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Ferromagnetic half levitation of LK-99-like synthetic samples

arxiv.org

311–320 of 331 posts

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#311
post #268

Earlier quoted context omitted.

It's not that it's strange, it's that it is transparently silly to claim to precisely quantify in the absence of anything resembling sufficient information for the problem to be treated probabilistically.

Ya what if you just don’t know

Any jackass off the street can just not know things! If you want to get invited to the in-crowd's house parties, you're going to need to do a lot better than that.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#312

Earlier quoted context omitted.

If LK-99 has the same resistance as the weight of a levitating frog, it's a superconductor

What does it mean for an electrical resistance and a weight to be the same?

It means you ought to check the aforementioned monty python bit.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#313
post #45

Earlier quoted context omitted.

What you'd have to do is 1) create bulk LK-99, 2) prove that that's what you'd created, 3) possibly also show that it's monocrystalline or something, and then 4) show that there's electrical resistance. The problem is that the stuff is really quite difficult to synthesize reliably. Until that can happen, good luck finding out in either direction!

It's definitely difficult to synthesize reliably when people dismiss any replication attempt that doesn't show superconductivity as a priori not being the right compound.

Heh. But it does sound like it's honestly pretty difficult to make, too.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#314
post #144
post #120

Earlier quoted context omitted.

You're saying that, if this had been real, the stock market would have known about it before the scientific community? How exactly? The markets do predict things but they can't synthesise correct information out of nowhere. Wall Street stock brokers weren't exactly going to sit down and start trying to replicate these results to see if they could cash in on it

Contrary to bored laymen on the internet willing to believe anything for escapism, the stock market usually reflect the outside view base probabilities (~0% in the case of LK-99 being real)

I would rather go with the large number of research groups who have scrambled to try to reproduce the results. They clearly did not estimate the probability to be 0. I don't see how any (correct, informed) predictions from the market could come about before experimental verification.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#315

Earlier quoted context omitted.

What benefit does that bring?

To stop the waste of resources in case the whole thing turns out to be a dud. By providing proof that it is not many more resources would become unlocked.

Grinding against worse leads is not a better use of resources.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#316
post #284

Earlier quoted context omitted.

Huh? I think he's saying OR not AND. Why would two separate pieces of evidence make the whole less probable, that makes no sense, whether you spell out the whole thing more formally or not.

So if I find 10 people that claim, each with a 10% likelihood of being true, that the dark side of the moon has a scar that looks like Pikachu, then it’s 100% true? That doesn’t make sense either. Seems like someone is falling prey to an intuitive fallacy of probability. The weird model is just wrong in the first place. The commenter we’re discussing conflates the probability of two people saying something with the p…

Of course you don't add probabilities, but for small probabilities it's an ok estimate. The chance of getting a single heads in N coin flips is one minus the probability of always getting tails, so 1-P(tails)^N. If P(heads) and N are small (e.g 0.1 and N=2), adding the probabilities is a perfectly reasonable estimate, just plug in the numbers and check for yourself.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#317

Earlier quoted context omitted.

There are 2 things in favor of the Korean team - Hyun-Tak Kim is unlikely to ruin his career and legacy for something careless and frivolous. But stranger things have happened, so lets assign a 10% probability to give some benefit of doubt to the team. - The various DFT papers show interesting flat band structures. But DFT is an approximation and also they do not take into account electron electron correlations. So l…

Repeat after me: Flat bands do not imply superconductivity. DFT calculations cannot be used to predict superconductivity. DFT is a single-particle calculation. Superconductivity is a multi-particle phenomenon. At most, the preprint(s) you're referring to suggest that maybe (under their unverified assumptions) electron-electron interactions could lead to interesting physics in that material. It provides no evidence fo…

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Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#318

Since someone blamed "Soviet fan fiction" in which I did take a part (oops) [1], let's make my opinions explicit. I'm very sure at the moment: - That the publish of two arXiv papers was accidental and the second paper was only published to claim the proper authorship, thus the exact publish date was never controllable. - That top-tier Chinese universities do use Bilibili to post early results. This makes very hard to…

I realized that it might sound like that my points were changed after the fact. I want to make sure that the current replication efforts didn't affect my confidence of these points at all, because the research group has indeed predicted most difficulties in current replications including this (e.g. they thought searching for SC in single crystals hindered the research). The fact that Chair was a sort of madman makes it harder to talk about their intents, and my articles were written to highlight those aspects better.

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#319
post #298

Earlier quoted context omitted.

Maybe it is the most natural question which comes to a lay person like me when it comes to superconducting. Not everyone can be as knowledgeable, or in the loop as you are. And I assure you that I am no bot. I acquire sustenance, go into low energy states and have a lifetime warranty like all fellow meatbags.

Wait, you got a lifetime warranty? xD

Yep. It gets void when I die

Re: Ferromagnetic half levitation of LK-99-like synthetic samples

#320
post #151

Earlier quoted context omitted.

> Hyun-Tak Kim is unlikely to ruin his career and legacy for something careless and frivolous. you came with presumption that this man knows & understands the subject matter. that is a very bold assumption given the mounting evidence against such brief. > so lets assign a 10% probability why 10%? not 0.01%? because of his "prof." title or previous publications? Surely that won't change the course of nature I thought?…

> you came with presumption that this man knows & understands the subject matter. that is a very bold assumption given the mounting evidence against such brief. Not OP but "this man" has published enough papers on superconductors[0] that yes, he absolutely deserves the benefit of the doubt. [0]: See e.g. https://scholar.google.com/scholar?hl=de&as_sdt=0%2C5&q=hyun... or https://scholar.google.com/citations?user=_P8mu…

making a few PDFs publicly available doesn't change the course of nature. he is now in the position to fully explain to the world what is going on here as no one seem to be able to reproduce what he claims.

given such facts, it is totally reasonable to question his expertise on the concern subject. you are free to judge people purely based on how much they publish, I totally respect that.

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