The Summer of LK-99
In July 2023, the internet briefly believed physics had been solved. A team of South Korean researchers posted two preprint papers claiming to have synthesized a room-temperature, ambient-pressure superconductor — a material called LK-99, a modified lead-apatite structure doped with copper. The papers were thin on detail and heavy on implication. If true, LK-99 would enable lossless power transmission, magnetically levitating trains that didn’t require cryogenic cooling, and MRI machines that could operate without liquid helium.
What followed was perhaps the fastest collaborative scientific investigation in modern history. Within 72 hours, independent labs around the world were attempting to replicate the synthesis. Within two weeks, the physics community had reached a consensus: LK-99 was not a superconductor. The apparent levitation in the Korean team’s video — a small rock partially floating above a magnet — was likely ferromagnetism, not the Meissner effect. The resistivity drop was likely a metal-insulator transition in copper sulfide impurities. The superconducting quantum interference device (SQUID) data was inconclusive.
By August 2023, LK-99 was dead. But the episode revealed something important: the world is watching. A genuine room-temperature superconductor would be the most transformative materials discovery since the transistor, and the collective response to LK-99 proved how desperate the scientific community — and the public — is for that breakthrough.
What Superconductors Actually Do (and Why Room Temperature Matters)
A superconductor has two defining properties: zero electrical resistance and the expulsion of magnetic fields (the Meissner effect). Below a critical temperature, current flows without any energy loss. This is not a modest improvement over conventional conductors — it’s a qualitative difference. A copper wire carrying electricity loses 5-10% of its energy as heat. A superconducting wire loses zero.
The catch, and it’s a big one, is that conventional superconductors require extreme cooling. Niobium-titanium, the workhorse of MRI machines and particle accelerators, superconducts below 9.2 Kelvin (-264°C). The “high-temperature” cuprate superconductors discovered in 1986 operate above the boiling point of liquid nitrogen (77 Kelvin, -196°C), which sounds absurdly cold but is warm enough to make them practical for some applications. The record for confirmed superconductivity at ambient pressure is around 138 Kelvin (-135°C), held by a mercury-based cuprate.
A room-temperature superconductor — operating at 293 Kelvin (20°C) and ambient pressure — would change everything. The US Department of Energy estimates that 5-10% of all electricity generated in the United States is lost in transmission and distribution. Superconducting power lines would eliminate those losses. Superconducting magnets would shrink fusion reactors, enable compact maglev transportation, and make MRI machines orders of magnitude cheaper to operate. Superconducting electronics would eliminate heat as a limiting factor in computing. The economic impact would be measured in trillions of dollars.
What We Actually Know: The Real Room-Temperature Candidates
The confusion around “room-temperature superconductors” is largely created by the media’s conflation of two very different things: superconductivity at room temperature (which no material has demonstrated at ambient pressure) and superconductivity at high pressure (which several materials have demonstrated, sometimes at near-room temperature).
The real scientific frontier is hydride superconductors under extreme pressure. In 2020, a team led by Ranga Dias at the University of Rochester reported superconductivity at 15°C — actual room temperature — in a carbonaceous sulfur hydride. The catch: it required 267 gigapascals of pressure, roughly 75% of the pressure at the Earth’s core. Dias’s subsequent work has been controversial; several of his papers have been retracted, and his claim of room-temperature superconductivity in nitrogen-doped lutetium hydride (published in Nature in March 2023) was retracted in November 2023 following concerns about data integrity.
Meanwhile, more reliable results have come from other groups. Mikhail Eremets’s lab at the Max Planck Institute for Chemistry reported superconductivity in lanthanum hydride (LaH₁₀) at 250 Kelvin (-23°C) under 170 gigapascals. Subsequent work has pushed this to 260 Kelvin in related compounds. These are genuinely impressive results — high-temperature superconductivity at pressures achievable in diamond anvil cells — but they’re not room temperature, and they’re certainly not ambient pressure.
The theoretical understanding is advancing. First-principles calculations, pioneered by groups including those of Lilia Boeri and members of the Simons Foundation’s collaboration on the many-electron problem, predict that certain hydrogen-rich compounds should superconduct at high temperatures under pressure. The challenge is synthesizing these materials and measuring their properties with confidence — a task complicated by the fact that diamond anvil cell experiments produce tiny samples (micrometre-scale) and are notoriously difficult to reproduce.
What the Physics Community Actually Concluded About LK-99
The LK-99 episode wasn’t just a null result — it was a masterclass in how modern science self-corrects. Here’s what happened, in order:
July 22, 2023: Two preprints appear on arXiv from Sukbae Lee, Ji-Hoon Kim, and colleagues at the Quantum Energy Research Centre in Seoul.
July 25-27: A team at the Shenyang National Laboratory for Materials Science in China produces the first independent replication attempt, reporting no superconductivity. Other Chinese labs follow within days.
July 31: The University of Maryland’s Condensed Matter Theory Center publishes a theoretical analysis suggesting LK-99 could be a flat-band material with interesting electronic properties, but not a high-temperature superconductor. The Simons Foundation posts similar analysis.
August 3-7: Multiple labs report synthesis of LK-99 with no superconducting transition observed. The Korean Society of Superconductivity and Cryogenics announces the formation of a verification committee.
August 16: Nature publishes a news article titled “LK-99 isn’t a superconductor — how science sleuths solved the mystery.” The physics community moves on.
