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Superconductor news: What’s claimed, and how strong the evidence seems to be

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Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#141

Post by floxy »

macromaniac wrote: post #117
carabiner wrote: post #92

Researcher 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…

He doesn't provide an actual counterargument,he just says he doesn't like the data without explaining why. His earlier comment that graphite can do the same thing is untrue afaict. Graphite can repel the magnetic field but it would slide off, this is why in diamagnetic experiments multiple magnets are used to keep it in place. In the video it doesnt seem to be sliding anywhere, so imo the video is not showing diamagn…

>so maybe it is just diamagnetism.

Superconducting levitation is just due to the perfect diamagnetism of the superconductor, right?

https://en.wikipedia.org/wiki/Superdiamagnetism

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#143

Post by [deleted] »

fluidcruft wrote: post #110
carabiner wrote: post #92

Researcher 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…

Another interesting comment by that redditor https://www.reddit.com/r/technology/comments/159jojs/comment...

[deleted]

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#144

Post by _0ffh »

carabiner wrote: post #92

Researcher 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…

>> they do not have scientific knowledge of the background theory

One of the co-authors of the 6-author-paper, Hyun-Tak Kim, is at least answering questions about superconductor theory on Quora starting five years ago, whatever that counts for.

He states there "I am studying the MIT mechanism in strongly correlated systems, the high-Tc mechanism in cuprate superconductors, the MIT devices, and quantum transistors.".

https://www.quora.com/profile/Hyun-Tak-Kim?share=1

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#145

Post by JumpCrisscross »

mataslauzadis wrote: post #25
marcosdumay wrote: post #14

Earlier quoted context omitted.

It doesn't require the kind of equipment that you have to justify to accountants and run at full capacity. And while the reactants are things that I believe most labs won't have at hand, they are the kind of thing anybody can buy on the web to arrive this week. Whether people will stop what they are doing to verify it is literally a matter of people stopping what they are doing. University labs are usually quick on t…

One of the elements used here is phosphorus (P) which is regulated by the DEA in the United States, and can't just be purchased online

> One of the elements used here is phosphorus (P) which is regulated by the DEA

I would have figured ATF. What drug can you synthesize with phosphorus? (EDIT: Apparently meth [1].)

[1] https://www.federalregister.gov/documents/2000/09/25/00-2455...

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#146

Post by littlestymaar »

bluGill wrote: post #101
scarmig wrote: post #65

Earlier quoted context omitted.

Yeah. BCS was proposed a half century after the first conventional superconductor was discovered, and even today we don't have a convincing mechanism for "regular" high-Tc superconductors. But if it superconducts, it superconducts, and research into the how is useful but not a blocker to using it.

That depends. If it super conducts, but it isn't useful in the real world, then we will be waiting for theory to - hopefully - give us some insight into how to improve things to useful. This only can carry a small amount of current. I'm not sure how to figure out what small means (numbers are given in the article if you know how to use them!), but if the losses using regular wire are less than the energy needed to ma…

> This is made out of lead. Even if it is useful for transmission, the difficulty of working safely with lead in a factory may mean it is impractical. Or it make leach lead into the real world making it not safe to deploy.

Lead is still routinely used in many applications today, either in metallic form, from ICE car batteries, to fishing or hunting gear, or as chemical compound in different kinds of glass. And the same can be said about other heavy metals like Cadmium or Mercury. Industries also routinely work with much more nasty things than lead, so it really doesn't sound like a show-stopper.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#147

Post by littlestymaar »

ortusdux wrote: post #87
eig wrote: post #17

This 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

The common point being that it levitates, at room temperature (so no cryogenic fumes on the video), but that's exactly what you'd expect from a room-temperature SC… The big difference between your graphite video and the one from yesterday is that the later doesn't move, whereas the former never rests.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#148

Post by IshKebab »

willis936 wrote: post #139
whatshisface wrote: post #119

Earlier quoted context omitted.

It is clearly resting on the magnet. I don't know the mechanics off the top of my head, but that is enough mechanical constraint for a pair of permanent magnets to levitate.

It isn't. Permanent magnets would be unstable. This would have to be a diamagnetic or superconducting material.

It is, depending on how big the contact patch is. But does look pretty small in this video and it doesn't really behave like a permanent magnet would.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#149

Post by NoMoreNicksLeft »

cperciva wrote: post #44
fortysixdegrees wrote: post #23

This is going to mess up RoHS https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Subst...

Not necessarily. The "strained crystal" approach probably extends to other elements; mixing Pb and Cu works well since there's a large difference in their sizes, but rare earths might work just as well as Pb.

Can we get those in volumes necessary to do high voltage lines though?

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#150

Post by RyanAdamas »

groestl wrote: post #91
scarmig wrote: post #3

One 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…

Wow, that's pretty damning. Good one.
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