What happened with the room-temperature superconductor claims, and where does the science stand?

The answer

In July 2023, South Korean researchers led by Sukbae Lee and Ji-Hoon Kim published preprints claiming LK-99, a copper-doped lead apatite, was a room-temperature, ambient-pressure superconductor - which would be one of the most important discoveries in physics history. The announcement sparked a global race to replicate the results. Within weeks, dozens of labs worldwide attempted reproduction. By August 2023, the consensus was definitive: LK-99 was not a superconductor. Studies from institutions including Argonne National Laboratory and the Max Planck Institute showed the observed resistance drop was caused by a copper sulfide impurity (Cu₂S) undergoing a phase transition. The legitimate quest continues; in 2024, researchers at the University of Rochester faced retraction of their nitrogen-doped lutetium hydride claims, further highlighting the field's challenges.