The evidence for it first came from a study of the isotope effect on critical temperature which created a band gap.  Developed by the use of an earlier approach meant for explaining polarons, it has been used to explain glitches or jumps in pulsar rotational periods and the 
The evidence for it first came from a study of the isotope effect on critical temperature which created a band gap.  Developed by the use of an earlier approach meant for explaining polarons, it has been used to explain glitches or jumps in pulsar rotational periods and the superfluidity of helium.  Basically stating that coupled electrons can act like bosons, this theory requires the interaction of a crystal lattice by means of a phonon interaction to pair electrons close to the Fermi level into Cooper pairs.  FTP, name this theory dealing with Type I superconductors developed and named for men named John, Leon and Robert who shared the 1972 nobel prize.
The evidence for it first came from a study of the isotope effect on critical temperature which created a band gap.  
BCS Theory or Bardeen-Cooper-Schrieffer Theory