And some commentary on the paper:
https://www.science.org/content/blog-post/breaking-superconductor-news
Here’s a video of a macroscopic piece of the material magnetically levitating.
Sure, it could be faked, but that would be a bit more than the usual “massaged the numbers a bit to discover a really small effect” stuff.
At first sight, it looks fake:
- A levitating superconductor locks into place onto the magnetic lines, it shouldn’t be bouncing up and down like that while touching the magnet with one side.
- Pyrolytic carbon can levitate on a magnetic pole grid at ambient temperature and pressure, while magnetic poles can be “printed” onto a single magnet slab, giving the illusion of superconductive levitation where there is none.
- At one point in the video the piece of material falls down completely to the magnet, then it bounces back up when pushed to another point, which looks less consistent with superconductive levitation, and more with a prepared trick magnet.
As I said, it could be faked. But that fakery would involve a very deliberate premeditated fraud and when it is found out (as it will be in short order with something this extreme) the three researchers involved in this would be completely ruined. What are they gaining out of this that would be worth it?
Also, if they’re rigging up a complete fake, why would they half-ass it? If your first take has the fake superconductor fall down why not delete that one and do another take where it doesn’t?
I’m not saying this video is proof, I’m saying that this is not some Em-drive situation where the results are so fine and fiddly that it’s only barely peeking through the data and it could be a result of tiny errors and wishing really hard. The comment I was responding to was talking about how difficult it is to measure the properties of microscopic crystals and I was pointing out that this is a big ol’ chunk of stuff being poked around with the tip of a finger and hovering millimeters over a magnet. This is going to be straightforward to verify.
Edit: Found the companion article that’s specifically about the levitating sample.
I see.
Reading the article, it seems to be on one hand promising, but on the other the characteristics of the material seem to be somewhat flimsy, and they seem to have made a few different samples then modified them between tests.
The final result of becoming an ohmic metal at 127C, with at least a couple orders or magnitude jump, seems to be consistent, so that’s something. The behavior below 127C though, looks kind of iffy. Maybe because they tried different manufacturing and processing methods, maybe because of the different breakdowns they describe in the article… which they don’t fully describe reversing, so it gives the impression of being a borderline one-way only superconductor that starts conducting at about 25C, and in a real world application could lead to a cascade effect from there. There seem to be no recovery behavior tests either, which could be understood for an initial paper, but is a pity not to have them.
The measurements they show on the graphs, are for very low voltages and intensities, so that maybe could explain why the piece on video fell down (lost superconductivity due to overheating), then sprung back up (when it cooled down). Or maybe they just blew on it to cool it down enough (which would be interesting on itself). The material structure transitions are somewhat complex, and happen basically all over the range from -75C to about 50C, changing its characteristics.
You’re right, this seems much more solid than the Em-drive case. It needs better reproducibility and better characterisation, but otherwise looks promising for at least some applications.
Welp, here’s Nature delivering the verdict. Pretty much on the schedule I expected, and here’s the update I’d promised myself I’d do.
LK-99’s amazing properties are Cu2S’s amazing properties. It’s a chunk of stuff with embedded copper sulphide. Like I said, it’s hard to verify the properties of one material mixed in with other materials, and in this case they didn’t even try very hard.
Here the microscopic crystals were the impurities not the “superconductor”, but it’s the same issue.
That behaviour looks pretty normal for a Type-I superconductor, the “locking on” you are referencing is a property of Type-2 Superconductors. For more information search Meißner-Ochsenfeld Effect (ideal diamagnetism, type 1 SC) and flux pinning (type 2)
I have a fair bit of experience with superconductivity and the submitted manuscript on arXiv looks solid, I didnt notice anything suspicious
Edit: the falling down may be because the material is not superconductive throughout, it looks like it falls down, rotates because of the magnetic field (maybe the non superconductive phase is magnetic?) then pops back up because the magnetic field of the magnet is once again strong enough to lift the sample (the Meißner effect dispels the field inside the Superconducter by generating shielding currents just below the surface, thus “mirroring” the field of the permanent magnet)
