4 ms·

Its been awhile since I followed this. What was the takeaway? Is this our generations cold fusion?

bradrn 3y ago
The takeaway is: LK-99 is definitely not a superconductor. The apparent observation of zero resistance can be explained due to a well-known phase transition of copper sulfide, combined with sloppy data analysis. The half-levitation seen in images and videos can also be observed in perfectly normal non-superconducting materials.
- chihuahua 3y ago
  I think the "99" in LK-99 refers to the year it was first created by the authors of the paper. Were they under the impression that it was a superconductor for the past 24 years, and only found it it was bogus because it attracted worldwide attention this year? If so, that seems strange. I can see how one might make this compound, do some tests on it, and think "oh it's a superconductor" for a few months, but then surely they would do more tests to explore its properties and discover it's not a superconductor. Did they remain deliberately ignorant for 24 years?
  - teraflop 3y ago
    I don't think the inventors actually thought they had samples of a superconductor for 24 years. My understanding is that they thought they'd detected signs that LK-99 would be superconducting, if they were able to come up with a process to synthesize it with sufficient purity. They spent 24 years (slowly, and without a lot of funding) trying to do that. And over the last couple of years, they started to convince themselves that they had succeeded.
phkahler 3y ago
Yes, the bureau of technology control has debunked it and taken it for internal use. ;-)
jiggawatts 3y ago
The experimenters fooled themselves by accident, which is a common occurrence in all human endeavours, including science. The scientific method corrects for this via peer review and reproduction of experiment results. The reproductions showed: 1. The ingredients commercially available have iron impurities. The oven baking process causes the iron to separate out, often towards the edges of the material chunks. Iron is ferromagnetic. 2. The LK99 material itself is strongly diamagnetic, which is interesting in and of itself, but obviously not world-changing. The result of the combination of the above two is that the iron impurity is attracted to magnets, but the rest of the LK99 material is repelled. This makes samples "stand up", but not hover like a true superconductor would. All of the third-party reproductions showed this effect, none showed samples truly floating. Similarly, the conductivity tests were zeroed badly. True superconductors have a step-change in conductivity, whereas the graphs measured by the korean team showed a rapid change followed by a slower gradual decrease. The lowest resistance they measured was still very high, comparable to metals, not superconductors. This is a common issue with fringe research into superconductors: the "signal" they're looking for is a step-change in conductivity because it is easy to measure and rare in most normal materials. However, sudden conductivity changes can occur for all sorts of reasons. It's necessary, but not sufficient for superconductivity to be confirmed.
- tomrod 3y ago
  Fantastic explanation. I appreciate your clarity.
- naasking 3y ago
  > The scientific method corrects for this via peer review and reproduction of experiment results. By reproduction, yes. By peer review, no.
  - jiggawatts 3y ago
    https://youtu.be/zl-AgmoZ5mo https://youtu.be/zl-AgmoZ5mo
    - naasking 3y ago

The takeaway is: LK-99 is definitely not a superconductor. The apparent observation of zero resistance can be explained due to a well-known phase transition of copper sulfide, combined with sloppy data analysis. The half-levitation seen in images and videos can also be observed in perfectly normal non-superconducting materials.

chihuahua 3y ago
I think the "99" in LK-99 refers to the year it was first created by the authors of the paper. Were they under the impression that it was a superconductor for the past 24 years, and only found it it was bogus because it attracted worldwide attention this year? If so, that seems strange. I can see how one might make this compound, do some tests on it, and think "oh it's a superconductor" for a few months, but then surely they would do more tests to explore its properties and discover it's not a superconductor. Did they remain deliberately ignorant for 24 years?
- teraflop 3y ago
  I don't think the inventors actually thought they had samples of a superconductor for 24 years. My understanding is that they thought they'd detected signs that LK-99 would be superconducting, if they were able to come up with a process to synthesize it with sufficient purity. They spent 24 years (slowly, and without a lot of funding) trying to do that. And over the last couple of years, they started to convince themselves that they had succeeded.

phkahler 3y ago

Yes, the bureau of technology control has debunked it and taken it for internal use. ;-)

jiggawatts 3y ago

The experimenters fooled themselves by accident, which is a common occurrence in all human endeavours, including science. The scientific method corrects for this via peer review and reproduction of experiment results. The reproductions showed: 1. The ingredients commercially available have iron impurities. The oven baking process causes the iron to separate out, often towards the edges of the material chunks. Iron is ferromagnetic. 2. The LK99 material itself is strongly diamagnetic, which is interesting in and of itself, but obviously not world-changing. The result of the combination of the above two is that the iron impurity is attracted to magnets, but the rest of the LK99 material is repelled. This makes samples "stand up", but not hover like a true superconductor would. All of the third-party reproductions showed this effect, none showed samples truly floating. Similarly, the conductivity tests were zeroed badly. True superconductors have a step-change in conductivity, whereas the graphs measured by the korean team showed a rapid change followed by a slower gradual decrease. The lowest resistance they measured was still very high, comparable to metals, not superconductors. This is a common issue with fringe research into superconductors: the "signal" they're looking for is a step-change in conductivity because it is easy to measure and rare in most normal materials. However, sudden conductivity changes can occur for all sorts of reasons. It's necessary, but not sufficient for superconductivity to be confirmed.

tomrod 3y ago
Fantastic explanation. I appreciate your clarity.
naasking 3y ago
> The scientific method corrects for this via peer review and reproduction of experiment results. By reproduction, yes. By peer review, no.
- jiggawatts 3y ago
  https://youtu.be/zl-AgmoZ5mo https://youtu.be/zl-AgmoZ5mo
  - naasking 3y ago