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Comment by iraqmtpizza | Hacker News Reader

I don't see how 0.002 ohms per cm could be confused with superconductivity. Is that not orders of magnitude too high? Or there are no instruments which can directly measure resistance more precisely?

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Yes, that was my first thought. There are absolutely instruments which can directly measure resistance down to 10E-8 ohms/m or lower, and I would expect any lab doing research into superconductivity to at least have one of those.

Also, "not a superconductor" means that it can't superconduct at any temperature. Where is the evidence of that? Or it's just clickbait?

By that logic we might as well say that wood is a superconductor

Nobody has tested it at 0.0000000000000K after all

Testing at 5 Kelvin is not hard. You don't have to take everything ultraliterally.

And science isn't about saying wood isn't a superconductor because it's impractical to test. That's not a result. You may be getting science confused with engineering.

One group claimed that their sample of LK-99 went superconducting at ~110K:

https://arxiv.org/abs/2308.01192

The conclusion is a bit clearer: they think they observed what seemed like zero resistance at the temperature but they are unsure it was actually superconducting, hence the title being the measured resistivity instead of superconductivity directly. It's also possible (and far more likely IMO) them reaching the noise floor of the instrument was not the same as the sample actually having 0 resistance. Superconductors have a sharp dropoff at the critical temperature whereas their sample seemed to just continually have less resistance until the noise floor of the tool.

It'd be cool to find it was superconducting at a temperature near that high though. That'd still be one of the best high temperature superconductors we've found.

The units for resistivity would be ohms*cm (Ohms times a length), not Ohms per cm. Then if you divide by the cross-sectional area of a sample, you would get the resistance per length.

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

Yes, I was typing faster than I was thinking. I should have said Resistivity instead of Resistance and ohms.m instead of ohms/m. My point is still valid, though.

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