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Comment by hliyan | Hacker News Reader

According to this: https://twitter.com/Andercot/status/1688598313497694208

"...there is a less well-known exception to this rule called Brauenbecker extension which provides a mathematical proof that levitation is possible with a simple diamagnetic in a dipole field so long as the diamagnetic material mass is very small relative to the strength of the magnetic field."

I was very hopeful in the early days and was following the developments eagerly. Unfortunately, now I'm 99% convinced that LK99 is not a superconductor. Hopefully, what we learned from the saga and the momentum will help advanced the field a bit faster.

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Maybe a cautionary reminder to not listen to random influencers on Twitter. The expert community was really silent and reserved from the beginning as they've seen such wonder materials many times.

Having worked in that field for many years I'm personally skeptical that there ever will be an ambient-pressure, room-temperature superconductor. The band structure and interactions that need to be present in the material are just one requirement for superconductivity, the other is that the ground state can actually form and won't be destroyed by thermal noise. However, the strong electron-phonon interaction required for (classical) superconductivity also makes the system susceptible to thermal noise, and in my opinion the thermal noise level at 290 K is just too much even for an ideal superconducting material.

Yes, I only listen to people with handle like "ThePhysicist" or "theMaterialPhyisicist" at hackernews.

I think the point is you can probably ignore everyone who isn't giving a Nobel acceptance speech.

That’s why I personally only listen to the opinions of people with handles like "Planck54", "The1965PhysicsNobel" or "EconNobel94" on hackernews.

Sorry, I couldn’t resist.

N.B. I also tried to find some noteworthy Fields medal winner, but refrained since it appears I don’t know any of them, and that the committee’s choices and motivations have been subject to controversy [0].

[0]: https://www.science.org/content/article/fields-medal-was-nev...

Sure, but every now and then people get into an argument with a Putnam prize winner or the inventor of some Internet Protocol details and find themselves caught out...

I would bet picodollars that rarely happens here…

It happens more often than you think. For example it has happened a bunch of times that people have argued against PostgreSQL core developers about the internals of PostgreSQL.

I know most of their usernames so it is always a great laugh for me.

I think you missed the GPs subtle point.

Hehe. Nice one.

But the high temp cup rate superconductors don’t follow classical landau theory afaik

I don't see anything bad with this hype cycle :

  - these guys thought they found something
  - turns out it probably wasn't superconductors but it's an still interesting finding
  - there was no fraud and something new was discovered
  - material science got a bit more mainstream exposure

I'd rather see that than another crypto or AI hype cycle

No, it really wasn't that bad.

The annoying part, at least for me as someone who, uh, I guess used to go to a lot of colloquia on this stuff?, is the part you left out: people pre-judged the outcome (of all three phenomena you mention!) and then got really, really cranky with anyone who dared challenge their position.

If you (generic rhetorical you) want to believe that LK99 is going to superconduct, or that Bitcoin is going to the moon, or that AGI is coming next week, that's great. Really, it is! And you're allowed to talk about it, and put your money where your mouth is, and all that. What you're not allowed to do is get mad at people who respectfully disagree with you and point out why your dumb arguments are dumb. And you really, really, really need to pay attention, and not get more hostile, when your position starts to get falsified, as is/was helpfully possible for LK99 (but not so much those others). Do not hold fast to false things.

I understand that this is difficult when the people taking the other side are being equally awful, but such is life. We need to rise above, not get dragged down, lest everything fall into the same cesspools as contemporary politics.

> really cranky with anyone who dared challenge their position.

You could profit from those people, if you are confident in your position, by shorting some of the stocks that shoot up from people's pre-judgments on this matter.

Usually not because as the saying goes: the market can stay irrational longer than you can stay solvent. Most people simply cannot afford to make those bets against the market.

Since this was an exceedingly short cycle, we were spared one of the negatives. Well, mostly:

  - some folks massively hype this as the "next big thing", extract money from investors and take mindshare away from more promising, but less exciting work

There is no shortage of subjects where exactly that is being tried.

