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Ferromagnetic half levitation of LK-99-like synthetic samples

arxiv.org

251–260 of 331 posts

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

#251
post #211

Earlier quoted context omitted.

Since this was an exceedingly short cycle, we were spared one of the negatives. Well, mostly: - some folks massively hype this as the "next big thing", extract money from investors and take mindshare away from more promising, but less exciting work

You say it’s a short cycle now. But I bet a non-trivial number of people are still talking about this and trying to get results long after the initial cycle. It took years for cold fusion research to go away.

So what? We can still have labels for fuzzy concepts like “took the world by storm, for 2 weeks”, even if a couple thousand people are still excited about it 2 years later.

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

#252
post #8

Has anyone even seen a ferromagnet stand up like that in a magnetic field?

Yes. https://nitter.net/VanGennepD/status/1688052003216261120 And this new paper finally rigorously explains away all the half-levitation videos. They can no longer be considered any evidence of SC at all.

Just remember, it’s their sample that they theorize it is. A theory/guess does not rule out superconductivity. Their sample if slightly different could also cause these effects. We need more than one and especially a concrete way to make this before testing. The formula isn’t shown in details from the original paper

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

#253

Earlier quoted context omitted.

What benefit does that bring?

Appropriate allocation of resources is intrinsically beneficial.

Exactly right. If we concede that our present level of societal R&D is appropriate then it's easy to argue that resources are presently wasted pursuing less promising leads.

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

#254
post #110

Someone on YouTube mentioned that LK99 is ceramic ie not metal which nullifies many of its potential uses even if it does turn out to be superconducting

YBCO is also not a metal and has also been hard to use, but it has its uses.

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

#255
post #4

After reading the r/physics thread on LK-99 [1] I've cooled significantly on the matter. Basically: people who work in SC think the initial science seems very sloppy and the replication attempts don't come close to what you need to demonstrate a RT SC [1] https://www.reddit.com/r/Physics/comments/15i3h9d/lk99_megat...

The SNR of this saga is very low. A speck of something floating under a magnetic field on a blurry video is not proof of room temperature superconductivity. We've seen memes, jokes, shitposting, bravado, Soviet fan fiction, play-by-play updates from non-SMEs cooking stuff under improvised conditions. No actual resistance measurement of LK-99 with a 4 point probe. If this is real, then discoverers found this in 1999,…

>No actual resistance measurement of LK-99 with a 4 point probe.

https://postimg.cc/TyYbv284

http://journal.kci.go.kr/jkcgct/archive/articleView?artiId=A...

Machine translated: https://www.docdroid.net/UiUrs8c/kci-fi002955269-1-pdf

Interview: https://hackmd.io/@sanxiyn/seize-interview

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

#256

I knew it was fake, there would have been a huge rise in the stock market. Financial markets would have sniffed this out. The market never lies. If anything, this was an obvious opportunity to short it on prediction markets.

> The market never lies

Whilst this can sometimes be true, e.g. Disney stock decline tied to "go woke go broke", in general this is demonstrably, incredibly false.

The market is based on a mix of widely known facts, speculation, hopes, dreams, fraud, and a bunch of other weird goofy phenomena.

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

#257

Earlier quoted context omitted.

If fake those researchers careers are over. Like, they'll have to go into programming or something. And they've also besmirched the good name of Korea, and their moms are going to beat the shit out of them for fucking up that bad. They've got a LOT to lose if this is fake, which is why I think it's most likely true. But hey, sometimes people just do crazy shit.

Impossible, wall street has some of the smartest scientists on the planet. They absolutely went through the research and determined it was a fake. Look at the AI boom, nasdaq rallied 40%. Superconductor would have had the same effect

...nothing happened to the markets ~2017 when the transformer architecture (behind the current AI boom) happened. Nor in 2020 when it was pretty obvious shit scales and generalizes well. ONLY when it got built into an actual product (ChatGPT) did the needle start to move.

Same with this, until someone figures out how to make WIRES from LK-99-like-stuff that can be made into useful MAGNETS, it will stay flat.

Markets may be very smart... but they're hyyyyyper-conservative :P (an it makes sense to be so, there's the $$$ powering agriculture and healthcare and pensions floating on the seas of markets nowadays).

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

#258
post #8

Has anyone even seen a ferromagnet stand up like that in a magnetic field?

Yes. https://nitter.net/VanGennepD/status/1688052003216261120 And this new paper finally rigorously explains away all the half-levitation videos. They can no longer be considered any evidence of SC at all.

This is suspect because to balance a magnet like that you’d need to make it very very specifically to make it balance like that. Which means as soon as you flip it, it would not float. In the lk99 samples both sides can float

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

#259
post #231

Earlier quoted context omitted.

You are right, but probability estimation of possibly novel phenomena is an ill posed problem. So either you do not model it at all, or come up with some mental model of what probability you are comfortable with and due to which factors; the factors being more important than the final number.

The exact numbers don’t matter, but your post indicates that you seem to have the wrong mental model of how to adjust your credences. The probability of each factor decreases the overall probability, not increases.

Alright lets do some calculations. Feel free to dissect the assumptions.

K event = Kim says Material L is RTSC

D event = DFT says L is RTSC

S event = L is actually RTSC

we have assumed P(S/K) and P(S/D) are each 0.1, though we could have chosen other numbers for them as well.

We want to estimate P = P(S/(K and D))

P = P((K and D)/S)P(S)/P(K and D)

Assuming Kim and DFT are in the business of making positive predictions, they always get it right when L is actually RTSC.

so P(K/S),P(D/S) and P((K and D)/S) are all taken as 1

hence P = P(S)/P(K and D) = P(S)/(P(K)P(D/K)) = P(S/K)/P(D/K) = 0.1/P(D/K)

(similarly, P = P(S/D)/P(K/D) = 0.1/P(K/D))

But ofcourse we dont know P(D/K) or P(K/D). We could check historical data on how often D aligns with K, a messy exercise at best. Say they dont perfectly align, then the conditionals are less than 1,and P>0.1. Even intuitively when K (or D) gets additional support in the form of D (or K), your P should increase, not decrease.

If we assume D and K align on average, then P(D/K) or P(K/D) is 0.5, and we get P = 0.2.

You may estimate everything above differently, thus getting a different P. You can also come up with your own way of modelling this. I came up with my particular estimate to understand how frequently should i follow the news, and care about the whole thing. You should model it according to your usecase.

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

#260

Earlier quoted context omitted.

Reminds me of how Data in Star Trek would say things like "There is a 79.85 probability of success". I mean, maybe it is possible to assign probabilities to future events that you have never seen before, but somehow I doubt it (with 12.88% likelihood).

> but somehow I doubt it You doubt it? That means you're assigning some underlying probability to the event (not) occurring. Why does it seem strange to you if people are explicit about their priors?

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.
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