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Wow, is this it? Is this the confirmation?
I believe there’s no way to stably suspend an object on permanent magnetic fields, so if this is stable and doesn’t fall down then it’s hard to argue superconductivity isn’t involved.
Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.
There have been quite a few papers about LK-99, but the only thing I want to see is whether we observer sudden drop of resistance to zero below the critical temperature that is well above the room temperature at ambient pressure or not. So far, I haven't seen one.
Typically you measure resistance that small like this:
+-
---------p p--------
This Wikipedia article has a good summary of the replication attempts to date (including this paper).
Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.
It’s difficult to rule out external factors - a badly attached probe could also result in zero resistance for example. Showing diamagnetism is one of the least error-prone ways to demonstrate the superconductor effect. That’s my understanding anyway.
No, a badly attached probe would usually show a larger resistance, not a smaller one. That's actually the easiest error to make, making improper contact with the sample. The resistance is measured indirectly using a reference current. So you'd measure a higher resistance or a break rather than zero if a probe were not attached correctly (unless the two voltage probes are touching but that would normally speaking be spotted).
The diamagnetism is simply easier to verify using an impure or small sample.
Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.
Why are folks trying to prove that this material is a superconductor in roundabout ways, like levitation, dimagnetism, etc? What is the reason they don't just test to see if electrical current flows without resistance? Surely there is something I am missing here.
I have heard people much more knowledgeable than me say that measuring true zero resistance is actually quite difficult and takes some degree of specialized equipment, especially with such small samples. That may be part of it.
Seems to be the same one that had a video a couple of days ago https://news.ycombinator.com/item?id=36953396 Back then, many asked if this was superconduction or merely diamagnetism. Does the new paper shine any light on this question?
The paper shows a clear phase transition to diamagnetism as the material is cooled. That would be seen in superconductors and not in regular diamagnetic materials. I'm not aware of any that have that kind of phase transition. Though since we're in weird territory here, it's important to note some weird non-superconductor behavior that's beyond regular diamagnetism might be going on as an alternative explanation. But…