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Ferromagnetic half levitation of LK-99-like synthetic samples

arxiv.org

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

#151

Post by tw1984 »

ironborn123 wrote: post #132
versteegen wrote: post #95

Very interesting comments on the paper by Prof. Michael S. Fuhrer https://nitter.net/i/status/1688755932275384320 > But I think they buried the lede a little. Ferromagnetism is novel and unexpected in this material system, and might be interesting. But strong diamagnetism even more so > Even if the diamagnetic fraction is the entire sample (appears less) then it would be the second-strongest diamagnet known (and pyro…

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…

> 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?

> and then from reputed Western researchers/labs.

what makes you discount inputs from Russian, Chinese, Japanese researchers?

You seem to have some really wired brief here, get some help I say.

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

#152

Post by kaffekaka »

throw-7462637 wrote: post #123
rurban wrote: post #77

Earlier quoted context omitted.

If you cite Korean (or Chinese or Japanese) names, please write them correct. There is no Hyun-Tak Kim, he is called Kim Hyun-Tak. Likewise Kwon Young-Wan. In Korean it's trivial to detect, in Chinese not so, in Japanese very hard.

Ouch. This comment backfired quite badly. Turns out the person being replied to is Korean, the commenter is likely not, and in addition this is how the authors wrote their names themselves. Yet I do not wish this comment to be snarky. I’m interested in the broader perspective (and I apologize in advance to the parent for using this as an hook). The comment seems common of the present era in which polarization (leadin…

Just like I want to believe LK99 is RTAPS, I want to believe that you are correct.

But just like with LK99, this might be wishful thinking from me. I am also getting old.

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

#153

Post by mkagenius »

InvisibleUp wrote: post #134
jossclimb wrote: post #133

Earlier quoted context omitted.

Coincidently this is the first time of hearing of nitter.net, do I need to open an account there too?

It's just a read-only Twitter mirror.

Well, time to make xitter.net then.

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

#154

Post by XorNot »

p-e-w wrote: post #85

So if good old ferromagnetism/diamagnetism is sufficient to explain the half-levitation shown in the video: How can I build my own half-levitating objects from standard materials? I've seen the science toys using pyrolytic carbon, but they are nowhere close to the effect from the video. Levitation height with pyrolytic carbon is like 1/20th of what the video demonstrates. The disc in the video looks like it's just ab…

Yes: https://twitter.com/VanGennepD/status/1688052003216261120

This guy goes into detail how he makes a practical fake which demonstrates the same behaviour: it's ground up carbon, superglue and some iron filings on one end.

The pivot point reduces the mass and weights it upright.

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

#155

Post by shawabawa3 »

Accujack wrote: post #67
delabay wrote: post #34

Earlier quoted context omitted.

Let's hope the growing mountain of evidence against original author claims causes them to move quicker with providing samples to bonafide labs and disclosing the full details of their manufacturing process.

What evidence? Absence of evidence is not evidence of absence. They haven't even officially released their final version of the paper, and a whole bunch of people who don't have full access to their data being unable to replicate their material well enough to convince the world doesn't reflect at all on the validity of their work. If the people to whom they have submitted their paper, data, and samples can't replicat…

> Absence of evidence is not evidence of absence.

Actually it is when labs all around the world are trying to generate evidence and failing

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

#156

Post by spiderfarmer »

chmod600 wrote: post #139
p-e-w wrote: post #125

Earlier quoted context omitted.

> One cannot measure superconductivity with an ordinary ohmmeter. But one can measure electrical resistivity, and if the material's resistivity is much lower than that of ordinary materials, that would be super interesting and valuable, regardless of whether it is a "true" superconductor or not. If this relatively cheap material had a resistivity around 1/100th that of copper, that would be an engineering breakthroug…

I think you are missing the point: a typical ohmmeter would have metal probes, so with a superconductor you would just be measuring the resistance of those probes. Any attempt to overcome that problem probably introduces a lot of chances for error or noise, or require some huge sample of the superconductor.

Zero resistance would be hard to proof this way, but why can't you compare measurements of LK99 with known conductors?

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

#157

Post by mkagenius »

ThePhysicist wrote: post #142
hliyan wrote: post #80

According to this: https://twitter.com/Andercot/status/1688598313497694208 "...there is a less well-known exception to this rule called Brauenbecker extension which provides a mathematical proof that levitation is possible with a simple diamagnetic in a dipole field so long as the diamagnetic material mass is very small relative to the strength of the magnetic field." I was very hopeful in the early days and was foll…

Maybe a cautionary reminder to not listen to random influencers on Twitter. The expert community was really silent and reserved from the beginning as they've seen such wonder materials many times. Having worked in that field for many years I'm personally skeptical that there ever will be an ambient-pressure, room-temperature superconductor. The band structure and interactions that need to be present in the material a…

Yes, I only listen to people with handle like "ThePhysicist" or "theMaterialPhyisicist" at hackernews.

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

#158

Post by xcdzvyn »

herewulf wrote: post #136
InvisibleUp wrote: post #134

Earlier quoted context omitted.

It's just a read-only Twitter mirror.

It "just" makes Twitter readable to the Internet at large.

"At large" is a strong term given the average person (even the average Twitter reader) doesn't know what it is ;)

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

#159

Post by culebron21 »

protastus wrote: post #26
VHRanger wrote: 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,…

Yes, that's what caught my attention too: no actual conductivity measurement, but only magnetic levitation.

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

#160

Post by [deleted] »

tw1984 wrote: post #151
ironborn123 wrote: post #132

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…

> 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?…

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