A particle Pauli invented to save physics wasn't caught in a lab for 26 years

In 1930, Wolfgang Pauli proposed an undetectable particle to explain missing energy in radioactive decay, calling it 'something no one will ever be able to detect'. In 1956, Clyde Cowan and Frederick Reines placed detectors next to a nuclear reactor and finally caught neutrinos interacting with matter, confirming Pauli's ghost particle was real.

— Clyde L. Cowan and Frederick Reines, Detection of the Free Neutrino: a Confirmation — Science, 1956