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In case others are coming into this thinking about LK-99, the article isn't about that.

I had figured the LK-99 team might actually have something interesting considering that they were promising a proper presentation of their work at the American Physical Society. I had heard it had been withdrawn and wrote it off as another case of academic fraud, but looking it up right now, apparently it's weirder than that.

Someone pretended to be the corresponding author and submitted a withdrawal, but this was fixed and the conference the presentation is at should be happening around these days.

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LK-99 is interesting because it really is like another example of cold fusion.

And I don't mean what you probably infer from that. If you look into the way that hydrogen adsorbs into a platinum lattice, and how phonon resonance modes can induce tremendous crushing forces on anything between two platinum atoms, cold fusion actually looks quite plausible. It's not like perpetual motion--there's a clear possible mechanism for it which is surprisingly fully compatible with the laws of physics as we understand them. That said, Pons and Fleischmann rushed publication on shoddy data, making a mockery of themselves and causing cold fusion to become an untouchable subject no one would go near a generation later due to perceived guilt by association.

The theory behind LK-99 is pretty solid. The linear structure of these apatite compounds create chains of conductive electron bands that in theory might have sufficient band gaps to enable superconductivity. If you could get atomic precision in the copper/lead alternating pattern that creates those stresses. However I fear any research into room-temperature linear superconductors will now be as taboo as cold fusion.

> That said, Pons and Fleischmann rushed publication on shoddy data, making a mockery of themselves and causing cold fusion to become an untouchable subject no one would go near a generation later

Yes, they were shoddy

But no, the field was swamped within weeks with people trying to replicate it. It has lost its luster, and become a parody, but that is because it was wrong

It took a decade for the excitement to die down

Pons and Fleischmann's experimental setup did not produce cold fusion. But some other variation or different catalyst material might. Yet effectively no one has carried on this work.

LK-99, or at least the manufactured samples of it, is not a superconductor. But some other variation or different manufacturing technique might. Yet I predict no one is going to look very hard in the years to come.

> If you look into the way that hydrogen adsorbs into a platinum lattice, and how phonon resonance modes can induce tremendous crushing forces on anything between two platinum atoms, cold fusion actually looks quite plausible.

No, it is not. These things are well understood. The behaviour of hydrogen in crystals is studied a lot. In metals because of issues with hydrogen embrittlement and fusion stuff, in some oxides for the storage of hydrogen for energy applications, and in material in general because proton irradiation is a common tool when studying them. All of this to say that this is not something that was never investigated.

> It's not like perpetual motion--there's a clear possible mechanism for it which is surprisingly fully compatible with the laws of physics as we understand them.

The orders of magnitude just do not match. The pressures involved is typically 1 GPa (usually less in metals, more in ceramics). That is far from enough to bring nuclei sufficiently close for fusion. There is a reason why nobody claims this, and it is not because we don’t look at the behaviour of hydrogen (or other light nuclei like deuterium, tritium, helium, or lithium for that matter).

> The theory behind LK-99 is pretty solid. The linear structure of these apatite compounds create chains of conductive electron bands that in theory might have sufficient band gaps to enable superconductivity.

Again, it is not. Some preliminary electronic structure calculations showed interesting features, but these features were no indication of superconducting behaviour, and indeed LK-99 is not a superconductor. There were plenty of people who tried to reproduce the results and it clearly showed that the initial paper was wrong.

> If you could get atomic precision in the copper/lead alternating pattern that creates those stresses.

Our understanding of what causes superconductivity and the creation of Cooper pairs is not complete. Otherwise, we’d design materials with the right properties from the beginning, rather than testing a lot of stuff just to see what works.

> However I fear any research into room-temperature linear superconductors will now be as taboo as cold fusion.

Contrary to cold fusion, superconduction is actually a thing. Current high-temperature superconductors work at the temperature of liquid nitrogen; finding one that works 100K higher is not that much of a stretch. The gap is not 6 orders of magnitude like with cold fusion.

In fact, there is quite a lot of funding for research on high-temperature superconductors even this year so your fear is not really well founded.

Orders of magnitude variation in phonon energy is a thing though. You can do the basic statistics of waves in the open ocean and show that waves will never get high enough to crest an oil rig in the North Sea. Then go search for "rogue waves" on YouTube and watch it actually happen.

We're just starting to get a handle on the mathematics underlying this phenomenon, but it does exist. And the causes of the phenomenon transpose directly into crystal latices. So we absolutely should expect "rogue phonons" that have energies orders of magnitude above average phonon energy, enough to overcome Coulomb barriers and trigger D-D or D-T fusion reactions.

Of course thinking of using this to generate energy is something else entirely. It's a freak occurrence, and if there is a way of making it predictable or enhanced in some way, that solution is not obvious. But it should be detectable with very sensitive equipment, and would be a wonderful experimental physics result.

> Orders of magnitude variation in phonon energy is a thing though You can do the basic statistics of waves in the open ocean and show that waves will never get high enough to crest an oil rig in the North Sea. Then go search for "rogue waves" on YouTube and watch it actually happen.

Not at that scale. 10m waves are common. 5 orders of magnitudes from this is not a rogue wave, it’s a wave that goes higher than the moon. I understand you are convinced you had a bright new idea, but if you want others to be convinced as well you need more solid arguments than “it could happen”.

Again, the kind of stresses at the atomic scale in materials are a few GPa. You need much more than that, on top of a few million kelvins to have deuterium fusion (hydrogen is even harder).

> So we absolutely should expect "rogue phonons" that have energies orders of magnitude above average phonon energy, enough to overcome Coulomb barriers and trigger D-D or D-T fusion reactions.

We really should not, after just basic napkin maths. The energy given by 1 GPa is around 0.001 eV. The energy barrier for a deuterium-tritium reaction is 0.1 MeV. The difference is not an order of magnitude or two; it’s 8. It is just not going to happen in anything that looks like a solid, which is exactly why we do it in confined plasmas.

But even if we take this for granted and think a bit about the consequences it gets even more absurd. The same deuterium-tritium fusion reaction releases 17 MeV. This is going to first, melt the crystal close to where the reaction is taking place; and the shred the structure of the material over centimetres.

> It's a freak occurrence, and if there is a way of making it predictable or enhanced in some way, that solution is not obvious.

Or rather, it would be a freak occurrence if it were happening. The likelihood of this being in the same realm as a wave putting some water on the surface of the moon.

> But it should be detectable with very sensitive equipment, and would be a wonderful experimental physics result.

You don’t need very sensitive equipment to see the damage caused by 17 MeV neutrons in a crystalline material. Fairly standard electron microscopes are enough.

There's perhaps some misunderstanding about where "perpetual motion" comes from : it was about Aristotle's metaphysics, the best today's translation for at least some of these first devices would probably be "powered by changes in atmospheric pressure" :

https://www.ageofinvention.xyz/p/age-of-invention-why-wasnt-...

(Could skip to "Cornelis Drebbel".)

So the term was used more as a synonym for "continuously working", like a water wheel, without presuming any violation of the laws of thermodynamics that had yet to be invented :

https://www.ageofinvention.xyz/p/age-of-invention-perpetual-...

(Today we would call that one "a resume-padding buzzword.)

When physicists (I am one) talk about perpetual motion, we're making references to the results of statistical mechanics, not Aristotelian metaphysics.

It already happened a few days ago (March 4th). They showed more results, but nothing ground-breaking. There is another group that is also replicating the results and publishing results (SCT Lab or something). Their paper is currently pending.

They’re waiting for Arxiv to approve because patents may be denied if they go around that system.

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