guess work that was all wrapped up by multiple people testing their and others theories. You could probably wrap the whole episode up into a case study on what science actually is.
I also can't help but notice that the whole episode happened before the initial paper even made it through peer review, which I think raises some reasonable questions about the current bias of science, which leans very heavily on the value of peer review and little on the value of replication studies (with LK99 being unique in how much replication work was easily feasible and attractive).
In my opinion, many fields would benefit from actually committing and rewarding good replication studies, which can and should function as peer review or critiques of the original papers/discoveries too.
Maybe all of those PhD students would have their time better spent on this task than pretending, as if often the case, they've done some original work on an important theory that's found something "for the first time".
Maybe all of those PhD students would have their time better spent on this task than pretending, as if often the case, they’ve done some original work on an important theory that’s found something “for the first time”.
I mean I'm personally biased as a PhD student myself, but I think this is a great idea. I made the core of my project to basically take a picture of a phenomenon that has been inferred from spectroscopy but not observed directly. So verification, not exactly replication, but same idea. Turns out that doing something like this is very hard and makes a worthy PhD project. (I haven't managed it yet, and am starting to wonder if my eventual paper might actually end up being in support of the null hypothesis...)
But I'm also not looking to go into academia after I graduate, so I'm not to worried about trying for something high impact or anything like that. I think for someone angling to be a professor the idea of a replication or verification project may be a harder sell, which is largely down to the culture of academia and how universities do their hiring of post-docs and such. I mean, even in this case more people are still going to be familiar with the names of Lee and Kim than any of the researchers who put in work on replication studies (can you name any of them without checking the article?).
tl;dr definitely a worthy goal and replications should absolutely be encouraged, but it's going to take a while to change the whole academic culture to reinforce that they're valuable contributions.
Now let's see which youtube "science channels" do a debunk on their own content pushed out a mere month ago.