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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

#241

Post by matthewdgreen »

hliyan wrote: post #211
moonchrome wrote: post #204

Earlier quoted context omitted.

I don't see anything bad with this hype cycle : - these guys thought they found something - turns out it probably wasn't superconductors but it's an still interesting finding - there was no fraud and something new was discovered - material science got a bit more mainstream exposure I'd rather see that than another crypto or AI hype cycle

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.

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

#242

Post by whimsicalism »

ironborn123 wrote: post #205
layer8 wrote: post #192

Earlier quoted context omitted.

That's not how probabilities combine.

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.

dude you so do not know what you are talking about, the GP is talking about basic conditional probability rules lol

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

#243

Post by ThePhysicist »

killerstorm wrote: post #214
ThePhysicist wrote: post #142

Earlier quoted context omitted.

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…

Can you explain how 300K is fundamentally different from 90K? 90K is 20 times above temperature of liquid helium. Is there some law of physics which says that you can go 20x the temperature of liquid helium but not 60x?

It's the relative energy scales in the system that matter. You can e.g. compare the superconducting energy gap to a temperature, for Niobium the gap is around 2.3 meV which corresponds to about 27 K. For high Tc superconductors the story is a bit more complicated but their pseudo gap is 5-8 times higher, hence around 150-200 K. Niobium has a Tc of 10 K, high Tc superconductors (unpressurized) at most 150 K. What's safe to say is that if the temperature becomes significantly higher than the energy gap the superconducting state will be lost as there's thermal tunneling out of the state and it becomes thermodynamically "unfavorable" (this simplifies things). Now there's no reason that we couldn't find a system with a larger energy gap but that gap itself is defined by other properties in the system that have constraints on their own. Fundamentally there's no reason that there couldn't be a system that fulfills all these constraints at room temperature, but there isn't a reason why there should be such a system either. Then again there might be different superconductivity mechanisms that we don't know about yet and that we could exploit, but I think it's not very likely that we'll find a regular material system with these properties because there are not that many crystal lattices to choose from and we've been looking for more than 50 years.

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

#244

Post by sheepscreek »

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…

I think how people define superconductivity varies greatly in discussions.

Wouldn’t be the worst thing if we concentrated our efforts on proving zero resistance first. IMO, a “super conductor” should only be characterized as a material with zero resistance under certain conditions. Everything else should not be a requirement, but more like a side-effect that had been observed to go along (such as diamagnetism through Meisner effect).

Hopefully that will destigmatize future research efforts in both directions, namely towards finding zero resistance materials and those exhibiting diamagnetism.

The worst thing we can do to science is going on a witch hunt. Curiosity powers this discipline. We don’t need for encourage all crazy theories but discouraging that line of thinking entirely will lead to fewer new discoveries.

Fear driven science isn’t science at all.

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

#245

Post by fastball »

willis936 wrote: post #221
jacquesm wrote: post #29

Earlier quoted context omitted.

I hope that ultimately it will come to that because I don't think anything else will put this to rest one way or the other (unless it is 100% confirmed/reproduced by another lab). It also seems to be the shortest path to a resolution.

That also adds little value. It would add no information on whether or not the sample is a fluke. We need to understand the material properties and its composition.

If the original sample is superconducting, you can perform XRD / other analysis on it to establish a proximate structure and then simulate things / find better methods for synthesis.

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

#246

Post by OJFord »

ironborn123 wrote: post #205
layer8 wrote: post #192

Earlier quoted context omitted.

That's not how probabilities combine.

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.

That's not what GP means - even if you assume they're independent variables, 2x 10% probabilities combine to a 1% ('10% of 10%', they multiply, not add) probability of the total outcome, not 20%.

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

#247

Post by fastball »

willis936 wrote: post #238
jacquesm wrote: post #236

Earlier quoted context omitted.

If it is a fluke or not doesn't matter. The only thing that matters is whether or not it is real, not how it was made. If it is real then we can expend a fortune on the 'how it was made' question, if it isn't real we can all descend from this holding pattern.

What benefit does that bring?

Appropriate allocation of resources is intrinsically beneficial.

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

#248

Post by itsoktocry »

gilleain wrote: post #179
carabiner wrote: post #148

Earlier quoted context omitted.

I too like to assign probabilities to my vibes. Much more legitimate.

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?

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

#249

Post by itsoktocry »

smcl wrote: post #162
tw1984 wrote: 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?…

I've seen this on here before. Guys convincing themselves that they're being rational and you're being emotional - because they put little numbers besides their feelings and perform some calculations to produce a percentage that "proves" their theory about Antivax stuff, Putin/Ukraine or whatever is credible.

>their theory about Antivax stuff, Putin/Ukraine or whatever is credible.

Your politics are revealed with your choice of examples here.

Who needs a decision-making mental model when we can just trust what the experts tell us about these things, or maybe "trust your gut"? That's never failed.

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

#250

Post by hliyan »

Lockal wrote: post #220
moonchrome wrote: post #204

Earlier quoted context omitted.

I don't see anything bad with this hype cycle : - these guys thought they found something - turns out it probably wasn't superconductors but it's an still interesting finding - there was no fraud and something new was discovered - material science got a bit more mainstream exposure I'd rather see that than another crypto or AI hype cycle

Last time I saw this cycle with EmDrive - some guy created EmDrive (2001) - author argued for decades that EmDrive violates Newton’s Laws - author filled a group of patents, launched a new company "Universal Propulsion Ltd." (2016). But by this point, DOZENS of independent researchers had already proven that EmDrive doesn't create thrust. - NASA and DoD and a lot of smaller companies just threw money away testing som…

This is exactly right. The only difference here is that EmDrive straight up violated a law of physics, whereas high-temp superconductivity was just a matter of degree (pun intended). I was somewhat skeptical of EmDrive, but was very hopeful about LK99. Alas, it was not to be. We'll have to take the slow road to room temperature superconductors.
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