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Comment by jacquesm | Hacker News Reader

It's confusing. You'd expect both to be present or none, it is strange to have a material that is conducting and diamagnetic at room temperature and that shows super conductivity at much lower temperature. You'd expect the diamagnetism to disappear with the superconductivity.

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Multiple teams have said they had to produce 10 batches just to get one sample with properties worth reporting on.

Perhaps the simplest explanation is that different teams are all ending up with different variations of a common material, with different impurities, crystal structure, etc.

There's likely a whole zoo of interesting materials here!

Yes, I thought that that might be the case from day one. When they wrote that they had only a 10% success rate it was clear that they were not at all in control of sample purity. The big remaining question for me is what happens when they start traveling with the original sample to have another lab test their samples and how those results compare with both the original results and the independently recreated different samples.

There is a good chance that there will be substantial differences between them.

“Purity” is a really overloaded term here. There are vast set of material properties that simply don’t map to a definition “purity” as in some homogeneous concentration of a material. This is so early no one likely knows exactly what configuration of material to “purify” for the intended outcome.

There will likely be years of not decades of looking at differences in the materials and performance of related materials to more fully explore this discovery.

Yes, true, let me unpack that then:

- purity as in the sample is uniformly constructed of the right atoms but they are not in the right configuration

- purity as in the sample contains atoms that shouldn't be there in the first place

and finally

- purity as in: the sample that purportedly did show room temperature superconductivity turns out to be the impure one and that impurity is so poorly understood that we currently can not replicate it accurately, but a test by an independent lab of the sample would verify the properties as advertised.

All of these are possibles, and not mutually exclusive.

> purity as in the sample is uniformly constructed of the right atoms but they are not in the right configuration

The conclusions in the linked pdf suggest this may be the issue with LK99.

1. https://arxiv.org/abs/2307.16892

More than likely there is only one interesting material in this specific composition. But understanding the phenomenon we are observing in this material can potentially lead to the development of other materials which display these characteristics, and tune those to function in this way at specific temperature/pressure situations. If we develop efficient ways to produce these materials in bulk (which is orders of magnitude more complicated than just characterizing what we see here) it would be unimaginably revolutionary. But the energy required to do this at scale will likely require our civilization to utilize orders of magnitude more energy, so if this is practical for our daily lives on a wide scale I believe it's development will be contingent on harnessing fusion. Otherwise it will be limited to only the most extreme use cases in the way superconductors are currently used now.

My friend, what exactly do you think is so energy intensive with LK99 synthesis? I've briefly taken a look and the process proposed is really not that onerous in terms of energy consumed. It is a matter of perfecting the process that is the hurdle, we already spend tons of energy happily in similar industrial processes.

> But the energy required to do this at scale will likely require our civilization to utilize orders of magnitude more energy

As opposed to smelting aluminum or steel? And that creates stuff that is dirt cheap in bulk...

Observed effects which have been given a name != a single universal truth. Just because we have experimental evidence of effects and theoretical explanations for their occurrence prove we actually have defined the underlying phenomenon's which produce the observed effect accurately. The reason we experiment isn't to prove our theories are correct so much as it is to probe where they break down so we can further refine our understanding of the universe. What we are likely seeing here is the result of an organized pattern of atomic nucleii forming a lattice which creates the conditions for the movement of electrons to be easier (or harder) than expected at certain temperatures (with temperature being the property which induces strain on the lattice). This is very crude, but begins to explain the multitude of factors at play here.

Yes, that's true, but that would require a shift in our understanding of physics and everything about this saga so far has not done that. And that in part is a reason why people take this serious: it is believable. New physics would raise the bar considerably.

So for now I'm on the measuring error, impurity or process issue side of that without committing to which team I think has the problematic side.

The fact that our existing computational models are in agreement with the experimental behavior leads me to believe there is no new physics involved here. That being said this raises the question as to whether this class of material is known and characterized within our national research labs but has been kept classified, and if it was unknown it raises the question of why experimentation is what discovered it and why weren't we able to harness the computational model to identify it theoretically and develop a method to produce it practically prior to this. My money says there are people in this world who have long been aware of this, and its either already in use in a classified manner or it's interesting but there are other materials which are more practical in all use cases.

> why we [we]ren't we able to harness the computational model to identify it theoretically and develop a method to produce it practically prior to this.

Because the computational requirements are off the scale in the most literal sense. The search space is so large that you won't be able to come up with an improvement in efficiency for your search unless you guide it very carefully with experimentally obtained results and that's exactly what these people were doing as far as I understand it. You mix up a batch of stuff, test it for gross properties, do crystallography and then use the information from that to do some numerical simulations to check if your assumptions and observations hold up.

I don't think we had this compound before.

I think one factor that's overlooked with these simulations is that there are a ton of parameters to these which really hinder automated searching.

It's easy (relatively) to verify the results from a real world test since you know the physical parameters and can tweak the others based on intuition, where if the result matches the real world you can consider it valid, but if it doesn't you can have to check all sorts of things to be sure that it isn't a glitch due to some parameter not being reasonable.

That makes searching for materials really hard because you either need an absurd amount of computational power to be able to set the simulation parameters so high as to not worry about their effects or you get tons of false positives simply because the computer can't as easily tune those parameters to ensure it produces correct results.

As my PhD advisor has often put it regarding my own simulation work, if the simulations were that capable of modeling reality, there would be no need for billion dollar facilities to perform tests irl, you'd just spend all that on building many supercomputers.

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