"The weak force does not seem to hold anything together, only to break it apart. ...we do not observe s of the weak force. ...So the weak force seems a force apart... Interwoven with the surprising story of the weak force has been the story of s, arguably the most intriguing of the fundamental particles. ...the neutrinos provide a unique and valuable mirror on the weak force. ...In the 1920s, and for a while disputed the energy spectrum of electrons emitted in β decay. ...Chadwick demonstrated... that the spectrum was continuous, i.e. the electron could take on a whole range of energies. ...contrary to the single line expected from energy conservation if only... the electron and the nucleus, were involved... Neils Bohr advocated abandoning energy conservation... but in 1930 Wolfgang Pauli daringly proposed an unseen... neutrino... Pauli's intuition... inspired Enrico Fermi in his 'tentative theory of β decay'... to become the basis for ideas of a universal weak force."