Naive question, and I hope someone more knowledgeable than me can enlighten me here;
Why are we even testing for superconductivity with levitation, instead of just checking for current loss/heat loss while conducting?
Why are we even testing for superconductivity with levitation, instead of just checking for current loss/heat loss while conducting?
One cannot measure superconductivity with an ordinary ohmmeter. Electrodes, wires and the ohmmeter itself are resistive, the meter can never show zero ohms. You need to set an experiment up with a current source and a voltmeter to measure the IV curve across the material [1]. Even then, the voltmeter will never show "zero" volt because of noise, which needs to be minimized in the experiment and removed during post-processing. In this case, sample preparation is also problematic as the synthesized material is not uniform. And your measurement is also expected to be temperature-dependent to show the material's transition to a superconductor. It's more involved than seeing it floating on a magnet, to say the least.
[1] It's basically the same 4-wire Kelvin sensing used by all milli-ohmmeters. But to characterize superconductivity, you need to do even better. https://en.wikipedia.org/wiki/Four-terminal_sensing
But one can measure electrical resistivity, and if the material's resistivity is much lower than that of ordinary materials, that would be super interesting and valuable, regardless of whether it is a "true" superconductor or not.
If this relatively cheap material had a resistivity around 1/100th that of copper, that would be an engineering breakthrough, and determining that doesn't seem to require a super complicated lab setup.
Do we have an upper bound on LK-99's resistivity, and is that upper bound substantially lower than the resistivity of typical conductors?
https://www.digikey.com/en/articles/fundamentals-of-current-...
Measuring the resistance would also be frustrated by the superconductive material being scattered in the mass separated by highly resistive impurities, making it easy to get a false negative.
Asking out of curiosity as I would have assumed it's very expensive but there seem to be many groups of varying sizes doing these and quite quickly which I would have thought would be extremely wasteful but may suggest it's more economically feasible than I had thought.
and it looks like I know just as much that its a nothing burger, with maybe some sliver of novelty
we dont have a superconductor, as expected
Not everyone reads every (or any!) paper and story.
And I assure you that I am no bot. I acquire sustenance, go into low energy states and have a lifetime warranty like all fellow meatbags.
Note: I'm not a physicist. Just my understanding from reading.
https://twitter.com/MarkTyler81/status/1688736978437898240
LK-99 == alchemy RT SC.