Can one know how many people are in that market? When prediction markets where mentioned early during the LK-99 story, I looked a bit around out of interest, which platforms exist, which topics they cover, how many people participate in that markets. Where I could find the number of predictors, it seemed pretty underwhelming - one, ten, fifty, a hundred, I think the highest I ever saw was a bit over a thousand, but even then less than a hundred or so where using real money, the majority was using play money. Did I miss the place where everyone is? Is this to expected because the are so many topics you can bet on? Are the resulting prices still meaningful even with a small number of predictors only?

The sensible thing would be to bet against it - as shown by xkcd

Did that site predate https://xkcd.com/955/ or was it inspired by it?

They got about 50 degrees C, but note that the bulk sample and the more pure tiny sample are different.

It definitely contributes to the general feel that however this works, it's an inefficient synthesis that's problematically generating the material we want.

It certainly makes me wonder if something like molecular-beam epitaxy would be able to directly grow a more pure sample (but I imagine that's expensive and time-consuming to setup, plus not really what we're hoping for if we want to use lots of it).

326K (+127 deg F) and 340K (+152 deg F) for their less and more pure samples respectively. And, yes, if it's a superconductor as we understand them, that's the temperature at which it would have zero resistance as well.