The episode wasn’t a fraud — the Korean team appears to have genuinely believed their results — but it was a lesson in the importance of replication, peer review, and the difference between a preprint and a confirmed discovery.
Where the Field Actually Stands
The search for a room-temperature, ambient-pressure superconductor continues, but the physics community is more measured than the headlines suggest. Most researchers in the field believe that the hydride route — high pressure, hydrogen-rich materials — is the most promising short-term path, but that ambient-pressure room-temperature superconductivity may require fundamentally new classes of materials that haven’t been discovered yet.
In the meantime, incremental progress continues. Researchers at the University of Tokyo demonstrated superconductivity in a nickelate material (Nd₀.₈Sr₀.₂NiO₂) in 2019, opening a new family of superconducting materials beyond the cuprates. And practical applications of high-temperature superconductors continue to advance: superconducting fault current limiters are being deployed on power grids, superconducting magnets are being tested for fusion reactors, and the global market for superconducting products is projected to reach $12 billion by 2030.
Room-temperature superconductivity is not impossible. But it’s going to take more than a viral preprint to get there.
The Applications We Can Already See
Even without room-temperature superconductivity, existing superconducting technology is quietly transforming industries. The ITER fusion reactor in France, currently under construction, uses superconducting magnets made from niobium-tin and niobium-titanium to confine plasma at 150 million degrees Celsius. The LHC at CERN would be impossible without superconducting magnets, as would most modern MRI machines — the global MRI market alone is worth over $8 billion annually. Superconducting quantum interference devices (SQUIDs) are used in magnetoencephalography to map brain activity with millimetre precision, and superconducting fault current limiters are already operational on power grids in the United States, Germany, and China.
The next generation of applications is even more ambitious: compact fusion reactors that could fit on a factory floor, superconducting transmission lines that could carry power across continents without losses, and magnetic levitation systems that could transform transportation. These applications don’t require room temperature — they work at liquid nitrogen temperatures or below, with existing materials. The room-temperature breakthrough, if it comes, would accelerate all of them. But even without it, the superconducting economy is already here, growing quietly behind the scenes, powering technologies that most people use without ever knowing what makes them possible.
The Scandal That Shook the Field
The search for room-temperature superconductivity has been complicated by genuine scientific scandal. Ranga Dias, a physicist at the University of Rochester, published a series of papers claiming high-temperature superconductivity in hydride materials under pressure. His 2020 Nature paper reporting superconductivity at 15°C in carbonaceous sulfur hydride drew international attention. His 2023 Nature paper on nitrogen-doped lutetium hydride went further, claiming near-ambient-pressure superconductivity at 21°C.
None of it held up. The 2020 paper was retracted in 2022 after co-authors raised concerns about data. The 2023 paper was retracted in November 2023 following a Nature investigation that found data irregularities. Dias was placed under investigation by the University of Rochester, and his lab’s work became a cautionary tale about the difference between a bold claim and a reproducible result. The scandal did real damage: it consumed staggering amounts of replication effort from other labs, eroded trust in an already technically demanding subfield, and gave skeptics reason to view every new claim with extra suspicion.
The sobering lesson — the one the LK-99 saga reinforced — is that extraordinary claims require extraordinary evidence, and that the modern scientific reward system, which prizes high-profile publication, sometimes works against the careful, slow, reproducible work that the search for room-temperature superconductivity actually demands.
Where the Realistic Optimism Lives
Despite the setbacks, there are legitimate reasons for measured optimism. Computational materials science has advanced to the point where researchers can screen thousands of candidate structures for superconducting properties before ever synthesizing them in a lab. Machine learning models trained on known superconductors are flagging promising new material classes. And the experimental techniques — diamond anvil cells, ultra-high-pressure synthesis, precise transport measurements — have improved enormously over the past decade.
The most likely near-term milestone isn’t a room-temperature, ambient-pressure superconductor — it’s a high-temperature superconductor at more manageable pressures, or an ambient-pressure superconductor well above the boiling point of liquid nitrogen. Either would be a major advance, enabling cheaper medical imaging, more efficient power infrastructure, and new classes of electronic devices. The dream of ambient room-temperature superconductivity remains distant, but the path toward it is clearer than it’s ever been. The field will keep grinding — because the prize is worth it.
The Applications We Can Already See
Even without room-temperature superconductivity, existing superconducting technology is quietly transforming industries. The ITER fusion reactor in France, currently under construction, uses superconducting magnets made from niobium-tin and niobium-titanium to confine plasma at 150 million degrees Celsius. The LHC at CERN would be impossible without superconducting magnets, as would most modern MRI machines — the global MRI market alone is worth over $8 billion annually. Superconducting quantum interference devices (SQUIDs) are used in magnetoencephalography to map brain activity with millimetre precision, and superconducting fault current limiters are already operational on power grids in the United States, Germany, and China.
The next generation of applications is even more ambitious: compact fusion reactors that could fit on a factory floor, superconducting transmission lines that could carry power across continents without losses, and magnetic levitation systems that could transform transportation. These applications don’t require room temperature — they work at liquid nitrogen temperatures or below, with existing materials. The room-temperature breakthrough, if it comes, would accelerate all of them. But even without it, the superconducting economy is already here, growing quietly behind the scenes, powering technologies that most people use without ever knowing what makes them possible.
