Weak interaction

To provide a theoretical foundation for the recently observed neutrinos, Fermi suggested a new force of attraction between particles so close together that it only applied inside the nucleus. He showed that there was an interaction involved in connection with neutrinos that was like an electromagnetic interaction but much weaker. Despite being stronger than gravity, it was called "weak interaction".
 Enrico Fermi Italy 1934 Weak interaction

To provide a theoretical foundation for the recently observed neutrinos, Fermi suggested a new force of attraction between particles so close together that it only applied inside the nucleus. He showed that there was an interaction involved in connection with neutrinos that was like an electromagnetic interaction but much weaker. Despite being stronger than gravity, it was called "weak interaction".