Since it is apparently expected that the material is almost trivial to synthesize, I'm wondering why the original group hasn't tried to get an outside independent source to verify one of their samples before dropping this on the arXiv? Is there some other internal reason/pressure to release this now? Like they've tried to be in stealth mode for the two years since applying for the patent, but risks of leaks are growing, and now they are rushed? Or maybe they have had some independent outside confirmation, but I guess you don't need to share it if you know you've got the goods, and are confident that everyone will be able to reproduce it in short order. Otherwise, I'd think I'd be trying to have 100 samples queued up for anyone who wants to verify.
Superconductor news: What’s claimed, and how strong the evidence seems to be
201–210 of 501 posts
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#202Another comment from a well informed source on the topic: https://nitter.net/condensed_the/status/1684255515944034304 Also, on the sentences in the manuscripts trying to explain the effect: I think that is wild guess at best. The measurement results done in the manuscripts probably can be taken at at face value (at least until there is a reproduction). Whether they really indicate superconductivity or something else…
It's probably better to link to the original, not this mirror: https://twitter.com/condensed_the/status/1684255515944034304
Nitter is an alternative front-end that allow you to view the tweet and the response while Twitter only only to view the attached tweet only. So in fact , it's better that he used nitter rather than the "original"
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#203One odd thing that I've not seen any discussion on: the reported heat capacity of LK-99 decreases above 250K, which is pretty atypical. Has there been any commentary on that?
> Has there been any commentary on that? German, but nevertheless: http://blog.fefe.de/?ts=9a3f8740 "I work in the field [...] we don't believe a word of this. [...] The data set in Fig. 4(b) is also a treat. It is VERY unusual when the heat capacity decreases again at high temperatures. This can happen at low temperatures, but not at high temperatures. [...] My personal assumption is that the authors measured an ins…
A 4-point measurement of an insulator would show zero current, as far as I know.
A more plausible idea IMO is that it could be a 4-point measurement of a highly inhomogeneous sample. If the current probes make contact with conductive parts of the sample, and there is a conductive path between them, but one or both voltage probes are not contacting the conductive path, then the voltage measurement would be garbage and potentially zero.
I don’t think this is much of a problem when measuring conventional conductors (you don’t need a particularly good contact, which is much of the point), but a lot of superconductors are oddball materials where, under conditions where they fail to superconduct, they barely conduct at all.
So maybe the sample has a conducting phase and an insulating phase?
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#204Researcher on reddit thinks it's probably spurious measurement artifacts, not superconductivity: > I would say they are not faking it, but instead they just don’t understand what they are looking at. Based on what measurements they are doing, as well as how they are doing them, they do not have a good understanding of the standard processes to characterise a superconductor. Also, based on their analysis/discussion, t…
I’m curious how those page 3 I/V figures are just spurious measurement artifacts. They seem very clearly to be evidence of high temp superconductivity
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#205If this material does just what they say it does, what would it revolutionise? Or as the article talks about, is this just a pointer at other possibilities that would be the real game changers?
MRIs would be another revolutionized field. Cooling is a big size constraint and cost driver. You would still need a large amount of power if you want to have clinical scans at 3T or 5T, though, but in wealthy countries the number of MRI machines would for sure proliferate and it would probably become more routine. Low-resource environment deployments may become a tad more feasible, to be honest the power requirements will still probably be too high, but at least you wouldn't need an always-on source.
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#206Korean scientists are known for making a lot of bold and unreproducible claims.
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#207Earlier quoted context omitted.
Do you have a link handy for "we don't know how bikes work" ?
I'm assuming they mean the balance mechanism, and specifically what allows us to balance. How much is it the rider shifting their weight, how much is micro steering adjusts as we move forward, how much is the gyroscopic forces of the wheels, how much of it has to do with the angle of the handle bars to the wheel verse the center of weight. That said, I'm guessing this one is well understood by experts, but more compl…
I wonder what learning the specific system by which bikes are balanced would teach us about the world or human beings?
It's such a banal thing to be so fascinating.
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#208Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#209This video ( https://sciencecast.org/casts/suc384jly50n ) showing the Meissner effect should be the easiest to replicate: just send a sample to another lab and put it over a large magnet. As far as I know, the only explanations for this occurring is room temp superconductivity, or a strong diamagnetism (which would also be very cool to see)!
That video reminds me of the way pyrolytic graphite floats on strong magnets. https://scitoys.com/scitoys/scitoys/magnets/pyrolytic_graphi... https://youtu.be/Wk3seHNmNs8
It's true that pyrolytic graphite does this, but it's also worth noting that pyrolytic graphite is one of a very few materials that has such a strong conventional diamagnetism: the list includes pyrolytic graphite and metallic bismuth and ends there. I have actually searched the literature for such materials on a few occasions simply because they seem like they would make a fun decoration, and PG (and "highly oriented" PG) is pretty much the only one (bismuth is too dense).
Re: Superconductor news: What’s claimed, and how strong the evidence seems to be
#210This is an extremely useful summarization of the original paper. > The authors believe that the modified/strained structure of their material creates a large number of “quantum wells” between particular lead atoms and the adjacent oxygens of the phosphate groups bound to them, in effect making a two-dimensional “electron gas”. They propose that electron tunneling between these quantum wells, which are between 3.7 and…
> They propose that electron tunneling between these quantum wells, which are between 3.7 and 6.5 Ångstroms apart, is the superconducting mechanism. That is a very strange explanation. As someone who has done a decent amount of solid-state physics work, I would expect the explanation to involve a mechanism for pairing of electrons. Mere tunneling between quantum wells has been a staple since the "metamaterials" of th…
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