Discovery of Helium Superfluidity (1937-1938)
Pyotr Kapitza in Moscow and independently John Allen and Donald Misener in Cambridge observed that liquid helium flows without friction below the lambda point (2.2 K). Kapitza coined the term 'superfluid' by analogy with superconductors. Fritz London soon proposed the phenomenon resulted from Bose-Einstein condensation—quantum mechanics operating at visible scales.
Kapitza won the 1978 Nobel Prize (Allen and Misener were not recognized). The discovery launched low-temperature physics as a major field.
Superfluid helium became essential for cooling superconducting magnets in MRI machines, particle accelerators like the Large Hadron Collider, and scientific instruments requiring ultra-low temperatures.
Hydrogen superfluidity follows the same pattern: theoretical prediction, decades-long experimental challenge, eventual confirmation using innovative techniques. Both discoveries required extreme cold and opened doors to practical applications no one initially imagined.