Superconductors only work within a few degrees of absolute zero

What actually happened

The barrier was practical, not conceptual. Liquid helium is expensive, scarce, and difficult; liquid nitrogen costs less than milk. Anything superconducting above 77 K becomes an engineering material rather than a curiosity.

Georg Bednorz and Alex Müller found superconductivity at 35 K in a copper oxide ceramic in 1986, which was startling both because it beat the record and because ceramics are usually insulators. They received the Nobel Prize in 1987, an unusually fast turnaround. Within months, other groups pushed past the nitrogen threshold with YBCO at about 93 K, and the field erupted; a session at the 1987 American Physical Society meeting ran until dawn and became known as the Woodstock of physics. Two honest notes: nobody has a complete theory of why the cuprates work, and claims of room-temperature superconductivity keep appearing and keep being retracted, most recently in 2023. Room temperature is still ahead of us. Liquid nitrogen is not.