Superconductivity can occur only within a few degrees of absolute zero.

Superconductivity was discovered in 1911 in mercury cooled to only a few kelvin above absolute zero. For decades, every known superconductor required similarly extreme cryogenic conditions.

That history encouraged the expectation that superconductivity was inherently confined to the liquid-helium temperature range.

In 1986, Georg Bednorz and K. Alex Müller reported superconductivity in a ceramic copper oxide at a dramatically higher transition temperature. Other cuprates followed almost immediately, including materials that remained superconducting above 77 kelvin, the boiling point of liquid nitrogen.

That threshold mattered practically because liquid nitrogen is far cheaper and easier to handle than liquid helium.

“High-temperature” is relative. Even 77 kelvin is about −196 °C, nowhere near ordinary room conditions.

Later unconventional superconductors expanded the range further, but claims of near-room-temperature superconductivity—especially under high pressure—require exceptionally strong replication. No ambient-pressure room-temperature superconductor is established.

The overturned claim is therefore not that superconductivity has become warm. It is that it is restricted to within only a few degrees of absolute zero.