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Jul 27, 2023

LK

A physicist explains LK-99 and the appeal of “unidentified superconducting objects.”

This has been a landmark summer in the world of “floaty rock drama.” Two weeks ago, in a pair of draft papers that have not been peer-reviewed, scientists in South Korea claimed to have found a room-temperature ambient-pressure superconductor, and described how to make it. In theory, this magical material could revolutionize our world. It also levitates. The purported discovery became an internet sensation. Researchers and DIY enthusiasts alike rushed to replicate; stocks soared; the internet gossiped. But physicists urged caution: Previous claims of room-temperature superconductors haven’t panned out. So far, attempts at replication have come up short. The whole thing turned into a very nerdy social-media circus.

If you, like me, have been living under a rock (and not the floaty kind), you may not understand the significance of what’s being claimed here. Basically, a superconductor is a type of material with a special property: Electric current passes through it with zero resistance, meaning no energy gets lost along the way. This is a hugely valuable trait because resistance is the cause of considerable waste as electricity makes its journey through wires from power plants to electronics.

Superconductors are already in play today in particular fields—hospital MRI machines use them, for instance—but these superconductors need to be kept at extremely cold temperatures. The big claim behind the newly announced material—a mixture of lead, oxygen, phosphorus, and copper dubbed LK-99—is that it carries electricity with no resistance at room temperature. Such a material would be a scientific marvel that could completely reshape infrastructure and save untold amounts of energy. Due to an interplay of magnetic forces, superconductors also can levitate. Here, too, are some rather amazing, albeit theoretical, applications: What if, instead of running on tracks, trains floated?

The scientific claims being made are extraordinary—and facing a lot of doubt and controversy. So where does that leave the general public and our understanding of physics, not to mention of floaty rocks? I caught up with Douglas Natelson, a professor of physics and astronomy at Rice University, to discuss the pros and cons of physics going viral, his analysis of the new papers, and whether we are doomed to more floaty-rock drama in the future.

Our conversation has been condensed and edited for clarity.

Caroline Mimbs Nyce: I’m really interested in the bigger themes here: Is this a science story or really a technology story? Is it both?

Douglas Natelson: Condensed-matter physics—the physics of materials—is the branch of physics that actually impacts your everyday life more than pretty much anything else in the entire discipline of physics. And I think it gets short shrift compared to black holes and particle physics and so on. So in some sense, it’s very nice to see so much excitement about this branch in the field because condensed matter really does explain all the technology of why you and I are able to talk on the phone across the country. In a broader picture, it explains why you’re not falling through the floor right now, and why solids are solid, and things like how water boils and how magnets work. It really underpins pretty much everything around you.

Nyce: What is actually going on this week?

Natelson: Superconductors pass electrical currents—a DC current—with no resistance. The wires in your toaster glow because there’s current flowing through them and they have resistance, so they act like a heater. If you have a superconductor, the resistance is zero. It’s not just small—it is zero. Superconductivity was discovered 112 years ago at very, very low temperatures. It would be very exciting if you could get materials that did this at room temperature. Room-temperature superconductors, with the right kind of other properties, would be very useful for electronics, power generation, motors—all kinds of technologies. These materials also completely exclude magnetic field. They can levitate when placed close to a magnet. The technology people have talked about is magnetic levitation for trains, for example, where you could have a train that floats above the rails instead of actually rolling on the wheels on the rails.

So a couple of preprints showed up from some folks in South Korea, and the titles were somewhat attention-getting. They claim to have discovered a room-temperature ambient-pressure superconductor. One thing that distinguished this from some other past claims is that these folks actually did put in a pretty clear recipe of what they did in terms of making the material. So they said, We took these starting materials and baked them this way and ground them up and did this other stuff. And they pretty much gave us a step-by-step recipe for what they said they did. It’s very good that they actually published a recipe; you could imagine someone being secretive.

A bunch of people have sprung into action, including some amateurs on the internet. I think we will know something a lot more definitive relatively quickly. It takes a few days just to pull off what the recipe says. If you want to do it really carefully, it takes a bit longer than that. The figures, the graphs, the data in the papers, they look interesting. But the more you look at them, the more you realize there are some problems. There’s a bunch of odd things in the papers—which is exactly why other people need to check this stuff out.

There have been claims of exotic superconductivity before. They happen often enough that they have a nickname: unidentified superconducting objects. So why has this one gotten so much attention? I think Twitter—or X, or whatever we’re calling it—is an enormous amplifier. Before all of the social-media stuff, this went on in the background in sort of an ordinary science mode, and the public just wasn’t aware of it. And now with social media, if someone notices it, they can basically have a megaphone that talks to several million people.

Nyce: How do you feel about that dynamic?

Natelson: There are pluses and minuses. The speed with which information travels is great. I do think the problem is that people without expertise can’t tell the difference between stuff that should be paid attention to and stuff that should not be taken seriously. And it’s not great when things that are half-baked end up getting strongly amplified. I get nervous that people who know nothing about high-temperature solid-state-materials synthesis are trying to cook this stuff up on their stove. I’m just worried you could hurt yourself.

Nyce: “Don’t do it.” Is that your official recommendation?

Natelson: My official recommendation is “Don’t try this at home,” yeah.

Nyce: It sounds to me like you’re not terribly optimistic about this new discovery panning out.

Natelson: I think everyone should have the right level of skepticism. We’ll know a lot more when a bunch of other people make this stuff and do a bunch of careful measurements on it. One thing to point out is no one has actually shown true levitation where this thing is really not in contact with a surface. You see all these things tilting, which is interesting, but it’s not really floating.

Nyce: You mentioned that there have been hype cycles before—other “unidentified superconducting objects.”

Natelson: Hype cycle isn’t quite the right term. There have been other reports of room-temperature superconductivity before. And then in the classic pattern of these things, it’s never really reproduced. So far, they just haven’t panned out.

Nyce: Do you think we’re doomed to repeat this pattern?

Natelson: I’m not sure I’d use that phrase. The end point of having such a material is so tantalizing, right? It would be very, very cool if we could really use it at room temperature. That’s so exciting that there’s always going to be people looking for it. If you assume that every now and then people make mistakes, then I suppose at some rate you’re always going to get inaccurate claims. But there’s no rule that says that the physics of superconductivity can’t happen at room temperature. And so that’s why it’s so exciting.

Nyce: Should we feel jaded if the new discovery does not turn out to be the magical superconductor we’re hoping for? Or should we stay optimistic?

Natelson: I’ll turn it around and ask you a question: There are many, many drugs that have been proposed as potential cures for cancer. A lot of them end up just not working. Lots of drugs initially look pretty exciting, and then they don’t have the efficacy we thought they did. Are we jaded about that?

You need the attempt cycle. You need people to be trying these things for progress to happen. Not everything achieves the end goal you want necessarily, but you always learn something.

Nyce: What did we learn this time?

Natelson: I think it’s a little early to say what we’ve learned.

Nyce: Fair.

Natelson: I do wish that people would keep their powder dry a little bit. I wish the people who don’t have expertise would not necessarily make loud, declarative statements. If you look at the scientists on Twitter and other places, people are saying cautionary things, like “It’s interesting, but don’t jump to conclusions yet. We need to be careful and check this.” The media coverage I’ve seen seems to be appropriately measured.

It’s great that people are excited about materials. It’s easy to go through life and not ever really give it a second thought how amazing materials around us are. The fact that we actually really understand an awful lot about the properties of materials is a great intellectual achievement of humankind. I hope people have a little bit more of an appreciation for that after all this.

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