You say it’s a short cycle now. But I bet a non-trivial number of people are still talking about this and trying to get results long after the initial cycle. It took years for cold fusion research to go away.

So what? We can still have labels for fuzzy concepts like “took the world by storm, for 2 weeks”, even if a couple thousand people are still excited about it 2 years later.

It’s the original definition of a meme.

Last time I saw this cycle with EmDrive

  - some guy created EmDrive (2001)
  - author argued for decades that EmDrive violates Newton’s Laws
  - author filled a group of patents, launched a new company "Universal Propulsion Ltd." (2016). But by this point, DOZENS of independent researchers had already proven that EmDrive doesn't create thrust.
  - NASA and DoD and a lot of smaller companies just threw money away testing something that can't even work in theory
  - "there was no fraud" (allegedly), all blamed on measurement errors
  - mainstream exposure was pure hype, it was just electromagnetic/thermal effect, the research has yielded ABSOLUTELY NOTHING new.

This is exactly right. The only difference here is that EmDrive straight up violated a law of physics, whereas high-temp superconductivity was just a matter of degree (pun intended). I was somewhat skeptical of EmDrive, but was very hopeful about LK99. Alas, it was not to be. We'll have to take the slow road to room temperature superconductors.

Can you explain how 300K is fundamentally different from 90K?

90K is 20 times above temperature of liquid helium. Is there some law of physics which says that you can go 20x the temperature of liquid helium but not 60x?

Fwiw 77K is sufficiently cold that wild N2 gas molecules with pretty weak interactions are willing to play nicely with each other and condense...

It's the relative energy scales in the system that matter. You can e.g. compare the superconducting energy gap to a temperature, for Niobium the gap is around 2.3 meV which corresponds to about 27 K. For high Tc superconductors the story is a bit more complicated but their pseudo gap is 5-8 times higher, hence around 150-200 K. Niobium has a Tc of 10 K, high Tc superconductors (unpressurized) at most 150 K. What's safe to say is that if the temperature becomes significantly higher than the energy gap the superconducting state will be lost as there's thermal tunneling out of the state and it becomes thermodynamically "unfavorable" (this simplifies things). Now there's no reason that we couldn't find a system with a larger energy gap but that gap itself is defined by other properties in the system that have constraints on their own. Fundamentally there's no reason that there couldn't be a system that fulfills all these constraints at room temperature, but there isn't a reason why there should be such a system either. Then again there might be different superconductivity mechanisms that we don't know about yet and that we could exploit, but I think it's not very likely that we'll find a regular material system with these properties because there are not that many crystal lattices to choose from and we've been looking for more than 50 years.

I think how people define superconductivity varies greatly in discussions.

Wouldn’t be the worst thing if we concentrated our efforts on proving zero resistance first. IMO, a “super conductor” should only be characterized as a material with zero resistance under certain conditions. Everything else should not be a requirement, but more like a side-effect that had been observed to go along (such as diamagnetism through Meisner effect).

Hopefully that will destigmatize future research efforts in both directions, namely towards finding zero resistance materials and those exhibiting diamagnetism.

The worst thing we can do to science is going on a witch hunt. Curiosity powers this discipline. We don’t need for encourage all crazy theories but discouraging that line of thinking entirely will lead to fewer new discoveries.

Fear driven science isn’t science at all.

Andrew is mistaken, the paper he cites doesn't say that levitation is possible in a dipole field. Brauenbecker showed that diamagnetic levitation was possible at all (e.g. in a quadrupole field), but not in a dipole field.

Stable levitation in a dipole field is still thought to be something only type II superconductors can do, and Andrew should not uncritically repeat what he read on /sci/ - which is one of the only other google results for "Brauenbecker extension" currently (after his tweet).

The best we can hope for is that there is some sort of SC properties that can be investigated further even if this is not the holy grail moment many wanted it to be.

The amount of hyped discussion here on HN based on such scant evidence was astonishing.

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