# LK-99 in retrospect

About a year ago, there was a lot of public interest in a supposed room-temperature superconductor called [LK-99](https://en.wikipedia.org/wiki/LK-99). What I publicly said at the time was, basically:

1. We should remember the possibility that apparent levitation is from ferromagnetism or paramagnetism. Iron filings can stand up on a magnet, and [pyrolytic graphite can float](https://www.youtube.com/watch?v=QQPBEPiOpiM) over a strong magnet.

2. If we consider some known high-temperature superconductors:

- YBCO has flat sheets of copper oxide, and superconductivity happens along those planes. The copper in that has high positive charge density, comparable to aluminum atoms in alumina, which gives strong bonding to the oxygen.

- H3S ([paper](https://www.nature.com/articles/s41467-019-10552-y)) has unusually strong bonds between the sulfur and hydrogen, which only form because the atoms are pressed into each other with enough pressure to substantially compress liquid water.

Superconductivity comes from flow of [Cooper pairs](https://en.wikipedia.org/wiki/Cooper_pair), and the electron-phonon interaction must be stronger than random thermal movement. LK-99 doesn't seem to have any reason to have exceptionally strong such interactions. (Yes, I'm simplifying, you have to consider phonon bandgaps, but the point is at least directionally correct.)

3. The focus on "room-temperature" superconductivity is a bit silly. Even with systems using liquid nitrogen cooling, the superconducting wires are much more expensive than the cooling. What's really needed for superconductors to be practical is cheaper superconducting wires, not higher-temperature ones.

At the time, I found the unusual amount of public interest a bit bemusing. There have been various claims of near-room-temp superconductivity, but none of them attracted as much public attention as LK-99. A few months earlier, [Ranga Dias published a paper](https://www.nature.com/articles/s41586-023-05742-0) claiming room-temperature superconductivity; he's now up to [5 retractions](https://retractionwatch.com/2024/06/21/superconductor-researcher-loses-fifth-paper/).

What was different about LK-99?

- That was supposedly superconducting at ambient pressure, which makes it more practical, but also means less specialized equipment is needed to replicate it - or *claim to* replicate it.
- LK-99 had a video that appealed to people.

There were also a few social conditions that I think were important:

1. It had been a while since that last major excitement about fake science news. After some big story that turns out to be wrong, people are more skeptical of science stories in every field for a while, and then things gradually go back to a baseline. (That's how things were after eg the "arsenic in DNA" story, which didn't make sense either: arsenate esters aren't stable enough for DNA.) I understand the heuristic that people applied but the way it's applied here doesn't really make sense.

2. Misleading short videos + social media is a combination that hadn't really been applied to bad science stories before.

3. I think the atmosphere at the time had a lot of demand for ammunition in a wider techno-optimist vs techno-pessimist conflict. ("Room-temperature superconductors and Boom Technology making practical supersonic aircraft! We're so back!")

I think those overall conditions caused the LK-99 story to be self-amplifying, because:
- Several twitter accounts made fake videos showing "replication" of LK-99 superconductivity, because it was just good social media strategy. I think [iris_IGB](https://x.com/iris_IGB) is still up a lot of followers overall. Don't hate the player, hate the game, I guess.
- Some theorists jumped on the story by [finding](https://www.nextbigfuture.com/2023/09/a-superconductivity-theory-to-explain-reported-lk99-assuming-reports-were-correct.html) "theoretical justifications" because it seemed like a net career positive, statistically speaking.

In many cases, whether the social status of a scientific theory is amplified or diminished over time seems to depend more on the social environment than on whether it's true. For example, the amyloid theory of Alzheimer's is still going, and real money is being paid for drugs based on it that don't help people. The social environment created a demand for evidence, and so fake evidence was produced by people including the former president of Stanford.

For my part, a couple of the grad students I talked with seeing data falsification going on in their lab was a big reason for my skepticism of the university system when I was in high school. Later on, an acquaintance tried to make an issue out of apparent bad data and ended up being bullied by the professor to the point of suicide. (PIs have a lot of power over their grad students' life and career prospects.) But I wanted to warn people not to consider such things enough of a justification to avoid getting an undergraduate degree, with how things currently are. It's quite important to spend 16 years studying in school to get a certification that will get an HR person you'll never meet who spends one minute looking at your resume to not throw it out, and it does sound like a joke when I put it like that, but it isn't.

Anyway, if there's a moral of this story, I suppose it's that, if you're smart, you should learn enough technical details to be able to find experts to trust on your own instead of relying on societal consensus. Or maybe it's that you should understand the incentives of the people who determine which stories get spread and considered credible? Actually, maybe it's that people have biases towards believing or not believing in stories that often outweigh the evidence? Or maybe the moral is, real events don't have a single clear moral to them, but that's OK because you can read about as many as you want and average out the incidental details.