I just wrote a comment in another thread that's relevant here too. It looks like the first superconductor paper was released by a rouge researcher, without the agreement of the other two authors or the rest of the LK-99 group. This forced the LK-99 group to rush to publish the official paper, with a cost to quality. The LK-99 group released v2 a week later (on Saturday), and probably will continue to update it. A premature release explains many of the oddities about the two papers

The first paper submitted is titled "The First Room-Temperature Ambient-Pressure Superconductor." It lists three authors: Sukbae Lee, Ji-Hoon Kim, and Young-Wan Kwon. Its timestamp is Saturday, July 22, 2023 at 07:51:19 UTC. [1]

The second paper submitted is titled "Superconductor Pb10−xCux(PO4)6O showing levitation at room temperature and atmospheric pressure and mechanism." This paper lists six authors: Sukbae Lee, Jihoon Kim, Hyun-Tak Kim, Sungyeon Im, SooMin An, Keun Ho Auh [2]. Its timestamp is Saturday, July 22nd, 2023 at 10:11:28 UTC, or two hours and twenty minutes after the first paper. The second paper was updated a week later, on Saturday, July 29, 2023 at 01:53:47 UTC,

In both papers the first author is Sukbae Lee and the second author is Jihoon Kim, and in both their affiliation is given as "Quantum Energy Research center, Inc." in Seoul. The first paper posted has Young-Wan Kwon as third author. The second paper does not have Young-Wan Kwon as an author, and has four additional authors with various affiliations.

The second paper appears to have been was prepared in LaTeX, and the first paper appears to have been prepared in Word. The title and abstract of the first paper explicitly claim LK-99 is a room temperature superconductor. The title and abstract of the second paper don't explicitly claim that, though to me some of their terminology suggest LK-99 is a superconductor.

The accusation in [3] is that Young-Wan Kwon published the first paper without the consent of the rest of the LK-99 team, listed himself as third author, and left off the other four authors. The rest of the LK-99 team rushed to stuff what they had into the second paper, and released it 2 hours later [4]. This explains why there are two different papers from the same group submitted on the same day, it explains why the author lists are different between the two, and it explains why the second paper and not the first has been updated. I'm not in the field and have only read each paper once, so I'm not certain, but I'm betting it also explains a lot of the mistakes and messy bits of the papers.

This makes cautiously optimistic that this might be for real [5]. The papers on arXiv as of Monday night are consistent with a research group that succeeded in producing and identifying a room temperature superconductor using a fabrication process that is a bit tricky, and who were then forced to publish prematurely. There's nowhere near enough evidence to conclude LK-99 is a room temperature superconductor. But one failed replication doesn't prove LK-99 isn't a superconductor - if the fabrication process is finicky we'd expect to see a few dozen failed reproductions and a few successful reproductions.

Edit: Here's an appendix to bring us up to date to Monday night U.S. time. Two additional papers have been published in response to the LK-99 claims, for a total of four.

The 3rd paper is an unsuccessful attempt to reproduce the LK-99 group's results experimentally. It is titled "Semiconducting transport in Pb10-xCux(PO4)6O sintered from Pb2SO5 and Cu3P." 9 authors, all affiliated with the Materials Science department of Beihang University in Beijing. Timestamp Monday July 31st at 16:13:05 UTC. [6]

The fourth paper is a set of simulations of LK-99 that observes some similarities between LK-99 and other materials that are high-temperature superconductors. It is titled "Origin of correlated isolated flat bands in copper-substituted lead phosphate apatite." A single author, who is affiliated with Materials Science at Lawrence Berkeley National Lab in California. Published on Monday, July 31st, 2023 at 17:58:17 UTC. [7]

[1] https://arxiv.org/abs/2307.12008

[2] https://arxiv.org/abs/2307.12037

[3] This comment was originally written in reply to: https://news.ycombinator.com/item?id=36952499

[4] Though I don't think we know publicly whether the all authors agreed to publish the second paper, either. It seems equally plausible that some portion of the group rushed to publish, or even that one author published it independently.

[5] And by cautiously optimistic, I really mean "extremely excited and nervous, enough to stay up until 3am collating arXiv timestamps"

[6] arXiv link: https://arxiv.org/abs/2307.16802
HN link": https://news.ycombinator.com/item?id=36951140

[7] arXiv: https://arxiv.org/abs/2307.16892
HN: https://news.ycombinator.com/item?id=36951815